Helm and steerage dilemmas!

[TrentePieds]

Quote: "She is a David Folkes 39 built in 82,...

Would this be "Harricana"?

David Folkes was a half-fast welder who built boats a coupla miles from where I lived at the time. Half-fast welding does not suffice for building boats, and I'll bet you dollars to peanuts that your hull is out of symmetry. Young David did not, IMO, know how to control the distortion that is induced by the welding process. Not much you can do about that, other than "bugger the symmetry the other way" by means of a trim tab on the rudder.

To get a definitive answer to whether my surmise is correct you'd need to haul and "take off" the lines, then develop an ACCURATE Table of Offsets, a tedious process that's prolly beyond the capacity and the ambition of a yottie. It's a surveyor's job.

But don't despair. A trim tab, which is simplicity itself to make and fit, will totally conceal the problem. Conceal it. Not fix it. But for "messing around in boats" you'll be just fine.

TrentePieds

[Steven UK]

this sounds like the seals have failed in the double acting hydraulic ram. what often happens is that because the pressure is equal on each side of the ram but the surface area on the piston is not the same (because of the rod) then when oil leaks it will favor one direction. some times when the oil is locked in the system i.e. the rod and 'other' side of the ram are closed the ram will extend by its self because of greater force on one side and slight leakage.

if this was my boat (which is 18' long and has a tiller) i would pull the ram and reseal it, in most industries this is simple but i have never done a 'Marine' hydraulic cylinder (probably the same just costs twice as much).

i didn't read every post so you may already have this info.

good luck.

[Friendlyfolkes]

Originally Posted by Jim Cate

I'm still not sure what you mean by constant correction.

Is it that you turn the wheel a certain distance, hold that setting and the boat goes straight, or is it that you must continue to turn the wheel more and more and more in order to maintain astraight course?

Please specify, for it makes a big difference in the analysis of your problem.

Jim

Hi Jim, to clarify, as the boat wants to constantly wander to port I am constantly correcting to starboard in order to maintain a straight course.

Jack

[Jim Cate]

Originally Posted by Friendlyfolkes

Hi Jim, to clarify, as the boat wants to constantly wander to port I am constantly correcting to starboard in order to maintain a straight course.

Jack

Jack, I'm sorry, but that doesn't answer the question. What does "constantly correcting" mean? Is it holding the wheel off center to starboard, but at a fixed position, or is it turning the wheel a bit, and then a bit more, and then a bit more, never returning to a previous position?

It really does matter which one is correct, for they indicate different problems.

Jim

[TrentePieds]

Uhm... Try this Friendly - that should sort out Jim Cate :-)

If you put your king-spoke midships ("straight up") does the ship turn to port at a steady rate, and after you straighten her up, with your king-spoke now a tad to starboard, will she hold her straight track?

or

AFTER you put the ship on a straight track, re3gardless of where your king-spoke then is, does she slowly begin to wander off to port again so have to apply ADDITIONAL wheel to straighten her up again?

TrentePieds

[Friendlyfolkes]

Originally Posted by Steven UK

this sounds like the seals have failed in the double acting hydraulic ram. what often happens is that because the pressure is equal on each side of the ram but the surface area on the piston is not the same (because of the rod) then when oil leaks it will favor one direction. some times when the oil is locked in the system i.e. the rod and 'other' side of the ram are closed the ram will extend by its self because of greater force on one side and slight leakage.

if this was my boat (which is 18' long and has a tiller) i would pull the ram and reseal it, in most industries this is simple but i have never done a 'Marine' hydraulic cylinder (probably the same just costs twice as much).

i didn't read every post so you may already have this info.

good luck.

Thanks Steven, the cylinder has a one-way ram, so fully extended its hard to port and fully closed its hard to starboard. I will take it in to get tested.

[StuM]

Originally Posted by Friendlyfolkes

Hi Jim, to clarify, as the boat wants to constantly wander to port I am constantly correcting to starboard in order to maintain a straight course.

