Greetings to all ship modelers.

I was in the process of checking the bulkheads.
Everything seems fine, except for one small detail I overlooked.
I had projected the bulkheads, the keel, and the decks onto a 2D plane for cutting.

Since I had the chance to meet in person with a friend—who lives about an hour and a half away—who can perform laser cutting for me, I sped up the process to get some 2D files ready and identify any issues that needed resolving.

The software he uses for laser cutting is RDWorks.
I had read that while this program uses its own proprietary file format, it can also handle .DXF and .AI files.
When we met, I provided him with the files in both .DXF and .AI formats, exported directly from Rhino.
He couldn't open the .DXF file, but the .AI file worked. After making a few adjustments, we ran a test cut for bulkhead no. 19.
It came out, but it was much too small. Furthermore, the laser cut removed about 0.3–0.5 mm of material along the edge.
I’m not sure why the bulkhead was cut to such a small size.
A quick search suggests that the .AI format uses pixels as a unit of measurement, whereas Rhino uses millimeters; essentially, there was an issue with how the file was interpreted.

Since we were short on time, I took a copy of the RDWorks software (.exe file) to install at home and study.
I wanted to figure out how to set the correct dimensions for .AI files or how to get the .DXF files to open.
As it turns out, I managed to successfully import the .DXF file, so I’ve abandoned the .AI format. Other issues that needed resolving included the failure to display the frame numbers (which were visible in Rhino but invisible in RDWorks) and the need to distinguish between cutting layers and engraving-only layers.
Ultimately, after doing some research online, I managed to resolve both problems.

I am now proceeding along two paths.
One involves preparing PDF formats (on A4 and A3 sheets) so that the frames can be printed on paper—to be glued onto the wood—for manual cutting with a fretsaw.
The other involves preparing .DXF files for laser cutting.


The second image is a screenshot of the program RDWorks.

Does anyone know it or have you ever used it?

In my previous message (third and fourth paragraphs), I mentioned that I do not intend—at least for now—to use the 3D hull design to attempt a 3D print.

However, noting that there are many modelers on this forum who are highly skilled with 3D printers—such as Fishercat, ColRay, Simplesailor, PeterN, Olly999, Tim Morland, BobbyN, EdW etc. (apologies to any other ship modelers I may have missed who use or have used 3D printers)—I would like to make the design available to the friends here.

To make it usable, I will need to process the file a bit first; I will only do this if there is interest, as it is time-consuming.

Here is how I plan to process it:
First, it will be saved/converted into a format compatible with 3D printing software—which shouldn't be an issue, as I’ve done this before.

Also, as I mentioned, since it is a very long hull, I can scale it down to whatever size you prefer.
However, be aware that while scaling it down might allow for a single-piece print, the resulting model would be too small to convert into an RC vessel.
The alternative is to split it into three or four sections to be joined together.
To do this, I would need to modify the design to incorporate specific joining points.
Even with these joints, however, they wouldn't be enough on their own; applying resin to the hull shell would be mandatory.

If you would prefer something simpler, I can send you the lifeboats from my gunboat.

N.B. *The hull has not yet been built, so it remains an unknown quantity even to me.
Once I finish building it (using wood, metal, and traditional modeling materials), I’ll be able to tell you whether the design was truly successful. If the outcome is positive, the offer (which is, of course, completely free) will still stand, though—honestly—it might take me quite a while.
That is why anyone willing to take a chance and experiment right away will be accommodated.*

Good evening to all ship modelers, and specifically to those interested in planing hulls.

Before copying the drawings onto a 2D plane (I’ll dedicate specific layers to them so I can create lighter, standalone files while deleting the rest of the project, which will be saved under a different name), I am double-checking the keel, the frames, and the decks.

As you may have gathered from previous posts, although I created the hull—arriving, after several attempts and adjustments, at a shape that pleased and convinced me—I won't be using that 3D model directly.
Instead, using horizontal and vertical cutting planes on that 3D hull, I generated the keel, decks, and frames.

The construction method will therefore not rely on 3D printing the hull (which would be very difficult given the size—it would have to be done in sections that are hard to join); rather, it will be based on a classic skeleton (consisting of the keel, frames, and decks) over which the hull will be built by hand using either planks or strips (though I believe strips will be required).


So, the verification process involved checking the interlocking joints and the fit between the frames and the keel, between the frames and the decks, and between the decks and the keel.

Furthermore, since I might use laser cutting, I wanted to incorporate features that would make manual construction easier.
I’ll likely create two separate guides for two different approaches: one for manual cutting and one for laser cutting.

What do I mean by features to make things easier?
As you can see in the images, following the frames, you’ll notice the keel shown in red from a side view.
The keel is quite deep—likely deeper than strictly necessary—but this ensures more secure joints with the frames and greater structural rigidity for the skeleton. To position the motor, battery, and servo low down, it will be necessary to cut out significant sections of this keel.
This can only be done after the hull has been built and thoroughly reinforced.
Once the hull is assembled, removing the wood will be difficult, which is why I want to create the cutouts beforehand.
However, these cuts must not compromise the keel's structural integrity.

In the images, you can see the cutouts for the battery (white rectangular block), the motor (large reddish-brown cylinder), the propeller shaft and tube (same color as the motor), the servo (green), and the rudder shaft.
There will also be cutouts to join the keel if it is constructed in two parts.

The cutouts will be replicated on the reinforcement pieces.

The circles you see are intended to help align the keel with its side reinforcements.

If you look closely, you'll also notice cutouts for the electric motor and battery on some of the bulkheads.

After completing the checks—and before proceeding to create 2D copies—I am making alignment and verification components.

...perhaps the video makes certain things clearer than a single image can convey.

@ChrisF
Thanks Chris, I still have a lot of doubts about its success, but I'm very happy that you're following the developments.
If it fails, never mind, I'll have gained experience.

