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ContinuousWave: Whaler Performance
Raised outboard at rest - OK to dip in the water?
|Author||Topic: Raised outboard at rest - OK to dip in the water?|
posted 04-27-2003 08:49 PM ET (US)
When at slip, with Yamaha engine tilted all the way up, the outboard is totally out of the water. When I lower the fully raised engine just a few inches so its sits on its pegs when at rest, the bottom 3-4 inches of the skeg sits in the water. Does it matter if some of skeg sits in the water?
posted 04-27-2003 09:26 PM ET (US)
Most engine sit to low which in the lock position.
Don't allow the skeg to be in the water because you will get pitting or electrolosis even with good zincs.
Just tilt it as far as she goes & leave it "OUT" of the water.
I'v done that with all my engines & no problems.
posted 04-27-2003 10:27 PM ET (US)
You might want to try a 2x4 or similar wedged in to allow the motor to rest on a stop, keeps the motor out of the water and the constant pressure off the trim cylinders.
posted 04-28-2003 03:35 PM ET (US)
Is constant pressure on the cylinders a problem or will it cause a problem?
I have a brand new Johnson motor and I want to take good care of it. I noticed that Bombardier puts a little plastic part that they say is there to support the engine on a mooring. If I use it, a tiny part of the lower unit is in contact with the water, so I've been leaving it trimmed all the way up and not resting on that piece. Is this a problem?
posted 04-30-2003 10:30 AM ET (US)
Fresh water or salt? Whats important here is to keep the exhuast intake out of the water especially in fresh water lake enviroment. this keep the "lake scum" build up out of your intakes. So too it would keep salt out of your intakes. In fresh water, as long as the skeg is painted you will develop a scum that can be sponged off and salt water should not be a problem. Im in a lake and I get the scum on the sked and bi-annually clean this but really as long as its not getting in the internal lower exhaust your not going to do any damage. Also whether you use you lock or tilt above to clear completely its not too much pressure on the transom. the lock is for pressure caused by trailer travel like a transom saver. but in the water,the water itself is a perfect spring cushon and the motor weight under wakes for exapmple is only disbursed into the water and not really placing any additional pressure anywhere.
posted 04-30-2003 05:27 PM ET (US)
I may be wrong but I always felt that if you took the pressure off the trim rams the seals would last longer. If the motor is extended all the way in the up postion and is not resting on a stop. It seems that the bouncing of a wake would exert greater pressure on the rams seals than if the motor were resting on a stop.
posted 04-30-2003 08:00 PM ET (US)
In support of Brian's theory (that trailering with the engine on a mechanical stop instead of a hydraulic one is better), I have this anecdote.
I never had any trim or tilt problems with my engines, and I typically trailered them in the up position using the mechanical stop to hold them.
One trip I trailered about 800 miles with the engines tilted up slightly, resting on the dual trim tab cylinders (not the single tilt cylinder). After that drive the port engine began to show some leaking and would slowly lose its position. A bad seal? A coincidence?
posted 04-30-2003 08:08 PM ET (US)
When leaving the boat in the water with the engine tilted up, be sure there is some zinc sacrificial electrode in the water, somewhere.
Usually extra zincs are mounted on the transom bracket of the engine, and sometimes there are cap nuts of zinc on the mounting boats, too.
If there are no zincs in the water that are in contact with your engine, the alumimum skeg becomes a prime candidate for galvanic corrosion from stray currents, etc.
posted 04-30-2003 08:44 PM ET (US)
My engine is in salt water at a marina. Based on great advice received here, I'll raise the engine fully and make an improvised shim for support so that no part of engine will sit in water and no pressure will be exerted on cylinder/seals when at slip. Thanks again.
posted 05-01-2003 09:27 AM ET (US)
After engaging the stop, I also continue to cycle the rams all the way into their housings to prevent damage and funk build up.
posted 05-01-2003 12:14 PM ET (US)
I don't know what brand you ahve, but the new Johnson/Evinrudes don't allow you to cycle the rams back into their housings - I did that with my old Johnson, though.
