On Jul 5, 11:09*am, Jay wrote:
On 7/5/2011 8:01 AM, jamesgangnc wrote:





On Jul 3, 12:45 pm, *wrote:
On 7/3/2011 10:43 AM, RG wrote:

* *wrote in message
....
I recently boat the referenced boat from a private party. *The boat
was in mint condition with only 44 hours on it. *Test drove it and
seemed to work fine. *Now that I've driven it more i'm a little
concerned about some engine noise / minor vibrations. *It seems when
I'm on plain, the engine noise / vibration is normal if the trim is up
(even by one notch). *But if I trim the motor all the way down (while
on plain), the engine noise increases and so does the vibration. *The
vibration feels like it is coming from the engine area or towards the
back of the boat. *I'm not sure if I'm overreacting or if this is
normal. *I mentioned this concern to my wife and she didn't even
notice. *If anyone has any thoughts I would appreciate it. * thanks.

Congratulations on your boat purchase. *I'm sure it will bring you and your
family many hours of enjoyment. *There is nothing wrong with your boat, the
situation you describe is completely normal for a single engine stern drive
boat. *In fact, what is happening is that your boat is talking to you, and
telling you how it prefers to be trimmed for optimal cruising attitude. *And
what it is telling you is that just like most single engine stern drive
applications, it prefers a bit of positive trim while on plane.

Here's how to determine the optimal outdrive trim for your boat. *Trim the
drive to the full in (down) position and bring the boat to your normal
cruising speed. *Once at speed, gradually trim the outdrive out (up) and
notice the behavioral changes. *You will notice that noise and vibration
will diminish, as you have already made comment. *You will also notice a
slight increase in engine RPM and speed over ground without increasing the
throttle, due to the increased efficiency of the boat being in proper trim.
Keep advancing the trim until the boat tells you you've gone too far.
Evidence of this will be increased engine RPM without an increase in speed
over ground. *This is the result of the prop losing its grip on the water
due to cavitation. *This is a very undesirable condition, and the cure is to
simply trim the drive back in until it stops. *So, where the boat wants the
drive to be is where noise and vibration are minimized and speed and rpm are
maximized, while avoiding propeller cavitation. *Note where this position is
on the trim gauge, and just leave the trim there for normal cruising.
Depending on how the boat is loaded, you may or may not choose to trim the
drive in while at rest to allow the boat to come up on plane faster. *If so,
just advance the trim to its optimal cruise position once on plane. *Also,
you may or may not notice the propeller cavitating on very sharp turns with
the drive trimmed to cruising position. *If this happens, trim the drive in
slightly before making such a turn.

RG

Great advice except for the trim gauge. If they work at all they are
highly inaccurate. Their best use is to indicate weather the drive us up
or down.- Hide quoted text -

- Show quoted text -

They're fairly easy to fix and even easier to adjust. *If you use a
level while adjusting it you can get it pretty accurate. *Helps if you
have a buddy in the cockpit.

Cut wires=void warranty. Replacing those pucks without cutting wires is
a pain in the butt. There's a third way but that's pretty tacky.- Hide quoted text -

- Show quoted text -

What warranty? I solder the wires, paint them with liquid wire
sealer, then cover that with heat shrink. But I have a trailer boat
in fresh water so my situation is the best. Frankly I don't think
boats that live full time in salt water should have outdrives anyway.