Mouldless Fibreglassing

I'm a Design student and I'm attempting to make a fibreglass whitewater kayak. The only problem is that this will be my first time fibreglassing. AS I'm not trying to recreate the same kayak multiple times I wanted to forgo a mould, and instead lay matting over chicken wire until it hardens and I can remove the wire. Will this mouldless idea work?

Also, I'm a bit worried about the order that I work in. Do I apply the resin, then mats, then resin and repeat?
What brand of resin should I use?

Thanks so so much.

 

Yes, you idea will work, but you'll have a big mess on your hands and one butt ugly, absurdly heavy boat, when it's all said and done.

You want to forgo the mold, but then you want to make a chicken wire mold?

Look, do yourself a big favor and look up one off 'glass building methods. You can build over foam, cardboard, use C-Flex, plywood, solid wood, etc., but your chicken wire idea is literally full of holes.

The advantage of a good mold, building jig or plug is you can get fairly close, if not dead on finishes without back breaking fairing and gallons of filler.

 

Chicken wire can be used if you apply plaster over it while backing up the inside with a trowel like they do in ferrocement boat.

Or you can wrap the chicken wire in "saran wrap" and lay the glass over it and wet it with resin. But as PAR said, you will still have an ugly, lumpy looking boat.

One trick to reduce the pockmark is to pre wet the glass in another table, then patch it to the mold while it is green (tacky enough to hold its shape but not cured). Lay up the second layer directly to the cured initial layer.

 

My original idea was to lay the fibreglass matting over the chicken wire on the outside, so it's not really a mould.

I looked at some one-off building methods, but I'm worried because one website said that C-Flex was too heavy for a kayak. Is this true? Is there a different type of fibreglass that is lighter?

 

Perhaps this will give you some idea from Advanced Composite Moldmaking by John Morena.

For complex shape you may cut stations (headers) from plywood, fill up the empty spaces with low cost PVC foam, sand to shape, cover the surface with mylar packing tape and glass over it.

 

A male mold is still as much of a mold as a female one. Chicken wire has a number of inherent issues, that are far easier to over come if you just use another method. Yes, C-Flex is way to heavy for a kayak.

You will need a jig or mold of some sort, as wet 'glass doesn't hold it's shape without it. There's no avoiding this. Picture wet bathroom tissue paper, draped over chicken wire. It will sag and slump in every hole, making for a fairing nightmare.

Again, there are several one off, single skin methods, pick one . . .

 

Yes!! light weight glass !!

 

If you can "shape" chicken wire then you could shape Expanded Polystyrene foam (EPS) then you could glass it with cloth fabric and Epoxy resin (Def not Polyester resin as that will melt the foam) After you have finished the glassing you can eat out the foam with petrol or acetone solvent or even sandpaper at the front for your legs and even leave some to be shaped as a "seat" at the cockpit hole and just leave it in the back !

 

Again there are several one off methods, including using foam as a building jig. If expanded polystyrene is employed, cover it with packaging tape, clear plastic sheeting or what ever (there are a few choices) and the sheathing will not stick, eliminating the need to destroy the jig to remove the hull shell.

 

The chicken wire thing ! have you looked further and tried to find other types of mess to use with the chicken wire ? what about using blocks of poly styrene and shaping them ? :?: cover with a plastic and glass over the top then take the poly out in bits from inside then peel the plastic off the inside . Just go find a canoe the shape you are looking for a pluck a quick thin layer and cut that and reshape it then glass. :idea:.

 

where do you live. there are some good boat building courses run by tafe and other organisations. find an up coming course that is building canoes. i have heard the fees are quite reasonable and you get to keep your boat when finished. the big plus with this idea is having an experienced boat builder on hand for guidance.

 

Fairing chicken wire is a daunting project. It is much easier and cheaper to make the male mold (which is what you are making) in other materials like wood, foam or hardboard. However, making a male mold will increase the labor. You have to fair the mold and then fair the outside of the hull. It is better to make a female mold, fair it and be done with it.

 

I disagree Gonzo, I think it's best for a one off, to just fair the thing once over a male mold. Regardless of the mold material (plywood, foam, dried mashed potatoes, etc.) the fabrics are applied over it and then the outside of the hull shell faired. If some care was used in building the mold, the inside of the hull shell will be fairly good, possably not needing much fairing at all. This sure beats fairing a female mold, with it's concave surfaces, which can be quite daunting for a novice.

 

I see your point. However, male of female, he needs a mold. I remember seeing some people using C-flex and it took a huge amount of resin and filler to fair between the round fiberglass battens. It ended up heavy.

 

Thanks to everyone who has posted!

I'm leaning towards the foam idea, and covering it with tape. Is polystrene the same as styrofoam?

Also, how many layers should I do to ensure that it won't break the second it scrapes against a rock? The areas that will hit rocks badly (the bottom, lower sides and chine) will be covered with plastic so I just need the rest to be able to withstand a bit of a knock.