Hi all!

I’ve recently discovered the world of composites and have been fascinated with the whole subject and intrigued with what can be produced.

I am a very keen kayaker and have a burning desire to build a composite version of my current plastic surf boat, a Fluid Element which weighs around 15kgs and measures 202cm x 64cm (widest part).

I have tried paddling some other boats which are produced in carbon/kevlar, but due to their design I just haven’t got on with them aswell as my current boat. 

My boat was produced in carbon/kevlar in a limited amount (around 30), but these are very rare to come by and as you can imagine, fetch a large amount of money as they retailed at £1395 new. I am therefore planning a long-term project to build myself a composite version but have come across the usual problems that most people encounter such as which combination of materials to use.

I will be on a tight budget with not much room for error, so I need to keep costs down by using cheaper materials/resins if possible. I plan to take a mould of my current boat in either two or three parts, then create the boat using wet-lay and vacuum bagging.

My initial thoughts are one of the following four lay-ups with Polyester/Vinylester resin with a target weight under 9kgs:

(From Outside the boat to Inside the boat)

Outer layer of 300g Black Diolen 2/2 twill

1x 300g plain Diolen 2/2 twill

3mm foam core

1x 300g plain Diolen 2/2 twill

1x 300g Black Diolen 2/2 twill

or (if the Diolen only lay-up is not stiff enough)…

Outer layer of 300g Black Diolen 2/2 twill

1x 300g S-Glass 2/2 twill

3mm foam core

1x 300g S-Glass 2/2 twill

1x 300g Black Diolen 2/2 twill

or (if the lay-up needs to be stronger still)…

Outer layer of 300g Kevlar 2/2 twill

1x 300g Carbon 2/2 Twill

3mm foam core

1x 300g Carbon 2/2 twill

Or (if my budget will stretch to it)…

2 x 228g Carbon/Kevlar Aramid

3mm Foam Core

2x 228g Carbon/Kevlar Aramid

My question is, firstly will the lay-ups be strong enough for white water use in the sea (waves) with the odd scrape and knock from pebbly beaches? It will no doubt take more of a beating than a longer sea kayak as it’s more of a play boat style kayak. And secondly, which lay-up will be stronger? I could possible use a mixture of the lay-ups with a stronger/more expensive one making up the base of the kayak, and a cheaper one making up the top half of the kayak?

I have chosen to put either the Diolen or Kevlar on the outside layer to give better abrasion resistance and to protect the Carbon/S-Glass, however I have found some conflicting information online that suggests the Kevlar/Diolen should be on the inner layer?? Being that Kevlar/Diolen can take more damage before splitting, I would have thought if it were on the inner layer, the carbon would crack on the outside before the Kevlar/Diolen, whereas on the outside it would keep the cracked carbon beneath the layer of Kevlar/Diolen protecting the boat from splitting?

Pages where I have gathered inspiration has come from:

Kevlar Playboat:

http://shanesliquidlogic.blogspot.co.uk/2011/12/composite-playboat-prototype-1.html

Carbon Zet Playboat:

https://www.youtube.com/watch?v=IA9vkauvxGY

Carbon Vadja Playboat:

http://vajdafreestyle.com/en/Kayaks/Beast/Beast-series/

Lots more questions to follow no doubt, but any help/suggestions would be fantastic!

Cheers,

Junior.

I am also planning on building a kayak. Though 16ft fishing kayak.

What lay-up are you going for?

Won't carbon on the outside damage easier?

A few more questions in addition to my first ones!

1. When using a foam core (e.g. in a kayak hull), should the foam run right to the edge of the laminate? And if it should, how do you seal the ends?

2. Thinking about the design, I would like to have either an orange or white gelcoat for the top half, but have transparent decals (such as writing) so it shows
the Carbon underneath. How would I go about achieving this?

3. After watching this video... https://www.youtube.com/watch?v=0N-LiWRA7RQ
I have also been intrigued by Innegra and wonder whether this could be used within the layup to achieve a better result? Could someone explain what effect it
would have pairing it with Carbon, Carbon/Kevlar, S-Glass & Diolen in terms of kayak strength and durability? Would it work either side of foam core with one of the other
composites on the outside?

Yes the carbon will damage more easily. But also easier to repair. 

So how many layers would you recommend with something like Carbon/Kevlar?

So thicker layers would be stronger than multiple layers of a similar weight?

Can any of the EasyComposite staff lend some advice?