Progressing nicely Alessandro. The hull design will look very nice once built.

Chris

Good evening, everyone.

I’ve made some progress: I’ve redefined the keel (shown in red) and verified the interlocking joints with the bulkheads.
I’ve created pre-cuts in the keel for the motor, the propeller shaft, and the battery.
These cuts cannot go all the way through; otherwise, the keel would be fragmented and rendered useless.
They are partial cuts designed to facilitate the subsequent removal of wood and the drilling required (to make room for the motor, propeller shaft, and battery) once the hull is complete and reinforced with resin.
Anticipating the use of laser cutting, I split the keel into two sections, as the available laser-cutting machine handles boards with a maximum length of 65 cm.
I therefore designed a simple interlocking joint (I had initially considered a dovetail joint, but that would have taken too long) to join and glue the two pieces together.
Since a two-piece keel isn't ideal, I decided to add two side reinforcements (shown in black in the drawings). These reinforcements also feature pre-cuts to accommodate the battery and motor.
The circles you see are for aligning the reinforcements with the keel prior to gluing them together.

Adding these two elements meant I had to reshape the bulkhead joints to account for the new connections.

Bulkheads 13, 14, and 15 feature pre-cuts for the battery compartment.

I’ve also completed the joints between the lower deck and the aft bulkheads; the joints between the upper deck and the forward bulkheads still need to be done. I have inserted a former behind number 16 (designated "16 Post") because I plan to move the rudder servo compartment further back. In that case, I would keep the "16 Post" former and could dispense with former 16 itself.

Once all checks on the 3D design are complete, I will move on to the second phase: copying the parts to be cut into 2D—specifically the keel, the two side reinforcements, the formers, the two decks, and the horizontal bow supports.

@DJW
Very impresing planking job.
It's marvelous.

@AlessandroSPQR Hi Alessandro, you're very kind..! I think we all learn from others on here, I certainly do. If I can contribute too, I'm happy to share my experiences. I used double planking on my two Riva builds, to be honest initially because they came as part of the Amati kit for the 1/10th. I built the 1/5th using same plans and techniques. But yes this did allow me to produce more organic shapes, and blending between these shapes for different sections of the hull. I did use sheet ply for the stern planing section of the 1/5th as its a flatter area, then mahogany planking as the top layer. I also thinned and shaped the planks to get the shapes nearer the chines. And used a gooseneck scraper to help form the curves. I use scrapers a lot with planking to remove high spots, then sanding and so on. I must add, I did have a chine rail to give me the chine line, but its on the inside of the hull after planking over it, also providing strength. Hope that makes sense.

Final observation.. re Strakes, apart form providing lift and strength, I think they also have a purpose on full size boats to improve ride in higher sea states by breaking up solid waves a little before they impact the entire exposed hull and starting the lift before the full wave impact.

Just as another observation on chine rails here is a comparison between my Huntress and River Cruiser builds. The Huntress is a sports cruiser, designed for planing and has chine rails and strakes. The River Cruiser was a one-off prototype by Fairey for a river/lake cruiser and they used the Huntress hull as a basis. They increased the freeboard to provide more headroom and space within the hull but otherwise was unchanged.

It only had a low power engine so wasn't very fast (though it would have planed with a bigger motor!) and so didn't need strakes or even chine rails but it was fitted with the latter - spray wouldn't be much of a problem (though having said that, in my photo on the water they are deflecting water!) so I think they were fitted mainly for aesthetics and to lessen the impact of the high slab sides - the full-size boat has darker paint (I'm assuming dark blue) to the hull sides and just above the chine rails and a band below the rubbing strips to visually reduce the height - I've yet to do this on mine.

Whilst mine only has a small motor it is brushless though and I'm sure it would plane! I did resist at the lake trials!

@AlessandroSPQR I was hoping that David would reply with details of his reverse chines on his lovely builds.

Yes, chine rails are pretty easy to glue in place, especially as you have fitted rubbing strips on your previous builds, a very similar process. Sprakes are one of those parts of the build I wasn't looking forward to, but like other things weren't as bad as I thought they were going to be when I actually did them. My method is a combination of eye and precision. First you have to decide on how many - the full-size boat may have four per side for instance but on a smaller model that might be too many (unless you are truly building to scale) and look too fussy and close together so three might be better. Then you have to decide on positioning - the Huntsman 31 shown has quite a curve to the chine and so I positioned the strake adjacent to it so it looked right and then divided the distance between it and the keel equally for the others and marked their position with pencil lines - the curves at the bow were then done by eye and pencil marks put under them with measurements taken to ensure that they were as symmetrical as possible to each side of the hull. The layout of the strakes can vary on full-sized boats and even on the same design of boat as some of the Faireys have different layouts on the same hull design. Fitting the strakes to the Huntress was easier as they were parallel even at the bow and ran straight.

As has been said previously strakes are less important than chine rails and with questionable effectiveness on models - they can add to the aesthetics though. They can always be added afterwards. What would be interesting is if you tried the model after water-proofing the hull with resin to see how it performs - if fine, you could leave it, but if not (unlikely) you could then fit them and see if it does make a noticeable difference!

To help with your decision it should be noted that Riva Aquaramas, both full-size and as per David's models do not have strakes - I don't think the owners have to worry about borderline power or fuel consumption! 😄

@DJW
Thank you very much for your most welcome contribution, David.
I read your message with interest and admiration.
Compared to you and Chris, I feel like a dwarf when it comes to planing hulls.

One thing is certain: I can seek out all possible information and gather advice from the best to anticipate all sorts of issues, but I cannot bridge the experience gap overnight. I will inevitably make some mistakes, but I’m already enjoying the attempt.

I noticed that you built the hull using strips (classic planking, like that used for scale models of displacement hulls). The result is excellent; I imagine that choice was dictated by the very tricky and constantly changing curves typical of this hull shape?

