Hello All, This my first post here, and I'm a new whaler owner. Yes, one of those guys.
I have a--guessing because there is no hull ID number--a 1968 16-foot 7-inch custom Boston Whaler. I have a 1993 Johnson 70-HP engine installed. I work on smaller OMC motors, 70-HP and below. On another forum, I was given advice to install the motor "two-holes up." The motor came to me installed all the way down with the stern bracket resting atop the transom. In this position (all the way down), the motor had splash back and the boat porpoised at WOT when I trimmed up slightly to correct the splash back.
The folks from the other forum explained that traditional mounting height rules don't apply to Boston Whaler boatss. My experience is that the anti-ventilation plate typically should be mounted in parallel with the bottom most point of the vessel. I haven't had a chance to try the boat since remounting to the higher position (which is about 1.5-inch higher).
Any input andadvice is appreciated!
Thanks!
16-footer Engine Mounting Height
Re: 16-footer Engine Mounting Height
I don't think there is anything special about Boston Whaler boats regarding the optimum engine mounting height. What will work the best depends on the engine, the propeller, and the weight distribution for the particular hull.
Starting with the engine mounted at least one-hole-up is a good idea. Many find that two-holes-up engine mounting will also work well. Mounting an outboard engine in the lowest possible position is an old-school approach, and some think dealers tend to do this from concerns about safety and not about best performance.
How high the engine can be mounted will depend on the propeller being used. Some propellers are not tolerant of being run near the water surface, while others work best there.
The location of the anti-ventilation plate is generally not referenced to the hull bottom. The anti-ventilation plate (A-V Plate) should be running just at the water surface or just barely above the water surface when the boat is on plane at high speed with the usual engine trim. An earlier article shows several pictures of engine A-V plate position relative to water flow. See
A-V PLATE PICTURES
http://continuouswave.com/ubb/Forum4/HTML/006491.html
Starting with the engine mounted at least one-hole-up is a good idea. Many find that two-holes-up engine mounting will also work well. Mounting an outboard engine in the lowest possible position is an old-school approach, and some think dealers tend to do this from concerns about safety and not about best performance.
How high the engine can be mounted will depend on the propeller being used. Some propellers are not tolerant of being run near the water surface, while others work best there.
The location of the anti-ventilation plate is generally not referenced to the hull bottom. The anti-ventilation plate (A-V Plate) should be running just at the water surface or just barely above the water surface when the boat is on plane at high speed with the usual engine trim. An earlier article shows several pictures of engine A-V plate position relative to water flow. See
A-V PLATE PICTURES
http://continuouswave.com/ubb/Forum4/HTML/006491.html