Today's 4-stroke outboards are more reliable than ever before, with telecommuting maneuvering controls and on-board sensors to maximize performance and efficiency. But a four-stroke solution is not the ideal solution for repowering all boats. What are the challenges? What should you do before restarting? Here's the scoop from CALON.
First generation four-strokes all have one thing in common: they're heavy. When you add all those extra four-stroke components, such as oil pan, valve train, etc., the mass and weight of the engine definitely increases. The installed cost of a 200 horsepower outboard V6 engine from almost any manufacturer is now in the $10,000s, depending on your gauge package, controls, installation, etc. While it doesn't burn expensive two-stroke outboard oil, it does require additional maintenance.
If you are repowering a newer boat, then a four-stroke repower may be nothing to worry about. However, when considering a new outboard for a pre-2002 boat, there are concerns about which solution will work best, as these boats may not be designed with the necessary stern buoyancy to keep the cockpit drain above the waterline and add weight to the transom.
Tips for repowering older boats:
A drain above the waterline ensures drainage.
Wide chines are one way to help float heavier forces.
More submerged mounts provide more buoyancy.
In addition, the four-stroke is reducing weight, which should help when repowering an older boat.
The first thing a customer should do before repowering a boat is to contact the manufacturer of the boat and provide the boat's HIN [Hull Identification Number]. There really is no quick answer as to whether each model in the line, or even each boat built from a specific model, can be safely repowered with a newer four-stroke engine.
For repowering with engines of much different weight or horsepower, the added weight at the stern of the boat creates a significant change to the original center of gravity. To make matters worse, the weight and horsepower changes implied a new center of gravity to better fit the modified boat.
When our engineers redesign a boat for different power, I find that other changes are always needed. These can be as minor as a change in bracket flotation or a major redistribution of weight. Obviously, this not only complicates the project, but goes beyond just replacing engines, controls and fuel accessories. It is much simpler to select an engine package that closely matches the power and weight of the initial installation.
For example, if your boat is rated for two outboards and 400 horsepower, you might consider installing a 350-horsepower outboard. Doing so will give you a little less horsepower than the original twin installation. But with only one gearbox creating drag in the water, you may gain comparable speed and performance compared to two gearboxes creating drag. In addition, the cost and complexity of a large single engine installation may be less than that of a multiple engine installation because fewer gauges, wiring harnesses and propellers are required, and the control and steering equipment is simpler. Boaters who sail far from shore still rely on the redundant safety of multiple engines: if one fails, another can get you home.
Please drop ua a line at CALON if you want to know more about the outboard motors, we also have 2 stroke and c series for sale.