Purchased a Cobia 284 boat equipped with twin Yamaha HPDI 200 motors in 2000. From day 1 the motors in ocean seas drop RPM's from 2600 to 1900 while running. Sometimes they rev up on their own and other times do not. If the throttle is adjusted the boat eventually surges to 3300 - 3500 RPM's. Contacted Yamaha and they stated this is due to the boat not getting up on plane so the motors throttle down. This operation makes ocean fishing difficult and dangerous due to the engine surges in rough waters. Is anyone else experiencing this problem.
<br /><br />In rough water the drag on the hull changes drastically depending on where the boat is on a wave. Part of the time your boat is nearly on plane, part of the time it is bogging on an up slope. The engines respond to these changes in load by lugging down or accellerating. That is normal behavior.<br /><br />Think of it like driving a car that has no cruise control up and down steep hills. If you don't adjust the throttle you car will do the same thing.<br /><br />What are you fishing for at 2000rpm?<br /><br />Good luck.