Small row boat desing

Hello everyone, I'm sharing a W.I.P. that from time to time I'm trying to finish, now I'm in the phase of generating the technical drawings, everything is done with Blender, even the drawings, I would like to make sure that I make drawings that are complete with the construction information, but unfortunately I have no experience in boat building, and I am very likely to make several mistakes.
I would like it to be a boat that can be made from commercial wood planks.
The drawings that I really like are those of Paul Gartside, I really like the way he draws.


Right now I'm trying to understand how to create the various elements in 2D from 3D, I've found some problems that I'm trying to solve, so not everything at the moment is complete and correct, I have to think about how to generate the various elements, but for now I attach 2 images.

Any advice is very welcome because I would like to avoid making incorrect designs or worse, making something that cannot be built.
Greetings

 

Peruse the drawings of Atkin Boat Plans.
He designed billions of small boats.
You may not like the designs, but you'll get an idea of scantlings
and construction methods that are suitable for amateur building.

 

Nice drawings, but the proportions are off. The thwarts are quite low which would make rowing difficult. What do you mean by commercial wood planks?

 

Hello Pao,
I see you are using sawn frames. What type of planking will you use, in terms of wood type and whether it is butted together (carvel) or lapped in some fashion?

 

First of all,I think for an absolute beginner to progress to the point of creating an entire model of a boat is a good achievement.There is another point about the thwart than needs to be considered; the knees that brace it need to be supported by a longitudinal and are normally taken to the height of the sheer so that the inwales can perform this function.So that if you lift the thwart height and retain the sort of height of the vertical arm of the knee,it will be much better.Having a hanging knee terminate in the middle of a plank almost guarantees that if the boat gets squeezed,the point loading will split the plank.

I have seen enough drawings from Paul Gartside to know that he has a very clear drawing style and you would be doing well if you managed to convey information as clearly as he does.The choice of commercial planks is unusual for a small boat in this century as it is likely to result in a heavier boat than the use of plywood might,but centuries of tradition indicate that wooden planks can work very well.Carvel planking really needs to be kept afloat to prevent plank shrinkage causing leaks and it takes good woodworking skills to make it watertight in the first case.Clinker planking for the topsides might be more forgiving and if it does leak a little you can always add a bead of mastic to the lap for a bit of help.The difficulty is that tapering the lap at the stem is a process that requires some care the first few times.

Good luck with the project.

 

Thanks you rangebowdrie, I know some models of Atkin, but I will find out more and see what I can find useful.

Hi and thanks for the advice, I will try to make some changes, based on what you told me about the thwarts.

For "commercial planks", I mean standard dimensions, for example using planks 5cm high, 2cm thick and with length of 3~4 meters from which to obtain the various pieces, of the stations, and use for plywood planking, 8~10mm.
However, it is likely that I will be forced to reconsider many things.

Hi, everything is to be defined but I will use what can normally be found from any supplier, but I don't have much experience, so it is likely that based on the advice here I will have to review many things.

Thank you for your appreciation and for these tips on the correct position for rowing and so also the thwart as Gonzo suggest, I will try to make changes on these points and make updates that I will share here.

Yes, Paul Gartside drawings are also very compact, in addition to the beautiful graphics (handmade, truly impressive) they are full of information, it will be difficult to do what he does, but I will try to do the best I can.

My idea is to make this small boat, with processes that can be done on a workbench and in a small laboratory. For the side planking I thought of making bevels on the boards in such a way as to match the side planks, and then to make the boat watertight use epoxy resin and fiberglass fabric or similar.

Thanks you'll for the advice everyone, it's very helpful.

 

These are some images I made today, adding a dummy mannequin, to check the position, and some also on how the side planking of the boat and the frame are made.

The construction of the frame and the stations are still to be decided but I also tried to copy from others but trying to do them with simple measurements without being forced to use templates, but it will still be difficult.


The transom and keel are also designed to use a small 2.5~6 hp outboard, very small engines to attach quickly.
Greetings

 

Is the boat developable or unfoldable such that the 8-10mm plywood for the planking could be 4 pieces (sheer to chine, chine to keel, one for each side of boat) and not bother with bevels and laps?

 

Yes, I did it this way initially, the bottom of the hull is made up of only two elements.
Then I decided to make a model with multiple parts, also to reduce the deformation of the sides of the hull. When I finish this variant I will also make one with entire plywood sheets

 

A couple of comments on the latest version:the thwart needs to derive it's vertical support from a longitudinal attached to the inboard face of the frames.This will hold it at the correct height and if done correctly there should be a small gap between the ends of the thwart and the planking.The knees that I mentioned in my earlier post should take care of lateral stiffening by using the strength of the inwales to brace the thwart.For a discussion of the ergonomic aspects of rowing this page may be useful Fixed Seat Rowing Geometry https://angusrowboats.com/blogs/news/fixed-seat-rowing-geometry.

