Friday, February 25, 2011

Scantlings and the "expedition boat" ...

Scantlings . . . explains the structural strength through girders and I-beams in a particular section and scantling length is considered as structural length of the ship.

Many years ago I completed the first year of Naval Architecture at, what was then known as, the "Cod College". If there are two concepts that have stuck with me, they are "scantlings" and "Lloyd's Rules". If memory serves me correctly (and I'm not using Google here), to be considered insurable by Lloyds of London, ships had to have proper scantlings according to their size and application. I doubt that Lloyds was ever called upon to insure a kayak but I'd like to think that my new boat would fit the criteria!!

When building a boat there is a fine line between weight and strength. Are you willing to sacrifice weight for strength and vice versa. In researching my boat, I've found the term "expedition boat" often used to describe one that is made a bit more durable, often at the expense of lightness. Not being one to be THAT hooked up on weight, I've opted for the stronger vs lighter.

Case in point. Last night I installed the bulkheads. Tonight, the decision was how to strengthen them. The options were - a) fillet them in and then epoxy the surfaces for waterproofness b) use fillets and glass/epoxy the surfaces for waterproofness or c) use fillets and then glass the whole lot AND tape the seams!  I opted for "c" and filleted and glassed ALL bulkheads on BOTH sides and ran a 6oz tape around BOTH perimeters of all bulkheads. Excessive some may say but for the sake of those few ounces of cloth, tape and epoxy, I know that this an "expedition boat"

FWD bulkhead - 6oz glass on both sides, filleted and taped with 6oz tape.

 Rear bulkheads - 6oz glass on both sides, filleted and taped with 6oz tape. 

Having completed this, somewhat arduous task, I am now ready to fit the deck!!

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