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harbormaster
09-10-2004, 01:57 PM
I am planning out the install of A Latham dual ram hydraulic steering system.

In a twin engine installation, would you put the rams on either outboard side of the outdrives OR in between the outdrives? The inbetween looks alot cleaner. See the photo...

Hotspare
09-10-2004, 02:51 PM
Scot ,,, Clean looking setup for sure ...... But looks like your loosing some leverage being mounted to the inside of the tie bar ....... And also some stability by not putting the load between the drives on the tiebar exclusively ...... I think you'd get better leverage & mounting with an O/B instillation and have more stability in the ruff stuff ....... Just an observation ............. Bruce.

boldts
09-10-2004, 04:03 PM
Scot, just a thought here, but it also looks like the inboard mounting of the rams might limit the turning radius? Usually when mounted outside the drives, you have more room to work with and allow a sharper turning radius. Maybe they just use shorter cylinders when mounting inboard. I believe they are mounted inboard when there are other items like big KPlane tabs in the way of where the steering ram would need to be mounted. Kind of looks like that may have been the case in this picture. No expert here, just a thought.

MOP
09-10-2004, 04:42 PM
Scot I have seen them both ways, but have only installed outboard the limiting factor is the ram travel IE; length extended and collapsed. You can see if they will fit with a few measurements once the drives and wing plates are mounted. I think most like the look of outboard mounting, but mounting inside frees you of tab issues and is cleaner. The pictured setup is really neat with the telescoping swim ladder mounted above. There are no mechanical advantages or disadvantages, I would do it the way it works out for the rams you already have.

Phil

picklefish
09-10-2004, 08:26 PM
:lookaroun Since I know nothing about hydraulic steering except for what I've read in ads in Powerboat Magazine, let me throw in my two cents. The way they're set up in the picture one arm is pushing while the other is pulling. Wouldn't it be mechanically simpler if they were both mounted from the same side and working in parallel?

MOP
09-10-2004, 08:59 PM
Scot I was going through some of my old notes to get a base for your drive toe in setting, I feel you will need 1/2 to 5/8" to keep the drives from chattering. The prop shaft tips should be closer to each other from your center line dimension.

Phil

MOP
09-11-2004, 07:06 AM
As stated one pushes while the other pulls they do not simultaneously push against the tie bar, the tie bar assures they work in unison and maintain proper alignment. The same basic force would be applied at the ram in either location, there would be some change in force applied to the drives due to the angle. The question is better posed to the system manufacturer, in Scot's case he has a system and needs to fit it to its design.

Phil

BigGrizzly
09-11-2004, 07:51 AM
I have installed and helped install several sets of these, here is the scoop. Both Scotts are correct. However the inboard setup puts more stress in one single area of the transom. If places outbord the pressure is dispersed to the outter sides , which in most cases has the hull sides as strength. The sreering the rams actually have a push on one side and pull(and hold) on the other side. so both rams give support. As for cleaner look having seen both setups on the same type of boat , I for one do NOT think it is cleaner looking. This is my personal tast and not up for discussion. As for which is stronger- if the triangulation of the rams are the same than the strengh is also equal. My main concern is that the rams be level with the trim pivot on the gimble housing. Anything else is second class and won't go on my boats. Example of why. iI the rams are mounted above the pivot point and you trim up you are also fighting aginst the steering. I will end this now because the disscussion would be too long, and I don't care how so & so does it if it is not in the center it is irresponsible.

MOP
09-11-2004, 08:48 AM
Griz brought up the most important fact of the install the pivot location, which is essential. If not exactly on center line with the drive pivots it will cause the steering and trim to work against each other stressing both systems and over time one or the other will have the seals go or a line will pop if out of line.
Some will disagree but in any high performance setup I feel copper tubing helm to transom with over kill braided to the rams is the way to go, some feel the plastic absorbs some of the shock loading from the drive. If so it can also allow some unwanted motion.

