Hydraulic Mast Ram

[dohenyboy]

just bought a sailboat with one of these
I understand its purpose is to pre tension the rig.
I thought the turnbuckles would handle that
Have done some reading but its not basic enough for me.
Seek illumination

[Delancey]

Interesting, what kind of boat?

Technically-speaking, what you do with the ram is post-tensioning. There should either be a load chip or a story stick to read the loading, do you have either of these?

[dohenyboy]

fractional rig sloop, 12 metre.
i have no idea what you are talking about
such is the depth of my ignorance.
post tensioning would be after you finish sailing for the day?
I want to sail it

[Sailmonkey]

Is this a hydraulic back stay adjuster?

If so it's used to control mast bend and forestay tension. Usually tight when on the wind and slacked off of the wind.


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[dohenyboy]

got one of them too, but I have used a backstay adjuster before.
badly I might add.
I went to the doctor last week.
He said I only have 50 more years to live at best.
Trying to cram in as much gusto as I can in the time remaining.

[Delancey]

Hey that's great! Congratulations on the new boat, sounds like fun.

Back in the day when racing boats more than likely not had big overlapping headsails there was an incentive to have very narrow sheeting angles, and by extension very narrow shroud bases.

So basically a very narrow shroud base equals very high loads as the mast gets taller. Mast-step rams perform a simple function for a couple reasons, basically they jack your stuff up, in a way that is in practical or easy to do readily with turnbuckles.

Usually they come equipped with a "load cell" or "load chip" which provides a reading of the load the ram is producing (lap-top hook-up or instrument reading) or a the very basic level a stick with a mark (maybe multiple marks) where it should be at.

[Delancey]

Basically, shroud tension occurs as a curve in relation to the shroud angle at the top of the mast which equals compression at the base. You have a very jacked-up rig that requires greater tension than can readily be achieved with turnbuckles.

Hence a single point ram, at the step, jacks your rig up, pulling against the shrouds and pushing the keel out the bottom. Lot's of force.

[dohenyboy]

ok, I get it. I doubt there is more than a stick
hope the rig is not too "jacked up"

[delmarrey]

My boat was built with a mast jack. This was the days (1979) before computers and chips. It had a pressure gauge in which to make adjustments. But it's long gone now. Probably due to pulling out a chainplate, which has all been rebuilt and reinforced. Just the hyd back stay for flattening the main is all that's left. The hyd Vang's gone too.