Gas Saving Speeds
By Tom Neale, 6/1/2006
Gas Saving Speeds
1. When I want to go from a point “A” to a point “B”, I’ve found that usually the most economical speed is that which gets me a little beyond the point where I’m up on a plane.
2. I seek a stable plane, so that I won’t be coming off it when hit by a small wave or gust of wind.
3. Usually it’s most economical to get up to this point of plane quickly rather than slowly increasing the throttle and dragging the stern. Soon you’ll know the acceleration rate needed to reach a stable plane without overshooting and while being safe.
4. Don’t do this in a crowded area or inconsistently with safety.
5. The most economical RPM will vary with factors such as sea and wind conditions, hull condition, loading and weight distribution. Even boats of the same model and power configuration may have different performance parameters.
6. Weight and trim substantially affect performance. If I have a heavy load of passengers, I position them in the area(s) that helps the boat get on a stable plane at the least RPMs, assuming this positioning is consistent with safety. Other items, such as loaded coolers, can also make a difference. Soon, with experimentation, you’ll know how to distribute weight.
7. Trim tabs can be a great tool. However, they should be used to compliment or fine tune the boat’s plane—not to achieve it irrespective of the other factors I’ve mentioned. The boat should be loaded properly and powered properly before you start playing with trim tabs. The manufacturer of your boat may have some helpful suggestions with regard to use of trim tabs.
8. If you have an outboard or inboard/outboard, the angle of the drive relative to the transom is also important. Consult the manufacturer of the boat and the engine to get the best adjustment.
9. “Experimentation” should never be to the exclusion of full attention to traffic, conditions around the boat, the boat’s other performance issues, safety issues and prudent seamanship. It should only be done in open safe waters and conditions with no other traffic or obstructions. Be very careful anytime anyone is moving about in the boat underway. If they must do so when the boat is up on a plane (or running at any speed that could result in falling or instability), it’s best to have them crouching down so that they’re lower than the tops of the sides.
10. If I’m just messing around without a need to get anywhere, I get better economy going at very low RPM and not getting up on a plane.
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Copyright 2004-2005 Tom Neale