composite kayak construction

Submitted by Zoltan Sasadi on Sat, 06/06/2020 - 13:25

Dear All,

Firstly thank you for having me on the forum, and i hope that all members are doing well considering this world wide crisis..

I have composite industry background however i started my career as a wooden boat builder. I have built wooden power boats as well as composite sailing and motor yachts, but my main field is composite tooling.

I am currently in the R&D phase of building a kayak for mainly flat water use. The intention is to create a fast, lightweight yet sturdy enough kayak for a single paddler with some cargo allowance for few days trips, by combining the best characteristics of wood and composite.

I have already built a male mould which is suitable for vacuum infusion. My intention is to build the kayak from the inside out to have both inner and outer surfaces smooth.

The kayaks main dimensions are: LOA: 5.2m (17 foot), LWL: 5.29 (17.3 ft) due to reverse bow, Beam: 56 cm (22 inch)

I've been researching on the web for specific layup plans for different kayaks but very rarely find detailed layup plans as manufacturers tend to keep the details for obvious reasons (or i am just not good enough to use Google :D ), but with the information i have found so far i came up with a layup sequence and i was wondering if i could discuss it with you guys as i assume some of you have great experience already in building kayaks with different techniques. 

The inspiration behind the layup is cold moulding technique of wooden veneers.

The below sequence is based on a male mould (building from the inside out), where zero direction is along the chine:

 

-clear gel coat

-100 gsm (3.5 oz) 2x2 twill glass fiber ( 0-90 direction along chine)

-0.6mm straight grain spruce veneer (o direction along chine)

-320 gsm (11 oz) bi-axial glass or carbon fiber (+/-45 degree direction along chine)

-3mm 3D PET core

 -320 gsm (11 oz) bi-axial glass or carbon fiber (+/-45 degree direction along chine)

-400 gsm (14 oz) 2x2 twilll carbon fiber reinforcement on the deck at the cockpit area only (0-90 direction)

-0.6mm straight grain African mahogany veneer (0 direction along chine)

-200 gsm (7 oz) 2x2 twill glass fiber (0-90 direction along chine) on the hull and 100 gsm (3.5 oz) 2x2 twill glass fiber on the deck.

 

I will try to get all the layers up and infuse epoxy resin under vacuum pressure. As per my initial calculations the kayak would measure around 16-17kg  (35-37 pounds) without seat, footbrace, skeg.

I have mentioned glass fiber or carbon fiber as i am not sure whether one has a huge advantage over the other at this specific layup...

I would love to have some feedback whether the above layup would suit structurally for a kayak construction with the above mentioned intention of use?

Thank you

Regards

 

 

JohnAbercrombie

Sat, 06/06/2020 - 15:05

Why did yo decide on this style of construction?

How do you plan to keep the veneer layers aligned before infusion? And infuse through veneer?

It looks like it will be very heavy?

How did you make the male mold? Do you have pictures to share?

Hi John,

Initially the mould was made for building a cold molded kayak using out of autoclave, low temperature cure, epoxy resin film  as adhesive with additional carbon reinforcements on key areas such as cockpit, bulkheads etc, that it why it is a male mould and is being built from the inside out. Currently I have put that project on the side for several reasons, and i am looking for some alternative built method.

The veneer is only 0.6 mm thick and i am hoping that it will stick enough with the normal spray glue used in infusion process, but that is still subject for testing. This is plan "A"

 In case it won't i will leave the last layer of glass out from the initial infusion (which would be over the veneer layer) so i can just use tapes to hold the veneers on its place until the vacuum is applied. This is plan "B".

As for the infusion, it is again needs some testing, theoretically the resin should be able to penetrate through the joints of the veneer and get into the reinforcement, or else i can start the infusion from one end putting the feed line on the reinforcement (just need to leave it a bit longer than the veneer, which can be trimmed later) and have the suction point the other end therefore I can control the direction of the resin flow.

If neither of this would work as plan "C", i will do the infusion without the veneer and apply as a second stage process.

 

As for the weight i would be very happy to get some feedback which layers/ materials i should remove or replace, which are the ones i can sacrifice and still get a safe kayak, which can perform.

the mould was built as a traditional strip plank kayak with an aluminum strong back, marine grade plywood stations, meranti planks, and has 3 layers of wet laminated 300gsm CSM matt, i used high temp resistant epoxy resin and finally coated with Duratech paint.

sorry i ve been trying to upload pictures but for some reason i cant i reduced file size as well...any idea ?

cheers

 

Zoli