Question about Jack Plate

[weekends]

How does a Jack Plate workes and what't advange and disadvange?

[Barnacle Bill]

They raise and lower the motor vertically. Some have a greater set back which gives you more stability. Being able to raise it allows for safer running in shallow water. But I guess the most common reason for using them is more speed. You can get them fixed, electrically operated or hydraulic operated. If you get an adjustable it is highly recommended you install a water pressure gauge. Outboards don't go very far without water getting in them for cooling.

[CrappiePappy]

How does a Jack Plate workes and what't advange and disadvange?

It is often desirable to move the mounting point of outboard engines aft from the hull's original transom by several inches. The two principal benefits of this are:

The propeller runs in cleaner (i.e., less-turbulent or less aerated) water that exists behind the boat.
The engine can be raised (sometimes several inches) which reduces the hydrodynamic drag by having less of the engine lower unit submerged in the water.
The net effect of these changes is to increase the propeller efficiency (from operating in cleaner water) and to decrease drag (from reduction of submerged lower unit). This increases the potential top speed of the boat, and improves the overall fuel economy.

In addition, there are some more subtle performance benefits to this mounting technique:

Bow lift (in static trim) may be gained from the changed weight distribution aft. When underway this in turn may allow the engine trim to become more vertical, resulting in the propeller thrust becoming more aligned with the forward motion of the boat.
The engine thrust will be applied with a longer moment arm to the boat's center of lateral resistance and the boat's center of gravity, producing greater leverage of the engine thrust on both the boat's course and the boat's trim.
Operation in reverse will be improved because of the increased distance between the propeller and the hull.
Radically reduced immersion of the propeller may permit use of more efficient propeller designs, further increasing efficiency.
Underwater drag of the lower unit may be reduced when its trim becomes more nearly vertical because of improved flow of water around the "bullet" of the gearcase.

... cp

[poppop]

wow....impressive answer....

[old fuzzy]

cp just about covered it

[Phantom309]

Had to go to archives over at Catfish1.com to copy this message I posted for someone over there quite awhile back.
This is the way I see it from the way I operate my little boat.
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When I jump my boat up on plane with the motor jacked down and trimmed down, here's what I do.
First off, before gunning it I have my trim tabs all the way down (this will cause the bow to stay down= quicker hole shot).
I gun it WOT, the boat takes off and will attain a certain speed/rpm, at this point I bring my trim tabs back up to bring the bow up (so as to not have bow digging in the water) and can feel speed picking up. When I'm comfortable that the bow is approx right, then I start jacking the motor up (less foot in the water) and I can feel the speed pick up some more, and see the mph/rpm pick up. I jack it up probably three inches. Then I trim the motor up a bit and watch the mph/rpm increase even more and can feel the boat pick up even a little more speed.
There is a point where rpm increases but mph does not=not good, also got to watch water pressure guage to know water pump is getting enough cooling water, etc. So, ya gotta watch the rmp/ water pressure and not go beyond mfg recommendations.
So there are three toys to play with to squeeze max mph/shallow running performance out of the boat.
Once ya get used to playing with these things you don't really need to start out all the way jacked/trimmed down, etc. If I'm in plenty deep water I'll get all set and just leave them set for the whole fishing trip. Trick is using them in super shallow water.
Have a nice day
Danny

[weekends]

I like to thank every body for answering i learn alot.