Mercury’s commercial outboard range
US-based Mercury Marine, one of the worlds major outboard motor manufacturers, has introduced a range of more powerful outboard motors that have been specifically developed to meet the requirements of commercial operators.
Previously Mercury’s Sea Pro range was limited to smaller outboards such as the Sea Pro 25 two stroke outboard that is a 25 hp unit with manual starting designed mainly for small fishing boats but the expanded range now incorporates outboard motors up to 150 hp.
The latest additions to the Sea Pro range are based on the company’s range of four stroke outboards. Available in power options from 75 to 150 hp the new four model range is designed to meet the requirements of planing commercial craft such as RIBs and small harbour craft as well as fast fishing boats.
Although based on the existing range of Mercury four stroke outboards these new Sea Pro engines incorporate many modifications that recognise the fact that on commercial craft the engines can be in use on a daily basis and have more demanding operating characteristics that those of leisure craft.
Amongst the changes incorporated into the Sea Pro engines are modified swivel brackets to give added strength to this vital component of the engine. In commercial use this swivel bracket, that supports the full weight of the motor, can be subjected to considerable strain. The lower gearboxes have also been upgraded with specially toughened gear cases and internal components. These gearboxes are housed in a larger bottom end unit that can accommodate a larger propeller to help maintain the boat on the plane at lower speeds.
Recognising the fact that commercial engines can spend a lot of their time idling, the carburettors have been modified to give much smoother idling characteristics to the engine and to reduce the chance of stalling after idling for long periods. The water pumps have been replaced with stainless steel units that operate with a high volume low pressure flow to give them a longer life and better corrosion resistance.
All of the modifications to the basic outboards have been designed to ensure that these outboards can stand up to the tough operating conditions that can be experienced by engines used for commercial operations. In addition to improving the reliability of these four stroke outboards, the modifications also include improvements that reduce the chance of corrosion affecting the performance. These changes recognise the fact that commercial outboards can operate with many more hours per year that most leisure outboards.
By Dag Pike
