Twisting Hulls

[middle_watch]

I find that when making a ply keel and bulkheads with balsa planking I have to be very careful to jig it down tightly while working as it twists very easily until the fibreglass is applied.

My father in law watching me struggle with some humour as my current bow decided to go it's own way and suggested I use MDF for the keel and bulkheads as ply is notorious for warping itself out of shape.

Anyone used MDF for plank on frame?

[ARH]

I find that when making a ply keel and bulkheads with balsa planking I have to be very careful to jig it down tightly while working as it twists very easily until the fibreglass is applied.

My father in law watching me struggle with some humour as my current bow decided to go it's own way and suggested I use MDF for the keel and bulkheads as ply is notorious for warping itself out of shape.

Anyone used MDF for plank on frame?

Its not the keel or the frames, its how you do the planking, you have to work either side, a few planks at a time, do to many on one side and it will curve , if you do not weight it down it will (HOG, ) bend up in the middle. ARH

[middle_watch]

Must be me, I have keel, deck and frames made up, even put guides on the bottom of the deck to locate the frames properly and make sure they were square, but when I lifted it from the jig to turn it over to start planking it twisted, mainly at the bow, does not help having the deck broken there for the rise of the forecastle. I had to screw it firmly down onto another jig designed to follow the contour of the deck before I could start planking.

My problem seems to be the keel, which is two lengths of 4mm ply glued together to make 8mm, is just not rigid enough and allows the frames to cant to one side or the other.