Navtec back stay adjuster question

[Northbound44]

I bought a Navtec integral backstay adjuster model A370-A-12 that seem to work well and have no external leaks.
When I pump it up to the maximum, it reached 3200, then, after one day, decrease to 2200 and stabilize thereafter.
I am wondering if the pressure decrease is normal or the result of an internal leak.


Jacques

[Northbound44]

Is there anyone who can confirm if a pressure drop in 24 hours is normal on a hydraulic back stay adjuster?
Thank you.


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[UNCIVILIZED]

I'd think that if there were a leak, at least in the unit, that you'd notice it. As the oil in them is slippery as ****.

Assuming that it's a unit without a locking mechanisim. Then it'd make sense to check, whether, when you pump it up that high, if perhaps the headstay or backstay is stretching in that the frame that you mention. Thus, later, causing the lower pressure reading in your adjuster as the rigging stretches.

Simply attach a stick/batten, with measured off markings, to the base of the unit. And add a piece of tape to your backstay, down low, near the unit, to use as your index marker.

Then pump up the unit to X psi, & denote where the piece of tape on your backstay is vs. your measuring batten. And then check it every few hours, or at the end of each watch.
If the tape's moved much in 24hrs, then odds are there's a small leak in the unit somewhere. And if not, then you're rigging's just stretchng a bit, due to the pressure from the backstay adjuster.


One other possible cause for the pressure drop, is that when you crank up a backstay, you can literally bend the hull to curve into a bananna like shape. Either right away, or over a bit of time. Which again, results in the pressure in the backstay adjuster dropping.
And there are tests which you can do for this as well.

Regardless, you can always contact a reputable rigger about it, & or Navtec.
Also, on some units, it's possible to install a mechanical lock onto the unit, so that when you have a lot of load on your backstay for a while, the lock takes the load, instead of the "plumbing". Though I don't think that such is the case on this one, but it couldn't hurt to check. And such a mod might be a non-OEM one.

BTW, if the above description doesn't adequately describe how to test things/make sense, LMK. As I'm low on eloquence right now, due to a caffeine deficency


PS: What size wire/rod are your headstay & backstay? As most rigging's not hard to stretch significantly to begin with, & if it's thin, then it's that much easier.

[Northbound44]

Thank you for taking the time to answer me.
In fact, I did not install the adjuster yet, I just pump it up until the end fitting touch the base of the cylinder and until it reach the relief valve pressure.
My boat is a Hylas 44 with 3/8 backstay.

Regards,

Jacques


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[UNCIVILIZED]

Given that it's operating in a no-load state, then I can't say what to expect for certain. But they're designed to operate with a pull against them, so I'm guessing that what you're doing isn't a realistic test of how well the unit actually operates, or doesn't.

And were it me, I'd refrain from doing such "tests" to it that way. As to some degree, it's like dry firing a bow. Meaning drawing it, & releasing the string, without an arrow. The energy has to go somewhere, & it may not be the healthiest thing for the machinery.

I'd say that a real world test is needed in order to really determine if there's any issue at all. Which is easy enough to do, without having to put it onto the boat/backstay.

[Sailmonkey]

I'll second that. It will never be completely retracted on your boat unless you've done something awful to the rig.


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