Hi!
I'm from Sweden and found this really interesting forum just now.
I'm doing a lot of adventure racing and paddling is one of the main parts in competitions.
So, i would really like to make my own kayak, but this one will be like a surfski, something like this;



I have a few questions I hope someone can help me with:
First, I would like to build a boat as light as possible, in carbon fiber / kevlar. How thick should have the hull and deck.
Then I do not know if it is possible to make use of rasin infusion technology or whether to try to vacuum bag. I am puzzled, however, if you have time to wet-laying the entire hull and then on the vacuum bag before the rasin time to solidify.
If one would use rasin infusion, how often you need to outsource distribution tubing to cover the entire hull?
Then I also wonder how best to put together the hull and deck. I saw the movie on kayak repair and which used some form of kevlar tape. Is it the best thing to use or is there something else?
Hm, these issues are perhaps slightly messy but I am so grateful for all the help I can get.
Thanks in advance,
Staffan, Sweden                                                    

Hm, sorry for the bad english in my last post. I wrote it in the middle of the night and my English is not quite what it should be.

But, I wondered about the layup resin infusion and concluded that this should be a way that can work, right?!
I have the resin feed spiral in det middle and the red circle around it is connected to the vacuumpump

Then I also wondered if I need something that statutes up between the hull and deck. I come to sit on the deck, so to speak, and it aknske must have some reinforcement to keep well?
Hm, I really feel that I have a lot to think about before I'm in the target with this ...
Grateful for tips and ideas!                                                                          

A kayak is normally between 0.5mm and 1.5mm thick depending on the usage.  Bouncing it off rocks in rough white water and you need a thick hull.  A streamlined racer for smooth waters can be fairly thin. 

Resin Infusion is a great idea for a kayak as it will give you both a light and strong part if done correctly.

When planning resin feed and vacuum lines you need to consider where the resin will flow.  Resin will try and take the path of least resistance.  On your picture, unless you can control the vacuum line around the hull, you may have a problem where the resin reaches the edge in one place and then struggles to get to the edge else where.

You can eliminate that through careful planning. Potentially you may want 2 or more vacuum ports which you can open and close at will to control where the resin flows to.

In your case it might be easier to control if you go from one side of the canoe to the other.

Kevlar tape/braid is commonly used as one of the reinforcements used when joining a kayak deck and hull together.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

Warren-
for the hull joining, is it done on the inside seam and the outside seams with tapes and resin?

just for my own info. i cant recall all of the video i saw way back when. to me it makes sense to make the tapes and resin on both sides
of the joint


thanks


scott

CarbonFiberCreations

Go and have a browse of double dutch and vajda kayaks.  Yes, I know they are slalom boats but have a read at the construction lay-ups.  Might also be worth looking at murky water and angst kayaks.  These are squirt so are a heavy construction but will detail the seams.  Typically for a boat like you are suggesting a single layer of 600g followed by 4mm PVC foam and then 2x200g layers will give a nice light rigid boat.  Seams are typically 4-6 layers of kevlar tape.  The very ends of squirt boats have an 'end pour' as the ends are inaccessable.  This is a mix of chopped ends and resin poured in to seal the ends.  Shouldn't be needed for a surf boat though.  Hope this helps?

Thanks for all your tips a ideas!

Great to know approximately how thick kayaks are, because it's one of my major concerns.

Concerning the choice of the type of fabric, I guess they are plain CF is best for kayaking, or am I wrong? Could it be good to use Kevlar / carbon hull to get a little more durable hull?

Interesting what you write on the planning of the infusion Warren. I looked at this video,
,
and where they seem to use the spiral tube to distribute the vacuum around and then add resin spiral tube in the middle and spread it on three different sites. Do you think it will work? It feels like it should be the most evenly around the entire canoe.

So, FLD, you believe in a sandwich construction. I've been thinking along those lines but most kayaks of this sort are not built with sandwich construction.

Now I'm planning the orders from composites easy! I'm really looking forward to get started!

I've paddled for years and sandwich constructed boats are FAR more rigid than a non cored boat.  The downside is that they are harder to repair if you bash one.  As far as reinforcement type I've had boats made from everything from spread tow cloth to diolen.  Ultimately carbon will be more rigid but carbon kevlar will give you a little more durability.  My last boat was carbon/foam/carbon-kevlar. 

Reinforcing a join on both sides is always strongest.

That infusion video seems massively over complicated for a simple bonnet!! They could have used one resin feed and one vacuum feed.

It does show how you can control where the resin goes by having multiple feeds though, however it is uneccesary on that part.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

OK, I realized that I have only paddled "regular" kayaks and no surfski's and these have rarely been out of the sandwich construction is. But I agree emd you, it's obvious stronger. The question is how much weight increases, I have seen that the Easy Composites has different core materials.
Something I'm a little worried about is exactly how I'm going in a good way to get together and decks. It becomes extremely thin edges to be joined. It will be that much easier with a sandwich kostruktion!