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A. Normal maximum RPM = hull problem.
If the boat is performing poorly and the maximum RPM's are normal and what you are used to, you can look to the
hull and some of the external parts. These include:
1.
Overload:
Too much weight aboard.
2.
Balance:
Either too much weight aft, which will cause the nose to be too high and make planing difficult, or if the weight is
too far forward, it will cause the nose to plow, difficult steering, wetness, and poor top speed.
3.
Reverse bucket:
Is the bucket dragging in the reverse stream? Make sure the control is fully up.
4.
Excessive hull drag:
Is there some external hull obstruction such as rough surface, broken keel strips, or other reason im-
peding the smooth flow of water over the hull bottom? A visual check on the trailer should reveal if there is. Metal hulls can
have a "hook" bashed into them forward of the transom which can cause the bow to plow. The planing surface forward of the
transom six to nine feet should be true and flat.
B. High rpm = jet unit problem.
Higher than normal RPM's, lack of thrust, slipping clutch feel, engine racing and no go?
1.
Blockage:
The most common problem is weeds and stones blocking the intake grate. Also be aware of ski rope, fishing line
and plastic bags winding around the pump shaft. Small sticks and stones can become lodged in the impeller affecting the per-
formance dramatically, objects trapped in the impeller can cause the rotating assembly to be out of balance, causing severe
vibration. Make sure the water passage through the jet is clear.
2.
Impeller wear:
The heart of the jet is the impeller, and its condition. If you run in shallow gravel beds or across sandbars the
leading edges will become dull and inefficient. Pumping sand will increase the wear-ring to impeller clearance. Causing cavita-
tions and loss of performance.
3.
Bowl / stator vanes:
Its not too much of a problem, but the leading edge of the fixed stator vanes can become blunt and
damaged.
