Back stay adjustment

[Chris Connor]

Good morning all.

Just wondering if anyone has installed any form of adjuster for the back stay in the Catalina 310?

I have been considering it. It would appear to be one of the few sail controls not available in the original configuration.

I would appreciate your thoughts.

Regards

Chris

 

[Witzend]

No, but I would also like to do the same so I can match the proper luff hollow cut into the head sail as conditions change. Use to race a J22 and used one all the time.

 

[valcour]

Adjustable Backstay

Because of the design of my bimini, I could not use the type that pulls the two wires together, so I installed a 16:1 adjustable backstay by drilling an additional hole in the flounder plate for a block, then doubled that into another block and a 4:1 adjuster. I left the OEM backstay in place for redundancy, and just backed the turnbuckles off. The only trick is to find a couple long chain shackles that will fit over the turnbuckle tangs and have the pin fit also. If you disconnect the backstays and bring them forward you can reach everything from a step ladder on deck.

 

[Witzend]

Very well thought out! No qualms about drilling a hole in the flounder plate? Bitch drilling stainless must go slow with oil. I suppose you could used a cable clamp just above the flounder plate with a 1/4" eye bolt inserted in the other half of the clamp to attach the block to.

 

[valcour]

backstay

I'm a structural engineer by trade, so i'll admit it did perform some mental calculations on the shear load in the fish plate. Even if you pull 100 pounds at 16:1 it's less than a ton of load so it is nothing to worry about. Keep the edge distance similar to the other two and you are good to go. Just drill slow with a couple of intermediate bits. If you go the wire rope clip method they should be re-torqued periodically (but if you leave the OEM wire in place even if it slips its no big deal).

 

[Don Guillette]

Why do you want to install a backstay adjuster?

 

[Witzend]

When a sail maker designs a head sail they purposely cut a curve in the luff of the sail. This cut is known as the Luff Hollow. The Luff Hollow should match the sag in the forestay. In order to keep the sag matching the luff hollow curve through out the load range of the sail the backstay is employed to change the tension on the forestay.

 

[Don Guillette]

Well, here's what happens when you crank on your backstay adjuster. The main reason to use the adjuster is to take out the fullness in the mainsail. This works great on a J boat or America Cup boat that have bendy masts. You can see how it functions by bending your index finger. The movement of your knuckle is pulling the fullness out of the middle of the mainsail. Cranking on the backstay adjuster on a j boat also moves the DRAFT POSITION.

Unfortunately, the mast on a Catalina and most productions boats resembles a telephone pole. In other words, you can't bend it - you end up raking it back. What happens then is the boat thinks you've picked up the mast and moved it aft. This causes weather helm, which is not all that bad, assuming that is the effect you wanted.

I had one of the nicest looking Garhauer backstay adjusters that they make. I never used it. I kept it there because it looked trick.

 

[Witzend]

Your correct Don on it's use to de-power the main on a J boat, but on the 310 the only reason to use it would be to match the luff hollow on the fly.

 

[Chris Connor]

Hello Don:

To be honest, I asked the question to determine if anyone thought it worthwhile to install the backstay on this model of boat. I am very happy with the sail controls that I have but several times last year I thought my forestay was sagging too much and believed that I could take some of that out with an adjuster. Perhaps I just need to tune my rig.

I am definately having second thoughts about the benefits of fitting the adjuster now.

I use your reference cards and book when sailing last year. It has helped me greatly in trimming my sails.

My great problem is that our season is so short and I am away overseas for at least half of it that I don't get to sail as much as I would like!

Regards,

Chris

 

[Chris Connor]

Ahoy Witzend!

Thank you for replying. If I may ask,... have you installed a backstay adjuster? Do you believe it beneficial?

Regards

Chris

 

[Witzend]

Hey Chris,
Depends on how tweeky you want to be. As Don has indicated there main function is to bend the mast flattening out the main, but this only works well on fractional rigs with flexey masts. In our case it's only benefit would be as I have previously stated. Tune your rig for 15kn and forget the back stay adjusted unless you are club racing and want to get the luff hollow matched in light air. If your sails are old and blown out it won't matter anyway.

 

[Don Guillette]

Chris: Here's the problem with sail trim control adjustment and it is a common one. I can't tell you how many boats I've been on where the skipper orders a sail trim adjustment and I say to myself I wonder why he is doing that? If I'm a guest on board I just do it because I'd like to come back sometime. If, on the other hand, he has requested my help, then it is a different story - every sail trim adjustment has to have a reason and he has to tell me what it is.

As you know because you have my book, all the sail trim controls for the main and jib are adjusting 4 things and they are draft position, draft depth, twist and angle of attack. There is only one sail trim control that adjust only one element and that is the traveler. All the other controls adjust at least 2 element. In the case of the mainsheet it is 3 and in the case of the fairleads it is all 4 element!!

To get to your question. Probably the back stay adjuster is the last sail trim control I would add to a production boat. I'd spend my money on an adjustable fairlead system first plus some other items.

I know guys that swear by the back stay adjuster and the trick is to use just a little of it - like just a couple of degrees of rake. Most skippers go to far with it and things get worse because they didn't know why they were doing it in the first place nor what they were looking for.

If you have a loose forestay have a local rigger adjust it. Using the backstay adjuster to tighten the forestay just adds other sail trim problems.

I hope I have not added a lot of confusion to this subject as I'm just a common seaman giving his opinion. Perhaps you could pop on over to the SAIL TRIM FORUM and present your question there. Actually, I'll present it and we'll see what happens. With the added info you'll get you can make a sound purchase decision.