JackPlate.hu
Expert in suspension of marine and sweetwater outboard motors

The optimal operation and movement of a medium-sized (450cm-650cm) boat with a properly selected performance outboard engine, adequate lifting/gliding properties, maximum top speed, and optimal engine consumption, -of course, with the weight transported (persons + equipment )- , are mainly defined by three main things.

The best holeshot, and optimal flying depends on:

• Actual depth of gearbox, propeller drive, so the exact propulsion, ie precise adjustment of engine height!
• Geometry of the propeller used on the engine (size, pitch, and number of leaves)!
• Choosing and using the right trim angle when starting or travelling!

The outboard, operated at the optimum engine height, delivers its performance as efficiently as possible, as the drag effect on the gearbox is balanced at this height by the drive, ie the power, thrust and efficiency of a well-sized propeller!

• If the motor operates too deep, energy loss will occur due to the fluid resistance which causes performance problems
• The ventilation plate is under water, which means unnecessary braking and even splashing, spraying
• If it is too high, the impleller doesn’t push enough water to engine cooling system, causing overheating, and the propeller may ventilate, loosing throttle, performance because of underloaded propeller leave operation on the top (sounding, cavitating sound)

The engine, operated at the ideal, precise engine height, is almost automatically set to the right trim angle during a perfect (ideal) glide/fly because the gear angle gives the highest power at the ideal trim angle position, where the drive thrust vector achieves the perfect horizontal position!

• In the case of a poor trim position, the position of the hull on the water is not correct, so that the balance of perfect buoyancy/flying is not achieved.
• The propeller ideally delivers power most efficiently in a horizontal position, in a state where the direction of propulsion is exactly parallel to the water surface, with each leaf operating at the same pitch angle at each rotation angle. This condition is clearly the result of the exact engine height!
• The oblique, non-horizontal propeller is overloaded at the bottom and catches little water at the top (underloaded, or vice versa depending on the trim position) i.e. the force vectors are asymmetrical, which is harmful and means a very serious loss of power!

A well-sized and horizontally operated propeller will drive our engine into the highest speed range (6000-6300Rpm)

• In fact, in this state we experience exactly what size propeller is the best choice for our particular hull, on the optimal engine height, the given power of the engine!
• So, after all, the optimum engine height will show the perfect trim position, and at this trim angle, a well-sized propeller will deliver maximum engine power for the most efficient travel!

Installing a properly sized JackPlate on a fishing boat eliminates any problems that result from our outboard engine obscuring or falling into the line of our side-view sonar, meaning we usually experience poorer sonar images on the portside. The perfect sonar image depends on many parameters, but a masking engine gearbox and that’s why the need of continuous trimming up the engine will make the sonar experience worse in all respects, a problem that can only be solved by mounting the motor backwards, ie installing a Vance JackPlate of the right setback!

A Vance jackplate setback allows the transom mounted side scan transducers to ”view “away between the transom and the gearbox without any coverage.