I don't know how readily you can find commercial planking of a suitable thickness for a boat of this size and it is a long,hard process to reduce them in thickness without a fairly powerful machine to help.I believe I am correct in thinking that the flare of the sides is an intentional way to avoid wasting wood,in much the same way that New England dories used straight planks for speed and economy of building time.A cardboard model will be a useful thing to determine how much or how little shaping of planks will need to be done.Plywood will have an advantage in this respect and may allow you to create a lighter boat of equal strength.

Epoxy is strong,expensive and can be a health hazard so I tend to avoid it except where essential.There are those who wouldn't be able to build a boat without a suitable material to fill the gaps and bond a sheathing material over the whole thing and they promote it's use but it isn't essential.

 

Hi wet feet, I had used some references for the position of the rower, but I will do more research about it and your link helps, regarding the side walls, it is very likely that the design of the boat will be with plywood, probably everything could be done in plywood, I mistakenly said wooden planks but my idea is to use this type of wood, in fact I did research in this direction while time ago.
Using resin allows you to waterproof the hull efficiently, but I will try to do the drawing in as much detail as I can, so as to also allow for a different construction even with planed wooden planks.
Thanks for the tips and as soon as I make progress I will share them here.

This boat everything started with Blender and FreeShip, in fact first I made the simple hull in Blender and then imported the model into FreeShip, then I decided to make the detailed model, a job that I only recently started doing , I attach the results obtained with FreeShip, and I also made an approximate calculation of the weight of the model using marine plywood and my little boat weighs around 52kg but it is likely that I will have to add a couple of kilos for the metal parts and screws.


Design length : 3.007 m
Length over all : 3.007 m
Design beam : 1.133 m
Beam over all : 1.133 m
Design draft : 0.151 m
Midship location : 1.500 m
Water density : 1.025 t/m^3
Appendage coefficient : 1.0000
Volume properties:
Displaced volume : 0.156 m^3
Displacement : 0.160 tonnes
Total length of submerged body : 2.803 m
Total beam of submerged body : 0.920 m
Block coefficient : 0.4002
Prismatic coefficient : 0.5837
Vert. prismatic coefficient : 0.5517
Wetted surface area : 2.082 m^2
Longitudinal center of buoyancy : 1.467 m
Longitudinal center of buoyancy : -0.801 %
Transverse center of buoyancy : 0.000 m
Vertical center of buoyancy : 0.102 m
Midship properties:
Midship location : 1.5000 m
Midship section area : 0.095 m^2
Midship coefficient : 0.6857
Waterplane properties:
Length on waterline : 2.803 m
Beam on waterline : 0.920 m
Waterplane area : 1.870 m^2
Waterplane coefficient : 0.7255
Waterplane center of floatation : 1.397 m
Y coordinate of DWL area CoG : 0.000 m
Half entrance angle of DWL : 35.622 degr
Transverse moment of inertia : 0.098 m^4
Longitudinal moment of inertia : 0.802 m^4
Initial stability:
Vertical of transverse metacenter : 0.731 m
Transverse metacentric radius : 0.629 m
Longitudinal transverse metacenter : 5.236 m
Longitudinal metacentric radius : 5.135 m
Lateral plane:
Lateral area : 0.310 m^2
Longitudinal center of effort : 1.525 m
Vertical center of effort : 0.088 m
Hull characteristics above waterline:
Lateral wind area : 1.225 m^2
Z coordinate of wind area CoG : 0.364 m
X coordinate of wind area CoG : 1.493 m
Distance from wind area CoG to DWL : 0.213 m
Distance from bow (FP) to wind area CoG : 1.513 m
Minimal board height over DWL : 0.230 m
Minimal board height over DWL : 7.665 %Lmax
Stability characteristics:
Test stability coefficient : 2.017 if >= 0,8 then OK


Greetings

 

you have shown design draft as 0.001 meters. The actual draft is likely to be about 10 cm. The estimated weight is probably higher than a boat of that size needs to be or ought to be unless it is intended for war. I presume that the total weight includes one oarsman and whatever other items are carried in the boat.

A lightweight boat is more easily propelled than a heavier one. On the other hand a heavier boat tends to carry its way better between strokes. The drawings show a lot of framing for such a small boat.

It is clear that you are approaching this project with careful study while heeding the advice from the forum respondents. That is refreshing because we get a lot of new posts from beginners who already know every thing.

 

Yes that is an error due to the fact that initially I used the DWL line as the baseline, then with experience I realized that it generated errors, now I have corrected and moved it, thanks it was an old model that I had not corrected.