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First time mast stepping was quite an experience. Now I need some advice on rig tuning. Does anyone have approx. tension settings? Can I use a Loos type tension guage?
What Mark do you have ??? Yes, you can use a Loos gauge.
I have a '76 Mk III
Chris,and everybody else, Hi I'm John Graeb and a new 27-5 owner also and have the same questions and a whole lot more.... So anyone out there with a mark 5 please rsvp on this forum or E me directly. I'm looking for details and opinions on racing the boat. I had a C&C25-1 for 19 years and won boxes of trophies with it but this boat is definitely more squirrelly but responsive. I,ve had 3 friends own one of these and I bought it off of one of them. What I'm looking for is such things as...headstay length, rig tensions (shrouds and headstay), sail combos per windspeeds, weight placements, babystay tensions, and opinions on... weather helm, oversized chutes, 170 jibs, #2 jibs, different tillers(J24?) I have my first big race of the season NEXT WEEKEND!! (2 day @ Block Island) with nothing but a couple of informal Wednesday nights under my belt, the first local race of the year was canned by the weather and I can't make the 2nd race this week sooo... I need all the help I can get. please RSVP ASAP !!! (EDIT: Email address removed - Admin)
Last edited by (2009-11-30 23:08:00)
The Loos gauge (Pro2) settings for 7/32" are:
24-26 Aft lowers
26-28 Forward lowers
30-32 Uppers...
(This assumes adjustable backstay set to give about 8-12in aft rake)..
Hello,
I also have a C&C 27 MKIII, and can give you some info about tuning the rig. First, the 7/32" wire you have has a breaking strength of somewhere around 6,300 lbs. You will want to tune the upper shrouds to about 15% of their breaking strength, or 945 lbs. This is just a starting point, as you will then sail the boat and see if you need more tension. For the lowers, the starting point is 10% of breaking strength, thus about 630 lbs of tension, though on my 27 MKIII, I ended up at about 700 lbs + of tension to keep them from getting floppy at about 15 - 20 degrees of heel.
As for rake, You will want to mess around with this until such time as you get a little bit of weather helm under normal sailing conditions. We are talking small amounts of weather helm here, as in it just wants to turn up a little bit (and slowly) into the wind at say, 10 - 15 degrees of heel.
As for the process, here's how it all works.
1. Hoist the end of a tape measure partway up the mast. It doesn't matter how far. Measure over to the toerail (I measure to an acorn nut on the toerail so I know I'm measuring to the same spot side-to-side). Check the measurement on the other side as well. Center the mast so the measurements are the same. While doing this, tension the uppers somewhat, but not all the way. Say... about 350 lbs of tension - not enough to induce bend, but enough to hold the mast solidly in place. By the way, do all this tuning with the backstay adjuster loose, and the boom not tensioned against the topping lift.
2. With your rake set, begin tensioning the lowers. Sight up the mast slot to make sure the mast does not bend in the middle one way or the other. Offset any bend by tensioning the lower stays. Get it straight. One way to tell is to hook the main halyard at the gooseneck, and tighten it relatively firmly. The tension on the halyard will keep it straight enough to sight the mast & look for bend. Then look at the side of the mast, and induce a small amount of bend in the mast. The small amount is say, no more than 1/2 the width of the mast. That bend should go forward, and NOT aft. Accomplish this by tightening the forward lowers evenly (and watching for inducing lateral bend!). Once the amount of bend is right, then tension the lowers (again watching for bend) to "freeze" the amount of bend in place. Then tension the lowers evenly to get to the 630 lbs of tension.
3). Tension the uppers to 15% of breaking strength.
4). Go sailing. Get out in enough wind to heel the boat about 15 degrees. Watch to see if the shrouds go loose. They should get a little looser, but not be shock loading over waves. If you see the shrouds going "boing", they're shock loading. Site up the mast, and see if the masthead is tipping off one way or the other laterally. This is should not happen, and should be adjusted out.
Once you get this done, it should be finished. Mark the spots on the turnbuckles with rigging tape so that next time you step the mast, you can tension right to these spots and be close (if not right on).
Hope this helps,
Bruce, C&C 27 MKIII, "Moonstruck" - Chicago
With respect to fore and aft mast pre-bend, "That bend should go forward, and NOT aft." I presume this means the mast show bow aft meaning convex forward (concave aft), so that looking from the side, the mast curves forward in the middle and aft top and bottom?
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1974 Mark II C&C 27
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1974 Mark II C&C 27
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A mast that bows aft (concave on the forward side) is referred to as having 'inverse' bend. This is bad, as on a very bendy mast it's often a prelude to failure. On the tree-trunks we have, this risk is minimal to non-existent, but it will make your main unreasonably full.
David Weatherston
Towser, Toronto
C&C 27 Mk IV
David Weatherston
Towser, Toronto
C&C 27 Mk IV
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What tension should the forestay and backstay be on MK III? are these adj before or after shrouds?
how much rake should there be without any tension on backstay adj? 6"?
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