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Hydraulic backstay ?

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Created by sunycoastguy > 9 months ago, 25 Feb 2018
sunycoastguy
QLD, 223 posts
25 Feb 2018 7:01PM
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Hello all
My hydraulic tensioner needs oil how do you top them up with oil. Also i can only pump it up to about 400psi then it wont go up anymore. And it has a very slow leak. Cant find info on net. Or do i send these away for a service? If so who does it
Cheers

rumblefish
TAS, 824 posts
25 Feb 2018 9:16PM
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sunycoastguy said..
Hello all
My hydraulic tensioner needs oil how do you top them up with oil. Also i can only pump it up to about 400psi then it wont go up anymore. And it has a very slow leak. Cant find info on net. Or do i send these away for a service? If so who does it
Cheers


Firstly fill it with oil and if it still wont go to high pressure it needs to go to a hydraulic shop and will need stripping down and the seals replaced and maybe the bore and rod honing. Cost could be any where from $200-$600 depending on the seals.
Could also be too far past it inside, it may be not worth replacing.

What sort of boat? If it's a masthead rig and you hardly ever adjust consider replacing with a turnbuckle and/or a wire strop

cisco
QLD, 12361 posts
25 Feb 2018 9:13PM
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^+1
As Rumble says, probably not worth it and replace with mechanical or tackle system. Hydraulic backstay tensioner is overkill for anything less than 40 foot.

If you want to persist with it you could talk with these guys:- www.fleet-hydrol.com.au/
or
I am sure your local Enzed shop could help.

Ramona
NSW, 7727 posts
26 Feb 2018 8:09AM
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Mate with the alloy Cole 42 rebuilt his. He made a new piston and fitted new O rings. Probably cost less than ten bucks but his labour would have been heaps!
I have the turnbuckle wheel set up but would consider a tackle system and keep things simple. The hydraulic system is a good conversation piece though!

sunycoastguy
QLD, 223 posts
26 Feb 2018 6:32PM
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Thanks heaps guys with the tackle, is that like the one on main sheet, should i get similar size rope
It a 31 foot mast head rig, ive looked at other boats near me to copy but most have double chainplate.

SandS
VIC, 5904 posts
26 Feb 2018 8:07PM
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be very cautious playing around with hydraulics, would be a good job for an expert i recon .

Junkyarddog
VIC, 14 posts
26 Feb 2018 10:02PM
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Select to expand quote
sunycoastguy said..
Hello all
My hydraulic tensioner needs oil how do you top them up with oil. Also i can only pump it up to about 400psi then it wont go up anymore. And it has a very slow leak. Cant find info on net. Or do i send these away for a service? If so who does it
Cheers

Junkyarddog
VIC, 14 posts
26 Feb 2018 10:08PM
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Highly recommend the team at www.fleet-hydrol.com.au. Based in Sydney .Experts in the field . Very helpfull and good value.good turnaround time as well.
Well worth a call and a chat.
Cheers JYD

cisco
QLD, 12361 posts
26 Feb 2018 9:43PM
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sunycoastguy said..
Thanks heaps guys with the tackle, is that like the one on main sheet, should i get similar size rope
It a 31 foot mast head rig, ive looked at other boats near me to copy but most have double chainplate.


For a 31 footer with mast head rig, a hydraulic backstay tensioner certainly looks like overkill.

With the distance you have between backstay and chain plate, you have more than enough room to fit a 4:1 tackle with spectra line led through a clutch to a jammer or cam cleat to a winch.

If your mast is not tapered at the top, the purpose of the backstay tensioner is to take out forestay sag only and needs to have some power.

If it is tapered it's purpose is dual by taking out forestay sag and inducing mast bend to flatten the main sail.

With a tackle system using 6 or 8 mm spectra, the line will have more load capacity than your backstay assuming it is 6, 7 or 8 mm.

Most 4:1 double blocks I see have attachment shackles that appear to be of less load capacity than the blocks or tackle. Swivelling blocks should not be necessary in this application. Swivelling blocks of the same size tend to be weaker than fixed blocks.

In summary, make sure the attachment shackles have a load capacity at least 75% of the backstay load capacity.

I hope this helps. Cheers Cisco.

rumblefish
TAS, 824 posts
26 Feb 2018 10:43PM
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Select to expand quote
sunycoastguy said..
Thanks heaps guys with the tackle, is that like the one on main sheet, should i get similar size rope
It a 31 foot mast head rig, ive looked at other boats near me to copy but most have double chainplate.


No, massively more loads than your mainsheet.
Forget a tackle, waste of time and money on your boat.

Talk to your local rigger about replacing with a wire strop (I see in your pic there is already a turnbuckle under the hydraulics), the existing turnbuckles should be all the adjustment you need.

If you don't have a l9cal rigger, PM me and i can supply parts for you to install.

rumblefish
TAS, 824 posts
26 Feb 2018 10:48PM
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Select to expand quote
cisco said..

sunycoastguy said..
Thanks heaps guys with the tackle, is that like the one on main sheet, should i get similar size rope
It a 31 foot mast head rig, ive looked at other boats near me to copy but most have double chainplate.



For a 31 footer with mast head rig, a hydraulic backstay tensioner certainly looks like overkill.

