By Thomas P.

As we saw in the previous article concerning the appropriate mounting height of our engine we can not achieve at the same time, in the same combination boat-engine-propeller, both the maximum speed and the greater thrust at low rpm. The solution to this problem can provide the use of a hydraulic Jack Plate which enables us to adjust the vertical position of our engine only with a button, even when the boat is on plane.

Power Lift

First of all, by using the Jack Plate we can easily find the appropriate height of our engine on transom for all-around use, simply by measuring the performance of our boat in every lift position separately. We do not need to go to the workshop each time to raise or lower the engine until we find the right mounting height on the transom.

Without mounting the Jack Plate we are forced to weigh our needs and get an average performance of the combination engine-propeller-boat, while with the Jack Plate we can get the maximum performance of our boat in all circumstances without compromise.

Generally we can have the engine at very low or very high positions according to our desires or needs. For example we can lower the engine when we want to get on plane faster or when we need great thrust at low rpm, when the resistance is too large. But when the boat gets high speed and its wet surface is less, which means less resistance, then we can raise the engine higher so as to minimize the exposure of the gear case in the water and thus to achieve lower fuel consumption and maximum top speed.

The advantages, however of Jack Plate's use are not only these.

Submerging the lower unit of the engine lower, beyond the maximum thrust obtained by increasing the performance of our boat when we are overloaded or when facing rough weather, we can achieve high angles of trim, which allow us to lift the bow higher when conditions require.

The use of Jack Plate still gives us another important ability: to get the maximum performance from each propeller which we have matched on prop shaft. Simply because all propellers are designed differently and some may perform better when they are submerged in water and some others when running near the sea surface.

 Power Lift

For example, let's suppose that we use a specific 3-blade propeller and we managed to find the perfect for this engine mounting height to get the maximum performance. What happens when we want to try another 3-blade propeller with greater angle of rake or a 4-blade one which is designed to run higher? Surely it is pointless to compare the new propeller at the mounting height on which we used the first propeller. And of course it is certain that then our conclusions will be incorrect.
If we have the Power Lift we can easily raise the engine higher and see accurately the behaviour and performance of our new propeller. So depending on the prop we use we can adjust the ideal mounting height of our engine for this one.

Certainly the use of Power Lift allows us to move into shallower waters and lift up our engine so as to be completely out of the water when our boat is docked at a marina or a harbour.

Power Lift

It is still a fact that sometimes our boat's centre of gravity is shifted further back or ahead depending on our loads or on which of the two fuel tanks is filled. Even in this case the Power Lift helps us to correct the negative effects of changing the centre of gravity in our ride.

From all the things mentioned above it is obvious that with the use of Power Lift we can improve the performance of our boat and get maximum performance every time, through the whole range of engine's rpm, depending on the usage, the loads, the weather conditions and the propeller we have.

And all these of course, provided that we experiment with the Power Lift a lot and learn how to use it properly.

...keep Ribbing!

 

Delipoulios Marines