Low Cost Stay Tensioner - Progress & More Questions

[rardiH36]

The other day I cobbled together a backstay squeeze tensioned in the manner of the thread last week using a set of snatch blocks that were on hand. Then went sailing. Into the wind, the forestay didn't bend as much and the belly of the jib seemed a bit tighter.

Now I've "upgraded" to something more lasting using other bits and pieces from my block and tackle boneyard box. See picture below. Action of the blocks moving against the stay is smooth.

The second picture shows how I am thinking to attach the downhaul line, which would like your opinions. (The knot just temporarily made as a rushed to leave the boat this afternoon. I will do a better job of attaching the line.) You are looking at the port backstay line as it attaches to the deck near the stern. One side will be the bitter end (as in the picture). The other side will attach the block and tackle arrangement to increase the purchase. I am thinking 3:1 for the block/tackle x 2 for the mainline leading through the block at the bottom of the ring. Say I pull the line moderately hard at 60lbs. That would equate to 180 lbs. tension on each side. I think that will not be an issue for the attach points (as in the picture). Much more tension already exists from the stays at natural tension, and the increased tension caused by the squeezing of the backstays by the blocks.

Thanks for your opinions.

regards,
rardi

 

[Ed Schenck]

No help here Rardi. I didn't even know the H36 had a split backstay. Makes "tuning" easier than my single that's for sure. And your rig looks professional although we cannot see the bottom. Is there enough purchase to run real loose down wind and still get the mast back for windward?

 

[Ted]

Purchase power

A 3:1 purchase doubled as you have done will be marginal purchase for a 36 foot boat. The pincher blocks will up your power but the real test will be to check the tension in your headstay and backstay. If you can increase the tension in these stays to 15 -18% of breaking strength of the wire, you have sufficient power in your setup. I have a 4:1 doubled with pincher blocks on my 29 footer and really have to lean into it to get sufficient tension going upwind. Keep in mind that as the pincher blocks move down the split backstay, it becomes more difficult to tension the split stays due to the geometry of the setup. Your end connection seems a bit awkward. You might try fitting a shackle in tandem with the existing fitting so that the shackle pin replaces the existing pin. The new shackle will provide a smoother fitting to tie off to. Better yet, put an eye in the end of the line. Keep the new shackle on the inboard side of each chainplate so your line runs clear of the split backstay.

 

[Hermit Scott]

Has anyone thought of using a solid block where you have the tensioner so the tension wheels can be on the out side of the split backstay wires AND the wheels for the rope used to tension it can be on the outside of the stay wires also, leaving the middle open? I can draw a picture if this description is not clear.
Like I said before my tensioner pulls to one side, but your set up looks better because it pulls symetrically in the middle, with out having to bolt through the transom.

 

[Joe]

I think you need more than 6:1 purchase for a boat your size.... 8:1 at least. Check out the systems shown in the links. Also, I would use wire or hi tech line rather than dacron rope for the single lead.

http://www.wichard-usa.com/Boat pages/Backstay page.pdf

http://www.harken.si/cms/images/stories/Harken/katalog/Intro/str35,36,rf_back1.pdf

 

[rardiH36]

Joe:

Thanks for the URL's. And your suggestion that I should be considering 8:1 or more. Wichard's system "C" is the one I was thinking to adopt. I have a lonely unused triple/double block set looking for a purpose. This will give 5:1 x 2 for = 10:1 total. Looks like I'll need quite a few more feet of rope. I can set up the 5:1 portion so the lead will feed nicely into a camcleat.

 

[Alan]

A much less complicated and far more powerful setup would be to replace the tri-plate at the split with a block attached to the backstay. Then run a line from one corner of the boat over the block and back to a turning block at the other corner. Then run the line forward to the winch through a stopper.
Now you have loads of power with minimal lines and gear. I use this setup on my boat but modified to run to either winch. This setup allows easy and powerful adjustment of the backstay.