With the distance you have between backstay and chain plate, you have more than enough room to fit a 4:1 tackle with spectra line led through a clutch to a jammer or cam cleat to a winch.

If your mast is not tapered at the top, the purpose of the backstay tensioner is to take out forestay sag only and needs to have some power.

If it is tapered it's purpose is dual by taking out forestay sag and inducing mast bend to flatten the main sail.

With a tackle system using 6 or 8 mm spectra, the line will have more load capacity than your backstay assuming it is 6, 7 or 8 mm.

Most 4:1 double blocks I see have attachment shackles that appear to be of less load capacity than the blocks or tackle. Swivelling blocks should not be necessary in this application. Swivelling blocks of the same size tend to be weaker than fixed blocks.

In summary, make sure the attachment shackles have a load capacity at least 75% of the backstay load capacity.

I hope this helps. Cheers Cisco.


Sorry Cisco but you would need atwo double blocks with approx 4000kg breaking load each!! Probably $700 a pop!!
Only safe way is with a cascade system but as said in my other response, waste of time in a masthead 31ft boat.

cisco
QLD, 12361 posts
26 Feb 2018 10:43PM
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Got a pic of a "cascade system" Rumble??

I have a high load block on my 8 mm backstay with a 6 mm 7x19 strop fixed one end and going to a 4:1 tackle the other. Non tapered mast, Marconi single spreader rig.

Any suggestions welcome. Can post pics.

rumblefish
TAS, 824 posts
1 Mar 2018 2:26PM
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cisco said..
Got a pic of a "cascade system" Rumble??

I have a high load block on my 8 mm backstay with a 6 mm 7x19 strop fixed one end and going to a 4:1 tackle the other. Non tapered mast, Marconi single spreader rig.

Any suggestions welcome. Can post pics.

Not real easy to post photos withb phone Sorry, just google 'backstay cascade system'

My point is with a masthead rig the block attached to the wire needs to be as strong as the wire, and the system have enough purchase so that a person pulling 40kg on the control rope can create a force on the backstay about 20% of the wire strength.

This means for a 6mm backstay (single backstay on up to about a 35 footer) the first block needs to have a breaking strain of 4000kg and you will need 20:1 purchase system!!
On a masthead rig you basically set and forget the backstay tension, hence why a turnbuckle is preferred.

Planeray
NSW, 217 posts
1 Mar 2018 2:56PM
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cisco said..
Got a pic of a "cascade system" Rumble??

I have a high load block on my 8 mm backstay with a 6 mm 7x19 strop fixed one end and going to a 4:1 tackle the other. Non tapered mast, Marconi single spreader rig.

Any suggestions welcome. Can post pics.


Harken has an awesome website with a heap of suggestions;

www.harken.com.au/content.aspx?id=3896

Tamble
194 posts
1 Mar 2018 1:56PM
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Seldon are worth looking at too
www.seldenmast.com/en/technical_info/manuals_for_assembly.html

If you can roughly align a rope jammer with a winch you can greatly reduce the purchase you need on a pulley system. Modern yachts have 6 to one

madmission
VIC, 234 posts
1 Mar 2018 6:09PM
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IMHO
I am a simple farmer , dont be too frightened by hydraulics my experience is they are usually relatively cheap and easy to repair especially if as you say they work but just leak over time providing no serious damage to cylinder may be worth investigating some maintenance.
You may find that because of the low oil you are pumping air and thats a lot more compressible than oil and shows up as a gradual decrease in pressure.
I also operate hydraulic backstay , mainsail trimming weekly on sydney 32 so can appreciate the marine environment and hydraulic applications.
good luck

rumblefish
TAS, 824 posts
1 Mar 2018 8:23PM
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Select to expand quote
Tamble said..
Seldon are worth looking at too
www.seldenmast.com/en/technical_info/manuals_for_assembly.html

If you can roughly align a rope jammer with a winch you can greatly reduce the purchase you need on a pulley system. Modern yachts have 6 to one


Actually 'modern' boats with swept spreaders don't need the backstay to stop the mast falling fwd are more likely to have 16, 24 or 32 to one on their backstay or no backstay and twin masthead running backstays with 2 or 4:1 run to a winch either side.

sunycoastguy
QLD, 223 posts
1 Mar 2018 8:47PM
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Thanks heaps for the advice, hay rumbalfish with the cascade system would i need two chain plates for that to work?

rumblefish
TAS, 824 posts
1 Mar 2018 9:55PM
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sunycoastguy said..
Thanks heaps for the advice, hay rumbalfish with the cascade system would i need two chain plates for that to work?


No but a single rated (ronstan) bow shackle should work, max pin size to fit chainplate hole which is probably 1/2".

But IMHO a tackle system is s waste of time and a big failure point for a MH boat.
If you really want length of adjustment put two turnbuckles inline.

Ramona
NSW, 7727 posts
2 Mar 2018 6:55AM
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This is Curlew, the 39 foot S&S on eBay at the moment. The hydraulic backstay has a remote control but would be similar as yours. As long as the bore and piston are not pitted the problem would be most likely the same. "O" rings are very cheap.



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"Hydraulic backstay ?" started by sunycoastguy