Power trim
As power trim a device is known for motor boats with Outboard or Z-drive with which the position of the drive to the transverse axis can be tilted. This allows the position of the propeller to be adjusted in relation to the water surface if the boat changes its position due to load , speed or waves.
A neutral trim is achieved when the propeller axis is exactly horizontal . Since the best efficiency is achieved in this position , a well-trimmed boat can be driven faster and more energy-efficiently than one whose propeller axis deviates from the horizontal.
To a certain extent, if the engine is sufficiently powerful, the position of the boat can also be influenced by a power trim. In this way, on the one hand, uneven loading (and its negative influence on the boat's handling behavior) can be counteracted to a certain extent, and on the other hand, the bow can be lifted a little out of the water during the journey through the interplay of power trim and drive power, which removes it from the water wetted area on the fuselage can be reduced, which means a speed advantage especially with gliders under certain circumstances.
In motorboat racing , power trim became vital with the introduction of the " catamaran " type of boat . Due to the design, the wind and headwind lift the boat at the bow. Depending on the strength, this buoyancy must be counteracted by the position of the power trim so that the boat does not roll over backwards.
technology
A power trim usually works electro-hydraulically. A hydraulic cylinder is mounted between the part of the suspension fixed on the boat transom and the shaft . The electrically operated oil pressure pump is usually located separately from it inside the boat. The pump is operated via electrical switches and pulls the piston in or pushes it out.