Lock Crowther 1962 Kraken 25 trimaran build and rebuild log

Thanks OS, It's good to have it done at last! The floats are like toys by comparision I've already done one float side and hope to have them both done soon. As much as the cold mold has been a tedious procedure I have enjoyed the build. You get good at putting in and pulling staples I've used and pulled over 10,000 on this job. The packing strap makes that part easier though. As nice a result as the triple diagonal gives I'd go for the double diagonal next time so much less work and just a bit more time working the veneers around the hard turn to the bilge at the back of the main hull.

 

I've moved onto laminating the second float side having completed the first diagonal veneer layup I'm laminating on the second and final veneer. I've also purchased a Barton snubbing winch to replace the original and very heavy bronze snubbing winch.

 

Looking good, Corley, the bending wood method is very attractive. Now, what sort of rig are you going to put on the 25?

 

I'll probably use the original rotating aluminium mast. Initially I was going to build a carbon wing mast for the boat but I'm going to "cheap out" a bit and save some money towards my Formula 40 build. I've had a sail loft (UK Halsey) quote out on my sails and I was surprised that carbon laminate sails were not that much more expensive than tape drive or dacron sails so that will be the path I'll go down.

They have proposed a quite flat cut assymetric spinnaker almost a screecher to power the boat up more over the standard C class rig I'll probably just run with the standard sailplan and see how we compare to the other boats in the club and if needed get the spinnaker made at a later date.

 

I've completed the double diagonal float lamination, pretty quick and straightforward versus the main hull I've nearly got a proa now one float hull left to laminate for it to become a trimaran a bit of glassing then onto the interesting fitout stuff and crossbeams.

 

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Corely, congratulations on your progress! What is the orange material appearing to hang off the boat?

 

I used one of the original floats with one diagonal lamination removed as my float mold form there is a layer of thin plastic in between to prevent epoxy seepage from the new lamination sticking to the old float. I dont have to be too worried as the first diagonal lamination in this case is laid up dry with no edge glue. I did a trial run to see that it would release when I had completed one side. I'm going to lift the new float lamination before glassing the two sides together with double bias so if the worst comes to the worst I can cut it down the centreline and rejoin.

 

The project is coming along although in many ways it would have been easier to make a new float mold rather than using the original float with a veneer removed as a mold. The advantage of building the mold is you can setup the position of internal bulkheads prior to lamination which gives you much better certainty of positioning.

The main problem is Lock moved a lot of things around on the boat relative to the plans while he was experimenting and nothing really lines up. The floats are also custom, shorter than the ones in the plans and came out of his head undocumented so it's a bit of a challenge getting everything right. I'm still half inclined to cut the deck off and have a look at his bulkheads for reference.

What I've settled on doing is laying up the float laminations and cutting them into two halves down the centreline then I'll glass the inside of both halves with 265gsm double bias glass refit them to the mold with screws and hold the gunwhale area with a deck jig I should then be able to take the original positioning of deck gear and crossbeam mounts as a reference. I'll then join the float halves down the centre with a tape of 400 gsm double bias pour an epoxy keelson on the inside and more 400gsm as a tape on the outside and glass the outside of the shells with 265gsm double bias fit internal bulkheads and finally join the deck onto the float.

If I was building in WRC I would not glass inside and out simply sheath the exterior with 200gsm boat cloth however the paulownia I've used for lamination is really soft and will need protection. I hope to prevent bruising when I hit anything the advantage though is if you choose to glass with double bias is it reduces print through from the lamination process and makes getting a fair exterior a much less onerous task it should also sandwich the internal lamination and make it less easy to puncture and significantly stiffer I will suffer some weight penalty though.

 

I've popped off one of the hull sides and sanded the inside of all the epoxy lumps and uneven sections in preperation for the first layer of glass. I'n going to drape plastic back over the float mold. Then I'll drop the hull section back into the lower edge and screw the top edge back into the keelson of the old float/mold to let the glass set off in the correct shape. The lamination is quite stiff it feels about the same as a 6mm sheet of gaboon ply as a reference. The advantage of the half hull approach is I can glass the inside easily with good access to the very fine bow and stern section.

 

Corley I am wondering why you are glassing the inside of the amas? Your construction seems more than adequate for the boat size.

 

I'm aiming for low maintenance as it's really hard to get to the inside of the floats glassing should help prevent me having to revisit any areas where water may get trapped by helping increase the epoxy film thickness I'm also a little dubious about the ability of the inside of the paulownia being able to take the loads where the bulkheads meet the inner skin even with a taped fillet, with DB glass on the inside it should spread the loads from the glue fillet sufficiently over the inner skin to prevent delamination. An additional reason for my concern is the nearly flat areas of the float around the bow and stern if everything was curved I'd not worry about panel stiffness.

Where we sail the courses are sailed around channel markers and those buoys are a scary thing to hit particularly with an outgoing tide I want to cater for a hard impact against one of those areas and be able to take the risk of going aground with some confidence if I was just sailing off the beach in placid conditions I would not worry at all but the boats that can stay out in a range of conditions generally win the race series not always the fastest boats.

The double diagonal lamination is really light I have not weighed it on scales yet but my guesstimate is about 5kg's a side so a little extra weight can be tolerated. If I can get the float weight somewhere around or below 20kgs each faired and painted I'll be very happy. Just out of interest the original floats weighed in at 40kgs each that was with years of paint and quite a bit of moisture content increase they were also fitted with hardwood bulkheads nailed and glued into position through the skin that were quite heavy this time the bulkheads will be filleted 6mm gaboon plywood.

My aim with these floats is to make them strong but not too heavy I have one of the other floats with it's skin still on and I'm going to take a mold off it to make super light cored floats in the future.

 

I've glassed the inside of one float side with double bias glass (265gsm) and refitted it to the mold. I have a thick plastic sheet seperating the glass from the mold underneath It's not strictly a mold release membrane but it's done the trick so far (no problems so far pulling bits off).

I've also sanded the inside of the second float half in preperation for the glass unfortunately no photos of the glass on the inside of the first float side too much of a rush to get everything wet out and positioned.

 

Just a little note to say my project is still making progress and will post some more pictures soon. On Friday 18th we have welcomed the newest member of our family Georgia Grace into the world. She arrived weighing 3.88kgs and mother and baby are well.

I've indoctrinated my other two and a half year old daughter Emma with sailing words and she now points at pictures in Seahorse magazine and says "spinnaker" which makes her dad smile (I'm already sizing her up for a trapeze harness). Georgia is going to learn how to say "trimaran" early on I hope

 

Congratulations, Corley!

 

Thanks, Doug!