Phil

BUIZILLA
09-11-2004, 08:50 AM
My main concern is that the rams be level with the trim pivot on the gimble housing. Anything else is second class and won't go on my boats.
Randy is very correct, and from the looks of the picture, it appears this was done. Well thought out installation, IMO. If you study the pic carefully, it's obvious that there is no way the rams could be mounted outboard of the drive trim centers because of the proximity of the K plane orientation. The boat in question here is a narrower beam, wide crankshaft centers, with restricted external ram mount options. In this boats specific case, the installation is well thought out, clean, and functional, FOR THAT HULL.
As for which is better Scot??? I would guess it depends on your beam, and your existing drive centers, of your installation.

JH

BUIZILLA
09-11-2004, 09:10 AM
some feel the plastic absorbs some of the shock loading from the drive. If so it can also allow some unwanted motion.Phil
Okay, i'm confused... :rolleyes: if it allows absorption, how can it also allow unwanted motion? :lookaroun

JH

Cuda
09-11-2004, 10:30 AM
Okay, i'm confused... :rolleyes: if it allows absorption, how can it also allow unwanted motion? :lookaroun

JH


That's exactly what I was thinking. The only way to absorb shock is by something moving, which would be counter productive in a steering mechanism.

MOP
09-11-2004, 01:53 PM
Plastic tubing will expand and contract very minutely, any side thrust transmitted from the drive to the steering system will cause this. With plastic one line will expand slightly and one will contract slightly allowing fluid motion within the system, which in turn will allow the drive to move side to side the movement may be slight but never the less present. On long tubing runs like in Scots size boat this is magnified due to the length. On our smaller sized boat it is more than likely not measurable due to the short runs. The motion is similar to having a bubble in a line, it takes some of the solid feel out of the system. A well setup system should feel as if the wheel is connected directly to the drive with no play. When plastic is used it should be routed low in the cooler areas of the engine compartment and protected from all heat sources that will help to minimize other than the normal design wall deflection under pressure.

Phil

gcarter
09-11-2004, 03:41 PM
My $0.02; you can never get all the play out of ANY steering system. On any hydraulic system, you'll have some tolerance in the piston seals, the cylinder and rod end bearings, the hoses, the hydraulic control valve, the outdrive steering bearings (remember...the bottom bearing is plastic), the transom mounting brackets, and finally flex in the transom itself.
After all, what do you want. It could be a case of gnat straining!!!! :banghead:

smoothie
09-12-2004, 04:10 PM
George,no harm intended but thats why boaters install it,believe it or not there is no play what so ever,think about if one is pushing and one pulling agianst each other,the key is to get all the air out of the lines so the system isnt mushy.

cigarette30
09-13-2004, 02:16 PM
Scott,

I tend to think the outside is "cleaner", and as far as "play" I have zero, the drives simply don't move without the streering wheel, and then only the exact amount..... it's the way to go.

Forrest
09-13-2004, 02:32 PM
Plastic tubing . . .

I wouldn't trust plastic tubing on any high performance installation. Use only real high-pressure hydraulic hose and fittings of suitable rating, especially if you are running a power-assisted hydraulic steering system - you know, the kind of steering that uses a Char-Lynn type helm unit. Plastic and copper tubing is OK for Seastar and Hynautic setups on outboards. Also, copper tubing is real pain to run and is subject to crack. I won't do that again.

gcarter
09-13-2004, 03:18 PM
OK everybody, let me amplify a little.
In spite of the feel of your hydraulic steering, it still has play in it. If you were to install some instrmentation on the transom to the cylinder ends, the drive pivots, etc, you would see it does move in relation to the loads applied to it. It has to. These boats are tough but they're not built like bank vaults.
So all I'm saying is the wheel play has been reduced from several degrees movement to probably several minutes or seconds.
Anyway, it's imperceptable. Hydraulic steering is the ultimate in steering systems.
There are excellent hydraulic plastic hoses available that are good for 2-3 k psi and are thin and flexible. Parker & Aeroquip both supply such products. I don't know the numbers, I've been out of it 18 years.
There was a question here a while back about the standard operating pressure of the GM pump. I dont think it ever got answered. But if I were to guess, it would be normally in the 300-400 psi range (I'm just guessing here) and it probably relieves at 800-1k psi. Anyway, not a lot of pressure.
I've designed systems upwards of 30k psi. Now THAT'S a different world.