@ChrisF
Hi Chris (in reply to post 107).
I think installing the chain rails after completing the hull is a fairly easy task, and I’ll go ahead and do it, given their function and the advantages you pointed out.
On the other hand, I find installing the "strakes" (which I’d ​​like to avoid if possible) a bit complicated. It’s not the gluing itself that’s hard, but getting them positioned correctly seems very difficult to me.
How do you manage to position them so perfectly (with the right alignment, angle, and equal spacing between them)? Is it just a matter of eye and experience, or do you have a precise method?

@ChrisF
Thanks a lot, Chris; you replied even without the photo (sorry, I had forgotten to attach it, but I’ve done so now).
Thanks to you and the other experts on motorboats and planing hulls, many aspects and terms are much clearer to me now.
Based on what I’ve learned from you, I’ve decided to continue the design without including "chine rails" for the time being; however, I will add them during the construction phase—after the hull is finished but before painting.
As for the "strakes," I’m not sure about including them; I might add them later on if they prove to be absolutely necessary.

My contribution to the chine chat. Before building my Amati Riva Aquarama I looked at plenty of 1/10th Aquarama builds on YouTube and was concerned that the Amati design put too much weight forward. It's designed primarily as a static kit so can't really criticize, but for RC use it needed to generate more lift forward and deflect water away. Water had a tendency to go round the 'chine' and up the hull side, ploughing through the water, maybe that's a (water) scaling issue as the full size boats cope just fine.

So I Took a few steps, building the bow as light as possible, use belt drives to keep the shaft angle low so the stern is not pushed up... And I modified the chines, the pics are of my 1/5th, I did same to 1/10th and it's working well on both boats. As Chris mentioned, I tried to integrate and blend the mod into the hull shape rather than add a chine rail, I made the V of the hull very slightly deeper at the forward third of the hull, and created a curved top end to join back to the original chine line, so visually when the boats are on the water, they look correct. Hopefully the pics show the mod, in particular on the line drawing you can see the original feint line of the hull, with my modified bolder line.

Technically I think this creates a 'reverse chine' where the resultant scoop shape forces water back down, rather than up or sideways. So as the boat moves forward, more lift is generated, in the case of the Riva that's only up at the bow. Another possibly significant point in the general chat about chines, I left the chine as per design further aft as extra lift there would actually be counter productive as it would lift the stern and so push the bow down... Anyway, I'm pleased with the result on both builds, they clear water away well, they come back dry on the inside, and they rise onto the plane in a suitable manner..!

Photo of the stern of a Huntsman 28 which shows the shape of the strakes I was talking about. Not very clear but you can see one a little way in from the side/chine rail. On full size they change shape and get smaller as they approach the bow but not practicable on a small model so I use smaller section ones that look acceptable at the bow. I've used small square section with the corners rounded off on my Huntsman 28 and on my others triangular section.

Found this which is useful but loads of other information available.

https://atlasboatworks.com/hull-strakes-an-introduction/

@AlessandroSPQR Hi, the others are called strakes. On full-sized boats where increasing power of the engines is expensive and uses more fuel they are primarily used to provide lift and help the boat get up onto the plane. Towards the bow they help with deflecting spray and so are also called spray rails though sprakes is the correct term.

However for model boats, certainly using brushless motors, power isn't a problem and they will plane easily and therefore aren't essential. Note that my Club 500 doesn't have any, performs well and is used for racing. My other plastic models do have strakes though, but only two per side given the small size of the models.

It is thought though that they might help with stopping the hull sliding sideways when turning. But more on this later.

The other thing is that many full-sized boats have sprakes and if building a near scale model like I do with my Faireys they need to be fitted. Also as Bob/Zooma says they improve the look of the hull and I will be fitting them to my future non- Fairey planing models.

As regards the hull sliding sideways, this is probably correct as in models they are usually the wrong shape! They are often an inverted triangle with the apex pointing downwards, whereas with full-size they have a flat side facing downwards. I'll post a photo of this tomorrow.

I agree with Fishercat that with most models sprakes offer minimal performance enhancement and I'll add chine rails/reverse chines to that as long as there is a sharpish corner, rather than rounded, between the side and bottom hull skins.

Chine rails/reverse chines are I would say essential though, as I said before, to reduce spray being thrown up onto the deck. I've even seen one model with chine rails that ran from the bow and about a third of the way back along the hull, looked a bit odd though!

@ChrisF
Thanks a lot, Chris; the difference between the terms "reverse chines" and "chine rails" is perfectly clear to me now.
I never would have figured it out without that first image you posted—great drawing.
I was completely off track; I thought the difference was between the chines along the sides and the ones under the hull.

At this point, I have another question for you. I understand that the chine indicated by the red arrows in the photo I reposted is called a "chine rail." Okay, but what do you call the chines (longitudinal ridges under the hull) indicated by the black arrows?

@AlessandroSPQR Drawing showing the difference between reverse chines and chine rails. As I mentioned before, reverse chines are usually used where the hull is made from fibreglass for example, which can be moulded to shape. All my plastic, ready to run models have reverse chines - photo shows those on my Club 500 - they aren't sharp on the outside corner but they do angle down to provide stability.

David (DJW) has incorporated reverse chines in his Riva builds, though he has planked his hulls which I think makes forming the chines a bit easier. I think it is going to be tricky for a hull skinned in thin ply sheets.

Another photo shows my Huntress hull where the chine rails are glued on and follow the chine or angle between the side and bottom skins.

@ChrisF
Thanks a lot, Chris—no rush at all, don't worry.

@AlessandroSPQR Yeah, protrusions on the frames to form the chines wouldn't be a good idea.

The term reverse chines isn't really very good as it conjures up something different to chine rails which infact do the same job, which is why I called them integrated in an earlier post as they are formed during the manufacture of the hull rather than being fitted afterwards. My photos earlier on show the two types.

