Tuning

Posted By: Peter
Date: 9/26/07 8:56a.m.

Report: outside forum guidelines

In Response To: What is the best way to tune the rig w/ no backstay? (Todd-2023C-SFBay)

As I recall this was talked about in an old thread somewhere. I can tell you how I have tuned my rig... First, and very important if you have used one before on your boat, beg, borrow, or otherwise obtain the correct size (for smaller wire) Loos Gauge wire tensioning device. They are not horribly expensive and are easy to use. Next, center your mast by measuring the outer shrouds to get them equal. Then set an aft rake to your mast. This can be as little as 2" or as much as 8" (which is about where mine is). Do not set a forward rake; err towards more aft rake if you are unsure. Rake can be a bit difficult to measure unless you are doing it in the water and at a dock with the boat well trimmed for ballast and sitting on her waterline. I do it by eyeball with the boat on her trailer. Looking at the mast step plate is not a good measurement for rake. If your only adjustment for the forestay is which bolthole you use on the tensioning lever, you might want to consider upgrading that with a turnbuckle. I don't mean replace the tension lever with a turnbuckle, but install a turnbuckle in the wire so that the wire length is fully adjustable. This is standard in a CDI furling system. Now, with the basic geometry set, you are ready to tension. Start with the outers. Use the tension gauge and the recommended setting printed on the gauge. I believe you will want something like 20% of that rated working load of the wire as tension, which is quite a bit. Tighten port and starboard turnbuckles equally (you do have turnbuckles, right?) and check with the gauge as you go. Notice that the headstay is not considered, only the shrouds. The headstay will be correct when the shrouds are. And yes, with no load on the mainsail, there will be considerable deflection possible on the headstay if you reach up and give it a pull. When the main is loaded up, this gets much tighter! Once you have the outers done, move to the inners. These will be much looser and the gauge is useless for these. The inners are for keeping the mast in column. They are a bit tricky to adjust but the idea is to get them as tight as possible without putting an aft bow in the mast. Take the boom off and sight up the sail track to see if the mast is curved. You want that puppy as straight as possible. When you are done, head out on a brisk day and you should see the leeward inners go a slightly slack while beating, but the outer should not become visibly slack. If you are running with a backstay rigged, a very slightly slack leeward outer might be OK. Once you have a good tune, you can maintain it pretty well by the feel of the wire (what note does it play when you twang it ), but that Loos Gauge is indispensable for the initial setup. I would STRONGLY suggest that setting wire tension based on whether it goes slack when on leeward is insufficient for this boat. Make sure you have circlips or cotter pins or whatever your favorite keeper device is installed in the turnbuckles. As a bit of discussion, and in response to Todd's noticing that things seemed to slack a lot after that rowdy day, if you still have your headstay attached to that bolt through the mast at the top, the bolt bends and the rig goes slack. In fact, I don't think that headstay arrangement will support proper wire tension for the rig. I replaced the bolt with a homemade stainless steel "hound" which works MUCH better and I highly recommend the upgrade. Hope this is useful! -Peter