Tuning the Rig

[wingman]

I have completed a first attempt at tuning the rig, except for the upper shrouds. I have a few questions for anyone who has done it before I replace all the cotter keys.

Are the lower shrouds 1/4 or 5/16 or 9/32? I cannot find my gauge I usually use to check the diameter, so I had to resort to the adjustable wrench and tape measure method, which is somewhat a swag. I get 1/4 that way, but my 1/4 open-end wrench (a cheap one, to be sure) is slightly too small.

The owners manual goes into great detail about how to set up the boat. It makes quite a difference if you do not follow it precisely. For example, if the B frames are not loose, the shrouds have a very different reading. Now, my B Frames have a very small region in which they are not in either tension or compression, so I had to be careful. Also, the backstay must be on tight!

However, the manual just says tighten the upper shrouds "until both shrouds are equally tensioned." How tight? What note should they play if struck?

I am 6' tall and I use the loos gauge as high as possible and still be able to read it, probably about nose level. I am trying to remember my static and dynamic load classes back in 1968 to decide if it matters whether I am at a certain point up the shrouds. I guess I should have tried it at 3" to see if I got the same reading. If I did, I would guess that the value is constant further up also. Anyone have an opinion?

Any other hints that may make this effort easier or more accurate?

Wingman

[Ron]

The boat is down in Florida and I'm not sure of the diameter of the cap and intermediate shrouds. But my copy of the manual gives 600 pounds as the recommended tension of the cap shrouds (the uppers). The intermediates are just "equal", but I'd assume it's got to be around 8 to 10 percent of the breaking strength of the wire. I'd go higher on both but it's probably not a good idea for a mast that gets stepped and un-stepped frequently. The one thing Tony was really clear about was that, after the cap and intermediates are adjusted, to make sure that both the A and B frames (which take the place of the lower shrouds), are in slight tension and not in compression. This could conceivably cause some damage if it was.

[simonhayes]

The lowest section of the cap shrouds he are 1/4" . I just bought the loos guage to measure them.

I had the same question about the upper shrouds. When I measure then both at the same point ( the one I could reach while balancing on the gooseneck ) they were about the same at approx 400 lbs of compression . This is less than 600 lbs for the Cap shrouds but were equal so I left them. I was thinking I probably need to tension them higher. I will get to that when I have solved my A frame tension problem (see other post )

[wingman]

Well, with rain and three weeks of business travel in Hong Kong, I have been delayed in my tuning efforts! I did determine that my lower shrouds are 9/32, not 1/4. BTW, you can only really tune the lower, outer shrouds and the intermediate shrouds that go from the outside of the lower spreader to the inside of the upper spreader. More on that later.

I did first borrow the cheap Loos tool and adjusted the lower shrouds to slightly over 600 lbs, based on 1/4 inch. on a day when it was blowing 15 - 20 and I had the first reef in with no jib, the shrouds were obviously not tight enough. Lots of sag! That convinced me to recheck the diameter, which proved that it was 9/32.

I looked on Loos website and there was a table for the P3 tool, which is used for the larger diameters. it showed equivalent measurements for 1/4 and 9/32 to get 600 lbs, so I still thought I might get away with using their smaller P2 tool. I did that adjustment while waiting for the P3 tool to be available from Amazon. When I finally got the P3 tool, I found that using the P2 tool had only adjusted the shrouds to #5, when #10 was required! So the interpolation between tools did not work.

Remember that all this adjustment was after doing the full adjustment of the frames, so, for better or worse, I am leaving the frames as they are, which is slightly able to wiggle, as I tighten the shrouds. I do test them after every adjustment to ensure that they are not in compression.

I finally adjusted each side to #11, which is just above 600 lbs. For reference, #15 is 900 lbs. I then went out in 12 - 14 knots with full main and jib. About 12 knots, the leeward shrouds were starting to get loose, especially the middle outside shrouds, which cannot really be adjusted. On my return, I check the lower shrouds and they now read #9.

My plan is to tighten slightly more and try one more sail in heavy winds before the winter, assuming I find time before more travel to Asia. I wonder how much temperature will affect the shrouds? As it gets colder, will the tension increase? It should, but will it be measurable?

Now imagine that you paid some rigger to do this work. I assume that the cost would be north of $300 if he also had to do the upper shrouds and the frames. That is the cost of the P2 and P3 tools combined. How would you know whether, on your first sail in high winds, the dynamic forces would not change the forces? Remember, at the dock you are doing a static setting. Once you start sailing, the load will distribute over the other shrouds.

Actually, the whole effort is pretty easy if you have the right tools. remember to keep the cable from twisting when you are adjusting the turnbuckle. Good pliers are required!

John

[wingman]

I discussed tuning with Tony at the boat show. He say all that follows is with the backstay off!

The critical part are the A and B frames. The b frames should be in tension, but if you are able to move them slightly where they meet the deck. This will prevent too much twist in the mast when it is under a heavy load. Too much twist and the A-frame can break at its connection to the deck.

The A-frames should be slightly loose for raising and lowering the mast, but for racing and for heavy weather sailing, you should have them in tension. This is most important to prevent the A-frame bending that some of us have experienced. Tony recommended to get a tapered bolt with a cotter key to replace the threaded bolt that is there now. This will allow a gentle tapping of the tapered bolt into the two overlapping holes.

he also has rigged a way to pump out the ama's whenever required, but it is much too detailed to describe here. He says a lot of water can collect there, even during a race, which is when a lot of water can be forced into the amas.

I guess I will redo my rigging when I launch in the spring.

John