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Torque Master and Other Non-High Performance Lower Units

  • November 26, 2018
Torque Master and Other Non-High Performance Lower Units

Allison Boats’ engineering stance for increasing speed is designing and building efficiency into the boat – not by adding more horsepower to the transom. One element of maximum speed on any boat is determined by the lower unit – also known as the gearcase.

Most gearcases (non-high performance gearcases) are limited to the speed with which it can pierce or separate the water. When the gearcase exceeds a certain speed, the gearcase nose separates or pierces the water to the point it creates a hole (or air pocket) in front of the propeller and skeg. This situation can cause a blowout. A blowout occurs when the propeller slips and the skeg loses lateral control resulting in the potential for the boat to make a severe directional turn to the left.

For example, if the blowout speed on a gearcase is 82 miles per hour (MPH), that is the maximum speed. It does not matter if you increase the horsepower (HP), the maximum speed does not change. A gearcase blowout can be potentially dangerous and at the very least, an unsettling situation for an inexperienced driver at speeds exceeding 80+ MPH. There are differences in the types of gearcases and their capabilities.

As an example, the blowout speed on the Mercury Torque Master gearcase is in the low - mid 80s MPH. Allison recommends smaller HP to preclude a potential blowout occurrence when operating with a Torque Master or other non-high performance gearcases.

Mercury’s Sport Master gearcase, a high performance gearcase, has low water pick-ups and a nose cone that enables raising the engine to reduce drag and increase handling and speed. Allison recommends the Sport Master gearcase for high performance and to preclude potential blowout occurrences when operating at speeds at or exceeding the low - mid 80s MPH.

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