Monday, July 20, 2009

Carbon Boom Rigging - Part 3

Installing more hardware, almost ready for line.

Detail showing aft mainsheet block installed. The hole in the bonded fitting had to be re-drilled and sanded smooth.

G10 mounting plate for the mainsheet block before bonding. The odd shape is to accommodate the Harken part so the block can pivot through the entire 180 degree range. A slight modification was also necessary to achieve this range.

The plates were sanded to the approximate profile of the boom. I masked the bonding areas and sanded the booms well for a good bond. They were bonded with West System 105/206 with 406 filler(colloidal silica) and a small bit of black polyester pigment.

This same epoxy/filler mixture was used to bond the outhaul cam cleat bases. Note that on these plates, I pre-drilled and tapped the holes. This way I could avoid adding holes to the underside of the boom near the vang fitting. I used some machine screws sprayed with Mclube to fill the tapped holes during bonding.

After I completed all the fillets on each G10 plate, I carefully removed the tape and wiped the surrounding area with acetone.

Outhaul cleat base on the underside of the boom near the front.

2 layers of 6 oz carbon were laid up over the top of the gooseneck fittings. Make sure you aggressively sand any bonding surfaces on the inside of the boom. There is likely still mold release/wax on the interior from when the boom was made.

The forward outhaul turning blocks were mounted and thru bolted using machine screws and nylon lock nuts.

The forward edge had to be sanded smooth after the layup had cured.

The G10 plates were re-masked sanded and spray painted black after they had cured. The hardware was then installed using Loctite blue.

For the mainsheet cleats, holes were drilled through the G10 plate and through the boom. Those holes were then tapped and fasteners were installed with Loctite. I talked with several people about putting these holes in the bottom of the boom. I wanted to avoid it if possible, but this ensures that the fitting will stay attached as it is not entirely relying on the bond. I used a hand drill to carefully drill these holes. In hindsight, I should have rigged up the drill press for this application to increase precision.

The vang strops were sewn using 1" tubular webbing sourced from APS. I also spliced a 1/8" spectra loop that was luggage tagged on the aft end of the strop to hook over the keeper fitting.

The keeper fitting was bonded on with a small loop (don't worry, those holes are not drilled in the bottom of the boom!). This loop is used for the mainsheet shockcord, which is inplace to keep things from hooking on the fitting.
The pole retraction thru deck sheaves were installed by drilling and tapping the boom. The fasteners were then installed using Loctite. I did not add any backing or reinforcement as these sheaves are very lightly loaded.


Next up is rigging the outhaul, pole retract, and the patented in-the-pole foreguy system.

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