Shroud tension

Discussion about Precision 27 and 28

Shroud tension

Postby Bob » Sat May 31, 2014 1:59 pm

I frequently get a question about tensioning P-27/28 shrouds. I just did mine and found my settings in my log book.

Using a Loos gauge, I set the upper and lower shrouds to 14-15. Backstay tension depends on your sail and how much you want to flatten it. Mine is pretty light.

If you don't want to invest in an overpriced tool you will use once a year (I was given mine from a friend who I helped sell his P-23) you can do it over several sailing sessions.

Firm up the shrouds and make sure mast is vertical. Use the halyard to measure distance to a point on each side of the boat.
Make sure mast is straight. Too much tension on one lower shroud will bend the mast. Lay down on the deck and look up the mast.
Go for a sail on a moderate day, about 10 knots. On a close reach the leeward shrouds should be slightly loose. Go back to the dock and adjust if you need more or less tension.

Remember, more boats have been damaged with over tensioning than under. The shrouds are there to hold the mast up, not warp the sides of the boat inward.

Don't forget to put the cotter pins/rings in the turnbuckles! If you are going to readjust several times, a quick trick is to put the top cotter ring in and tie the two turnbuckles together with a short piece of rope. Now they won't turn and the shroud won't turn in the fitting at the top of the mast.

Bob
P-27 #17 NanSea
Edgewater Yacht Club
Cleveland, OH
Bob
 
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Re: Shroud tension

Postby steve34609 » Mon Feb 29, 2016 10:05 am

Hi Bob,
We just took delivery of a 1991 Precision 27 over the weekend. On the way up, on the Gulf, to our homeport, in about 10 knot winds more or less, we noticed that the leeward shrouds were not taut. In fact, they were loose and moving about. Of course I see the need to tune the standing rigging immediately before sailing again. My question for you is simple. Knowing that the tension should be set at 14%-15% of breaking strength, what was your solution to the issue i.e. did you buy a guage, have it done yourself or 'guesstimate' the tension? Also, what is the gauge of the shrouds, forestays and back stays? Tension on the split back stay? Any insights would be helpful as there is very little info out there on P 27s. It's a great, well-built boat and we're happy to have her. Thanks in advance.
Steve
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Re: Shroud tension

Postby Bob » Thu Mar 10, 2016 5:37 pm

Leave it as it is. The lee shrouds should be loose sailing at a close reach in 10 knots of wind. The 14-15 is NOT % of breaking strength but the actual number using a loos gauge. Until I got the gauge, I would set it up and and sail to see if I got the slack in the lee side. You can use a short line run thru each turnbuckle so they are bound together to stop them from turning during the testing. Makes it easier than removing and reinstalling the cotter rings until you get it set right. BUT, this line method is NOT for long term as the wire cable can still turn a little over long term.

I think more rigging has been over tensioned with a gauge trying to hit some percentage of breaking strength. Not he way to do it with a Precision.

Backstay can be any tension. it is there to keep the mast up. Increase the tension to bend the mast if you need to flatten the sail for your most common wind speed.

Bob
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