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Saturday, November 03, 2012

Bow Pulpit/Sprit Part 1.5 is Complete

Part '1.5' of the bow "puplit", as I often mis-type, is complete. I call it part 1.5 as the original idea was to do this in three parts. But I ended doing part 1 and half of part 2 at the same time.

This is the "platform" portion and the construction is 316 stainless steel using 2 and 1.5 inch heavy gauge tubing with 1/2 and 1/4 inch plate.
View from above
Attachment to the caprail is via four plates: 2 fore, 2 aft. The aft plates are fastened using 6 (3 each side) 5/8-inch flathead socket cap screws threaded into half inch thick stainless backing plates (glued to the underside of the caprail).

The forward attachments are via two "straps" of 1/4 plate, bent and shaped to fit over the edge of the bulwark. These are fastened to the bulwarks using 6 ( 3 each side) 1/2-inch flathead socket cap screws threaded into 1/4-inch thick backing plates (glued in behind the bulwark).

The glued in backing plates keeps the tradition of  one-person-one-tool unfastening and removal. But actual removal will require mechanical assistance, like a forklift, due to the weight of the structure.

The straps serve other functions as well. Atop the straps are welded a pair of stainless chainstoppers that will handle up to 3/8-inch chain. It is through these that the anchor rode(s) will lead from the (future) windlass through rollers and over the side. The straps also act as rubstrakes so the chain does not chafe the caprail.

Straps and chain stoppers

Chain stopper, 'stopping' some sample chain
Remaining tasks include further test and design of the anchor slot cheek plates and placement of roller axles. This is to get an optimal setup for various anchor types such that they can be deployed and retrieved easily (ideally they will be self-launching).
View from underside
Final metalwork will include the anchor slots, the upper rail structure and tabs for mounting the "floor" pieces in the open areas of the tube structure. The current idea for these pieces is this fiberglass grating material, provided we can find a color we like, of course.
Material planned for "filling the floor" of the pulpit
Originally quite nervous, I am now very pleased with this project so far. Getting it "wrong" (misaligned parts, mounting holes, etc) would mean many trips back and forth to the metal fabricator for tweaking. In the end there was only one test fit, and it was spot on. All the credit goes to Craig, our stainless/aluminum fabrication guy here in town. He does stunning work.

Next for the pulpit is fashioning/fitting the bobstay. A fairly straightforward project.
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