Boating and Sailing.pdf - Moja ladja

If Your Prop Is Too Short …
Chapter 3: Picking a Proper Prop
Props that are too “short” or pitched too low may just about smoke the tires on the hole
shot, but they soon allow the engine to wind up into the stratosphere once the boat gets
on top. It takes real care not to over-rev the motor and break something expensive inside
with a prop that’s several steps below the needed range. If this is happening, you may have
to swap out a 17-pitch for a 19 or higher.
When Your Prop Is Just Right …
The idea is to choose a prop that will take you and your entire crew and all their food,
drinks, and diving gear up on plane quickly and without a lot of bow-rise, and then give
an effortless performance in the cruising range of the engine, about 3,000 to 4,500 rpms
for outboards and 2,500 to 3,500 for most inboards and I/Os.
Bad Vibrations
Vibrations from a prop usually mean there is some sort of debris on the blades or barrel.
An easy way to clear it is stop the boat, shift the engine into reverse, and let the boat slide
backward for a boat-length or so. This often unwinds the plastic bags, weeds, or whatever
has gotten into the prop. If this doesn’t work, you may have to shut off the engine, tilt up
the lower unit, and pull out the stuff by hand.
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Some boat dealers will assist
you in finding the best prop
for your rig by swapping to
achieve the best combination
of hole shot and top end.
(Photo credit: Frank Sargeant)