I carried out a little test yesterday. I have a supply of heat shrink insulation of around the right diameter. With a bit of heat it fits the shank of the eye bolts perfectly. So I'm thinking with a bit of mastic under the nuts and washers I shouldn't have any electrolysis problems. 

Gary Pick wrote: A friend of mine raised the issue of corrosion using stainless on aluminium. Do you consider this a problem?
With my eye bolts each end I was thinking of sleeving them with plastic tube.

Gary, sleeving them is the right thing to do. Also coating the hole with Tefgel works very well. Tefgel is expensive but you only need very little so the smallest tube will do the job.

Gary Pick wrote:I like the idea David, nice and simple. A friend of mine raised the issue of corrosion using stainless on aluminium. Do you consider this a problem?
With my eye bolts each end I was thinking of sleeving them with plastic tube.

Whenever stainless steel and aluminium are brought together, there should be something between them. A proprietary corrosion inhibitor, or even sealant. If there is no gap for water to lie in, there cannot be a galvanic cell to cause corrosion. A mechanical separator of plastic will also help.

Missed your post earlier Gary about how to attach webbing parrels. Have a look at the new sail photo gallery on my profile which shows some of the detail. The forward end of the webbing parrels are attached to shackles which in turn are attached to the batten forward end lashings. The after end of the parrels are attached to the battens with 2 or 3 turns of 3.5 mm polyester cord lashings around the batten. There are two small 'posts' or 'stops' on each batten which prevent the lashings slipping forward. These stops are made up of 12mm diamater by 12mm high high density plastic with a stainless steel screw through the middle. A simple elegant solution for which I can take no credit - the idea came from David Tyler.

What I mean Jeff is you can't just undo it, move it and do it up again.
The technique is very similar to what is called a Cobb & Co hitch.