I'm back home tomorrow so will show you my drawing for the proposed reverse/integrated chine on the Swordsman 37.

Trouble is my build blogs don't show the full build process as I started them off on another forum. I'll add some relevant photos.

@ChrisF
Thanks a lot, Chris, for this precise and incredibly useful information.
Based on what you’ve written, I think I’ll proceed as follows for now: I’ll build the hull following the original design—keeping it smooth and without protrusions (the alternative would have been to plan for projections on the frames right from the start, but that doesn't seem like a good idea to me).
Once the hull is finished, I’ll try to construct the chines by following the instructions that experienced modelers in this field—like yourself—might be willing to share with me.
I really need to save the photos of your builds from the early stages.
I came across them a while back but always struggle to find them again; if you could share a few links, I’d really appreciate it.


P.S. What exactly do you mean by "reverse chines," and how do they differ from "chines"?

@ChrisF yes. If I recall correctly, sharp chines on a planing hull make the hull more stable at speed. Sharp strakes or chines on the underside also help. Anything will plane, given enough power - and there is a small advantage in efficiency as well with sharp chines, however I doubt it would be measurable on a scale model not used for racing.

@AlessandroSPQR I was told years ago that chines with a sharp outside corner were pretty much essential on planing hulls. I haven't questioned this as all my planing Fairey models and my future builds have chine rails. These are usually square section and glued onto the hull following the line of the chine, so quite easy to do. The top corner can be rounded off and they can be made slimmer towards the bow.

The Swordsman 37 I'm doing for Zooma has reverse chines with the full-size boat being fibreglass. I've come up with a way of producing those on a timber hull but will be seeing what he thinks.

Anyway I thought I'd Google to see if chines were essential and the answer was no and also that rounded chine hulls can plane but that is not surprising, especially in a straight line.

But as I said, chines do help with turning and Google also says that they help with breaking the water cleanly away from the hull and stability.

But chines have another important role, certainly in the bow area, and that is acting as spray rails and keeping the deck and superstucture drier. Without them water goes up the hull sides, hits the rubbing strips and is then sprayed over the deck and superstructure making for a wet riding boat.

I think chines have less of an effect on models than full-size (apart from the reduction of spray) due to the greater power to weight ratio of models and the fact that water doesn't scale.

So I will be interested to see what your research produces and what your conclusions are for your design.

Chris

@ChrisF
Hi Chris, thanks a lot for the reply.

Let me clarify a few things to avoid any misunderstanding. I’m not a laser-cutting expert. I don’t own a laser cutter (I wish I did). Mike Stoney is the expert here.
I’ve used friends' laser cutters and I’m somewhat familiar with the requirements (though they vary from machine to machine)—that’s about it.
If plans don't change, I’d like to have the keel, decks, and just a few of the bulkheads laser-cut, while I cut the remaining bulkheads myself using an electric scroll saw.

How do you go about installing these chines?
Is it best to plan for them during the design phase, or are they added later during actual construction?
I’ve installed wales and rubbing strakes on displacement hulls before, but these chines seem trickier to create and position.

If you tell me they’re essential for stability when turning, then I’ll have to start looking into them.

Got back late last night after seeing our 3 month old grandson again.

I didn't know how much you knew about laser cutting but you have obviously got that covered.

Looking at your drawings again I think I misread them. I thought the outside edge with the rounded corners was the outside of the frame but can see now that it is the inside of the frame, so ignore my comments!

As for chines. Chine rails are often used on older timber hulled planing boats like Faireys. A piece of timber is applied to the hull following the line of the chine and for aesthetics is usually slimmer as it approaches the bow. The bottom corner needs to have a sharp edge where in the water, at the bow it can be rounded for looks. Integrated or reverse chines are usually used on fibreglass and aluminium etc. hulls where the hull is moulded or formed (unless it is something like a timber Riva!) and the chine can be more easily formed and be more attractive.

@ChrisF
Hi Chris, thanks for your input and valuable advice—I was really counting on it.

I’ve used a hand-held fret saw (an incredibly laborious task), an electric scroll saw (though it wasn't mine), and laser cutting (provided by two different people).
Laser cutting is precise and clean when done correctly; for parts with many recesses for interlocking joints—like the keel I’m currently building—it’s the best method.
You’re right about tapering the frames, but with laser cutting, I have a guide line etched in (just a reference mark on the opposite face of the frame); this helps me determine exactly how much material needs to be removed for the taper.

We’re in agreement regarding the deck. I don’t think there are any other solutions.

You wrote:
"""""I see that you have round chines? It will plane fine in a straight line but when turning it will slide sideways, though strakes will help to some extent. Planning hulls usually have a chine rail or integrated chine which digs in when cornering. Could be an interesting test though!""""
Which edges are you referring to? Could you point them out with an arrow?
Could you show me—using images or drawings—the solution you use? Specifically, what do you mean by "chine rail" or "integrated chine"?

Evening Alessandro. Good to see you back on this project. I have the same problem when leaving things, especially when it was over 12 months in one case! It took me a long time to get my head round it again and you also question why you did things in a particular way!

Couple of observations if you don't mind me saying. No need for laser cutting. This is a fairly recent introduction into model boat building and the vast majority have been built by cutting out by hand or scroll saw/band saw and accuracy is attained by cutting close to the lines and finishing off with sandpaper - that's how I've done all my builds. Fine if you already have one or know someone with one but unless you buy one and use for a number of builds is it worth it? Paying someone to do it is another option but with a prototype build there is always the risk of the parts not being the right size and having to be recut. And even if laser cut you still need to sand an angle on the edges of the frames forming the bow and other changes of direction. Scroll saws are great for cutting out!

The rear deck shouldn't be a problem if you make it in two pieces cut from front to back? Fit one half and then the other?

