Changing to manual back stay adjustment

[Cavalier 32]

Hi All,
My hydraulic backstay adjuster requires servicing; quote $400 to $800, won't know till they get inside.
So I am looking at changing to a manual arrangement. My Cavalier 32 has a single backstay connection to the hull and glassed and plated all the way down to the keel. To change to a manual system I am told I will need two chain plates on the transom. Don't like that idea as I would be concerned about the lay-up of the transom taking the strain of the backstay, even with backing plates etc. Question; How about a single block running from my existing backstay plate? Any guides on whether I could generate the pull required to tension my backstay? The mast is 11 metres and I am a cruising boat, so masthead tension isn't imperative, although is helpful. Is my rig to big to have a single block and tackle arrangement.
Cheers

Keith

[sailormed]

You could install something like the picture, but probably end up paying more then the repair. If it is for cost saving I would stay with the repair. Otherwise just go for a fixed back stay.

[Cavalier 32]

[QUOTE=sailormed;2801223]You could install something like the picture, but probably end up paying more then the repair. If it is for cost saving I would stay with the repair. Otherwise just go for a fixed back stay.

Thanks Sailormed. That was a consideration and you are right, the costs are the same or more for the servicing of the hydraulic unit. A fixed backstay is an option, but I am hoping to move one step up from that. I considered a simple Bottle Screw, but they need to be specifically the type that can be REALLY loaded and the price reflects that.

Cheers
Keith

[GordMay]

Originally Posted by Cavalier 32

... I considered a simple Bottle Screw, but they need to be specifically the type that can be REALLY loaded and the price reflects that.

Indeed.
Harken’s 6:1 Right Angle system is used on small (>29') cruising boats with a single line or wire backstay.
➥ https://www.harken.com/content.aspx?id=3896

Wichard ➥ Adjusters / backstay adjusters / with wheel / dia pin 12
➥ Backstay adjusters

[bootstrapper]

Hi, I have a hydraulic backstay adjuster , original equipement on my 1978 boat, it is very easy to strip and renew the seals, this is probably all it needs. On mine the top unscrews this allows the piston to be removed, unscrew the piston from the rod the remove the rod from the top housing. you now have access to all the seals which may well have part numbers on them. reassemble carefully with new seals and bleed at the hose connector, job done.hydraulic oil is readily available.I loosen the top before removing it from the boat, a pipe wrench with some rubber to protect the aluminium works for me. You have nothing to lose by trying to do it yourself.

[thunderhoof]

Don't be too quick to toss your old adjuster. My Navtec was not operating fully with no apparent leakage after 12 years.

There is a filling port on the cylinder near the handle end. I clamped the cylinder horizontal with the filler up and made a filling funnel of a plastic funnel and a nylon part that threaded into the cylinder and clamped on the funnel neck. Then I filled the funnel about halfway with light hydraulic oil. I slowly pushed and pulled the cylinder rod fully in and out until I saw no more air bubbles. I think I had to add some oil to keep the funnel from emptying. Then, being careful to exclude air, I put back the plug.

Works fine for three years.

[wmac]

The layup schedule of the glass in your transom should be more than adequate for a split backstay with two new installed chainplates which are properly backed on the inside of the hull. Loads on the fasteners for the chainplates are all in shear. They won't go anywhere. Combine with a Harken 6:1 or 8:1 backstay adjuster and your in business.

[stormalong]

Originally Posted by bootstrapper

Hi, I have a hydraulic backstay adjuster , original equipement on my 1978 boat, it is very easy to strip and renew the seals, this is probably all it needs. On mine the top unscrews this allows the piston to be removed, unscrew the piston from the rod the remove the rod from the top housing. you now have access to all the seals which may well have part numbers on them. reassemble carefully with new seals and bleed at the hose connector, job done.hydraulic oil is readily available.I loosen the top before removing it from the boat, a pipe wrench with some rubber to protect the aluminium works for me. You have nothing to lose by trying to do it yourself.

Be careful with that. Many hydraulic cylinders have a gas charge to push them out when the hydraulic pressure is released. My Navtec cylinders are built that way. The gas charge can push the piston out with lethal force. It has happened at least once that I have heard about.

[roverhi]

If your transom can't handle split backstay chainplates i wouldn't want to take the boat out of the slip. If you think the transom is too thin, you can add a couple of layups of fabmat and epoxy or epoxy fiberglass sheet to it. Because of the large angle of the backstay in comparison to the other stays, it has the lightest load. If your existing backstay chainplate is glassed into the hull I'd be more concerned with crevice corrosion in it.

Would go with a split backstay tensioner if that is most advantageous way for you to go. Have that on my 28'. With 4-1 tackle takes very little effort to set tension. Hydraulic backstay tensioners are expensive and not fool proof. A blown seal and the mast is going to be flopping in the wind. Probably not enough slack to to cause a failure but will make life interesting. Ratchet mechanical types work well but are expensive. Somebody has the ability to calculate the mechanical advantage of a single point block system but an 8-1 tackle might work.

[wmac]

The J 30 has as standard equipment a split backstay with a 6 or 8 to one backstay adjuster. The sail area is 444 sq. ft. as opposed to the Cavalier's 372. The J boat also has a cored hull. Never heard of a problem with backstays pulling out of a J 30. The least costly solution is still probably try to fix the hydraulic first then try a 8:1 Harken system to your original backstay. Good luck.

[zstine]

I blew seals in my 40yr old unit. Maybe there are some special ones with air springs, sound's rare. Do some research on yours. It is probably a simple tube with a piston, cap and some seals. I disassembled mine and took it to a local hydraulic shop that works on heavy equipment. They gave me a new set of seals for about $30. I put it together and it's been 3 years .... so.. learn how to unscrew the cap