PocketShip.net

I'm getting way ahead of myself here, but in reading ahead I became curious about the rake angle of the chainplate. In the manual it says to erect the mast and figure it out from there (I guess by stretching a line from the masthead). Or to "scale it off the plans." On the plans, I extended the line from the chainplate out to about 200 mm and came up with a rake angle of about 3 degrees aft. But the drawing in the plans is pretty small, i.e., if I didn't get the line exactly parallel to the chainplate drawing it could make a big difference.

Then I got to thinking (bad idea) and realized that the mast itself is not going to be perfectly straight, no matter how hard I try, so I should wait and use the line-stretching method. But what if I have to replace the mast some day? No way is it going to be exactly the same as the original mast, and you can't change the angle of the chainplate without weakening it.

So maybe the exact angle is not that important, as long as an approximately equal strain is placed on each mounting bolt.

It would be a huge help if those who have built the boat could let us know what the rake angles turned out to be.

How exactly I did this is lost in the dim mists of my memory. I'm pretty sure I scaled it off the plans, and it must have been close enough.

The best way would be to erect the mast in the driveway, complete with the little 3/4" block spacer in the tabernacle, with bits of string or your actual shrouds fastened to the mast. Drill the bottom hole of the tangs and pass a bolt through. Take up on the shrouds. The tangs will rotate into the perfect orientation. Drill the top hole. Done.

Simple enough. I'll wait and do it that way.

By the way I had been trying to do the angle measurement on Sheet 4, where I only had a very short line to try and extend accurately. Sheet 1 shows the shroud itself and gives me a much longer line. I extended this line down to the water line (the only horizontal line I could find) and found the angle to be closer to 87.5 degrees with a protractor, or drawing a triangle to the best of my ability it figured to be 87.52 degrees. The thing with these methods is that all sorts of inaccuracies can creep in--paper is unstable, etc., etc. Even if I settled on 87.5 degrees, how would I transfer that to my boat? Where is my horizontal or vertical line to measure against? They don't exist. If I had a perfectly level floor like Pete McCrary it might be possible, but I don't. So the method John describes with "bits of string or your actual shrouds" is the best by far.

I did exactly what John said: raise the mast and line up the wire with the chainplate. Well, I put in the top hole first, but I like the bottom hole idea better.

>>figured to be 87.52 degrees.

I'm not sure there's any feature on PocketShip worth measuring to two decimal points...

Kidding aside, everybody's deck-edge profile is going to vary by some fraction of an inch, so the empirical method---raising the mast and finding the chainplate angle "from life"---is the only way to be sure of perfection.

I recall creating a paper pattern because it was raining outside or something. I don't think the chainplate angle is perfect on PocketShip #1, but I haven't seen any harm come of it.

Mine was done with the mast up and lines pulled down to judge the angle. Too easy. All I can add is just how strong the mounting should be! When your under a 26 knot wind and the leeward shroud is flapping loose, you'll be wondering if you made the chainplate mountings strong enough!

Good one about the decimal places. Actually I had it figured to six places, but decided to round it down to two. Anyway, the practical way is the best way. Trig is fine if everything else is perfect, which it is not in the real world.

How could anyone get caught in a 26-knot wind? Seriously though, I hope the moorings for the chainplates are plenty strong, but I would rather sacrifice the mast than have the chainplate rip something out that would be much more difficult if not impossible to replace.

Take a read of this blog http://www.gaffrigsailinginwa.org/blog/

I can assure you, my little pocketship Precious Little performed extraordinarily against the other boats on the day. Certainly not as quick in the light winds though.

Thanks for the link--I looked briefly at the blog. Looks like fun and I'll read it more carefully later when I have time. BTW, I hope you didn't misunderstand my joke about getting caught in a 26 knot wind, because that's what it was, a joke. It's happened to me, and worse, on several occasions. That's the one thing I don't like about the Skerry--the only way to "reef" it is to scandalize the snotter (not making this up), and perhaps disconnect the sprit itself, but then you have a big triangle of sail flapping in the breeze. (You could unstep the mast, but you have stand up to do that--not a good idea in a little 100 lb boat. That's why I added a block and halyard so I can lower the sail while sitting low in the boat.)

Looking forward to the Pocketship with its two reef points.

P.S. Just now had time to read more of the article--not quite finished. Looks like you all had a great good time (except for the two capsizes) along with a lot of nail-biting.