Marine engines must, above all else be reliable. Engine reliability is especially important in pleasure boats, where the capacity of the crew to deal with mechanical problems may not equal that of crews of commercial boats. Today's marine engines have a long life; however, eventually either major repairs or replacement may become necessary.
It may be tempting that the value of a boat re-powered with a new engine will increase enough to fully offest the cost of the new engine and its installation. Although the boat will be worth more with a new engine, the increase in value in the used boat market may not equal your investment if you sell the boat. The same is generally true if you convert from gas to disel. The boat's value will increase, but probably not enough to fully pay for the conversion. That said, you are considering the rebuild or repower because you want to use your boat, not sell it.
Williams Marine will perform an evaulation to determine which plan is best for your boat.
Although rebuilding an existing engine normally poses a few challenges, the installation of a new engine usually provides significant performance and economic advantages. Many parts and accessories of a rebuilt engine (alternator, starter, waterpump) are usually retained and have an uncertain further life expectancy. All parts of a new power plant will be unused and the entire engine will carry a very valuable manufacturer's warranty. There are no hard and fast rules for deciding between rebuilding an existing engine or re-powering with a new engine. However, spending more than 40% of the cost of a new engine on a rebuild may not be a good investment. Williams Marine is a Yanmar and Volvo dealer that is equipped to provide your repowering project with years of experience and quality workmanship. We also have experience and access to Mercruiser, Universal engines as well as a complete machine shop for specific needs.
REASONS TO CONSIDER REPOWERING
Your engine is just not performing up to your needs and expectations.
There has been a major failure in your existing engine.
It has become a chore and financial burden to keep up wiht the little problems of your older engine.
You want to incorporate the latest in fuel injection or digital technology that your current engine does not support.
You want more power.
A new boat is out of your budget.
A few basic considerations will help define your re-powering project:
the engine must fit in the space available
the weight of the engine should not be much in excess of the unit being replaced with less weight generally desirable.
there must be sufficient clearance around the new engine for inspection and maintenance access.
the angle of engine to waterline, direction of prop
Unless the new engine can be properly mounted on the existing beds, new beds will have to be designed and installed. The fore and aft position of the new engine must be carefully considered. In many instances the new engine may acutally be shorter than the unit being replaced.
Insist that the installation employ the engine mounts provided or specified by the engine manufacturer. These mounts have likely been designed to minimize transfer of noise and vibration to the hull of the vessel. Useing non-standard mounts in order to improve the mounting position of the engine may create more problems than advantages.
Realistic power level: available power at maximum rpm, time limits (if any) at these power levels.
Engine size, weight shape: will it fit easily into the available space?
Shaft rotation: does it match the existing installation? If not, is there a dual direction gear box available?
Exhaust system requirements: compare with existing installation.
Consider displacement and maximum rpm limits for both existing and new engine.
Engine compartment design: adequacy of fresh air supply, exhaust of heated air, noise trapping of air intakes and exhausts, improvements likely to be required/desired.
Position of engine components relative to existing and constraints of engine compartments: will extensive rerouting of hoses, cables and controls be required? Will it be possible to gain access to the engine's components for inspection and service?
Engine controls and indicators: can the controls and indicators for the new engine be readily integrated into the existing panels?
Adequacy of existing fuel systems: If already diesel, is system in good condition? If power of new engine is significantly greater than that of the existing engine, will the present system hold enough fuel? If gasoline, will the existing tank material be suitable for use with diesel fuel? Can the required fuel return lines be added?