Tuesday, April 28, 2015

Furler and Gybe Preventer IPort side)

One of the things that one learns while single handing is that furling the jib in strong winds is quite a task. This is true even if you have already reefed down. Like many things on production sailboats the furler drum is about the minimum size that the designer could get away with. It really needs to be about twice the size.

Anyone who has ever hung on a line knows that you can exert a lot more force by pulling a line attached at both ends sideways then pulling at one end. This is called a catenary and the formula in Cartesian coordinates is:


On Reboot this involves knelling in the cockpit, pulling sideways on the furler line, and then while trying to hold it reaching over and taking out the
slack through the jam cleat. This evolved to running the line from the jam cleat to the winch. The problem was that the angle was acute and there still was no real way of preventing the line from slipping back as one tried to manipulate it. The old system looked like this:
Old Jam Cleat and Deck Cleat

When the sail was at the appropriate size the line was then lead back to the deck cleat and tied off. The reason is obvious from the picture (once you know what to look for.) Note the angle of the jam cleat. This cleat is supposed to be flat, the forces on the cleat have bent it upwards.

Over the past couple of days I have re-engineered the area so that the line comes back to where I am pulling on the side of the jib furling line. I also added a block to handle the port side gybe preventer. In the past it has been wrapped around another deck cleat. The new system looks like this:
The new system

The back power clutch is for the gybe preventer. The block in front turns the jib furling line around. The forward power clutch holds the furling line in place. The lines are missing as I am waiting for the 3M 4000 to dry.

I am planning on getting underway in a few days so there will be ample opportunity for a sea trial.

Fair winds and following seas :)

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