Lock Crowther 1962 Kraken 25 trimaran build and rebuild log

Here is my marked up scan of the K25 main hull sections in .pdf. I don't vouch it's perfect but it did work out ok for me. The boat of course is no cruiser but there is a reasonable amount of hull volume for daysailing gear/picnic basket etc around the daggerboard case area.

I glued in the deck and beam supports today.

 

Thanks!!! Will run them out and see where I land. Sorry for late response, been taking care of my dad a bit these past few weeks. He's had some minor health issues somive been pulling the load for him round there house.

Barry

 

No worries, hope it's of assistance, all the best.

 

A bit of work completed today I built a small rolling platform and cradle to carry the main hull so I could break down and remove the original strongback and clear up the workshop. In the next few weeks I should get the platform, crossbeams and old floats mocked up to confirm bulkhead positions and alignments.

 

Nice! Looks like you got the top form all sorted nice as well.


Barry

 

Hi Barry, It's not perfect and has a slight twist in the front and rear of the hull nothing that will cause problems but a fixed strongback while building would have been better as far as keeping things square.

 

For sure when your dealing with wood keep it locked down as long as ya can! Haha been thinking long and hard about how I'll proceed and for sure I'll do good strong back with a preset gunwale incorporated into molding. I'll be doing cedar, cause its abundant here, with cove and bead. Plan is set a nice 3 inch wale with a bead in it and start stripping right onto that. If I make it from a 3x1/2 I can shape it hull thickness plus a ledge for deck landing. Which I'm hoping gives more reference points for accurate hull shape. The one thing I'm hashing around is this, is it worth either raising free board or doing short ramps, in order to get rid of drop off where beams cut across hull? Or would a nice fairing on beams take care of that.


Barry

 

Oh and maybe for yours you can add some anti twist when you glass hull?


Barry

 

It's pretty minor I ran the plane over it today in a few selected locations and now the perfect eye is pretty satisfied. It wasn't much and I think I can tweak the last bit out when I fit the bulkheads and daggerboard case. The only thing I'd do differently is setup the case and internal bulkheads first, accurate measurements at the mold stage are a bit easier.

 

Just imagining how daunting a task that'd be with the overlapping strip. You'd have to run strips between bulkheads rather than over them, and glue to them but not hit strips. It's by far the most beautiful looking hull but man! lotta tricky work! What was your final hull thickness btw?


Barry

 

6.6mm on the main hull

 

It shouldn't be too bad to set those elements in position with a strip build just setup your mold segments as usual and since you don't have any battens fit your bulkheads and fair with a batten to the surrounding mold forms. You could even make them a bit undersize and make the gap good with some thickened epoxy when you pull the hull. The alternative would be just mark out and cut the daggerboard slot and fit the case once you turn the hull. It's not impossible to fit the bulkheads after constructing the shell anyway so do it that way if you like.

I'd keep the strips at the keelson and gunwale full length if possible and make up the short and tapered strips to fit round the curve of the bilge.

 

Well doing horizontal strip as I plan to do it's pretty straight forward, just like a canoe really. I was thinking more with the diagonal strip style as yours. But I gotta say, after reading this up a bit on gougeon brothers articles the diagonal strip method makes more sense now. The natural spring to wrapping that way seems to ease the need for some longerons in assembly. They show some assembly with very minimal framework for mold.

Barry

 

It's pretty cool to build with the cold molded method not especially quick but it does make nice shapes that shouldn't require too much fairing if your basic mold is right.

 

How much epoxy did you use on main hull?

Barry