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Message |
    
john nugent
Member
Username: johnnugent
Post Number: 14
Registered: 03-2008
| | Posted on Sunday, October 18, 2009 - 08:51 am: | 
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My 1987 Sundeck Tollycraft comes out of the water on the 21st and it has been a overall good season. One of the items I plan to look into is the rudders. While in the water i had a difficult time with marking sure the rudders were straight, which then would let me just use my engine controls when coming into my dock. So I figured if I turn the wheel all the way to starboard and then all the way to port, which took 5 full turns, it would mean the the middle would be 2 1/2 turns to starboard. I did that and marked the wheel with tape pointing straight ahead. On my next run out and back to the dock i just checked how the boat was running using my tape marking ( I was at no wake) and I was not going straight. So I did my 5 turns and 2 1/2 turns again and the tape mrking was pionting more to the port direction. I have done this several times and seem to come up with a different setting. My hydraulic resarvoir is full and at the correct pressure, all the conections seem ok, the rudders both looked good when she went in, in the spring. Has anyone ever had a problem like this |
makomark
Senior Member
Username: makomark
Post Number: 1697
Registered: 09-2008
| | Posted on Sunday, October 18, 2009 - 10:27 am: |
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What kind of steering system is it (who made it)?
Does it have one helmm station or two? |
Al
Advanced Member
Username: knuckle47
Post Number: 732
Registered: 09-2007
| | Posted on Sunday, October 18, 2009 - 10:55 am: |
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I am waiting also for an explanation on this one. Mine is a Hynautic, dual helm. I'm OK with repeatable results as I have done this also but when I get to full lock, it can still turn albeit with a shuddering feel to the wheel |
makomark
Senior Member
Username: makomark
Post Number: 1699
Registered: 09-2008
| | Posted on Sunday, October 18, 2009 - 11:41 am: |
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Trying to mark "dead Ahead" on a dual station is usually futile. Moving either helm's wheel will move the cylinder's piston and cancel the mark's usefulness on the other wheel.
The shudder Al refers to is the helm's pressure relief valve opening. It will cause the samme effect described above regarding the mark on the wheel. This means if you mark the wheel, then turn it to the stop and keep going until the shudder occurs, you've adjusted where 'dead ahead' is in relation to the mark (tape).
The older hynautics will do the same thing if the pressure reservoir gets low - wheel mmoves but cylinder doesn't = tape mark now invalid. |
diver dave
Advanced Member
Username: diver_dave
Post Number: 462
Registered: 08-2008
| | Posted on Sunday, October 18, 2009 - 01:11 pm: |
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Many hydralic cylinders are "unbalanced". My hynatic is, for instance. That means it takes a different number of wheel turns from lock to lock, depending on if you go CW or CCW.
Does your piston rod come out of both ends of the cylinder?
About the only way to reliably tell you where the rudders are is a dash mounted electrical rudder position indicator. |
makomark
Senior Member
Username: makomark
Post Number: 1702
Registered: 09-2008
| | Posted on Sunday, October 18, 2009 - 01:41 pm: |
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DD:
I only seen balanced (hydraulically) cylinders. Even my sea star is balanced (fluid coming out the cylinder on one side of the piston goes into the other end) and it's rod only comes out one end.
My was originally installed like yours; bit less 3 turns to go full over and bit over 2 for the other full over. I found the cause to be 'bad installation. When the cylinder failed, we got the newer mounting style and moved the mounting's center fromm original. End result was a much more symetric rudder swing.
I seen a couple of the stand-alone 'rudder transducers' and none of them were reliable. I've been told the ones to get are those designed for use with an autopilot system - they've known to last a while. |
Al
Advanced Member
Username: knuckle47
Post Number: 734
Registered: 09-2007
| | Posted on Sunday, October 18, 2009 - 05:17 pm: |
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AH!...Good explanation from both. Mine takes about 3 turns from "center" to hit either side swing. And I did do that tape thing up top but since I don't really use it, it never dawned on me that it is so far out of whack, it has no value.
The Bayliner has a wheel more like a car. With 3 spokes obviously set up to "look" centered. BUT, it is power steering for the i/o and is always the same.
I guess my biggest concerns are when pulling away from the dock and since I always open the hatches and check things before we leave, I'll center the rudders then, if they are not.
Do those rudder indicators have any good use on boats like these? |
makomark
Senior Member
Username: makomark
Post Number: 1704
Registered: 09-2008
| | Posted on Sunday, October 18, 2009 - 05:38 pm: |
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which "these" you referring to?