It's one thing to put the trailering support in place, but for mooring I doubt that wave action in a protected river area will cause a seal to wear out sooner if I leave the engine all the way up (and not resting on the cheap plastic mooring stop which I don't think supports the weight anyway).
posted 05-01-2003 06:15 PM ET (US)
If I may play sceptic here for a minute, how exactly does one know when the pressure is relieved from the trim/tilt cylinder? If a shim or piece of lumber or even the mechanical stop is used, then, consider the following: Before engageing, the cylinder is supporting the full (leveraged) weight of the outboard. When fully up, the outboard is almost completely balanced on the transom mount. As you lower it, the weight the cylinder bears increases. If you use something as a prop, then what will happen? As your outboard comes into contact with this prop, it will lodge, then if you overshoot just a bit, you will have actually applied a reverse force on the cylinder, accomlishing little. You will need to move it minutely up and down, and at best, guess when you find a point of equilibrium, especially if your boat is berthed and you can not stand behind the outboard and feel for play.
Jim, regarding your incident, consider the following, even though the cylinder is designed for in and out movement, you may have subjected the outboard to a bit of side play from turns, potholes, what not. The side play may have damaged a seal in your cylinder. Remember, the ram is made to move in and out of the cylinder, it may not be able to take too much side pressure, or at least not the seals.
posted 05-01-2003 10:04 PM ET (US)
Unfortunately I am not a mechanical engineer so my experience with hydraulic cylinders is limited to things that I have owned. But having a dairy farm in the family I was always taught to take the load off the cylinders when a piece of machinery was at rest. I am not arguing that my way is absolutely correct it is just the way I have been doing it and I have had great luck with my hydraulic cylinders. In my opinion when lowering the motor onto a stop there is no need to find the ultimate point of equilibrium the point is to take the static load off the cylinders. I have not seen an outboard manufacturer bulletin on this matter but my snowplow pump manual says to always lower the plow to a unloaded state when the vehicle is at rest. Works for me .
posted 05-01-2003 11:15 PM ET (US)
When the engine is not running, the load on the cylinders is from gravity.
When the engine is running the cylinders have to resist the thrust of the engine's horsepower, in this case 70-HP.
I would think that 70-HP pushing the boat through the resistance of the cylinder would create a greater load than the gravity of the engine when at rest and not running.
posted 05-02-2003 01:07 PM ET (US)
I vote we give JimH the honorary engineering degree. My 70Hp Johnson's resting lever fell off long ago. So, there she sits, partially raised in the tilt area (beyond trim cylinders), all the while she sits on the dock (yes on the dock). IMHO, If the tilt cylinder can bear the force of thrust beyond the range of tilt with the throttle at 3/4, then the force of gravity pulling on the thing resting at the dock is basicly inconsequential.
If you have equipment with hydraulics, and you leave the force on them, it tends to apply unnecessary force to the flexible lines, and in the event of a breakage while you are not attending that piece of equipment, it may drop and damage something below it. Ironically, the hydraulic unit of a power trim/tilt on an outboard typically does not have rubber lines, but uses a coiled metal tube to allow flexibility.
I side with JimH and find it difficult to believe that I'm more likely to blow a seal at rest, than if I am running 3/4 throttle and trim up beyond the trim range...
posted 05-02-2003 11:35 PM ET (US)
Having been similarly situated about five years ago, I called the outboard manufacturer directly. The answer I received was to keep the engine tilted as high as possible to allow the lower unit to clear the water.
Once tilted, the hydraulic rams, seals, and engine bracket should be sprayed with a thin film of silicone spray weekly. They also suggested spraying from the gasket for the cowling down the the lower unit with the same type of spray to protect the finish.
Having the boat in the broiling Florida sun during four months of those dreaded fires we had, I can attest to the fact that their suggestions worked beautifully.
posted 05-09-2003 04:11 PM ET (US)
To save some wear and tear(if there is any) I tilt all the way up and then a QUICK bip down to relieve the prssure. Never had a problem yet, same for outdrives. If you use a jack plate it will clear the water by about a foot and then using the trailer lock works.
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