I see that you have round chines? It will plane fine in a straight line but when turning it will slide sideways, though strakes will help to some extent. Planning hulls usually have a chine rail or integrated chine which digs in when cornering. Could be an interesting test though!

Chris

Good evening everyone; I’m trying to pick up the thread again.
It is quite difficult to remember exactly where I left off, what problems needed solving, and what decisions had been made.

I got a bit carried away; what started as a very simple project gradually became more complex.
Initially, I wanted to create a very simple—almost basic—hull, spending just one day on the design so I could immediately cut out the parts using my Proxxon scroll saw (which I still haven't used yet).
I wanted a hull with very simple lines that could be built quickly, allowing me to run experiments and tests.
However, as often happens with me, I kept making modifications along the way, searching for the aesthetic shape that appealed to me most.
Now, given how the project has evolved, laser cutting would be needed to accurately cut out the decks and the keel.

I am working on the interlocking system (decks, keel, and bulkheads).
Experienced hull builders wouldn't need to use so many bulkheads and horizontal guides at the bow, but I am trying to devise a construction method that works even for someone who doesn't know how to shape a piece of balsa wood for the bow section.

There are two decks. The rear deck—which sits lower—cannot be fitted onto the bulkheads because of the shape of the stern bulkheads, which taper inwards at the top.
The only solution is to split it lengthwise into two pieces.

@ChrisF


Hi Chris.

You wrote """"""If you don't have a protruding keel usual practice is to have it inside the hull and slot the frames over it. But if you have come up with an alternative solution, then great."""""""""""

In fact, that's exactly what I had in mind.
I'll have some difficulties at the bow and between the stem and the keel.
I could create pieces (keel and frames) that leave a lot to the builder's skill, but I prefer to create a project that's as easy as possible for anyone to build.

You wrote: """"""Have you decided on how you are going to skin your hull? The reason I ask is that hard chine hulls are usually fairly simple compared to round hulls, including warships and yachts, and you don't need many frames. Most of my builds only have between 5 and 7 frames, as apart from the bow there isn't a dramatic change in shape as you travel down the hull. All my hard chine hulls are ply skinned, with, in some cases, balsa blocks to form the bow, as the ply doesn't like being bent in two directions.""""""""""

You've hit another key point. I hope to build the hull with plywood and use just a few sheets, rather than resorting to a lot of strips.
I chose to place many of the frames in front, but during the construction phase I could do without some.
After the prototype, I'll be able to determine if many frames were superfluous and mark them as such, so other builders can choose whether to cut them out and use them or not.

Indeed, even though it's a planing hull, the shape has curves in many places, and the linearity is complex. A strip covering may be necessary.
At this stage, it's very difficult to say.

""""""""I've now got my Huntsman 31 ready for lake trials, including with the motor I recommended for you, so it will be interesting to see how it performs. It will be a few weeks away though, as I will be away soon."""""

It will be a very interesting test for both you and me.

@DWBrinkman
Hi dave, I'm making this little digression because you invited me to.
You're a globetrotter, and I greatly envy and admire your travel spirit.

Calabria has a very beautiful sea.
You've surely seen the Coast of the Gods (Tyrrhenian Sea) online, with Tropea and Capo Vaticano; then the Riviera dei Cedri (Tyrrhenian Sea), located in the northern part of Cosenza, home to the extraordinary Arcomagno Beach in San Nicola Arcella, and Praia a Mare, famous for its impressive sea caves (such as the Blue Grotto and the Lion's Grotto); but also the Costa dei Saraceni and the Grecanica Area (Ionian Sea). On the Ionian side, Le Castella (Capo Rizzuto Island) stands out, characterized by a striking Aragonese fortress located on an islet connected to the mainland by a thin isthmus of sand.

I can confirm that these are indeed the most evocative places in Calabria. Bear in mind that I prefer rocky coastlines alternating with coves and small inlets, arches and caves, rather than immense, long, straight beaches.

My son and I, with whom I still love long swims (no longer offshore but parallel to the coast) and returning either by swimming or walking if we're too tired, were making some considerations, comparing summer vacations in other countries. Indeed, in Italy, we're fortunate to have a sea that's warm for many months of the year. Despite the wealth of interesting wildlife, there are no dangerous animals, and there are no typhoons or other extreme weather events.

However, even though Calabria offers excellent places for swimming and a beach holiday, the best in my opinion is Sardinia.
Then there are countless other places that are truly unique and beautiful.
There are breathtaking cliffs and caves in Puglia, Campania, Sicily, Tuscany, and Liguria. For those who love long beaches, all of Italy is fine.
All the archipelagos and smaller islands are exceptional, but that goes without saying. The sea on the islands is increasingly cleaner.

Coral reefs, which are unique natural spectacles, are certainly missing, but throughout the Mediterranean, it's well known that the conditions aren't right (too many rivers and temperatures still too low in winter, for example) for their formation. Well, you can't have everything.

Hi Alessandro - I guessed you must have been away on holiday. As Dave says would be good to start another thread and hear more about it.

If you don't have a protruding keel usual practice is to have it inside the hull and slot the frames over it. But if you have come up with an alternative solution then great.

Have you decided on how you are going to skin your hull? Reason I ask is that hard chine hulls are usually fairly simple compared with round hulls, including war ships and yachts and you don't need many frames. Most of my builds only have between 5 and 7 frames as apart from the bow there is not a dramatic change in shape as you travel down the hull. All my hard chine hulls are ply skinned with in some cases balsa blocks to form the bow as ply doesn't like being bent in two directions.

But if your hull does have some curves in it then it will be better to plank it. As you know this normally requires many more frames closer together though if you diagonally plank using more stringers than just at the deck and chine then you can still only use a small number of frames. I did this with my Fisherman build though that is a round hull.