Jack

Frinedly, as Jim says, you are still not making it clear what you are talking about. Please look at my post #28 above and answer with a simple A or B.

[Friendlyfolkes]

Originally Posted by Jim Cate

Jack, I'm sorry, but that doesn't answer the question. What does "constantly correcting" mean? Is it holding the wheel off center to starboard, but at a fixed position, or is it turning the wheel a bit, and then a bit more, and then a bit more, never returning to a previous position?

It really does matter which one is correct, for they indicate different problems.

Jim

Jim, my issue is the latter of the two issues you described. If I start out with the king-spoke amidships and the boat travelling straight at my desired heading
she will slowly track to port such that if left uncorrected she will do a 180 degree turn in about 2 mins. Therefore I am constantly correcting to starboard about a half a turn every 30 seconds. Hope that clarifies the issue?

[Friendlyfolkes]

Originally Posted by TrentePieds

Uhm... Try this Friendly - that should sort out Jim Cate :-)

If you put your king-spoke midships ("straight up") does the ship turn to port at a steady rate, and after you straighten her up, with your king-spoke now a tad to starboard, will she hold her straight track?

or

AFTER you put the ship on a straight track, re3gardless of where your king-spoke then is, does she slowly begin to wander off to port again so have to apply ADDITIONAL wheel to straighten her up again?

TrentePieds

Yes to the second issue you mentioned above TP. She wont hold a straight course without constant (additional) correction to starboard.

[Friendlyfolkes]

Originally Posted by StuM

Neither am all. All of his answers have been ambiguous.

Friendly, please state clearly do you:

a. Have to hold the wheel in a fairly static position but off center.
or
b. Constantly have to keep turning the wheel further and further.

StuM, the answer is B

[StuM]

OK, that suggests that the hydraulics are the problem.

[Jim Cate]

OK, Jack, that's what we were looking for! I'm no hydraulics expert, but it sure sounds like leakage somewhere. I'll leave it to folks who actually know something to advise further.

Good Luck, mate!

Jim

[TrentePieds]

Friendy: You saved my day yesterday :-)! I had to attend a really ,really boring all day meeting, so my mind drifted. To port. Every time I brought 'er back, she'd drift off to port again!

Well, what came to mind is that along the way you'd mentioned Wagner steering. And that means POWER steering. Not just your garden variety displacement pump driving the ram, but a full blown servo-steering setup like those used in real ships. Wagner makes good stuff. They are a Vancouver outfit. They also make the AutoNav auto-pilot and I'll bet you you have one of those. Wagner steering and AutoNav are joined at the hip :-)

So, no doubt, what is happening is that you bring your ship on course, using the wheel. Then the autonav sez "this ain't right!", and cranks on a degree or two of port helm. You bring 'er back on course, and the Autonav sez "he's screwing up again", and brings the boat back on what the AutoNav thinks SHOULD be the course, but then doesn't centre when it gets there.

I don't know off-hand and don't have an AutoNav manual how to key in the desired course, but assuming you do that as per manual, the AutoNav should not be sending signals to the servo-motor that is part of the pump you say you have rebuilt. And that must be what's happening. If you don't turn the wheel and no signal is received by the servo-motor then the ship should track straight, once you've straightened 'er up with the wheel. That would be true even if there is hull asymmetry.

So either you are not programming the AutoNav correctly, as per the manual, OR the AutroNav is outta whack, which that sort of complicated doo-dad can easily get. So the first step is to read the manual and follow it PUNCTILIOUSLY. When you are happy that you've done that, the next step, bei mir, would be to disengage the Autonav COMPLETELY even if you have to go so far as to disconnect the wiring from the servo-motor. If that cures the problem, you'll KNOW that the servo is receiving spurious signals from the AutoNav. If that's the case, you'd better ask AutoNav. They are in a Vancouver suburb called Coquitlam. Ask Ms.Google how to contact them.

TrentePieds