One off fiberglass non mold resources

Oh I see clearly now. In the areas rhat have the higher the degree of logarithmic change in concave of hull shape, the closer the vertical paneling will have to be. And the more of the horizontal framing will have to be in those highly concaved areas. Gotcha. I was wondering why I didn't see more radically concaved shaping in boats and now I see how it gets tricky. I was looking at 3d printing as they have used that as a solution but after research into it, I realized 3d printing is 100x slower than watching fiberglass dry and about 2 to 3 times as expensive.

 

At the rear of the hull, where the change is abrupt and severe, they doubled paneling.

So I'm guessing for more than 50 % curve of the surface squared, requires another doubling of the framing. Or actually higher, the larger the boat, because of the cube law. I got it. Thanks.

 

That photo is showing Imp's IOR blisters...realistically no longer a thing to be designed in a hull.

 

3d printed hull

 

There are several options depending on size and shape. In no particular order, and of course some can be combined:

1. Put the male plug on a rotisserie, turn it while laminating so that gravity works for you.
2. C-flex
3. Infusion. The glass gets tacked with spray adhesive, then vacuum holds it in place.
4. Direct female mold. Instead of a plug you build a disposable female mold using the same techniques as for a plug.
5. Thermoformed or strip planked foam screwed from behind on battens.

Farrier tris were usually buildt with thermoformed foam on battens using female frames, the hulls split the vertically (no hull deck joint) and the frames rotated. Take a look at this site, The construction of my trimaran’s main hull part 1 https://www.fram.nl/mainhull1.html the photoalbum of setting up the first main hull half will make it plenty clear.

 

Can we be clear about how many moulds are required in total?I'm guessing a minimum of two and that is a lot of fairing.I predict getting very dusty and itching a lot before the project is complete.A good deal of thought has to be devoted to how the deck moulding(s) are attached and the usual inward facing flange may need detailed consideration.It isn't simply a question of creating a CAD model of the boat,you need to do the mental exercise of putting the various parts in place.A word of caution;getting a fair surface when building is always a demanding task and doing it with a concave surface pushes that challenge to a higher level.The whole process is much simpler with developable surfaces as it isn't quite as hard to build a disposable mould from melamine faced board and the finish is mostly there when the laminating is finished.So the slightly more distant consideration is whether the project is an exercise in designing or a way to get a boat at the end of the process.It gets more complicated if a bridge deck and superstructure are added to the vessel and bulkheads link it all together.

 

Simple shapes that don't require exact dimensions can be done at times without a mold, but complex shapes that require precise dimensions don't tend to be something that works well with a no-mold technique.

Wood and foam are relatively cheap, easy to source and work with, plus you can make changes to the mold as needed at every step of the process.

If time and cost is a concern, don't try to build a one-off custom 36' high performance trimaran with all new designs and techniques as a first project in the composites world.

 

I'm not I'm doing a 16' kayak sized hull trimaran. I have a mast and some other parts for it.

I am doing Sims on the design and will scale up after I get data. Will probably make one or two miniature rc sized prototypes.

I'm building a paddle board using that method.

 

Be aware of the many inherent problems scaling down or up.. I'm not versed to cite them all, but there are many.

 

Thanks man. I'm aware.

 

"If, for example, you multiply by two, then the length, beam and draft all double, the sail area increases by four times, the displacement (volume) goes up by eight times, and the stability jumps by 16 times."

 

Scaling down also can present weight challenges, etc

 

Have you started with the basics, and sketched out a rough general arrangement (still useful even if it is only 16') and a rough lines plan - and done a rough weights estimate to see if you will have enough buoyancy to support the weight of this trimaran?
If not, then it would be a good idea to start here, rather than getting bogged down on the finer details of concave curves in the moulds.

 

Yeah man. I'm in solidworks and going to do Matlab Sims at the college computer. Gg

 

Scaling up is more than just the stability and resistance from friction changes. The turbulent flow will start at the same distance from the leading edge, regardless of the actual length of the body. Also, the characteristics of a material influence the design at different scales. For example, a 1" balsa wood model will lay on its bottom with no problem. However, at 20' the weight of the boat will crush the wood fibers. Finally, any simulation is worthless unless you understand how the final product behaves. The basic rule of computers is: garbage in = garbage out. Trusting a computer program to the thinking results in disasters.