Forestay/Backstay length and tension.

KentB · **Posted:** 24 May 2017 13:29

When we purchased "Skybird" she was mast-down and needed new standing rigging.
Right away we put on new shrouds and a Harken Roller Furler.
One thing we noticed was in heavier air and waves, the cabin top around the main traveler would raise up and down substantially. Initially, I thought we had some structural deficiencies there.
Fast forward to yesterday. We stepped the mast and when tensioning the Port Lower, I could hear the cabinetry in the Head clunking as I pulled on the stay. I also could see the deck heave a bit.
We pulled the cabinetry and countertop and can see the lower part of the plywood bulkhead no longer is connected to the fiberglass pan (for the toilet and shower sump) this gives up a lot of leverage and puts all the stress on the tabbing which is tearing out.
Anyway, it appears to be a relatively easy fix, but got me to thinking...

I think the weight of the headsail furler is tricking me into thinking I have more backstay tension on than I think I do. The resulting movement had to be absorbed through the sail, sheet, traveler, cabin top. And also in the forward lowers.
I see that right now with the mast shims out, the mast appears to be raked aft slightly, which hints maybe I need to shorten the forestay a bit.
Anybody have any insight on how they set their lengths and tensions?

KentB · **Posted:** 24 May 2017 13:37

Sorry the pics needed rotated clockwise.

Velera · **Joined:** 29 Dec 2006 09:38 **Posts:** 656

A little hard to understand what is going on from the pictures. I will look at my boat tomorrow, but I do not think there is supposed to be any connection to the pan in the head. Some of the furniture is structural, but I do not recall that that part is. If the tabbing is loose on the plywood bulkhead, however, you do have a problem. I could not see the separation in your picture, but if it is there, it needs to be fixed pronto. You also need to understand why it failed did the bulkhead get wet and delaminate?
I think you may be correct about over tensioning the rig. I have the original manual and I recall that it says that there should be about a 4" sag in the headstay---it should not be bar tight--that will work the bulkheads loose. A little aft lean of the rig is fine a couple inches as I recall from the commissioning instructions.
FWIW
Ray Durkee
T 37 #373

KentB · **Posted:** 17 Jun 2017 07:46

It got fixed. We raced the "Mills Race" a night race on Lake Erie. Had a great sail, fantastic conditions and finished 4th in class (Jib and Main) - not bad for our first race. We were leading in the first leg, despite the light air that should have favored other boats. Better to be lucky than good, they say! Had we entered the "Cruising Class" we would have scored a first.
The repair was done by my brother in law and the tabbing was extended further down and is now connected to the shower pan (the part that attaches to the hull behind the toilet). All is well there so far. There was also a piece of plywood in that bulkhead that had been waterlogged that we replaced.
Our rig does appear to rake aft a few. Tensions look better this year. Still some slop in the lee shrouds when close-hauled and heeled good. (10-15 knots of air). A little worried about how much the leeward spreaders travel too an fro... I think they need some sort of plastic or rubber shim. Port side a P.O. drilled and tapped additional holes to limit travel that seems to work, but afraid it will wear away the aluminum eventually.
We still have the issue with the cabin-top heaving up while close-hauled. Clearly we have some structural issues to address there. Nothing a little time and epoxy wont fix...

Off to participate in the "Race for Hope" today.

cseltzjr · **Joined:** 16 May 2009 08:06 **Posts:** 236

Our companionway area also heaves under load. Further, there are small cracks in the fiberglass where it turns to the cabin top. I suspect they happened during an accidental gybe with one of the previous owners. They have not changed in the 18+ seasons that I have sailed the boat and I did have one accidental gybe about 10 years ago that disintegrated the traveler car. One of those things that I keep meaning to get around to. If and when I sell the boat, the buyer's surveyor will have a field day with it!

zdunc · **Joined:** 24 Sep 2013 09:20 **Posts:** 393

Same with my companionway if the main luffs in strong winds. Fix: bear off and stop the luffing.

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Forestay/Backstay length and tension.

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