Backstay adjustment

[Figment]

As the winds of autumn pick up, I've been adding more and more backstay tension, but reluctantly, as I don't like leaving the rig in full-tension all the time, and the turnbuckle isn't really meant for quick or easy adjustment. Over the winter I'd like to fit an adjustable backstay device, and I thought I'd get ideas ahead of time.

I don't want to go hydraulic. I know rigs of similar size have them, but it just seems like overkill to me.

I'm thinking of something along the lines of some cascading blocks with a spectra safety. Easy to lay on, easy to release at the end of the day.

I could be persuaded into a screw-and-wheel system though.

Who has what on their boats?

[catamount]

On my Peterson 34 GREYHAWK, I have a hydraulic system.

On our San Juan 21 QUASAR, I have a 25US4-1 Garhauer Boom Vang tackle with regular dacron line (whatever Garhauer includes in the package). I took the tail end of the line and tied a bowline through the holes in the centers of the blocks to act as the safety.

On our Laser, we just crank down on the mainsheet.

[Summersdawn]

Someday I will add a backstay adjuster to my boat (San Juan 24). I will be going with a cascading system. Ever San Juan 24er I've talked to with this system loves it.

[Tim]

I think the block and tackle setup is the way to go.

I hate those wheel things...and hydraulic would be simply ridiculous on a Triton--all the more so if you're worried about overstressing the rig with a simple turnbuckle.

[jollyboat]

I agree with Tim. On 346 I had the backstay shortend and I fitted it with a 4:1 fiddle block tackle. It worked well enough but on 466 intend on installing a 'gross/fine' arrangement as I found with the 4:1 set up I had to "yank" instead of a smooth pull. This method is also very inexpensive and gets the job done. It is easy to upgrade, and maintain.

[brucebrown100@yahoo.com]

Does anyone have any pictures of their block and tackle setup?

Thank You

Bruce

[Figment]

This is what I'm working on. I think the most costly element will be the labor for the spliced eyes in spectra.

[Tim]

Just what you need to really torque that headstay pin... ;<)

[Summersdawn]

If my math is correct, that would be a 16:1 purchase. The way it is set up there, I think you might have trouble getting enough adjustment to be able to put on much backstay. With all the cascading doubles, I believe would require a very large amount of vertical adjustment for that last block.

If I am looking at it correctly, to tension the backstay 1", the first block moves down 1", the second moves down 2" relative to the first block, giving 3" in total, the third block moves down 4" relative to the second block, giving 7" in total, and the fourth block moves down 8" relative to the third block, for a total of 15".

Below is a diagram of a cascading backstay adjuster from a 24 San Juan. For the same amount of tension as above, I "think" the first block (Harken 084) moves down 1", and the third block (Harken 086) moves down 6", for a total of 7". This I believe is a 24:1 cascading system. By reducing the purchase of the bottom system to 4:1, you would have a 16:1 saystem, and 5" of travel.

The system below requires fewer splices in the spectra as well.

If my math is incorrect, or I am looking at it wrong, let me know.

[Case]

Whoo... that (now) imaginary backstay of yours looks nice, Figment. But I think its a bit too complicated. I've tried visualizing it in my mind and there seems to be too many lines and so on. Perhaps my imagination isn't that great, though.

Why not a 6:1 set up (triple blocks) with a doubling block? That will be a 12:1 set up. Add a padeye with a beefy (big) backing plate under the deck just forward of the backstay chainplate and connect the 6:1 tackle to that padeye. Add another line to the top of the 6:1 and it goes up to a single block on the backstay and then goes to the backstay chainplate. I think this system would be simpler. You also can do the same with a 8:1 tackle, Harken has a nice 40 MM (?) Carbo quad blocks and you'll get a 16:1 system this way, too.

Garhauer has nice triple blocks but no quads so for quad blocks, you'll have go to Harken for that.

Somehow I keep feeling that my terminology for some things are incorrect. Please tell me if I got the terminology wrong.

Let us know what you eventually go with. I spend time looking at the Harken catalog when on the Throne often. Their diagrams on various systems are nice.

- Casey

[Figment]

I think all of your math and terminology are correct.
Boy this whole thing would be a lot easier if I could just talk myself into an off-the-shelf system, but having used a cascade like this on a couple of boats, I'm reluctant to go back. :)

Aesthetics are driving this design as much as performance, if not more so. A pair of 4:1 tackles have much more visual bulk than a cascade of smaller 2:1 bullets, I think.

The long travel of that last bullet has a couple of important virtues.
Most importantly, the travel will have a limit, which offers a way to easily set a fine-tuneable "safety limit" into the system. Once that bullet is double-blocked, even an adrenaline-charged gorilla like me won't be able to unintentionally overstress the rig. The same is true for triple-double tackle, of course, but I remember from my beach cat days that the crossovers required in such tackles induce a good deal of friction as the blocks are drawn closer together, right when you need it the least.
The secondary virtue of that long travel is that the position of that last bullet becomes an excellent "gauge" of how you have the rig set. The quickest of glances tells you if it's at the top, 1/3 down, 1/2 down, etc.

But for all that, it is a lot of moving parts, a lot of potential failure points, and quite impossible to describe over the phone to a rigger who hasn't used it!!! :)

[Summersdawn]

Well, if you are determined to go this way, I would suggest hitting the hardware store first, and picking up some cheap clotheline pulleys. That way you could mock something up just to make sure it will work the way you envisioned. You could also work out your lengths to make sure you get all of your splices in your spectra in the right spots. If it turns out to not work out for you, you're only out a few bucks.

Aesthetically, your system it should look pretty good, if I am imaging it correctly. Very sleek.

Something to think about is having a UV cover to wrap around the spectra line while the boat is not being used, as UV can damage the spectra.

[Ric in Richmond]

Catastrophic backstay failure would worry me in these set ups.

I mean a piece of wire from head to stern seems pretty fool proof. All those blocks and lines and pins and shackles. One goes and do you lose the rig??

At least with a split backstay or a hydraulic you are metal to metal all the way.

A small hydraulic with integral pump wouldn't be that offensive....just expensive!!

Do you all trust all those failure points introduced by block and tackle that much?

[Figment]

Hey, I may be crazy, but I'm not foolish!

I didn't show it in the sketch because it isn't a "working" component, but I absolutely plan to include a spectra safety line, eye-to-eye spliced to the end of the backstay, shackled to its own hole in the chainplate.

I've seen plenty of block-and-tackle backstay systems in place without such a safety, and yeah it creeps me out a little.

Funny you should mention the expense of a hydraulic unit.... I was discussing this thing with a rigger at the Annapolis show. His first reaction was "jeez man, for what you're going to spend on blocks and splices, I could hook you up with a hydraulic for $150 less".
As it turns out this is not really the case, but it was an amusing reaction.

[keelbolts]

You guys are working way too hard at this sailing thing. If you're dying to bend your mast just take a long screwdriver w/ you to turn the backstay turnbukle. When you get in, back off the turnbuckle. There's much to be said for backing off on the rig tension of an old wood boat when not in use. I imagine the same holds for old plastic boats.

[Figment]

J got a decent pic of the cascade today.



I left the yarns untucked in case I wanted to adjust any of the splices.

[Tim]

Extra telltales.

And fancy borders around your photos!