Jiblet design

No – not the guts of a chicken. The jiblets in a Split Junk Rig are the small jib sections in front of the mast. Since they are in clean air in front of the mast they should be more efficient than the main sections (mainlets?). hence they can provide a critical part of the drive of the sail. So their design is important.

I’ve been playing with some prototypes. The established thinking is that an angled shelf foot design is best, with the caveat that the actual sail shape will be different to the shape you think you’ll get. This tends to make me think ‘why?’ and try to understand how to get a predictable shape, when I should probably get on, make the thing and go sailing.

Ok – so first I tried a barrel cut jiblet. This was built into a panel with batten pockets and tapes to see how it all worked.

Barrel cut jiblet
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Moved blog to WordPress.com

The blog has moved to WordPress.com. I was running WordPress on Apache on Debian Linux at Bytemark, but it was taking too much effort to keep everything up to date. It is cheaper and more secure to move it to WordPress.com.

It is certainly an easy migration – very smooth and automatic.

Now I should have more time for sorting out boats!

Split Junk Rig sail plan

With the mast nearing completion it is time to finalise the sail plan. I’ve been using a scaled-down copy of the Poppy plan for the preliminary design. I’ve now followed through to make sure everything works ok.

As recommended I built a string and stick model of the sail. This is the first attempt – a copy of the Poppy rig. With old garden bamboo it looks pleasingly authentic!

Stick-and-string model – first iteration
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Owl: my current junk-rigged boat

I thought I’d describe my current junk rigged boat and show some of the design features. The boat is called Owl because it is green (as per The Owl and the Pussycat).

The boat is a 11′ GRP clinker-style boat originally built in the early 1980s for a gentleman to take his kids out in. I suspect it was adapted from a standard hull – probably designed for rowing or fishing. It had:

  • A flat centreboard that is a bit far aft;
  • A rudder that only just touched the water;
  • A standing lug rig that wouldn’t go upwind, with heavy yard and boom that reduced stability and threatened to hit heads.

However it did have a free-standing mast and, without the lug-rig up, was extremely stable. A perfect candidate for a junk rig!

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Mast partners sorted!

Figured out how to secure the mast at the partners. The rear chock now is ornamented by two bits of aluminium:

  • A plate on the bottom at the back to stop the back rising when the chock is pulled towards the mast;
  • A lashing point on the top of the block.
Rear mast chock with aluminium bits

In use it works like this:

Mast lashed in position

This is quick and easy to set up and very secure. I can lift the bows of the boat by pulling on a line to the mast top without any sign of the mast or chocks moving. As with all these things, once you figure out how to solve the problem it is easy and obvious.