I've now got my Huntsman 31 ready for lake trials, including with the motor I recommended for you, so it will be interesting to see how it performs. Will be a few weeks away though as I will be away soon.

Chris

@AlessandroSPQR Your thread on the planing hull is interesting.
BUT, I'd love it if you would start another thread referencing your holiday at "Calabria on the Ionian Sea". Not knowing anything about the area, I just did a little quick search ... it sounds heavenly!
We will be back in (northern) Italy with my wife's choir next year. Maybe we should plan an extension on our own and visit this area as well?
Dave B

Hello everyone.
Hi Chris.

I'm back after a bit of inactivity; I was swimming in Calabria on the Ionian Sea.

After modifying the hull, I started drawing the first lines of the keel.

So far, I've designed hulls with the keel protruding beyond the hull. This required a method of inserting the frames onto the keel that I'd become accustomed to.
In this case, the keel isn't exposed, so I'll have to adopt another method.
I've already thought of a solution that I'll show you later.

I also drew two decks, but only in 3D. It's still premature to transfer them to 2D for cutting out, including all the joints on the keel and frames.

Once the hull was complete, I started making the frames.
As you can see from the images, this is my method: I create vertical surfaces parallel to the hull.
The intersection of these horizontal surfaces with the hull will give me the frames.
I imagined making them 4 mm thick, so the distance between the pairs of vertical surfaces is precisely 4 mm.

The next step will be the very difficult one of creating the intersections of the frames on the keel and with the two decks.

The ultimate goal is to transfer the keel, decks, and frames into 2D sheets so that anyone can cut them out and create the hull skeleton.

@ChrisF
What you say is so true. Damn laziness.

Thanks for the information, some of which I understand!
Most users of the different kinds of software only use a small percentage of the capabilities of software, even for their jobs. I did data management for a few years before retiring and used Microsoft Excel a lot and sometimes in depth but even so I only scraped the surface of it's capabilities.

Same with Microsoft Visio which I used for architectural work which it's not designed for! And same for my boat drawings. But I had years of experience on the drawing board and so just work in the same way, that is 2D, which suits me. The hull for my Fisherman stretched my capabilies though as you have to visualise the curves in 3D and draw in 2D!

Most of my drawings are for models with hard chine hulls though so pretty easy in Visio.

We all tend to just learn enough to do what we need to do. I certainly do with my photographic software and only find out about other things when we need to.

@ChrisF
Since my last message, I haven't drawn anymore; in fact, I haven't even opened the drawing program due to lack of time.

You wrote: "Surprised you can't just alter the stern from a saved copy?"

Excellent point.

Rhinoceros is different from 3D modeling programs.
But before I try to explain the differences, you should know that I know how to use 15% (and probably less) of this program's commands and features.
I only use a minimal part of the software's potential (and I have an English version, which certainly doesn't make learning easier).
This is why I'm forced to redo the hull drawing almost from scratch. There could probably be a simpler and faster way.

That said, you should know that (I did some research on this topic and watched some video tutorials on the subject):

3D programs are based, as far as I understand, on three main modalities: the use of NURBS (Non-Uniform Rational Basis Spline); polygon meshes; and parametric solid modeling.
Rhinoceros stands out primarily for its native use of NURBS geometry, which allows you to create mathematically perfect surfaces and smooth curves, unlike most other software based on polygon meshes or parametric solid modeling.
Software like Blender, Maya, or 3ds Max use meshes (networks of triangles or squares).
Rhino uses mathematical formulas (NURBS). Surfaces remain perfectly smooth even when zoomed in to infinity. Polygons reveal facets when magnified.
Rhino is millimetric and exchanges clean data with CNC machines and 3D printers. Polygon programs are ideal for visually organic shapes, but they lack engineering precision.
Rhino is used for product design, architecture, and jewelry. Blender and Maya are used for animation, video games, and visual effects (VFX).
Programs like SolidWorks, Fusion 360, and Inventor are based on a rigid construction history and dimensional constraints.
Rhino allows you to "draw in space" freely and sculpturally, without having to define rigid geometric constraints before starting.
In parametric CAD, you change a dimension and the entire model updates. In Rhino (without specific plugins), radical changes to an advanced model often require rebuilding parts of the surface.
Rhino vs. BIM Software (Revit, Archicad)
In architecture, Rhino is used very differently than BIM programs.
Revit thinks in terms of real architectural elements (walls, windows, floors). Rhino thinks in terms of pure geometry (points, lines, surfaces).
Rhino allows you to create fluid facades, parametric roofs, and organic shapes that are almost impossible to manage in Revit.

To build solids, I start from lines and surfaces, not directly from pieces that I then model, but maybe that's just my limitation. It's also worth considering that I don't have many very important plug-ins.

Basically, now I limit myself to this.
1. I set the starting lines.
2. I create the surfaces, such as the hull, which is the most difficult part of all. Obviously, the difficulty depends on the type of hull. In fact, if I have to make the hull of a Springer tug, which is essentially a raft, it takes me two minutes. All I have to do is draw the profile curve, then the surface from that, and finally extrude this surface to create the volume. The hull of a speedboat is much more difficult, the hull of a clipper ship is even more complicated (obviously, I'm referring to projects that start from a blank sheet of paper).
3. I cut the hull surfaces to create the keel and frames, then build the hull skeleton on which I'll apply the planking.
4. When do I need to create volume and surfaces aren't enough?
As you may have realized, with this method, I can create a model from scratch without necessarily creating volumes; I just need 3D surfaces.
I need volume (and therefore I need to close the surfaces) in two cases: when I want to know the volume value, for example, the immersed volume to determine the displacement (i.e., the total weight) in advance, or when I need to 3D print a part. This part must be a solid.

Hi Alessandro

Surprised you can't just alter the stern from a saved copy?