Personally, I never found a need for one. I don't use the wheel in the slip area. Once departed, if the rudders are off center, it's pretty obvious and readily fixed. Even running 5 or 50 miles, if there are any seas or wind, you wind up steering to the 'electronics'.
Bet the bayliner has a cable from the helm to the transom; they usually don't stretch or compress enough to worry about. |
diver dave
Advanced Member
Username: diver_dave
Post Number: 464
Registered: 08-2008
| | Posted on Sunday, October 18, 2009 - 09:31 pm: |
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"I only seen balanced (hydraulically) cylinders. Even my sea star is balanced (fluid coming out the cylinder on one side of the piston goes into the other end) and it's rod only comes out one end."
To be clear for everyone: Balanced meaning that one end of the piston sees the full hydraulic pressure, the other side of the piston only sees the pressure reduced by the area of the piston rod. A balanced piston/cylinder has a rod attached to both sides of the piston, so it will see the same hydraulic action CW and CCW. More important for this discussion, is the fact the the "rodded" end of the unbalanced piston will need less high pressure volume of fluid for travel, but will require slightly more effort to turn when underway.
Also, the unbalanced cylinder setup will contain more fluid when locked in one direction than the other, so your system requires a resevoir to accomodate the variable volume. The systems without the air over oil container likely can't handle the unbalanced cylinders. |
diver dave
Advanced Member
Username: diver_dave
Post Number: 465
Registered: 08-2008
| | Posted on Monday, October 19, 2009 - 10:07 am: |
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Ha, so much for making that clear. Modified text below:
UNbalanced meaning that one SIDE of the piston sees the full hydraulic pressure, the other side of the piston sees the pressure reduced by the area of the piston rod...
The one advantage of the unbalanced cylinder is only one rod seal, not two. |
Al
Advanced Member
Username: knuckle47
Post Number: 735
Registered: 09-2007
| | Posted on Monday, October 19, 2009 - 10:54 am: |
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I would have believed that usually larger sail boats might take better advantage of rudder inicators. THESE meaning under 50' sedans, crusiers or convertibles |
Ted Broderick
Advanced Member
Username: tbrodes
Post Number: 105
Registered: 02-2008
| | Posted on Monday, October 19, 2009 - 12:06 pm: |
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I have a rudder indicator on my autopilot. Very helpful just to get everything centered while heading into the slips... |
makomark
Senior Member
Username: makomark
Post Number: 1709
Registered: 09-2008
| | Posted on Monday, October 19, 2009 - 12:24 pm: |
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Looks like today is ECD - error correction day.
Mine was the "rod comes out one side" flavor; the rod does penetrate both end caps but one end hangs free.
Dave - you say the unbalanced cylinder's piston see different pressure due to the rod: " the other side of the piston sees the pressure reduced by the area of the piston rod... " technically not correct. The pressure will be the same on both sides of the piston. It is the force that is reduced or increase due to the difference in area and that only comes into effect when the piston is moving. Using the sea star sizings, if it were unbalanced, the area difference is ~ 8%.
Do you have a part number for that unbalced cylinder; I'd like to see one? |
diver dave
Advanced Member
Username: diver_dave
Post Number: 466
Registered: 08-2008
| | Posted on Monday, October 19, 2009 - 12:58 pm: |
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MM, you are correct about pressure vs force.
Kind of a confusing set of terms; If I say each side sees a different FORCE then the piston will always be accelerating! Anyway, many of the end mount cylinders are unbalanced. This site even shows the difference in CCW turns to lock vs CW lock.
http://www.boaterscatalog.com/item--Teleflex-Seastar-Cylinder-Side-Mount--telefl ex-sidemount |
makomark
Senior Member
Username: makomark
Post Number: 1711
Registered: 09-2008
| | Posted on Monday, October 19, 2009 - 02:33 pm: |
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I find the sales literature is the biggest source of confusion. In the steering systems, it is the time variable pressures and forces that make things work (with minimal maintenance). Another case where Zero is a valuable number!
Thanks for the link, I still haven't actually touched one (guess I spent toooo many years in the outboard/trailer boat shop). |
Al
Advanced Member
Username: knuckle47
Post Number: 736
Registered: 09-2007
| | Posted on Monday, October 19, 2009 - 09:00 pm: |
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That is the cylinder I have on the 34C |
