Outriggers and pontoons for my design sailng kayaks

[Kayaqua]

Hi there all; I'm working on own design sailing kayaks and am now prototyping pontoon hulls and outrigger wings. Lots of work to do. I'm near completion of epoxy cream over foam pontoon plugs and now wondering best way forward. Do I take a hull off the male plug using fiberglass cloth or should I make a female mold. What weight of glass cloth should I use to take a hull off the plug. Can I use ordinary wax as a mold release. I'm planning on making a cedar & ply decks.

 

[rwatson]

If the plugs are a one time use only you can cover them with cloth/epoxy on the outside, then melt the foam with Acetone or similar.

However, as the hulls have flat sections, and it will be for sailing, I would expect that you will need to grind out the foam, leaving some inner ribs in foam, that will covered over with more glass for extra strength,

Most foam is too rough to just use wax as a release agent. Try a small test section, but I would expect that you will need to use plaster or even an epoxy/balloon mix to give a surface you can get really smooth, and then apply wax to that.

For the strip decks, you may get away with some temporary barrier like plastic sheeting, and staple the strips into the foam as you place them.

PS - I missed the bit where you said you already have covered the hulls in Epoxy cream, so my previous words may not apply. Are both those hulls the same ? Are you planning on making a whole lot of these ? These two questions will dictate whether you would do female moulds, or just build a hull on top of the foam.

 

[Kayaqua]

Yeah the foam has been well and truly covered with about 12 liters of epoxy cream because I wasn't happy with the V shape hulls I originally shaped. The decks are currently 4 mm ply but will latter be reshaped into curved to streamline around outrigger gull wings. Because it is a prototype asymmetric hulls and each is similar but not quite exactly the same I may or may not use these for production. Basically I just want to make a pair of lightest weight one offs without destroying these plugs as they may be just perfect for taking a female mold.
So I'm planning on refinishing them in gloss spray enamel, waxing and laying up some glass cloth to make a pair of hulls, which I can then maybe rib and deck with cedar & ply. I'm wondering what weight of cloth I can get away with. I have some 4 ounce surfboard cloth of top quality weave but thinking it may just be a little too light? But will be a relatively cheap way to go at this time. The gull wings I've also made in cedar and ply but will cover in foam to shape into more aerodynamic shapes.

 

[rwatson]

I suppose you could use 4 oz cloth to "lightest weight one offs", but only if you re-inforce them internally a lot once the thin skins have been created. Being a sailing craft, there will be plenty of stress on these hulls. Theres no way a 4 oz skin would stand up to sailing, and is probably going to be a bugger to pull off these plugs in one piece

 

[Kayaqua]

Yeah that's what I'm thinking! Actually the cloth is 405 grams which is more like 7 once I guess, so maybe with a couple of layups? I've never done this before so I have no Idea how difficult it might be to lift off the hulls from plugs. I just thought a very smooth glossy surface well waxed should be piece of cake?

 

[garydierking]

Yeah that's what I'm thinking! Actually the cloth is 405 grams which is more like 7 once I guess, so maybe with a couple of layups? I've never done this before so I have no Idea how difficult it might be to lift off the hulls from plugs. I just thought a very smooth glossy surface well waxed should be piece of cake?

Call Nuplex. They sell special products for preparing molds and will give you free advice.