Keep thinking I must dust off my TurboCAD and have another go at learning it. Trouble is I keep leaving it for such a long time I have to start from scratch! Microsoft Visio is not the program really for producing this type of drawing but I've made it work and I know it well enough for my needs. Actually I need to learn CAD as I'm thinking of getting the deck planking laser etched on my Christina build!

The replacement motor arrived yesterday for my Huntsman 31 and whilst I'm keen to try it in the bath it's just too hot for fitting that, the prop shaft and rudder and RC gear etc.! 😎

Chris

Hi Chris, I was completing the outlines to draw the keel and then the frames.
Here are some photos.

I stopped because I rethought the stern; I want to modify it; I like it, but I'll make it with a less pronounced slope.
So, unfortunately, I'll start from scratch.

@ChrisF
Thanks Chris that's exactly what I wanted.

Can you please repeat the length of the axis and how many degrees is the angle in the drawing in the last message?

Not sure what you mean by this, but if it's about the prop shaft:

Angle 13 degrees - it could have easily been less than this but it's a slow speed craft so not really important - though with the motor it has in it and the hull being based on the Huntress hull it would plane easily - I have resisted so far!
Prop shaft (M4) - 290mm, Tube (8mm outside diameter) - 240mm.

This boat is smaller than yours at 584mm.

The angles I've given so far in all my comments are from my drawings. It would be interesting if I measured the actual angles on the models as I always allow myself some looseness with the hole through the keel so that I can align the prop shaft accurately with the motor. Once I have done this using a fixed/solid coupling I glue the prop tube in place. So the angle has more than likely changed a little.

@ChrisF

Hi Chris, I wanted to reassure you on a few things.
You wrote:""""""+You also need to think about positioning of bulkheads/formers as Ideally you want to avoid the motor mount sitting on one as this can affect how low you can position the motor. +"""""
My method is this: Near the motor (once I've decided where it will be placed), I create special spaces in the bulkheads/formers. In practice, the engine doesn't rest on them but fits inside them.
A few images can help you better understand what I mean. The images are of a displacement hull, and the goal was to place it as low as possible and, at the same time, as far aft as possible.
That, however, was a different type of hull, and the electric engine wasn't tilted; now it will be a little more difficult.

You wrote: """""I know that you like short prop shafts, and that's a good idea, but don't worry too much about it. Some of mine are really long, longer than necessary, as in my early days I was nervous about cutting them down! You only have two bearings, whatever the length (though some folks introduce a middle bearing) and so the only thing affecting performance losses is the mass of the additional length of the inner shaft and an extra length of tube which is no problem for a brushless motor!"
This heartens me a lot because, from the tests I have done so far, I have seen that with very long shafts the resistance and Ampere absorption greatly increases. Here is another element in favor of choosing a brushless motor.
For information, I put three bearings (one also intermediate with internal spacers).



You wrote: """Have you allowed for the coupling in the prop shaft length you are working with? I can give you dimensions of the one I use in my planing models - keep away from those red plastic universal joint types! You can see I've used a UJ coupling in the River Cruiser but it's a better quality one and it's a slow boat. You need to allow for the amount of motor shaft and inner prop shaft going inside the coupling, which obviously affects the overall length of the motor and prop shaft."""""""
Thanks so much for the suggestion. I had foreseen and written it, but I suspected the translation wouldn't be very clear.
When I wrote: "The motor pinion should be added to the total length. It's a useful tool to keep aside," that's exactly what I meant.

I would prefer to use a fixed metal coupling.

I'm aiming to reduce the angle as much as possible because I know that various practical issues will increase it.

Can you please repeat the length of the axis and how many degrees is the angle in the drawing in the last message?

Good morning Alessandro and Harry (well good evening Harry!).

Like you I draw a composite of the whole prop shaft and motor set up to work out it's position and angle. Can't really tell from the drawings so far but are you leaving sufficient distance between the bottom of the motor and hull allowing for the practicalities of mounting the motor? This distance will depend, as I said before, on how you mount the motor and can soon add up when taking into consideration the motor mount and base it is fixed to.

I've attached a drawing of my River Cruiser. The keel is deeper than it needs to be, so yours can be less so, and it can be cut into at an angle for the mounting. As you can see I could have moved the motor further back as it is well above the keel anyway and plenty of prop shaft protruding through the keel for connecting the coupling. You also need to think about positioning of bulkheads/formers as Ideally you want to avoid the motor mount sitting on one as this can affect how low you can position the motor. With most of my builds I fixed the position of the formers first which explains why the motors are further forward. Actually whilst the drawing shows quite a distance to the prop tube the photographs show it isn't that great and I could only have shortened the shaft a bit. Differences are going to happen between the drawing and building - the drawing is only a good starting point to show that it's feasible!

I know that you like short prop shafts and that is a good idea but don't worry too much about it, some of mine are really long, longer than necessary as in my early days I was nervous of cutting them down! You only have two bearings, whatever the length (though some folks introduce a middle bearing) and so the only thing affecting performance losses is the mass of the additional length of the inner shaft and an extra length of tube which is no problem for a brushless motor!

Note that the keel design includes a raised piece for the rudder monting.

Have you allowed for the coupling in the prop shaft length you are working with? I can give you dimensions of the one I use in my planing models - keep away from those red plastic universal joint types! You can see I've used a UJ coupling in the River Cruiser but it's a better quality one and it's a slow boat. You need to allow for the amount of motor shaft and inner prop shaft going inside the coupling which obviously affects the overall length of the motor and prop shaft.

Chris

@canabus
Thank you very much Harry.

The standard pitch for props is 1.4 which the CNC props that are sold on Aliexpress.
These the dog drive setup.
They also have different complete drive line with or without plastic props.
The units have ball races both ends which maybe OK for fresh water but NOT for salt water.
I replace the lower bearing with tefron.
As for props 37 mm 3blade or 40/42 mm 2 blade.
I have used a 45 mm 2 blade but it's a bit power hungry.
Harry

@ChrisF

Hi Chris, I'm addressing you, but anyone (especially those with experience with planing models) can weigh in. So, when it's time to purchase electric motors, I'll ask you more questions and ask for more support. For now, I'll update you on the project's status.

