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Mechanical Steering Failure

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Old 01-19-2008, 05:55 PM
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Default Mechanical Steering Failure

I a recent thread I started (Best upgrades 496HO) the question was brought up about upgrading to HYD. steering when building a boat that will run over 70mph for saftey purposes.After I decided to take the plunge and purchase it.I called a long time friend a long time performance boat enthusiest, and to his knowledge he has never actually seen a failure occur from the mechanical steering or steering components caused by performance upgrades . Has any one had happen to them personally or know someone that this has happend to directly ,please no stories of things you might have heard at the bar.(True accounts only)
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Old 01-19-2008, 05:58 PM
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I havent seen one break at high speed, but my buddy did snap a steering cable in the harbor. Lost all steering, woulda really sucked at 70 mph.
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Old 01-19-2008, 06:19 PM
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I have had a personal experience. When a power steering pump belt broke, the prop/engine torque threw the boat into a full lock turn at full thottle. Threw myself out of passenger side bolster onto the floor in the back, almost threw the driver out of the boat. Driver was hanging over the side, still holding onto the steering wheel.

We got very lucky that we didn't hit another boat or the shore.

I installed full hyd, to the helm, dual ram after that. Best improvement I've every made to a boat. I'll personally never own another boat without it.

Do it before you make your boat faster. You and me both will feel safer!
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Old 01-19-2008, 06:38 PM
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I will definately be installing hyd steering along with the upgrades without question .The cost of the upgrade is peanuts in the grand sceme of things and saftey has no price. This thread is more or less just to find out any true failures caused by performance upgraded boats at speed.
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Old 01-19-2008, 06:51 PM
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I never saw it as a question of the cable system breaking under load at speeds above 70 mph, but rather a question of the amount of control. As boats go over 70mph, the actual amount of boat in the water is quite a bit less. This will cause the boat to respond less to the cable style steering system as there will always be a little slop. The movement of the boat at high speeds intensifies the slop that may be in the mechanical system and you will have less control. A hydraulic steering system has no slop because the fluid is incompressible. This system will give the best control over the boat at high speed without having any slop or play in the system.

Geez, was I long winded enough!
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Old 01-19-2008, 09:54 PM
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I had one break on my Hydrostream when I first got it. I was running WOT and coming into the channel. There was a HUGE boat in front of me that I was trying to beat into the river. Well I went to turn and the boat kept going strait. I was headed right at the paddle wheels!! I looked back and saw what had happened (break was just outside the boat so I could see it) and turned the wheel the other direction. It was SCARRY!! I got dual cable steering after that.
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Old 01-19-2008, 10:29 PM
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The issue canīt be about the steering breaking. If you lose the wrong hose on a full hydraulic system, you will have a big problem, and no control over the drive either, although the possibility of the drive flipping over to full lock is minimised.
The improved handling through better control, and elimination of chinewalk inducing transom play, is the big reason for full hydraulic steering.
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Old 01-19-2008, 11:40 PM
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I've experienced a steering failure at full throttle in a twin-engine performance boat without external steering, and I can tell you it's not a pleasant experience. Mine was due to an intake valve retainer breaking and dropping a valve on the engine that hosted the power steering pump; the engine instanteneously locked up and turned the boat 180 degrees on its rubrail (we were traveling appx 72mph). My hand got caught in one of the spokes of the steering wheel as it spun and two bones were snapped in the back of my hand and the wifey was nearly thrown out of her bolster. The incident only strengthened my love of McCleod bolsters and Formula Powerboats- a lesser V or lower quality seating may have been disastrous. We were otherwise uninjured and returned to the marina on one engine, where we cleaned out our underwear. The other boats we were with swore we had gone over when this occurred- they said all they saw was a 'wall of spray'.

My take on external steering-
1) A full external steering setup, helm to drive(s) with dual-rams is a necessity in a high-performance power boat
2) Hydrodynamic force on a propeller that comes instantaneously to a dead stop from engine or power steering pump failure is enormous, and its VERY possible that the drag on that prop could displace the fluid on any hydraulic ram causing a hard-over condition, even with external hydraulic steering.
3) Unless you have a power steering pumps one each engine (highly unlikely), and your steering system is equipped with a priority-valve system that can automatically transfer pressure to the good engine in case of engine or pump failure, it is possible to have an incident even with a full external hydraulic steering setup.

Mercruiser used to offer a priority valve kit for twin engine installations whereas an owner could have a pump on each engine for just such occcasions. To the best of my knowledge, this kit was discontinued nearly a decade ago. I've since farted around with the idea of designing something similar- I have a pretty extensive hydraulic background from my work on jet aircraft. Such valves are used quite a bit (both priority and sequencing) in aircraft hydraulic systems, especially in landing gear.
If there was any interest, I might pursue it further- it would not be too difficult to produce. As in Mercs design, one engine would be master, one slave, and upon the event of engine or pump failure, the valve would simply shift when it sensed loss of pressure on one side of its piston and transfer pressure to the steering system from the bad engine/pump to the good engine/pump. You would only feel a 'bump' in the wheel rather than a hard over, which would give you a much better chance at reacting to your failure i.e. chopping the throttles and keeping the boat on an even keel.
I'm sure the offshore racing guys and riggers have a much better knowledge of all of this than myself- I'm only speaking from my personal experience. I DO know that you should never skimp on steering, and if I ever get into another twin, I'm going to figure some way of running a pump on each engine.
Jim
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Old 01-20-2008, 11:39 AM
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you have about 400psi in each cylinder on a external steering system fighting each other to keep the drive straight ,what do you think would happend if you running at WOP and one of those cylinders/lines sprunk a leak??
I agree that hydraulic system is a better steering system and would help chine walk and better steering responce,I just dont know that is that much safer than cable steering.
with that been said I would like to upgrade my boat to full hydraulic because it chine walks,but I dont know that it would be any safe as far as loosing steering goes.

Last edited by boatnt; 01-20-2008 at 11:42 AM.
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Old 01-20-2008, 12:50 PM
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How does throwing a belt or a pump suddenly stop turning on the cable setup cause a boat to turn sharply? I'd just think the steering would get hard to turn. Must be wrong though.

I agree with some others. No one seems to mention the possibilty of a HYD hose/fitting failure, resulting in an immediate loss of control. There's alot of hose and fittings in a full hyd setup.

jafo,
Fountain uses the priorty valve on all their twin engine setups. I don't think it as 1 motor being a master, the other a slave. But as both suppling in a balanced equal output keeping the valve centered. But as soon as 1 motor dies, the valve shifts to block the dead motor and then goes solely on the remaining running motor. PS always.

I see tons of twin engine boats where both motors are eqiuped with PS pumps, hoses, and coolers, but only one is being used. The other motor simply has the input and output hoses connected in a loop to keep the system sealed, but with no belt installed. Merc ships the motors out equiped, the boat manufatures just leave the access. intact. Wouldn't be very hard to add the priorty valve and a couple hoses to have this option working. Why the boat makers don't add this little extra detail when both motors are eqquiped is beyond me. The additional cost has to be minimal.

Last edited by US1 Fountain; 01-20-2008 at 12:58 PM.
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