I'm so glad I've rekindled your enthusiasm!



ELECTRIC MOTOR AND PROPELLER DIMENSIONS

As you can see in the first two images, I've briefly drawn the dimensions of the purple propeller, the green propeller shaft, and the brown motor.

The cylinder representing the motor dimensions has a diameter of 50 mm (I don't think I'll use a motor with a larger diameter), and the cylinder representing the propeller dimensions has a diameter of 45 mm (again, I've considered the maximum; I don't think I'll use a larger propeller, probably 35 to 40 mm).

I've tried different lengths for the propeller shaft. As you can see in the first two images, the lengths are 250 mm, 300 mm, 320 mm, 350 mm, and 400 mm.
The 250, 300, and 350 mm lengths are commercial lengths, meaning I can easily find them online if I want to purchase them, so I started with those.
If I want to make the shafts myself, I can easily make them any size.

The motor pinion should be added to the total length. It's a useful tool to keep aside.



ANGLING THE MOTOR-SHAFT-PROPELLER ASSEMBLY

I combined the motor, shaft, and propeller into a single solid so that they could be oriented at the desired angle.

Very small angles are not possible for this hull and the assumed dimensions of the engine and propeller. In the third and fourth images, you can see that, at a 5-degree angle, the propeller would hit the hull and the engine would protrude from the outline.

As you can see in the fifth image, with a 250 mm shaft, an angle of at least 12 degrees is needed (measured between the propeller shaft and the keel), which you think is acceptable, so that's fine.

The sixth and seventh images show the 10-degree angle solution with 300 and 320 mm shafts.

The eighth image shows the solution with a 350 mm shaft; in this case, the angle was reduced to 9 degrees.

In the ninth and tenth images, the shaft is 400 mm long (I don't think it's commercially available, at least not at a low cost); in this case, the angle was reduced to 8 degrees.

I would never have chosen such long shafts (25 cm is already too long for my taste) if I had had a choice.
To minimize engine performance losses, I keep the shaft as short as possible.
In this case, I couldn't, unless I used a flexible shaft (but that's not a solution I'm very fond of, even though I often see it used in scale speedboats).

However, given the current situation, I would discard the extreme solutions (25 cm 12 degrees and 40 cm 8 degrees) and focus on those ranging from 300 to 350 mm, with angles of 9 and 10 degrees.

The entire assembly (engine-shaft-propeller) of any of the above solutions can be moved a little forward or a little backward. This will be determined by the position of the rudder and servomechanism.



READING AND EXPLANATION OF THE CURRENT DRAWING

I didn't draw the actual thickness of the hull. What you see in the drawing (blue hull) is therefore the internal volume.
It's a bit difficult to make myself understood because of the translation, but I'll try.
The volume drawing will be used to draw the frames. To make them, I'll intersect several vertical surfaces orthogonal to the keel at predetermined distances. The result of these intersections will be the individual frames, which I'll plot on 2D sheets for cutting by hand or laser (later you'll see better what I mean and how I'll do it).
The strips will be glued onto these frames, once cut, so the volume will be greater, considering the additional thickness of at least 1.5 or 2 mm.
This will result in some changes, for example, the distance between the propeller rotation and the hull will decrease, while the immersed volume will increase.



Any suggestions or comments are welcome.

I see on the site they are giving 10% off until tomorrow, I guess for Fathers Day, and so I've ordered one of those motors I recommended for use in my Huntsman 31.

This thread has been good for me as although I still have a passion for my Fairey builds progress had slowed on the earlier ones I'd started, partly due to starting my Faun and Fisherman builds. My enthusiasm has been reawakened to get the Huntsman 31 and Swordsman on the water, even if not completely finished, to see how my choice of motors for them works out as regards performance. My other builds have performed as hoped but I'm particularly keen to see how the Swordsman performs as it's a bigger and much heavier boat than my others.

So thank you Alessandro!

@AlessandroSPQR That's strange.

Try putting Overlander Batteries UK into Google and see if it comes up.

They state that due to Brexit they can't export outside of the UK mainland. Wouldn't have thought that would stop access to their web-site though? Maybe it does?

Chris

@ChrisF
Hi Chris, unfortunately I can't reach the link you posted. I'm getting this page.

@AlessandroSPQR The lower the better to some extent, though if you go too low you have to deal with water ingress through the prop tube and may have difficulty in mounting the motor low enough, due partly to how you are going to mount the motor - you will of course deal with this when you are working on your drawings. Many of my Faireys (planing hulls) are 12 degrees which matches the full-size boats and the Swordsman for which I showed the drawing is 11 degrees - this uses a 42mm diameter motor but it is a bigger model than yours at 838mm and so I could use a longer prop shaft to keep the angle down. And lowering the motor then affects the position of the prop and it's clearance. It is all a bit of a balancing act and a compromise - will be interesting to see what you come up with.

As I said, 42mm diameter is bigger than you really need, but your choice obviously, and for that size and bigger the choice of motors becomes less and less and the kV also and so you need bigger (more volts) and more expensive batteries. Whereas the 35mm gives plenty of options. This leads me to believe it would be difficult to find a suitable brushless motor for a big planing model, say over 50"/1270mm, as motors sold for boats don't have a high enough kV to produce a higher enough rpm unless say a pully system is used. Maybe have to look outside of model boat motors?

Anyway, for your research purposes here is a link to Overlander Batteries showing what motors they have. They have a smaller range of outrunners than they used to have, though still suitable for my needs, and have added more inrunners.

https://overlander.co.uk/

Unless you have any specific questions I won't say anymore for now and leave you to get on with your designing!