Indmar Premium 400, Operator'S Manual, Page: 37 / 124

2-15
GENERAL INFORMATION
© 2020 Indmar Marine Engines
Monitor the engine temperature gauge frequently. If your engine
overheats, carefully inspect the exhaust hoses for damage.
Damaged hoses can allow carbon monoxide gas and seawater to
enter your boat.
SELECTING A PROPELLER
For best engine performance and longevity, the wide- open-
throttle (WOT) engine operation must be near the top of, but
within, the specified WOT operating range. To adjust the WOT
operating range, you must select a propeller (propping) with the
proper diameter and pitch. The propeller which was supplied
with your boat was chosen by the boat builder for best all-around
performance under average conditions.
Load, weather, altitude and boat condition all affect WOT engine
operation. If you use your boat for several different applications
such as wakeboarding, barefooting and cruising, it may be
necessary to have 2 or more propellers which will allow the engine
to operate in the WOT range for each application.
Propping the boat should be done after engine break-in and the
initial 10 hour dealer check. The boat should be loaded the way
it would normally be for each application. For instance, if you are
propping for wakeboarding, fill the ballast tanks if equipped and
add all the people and gear you would normally expect to carry
in the boat. Take the boat out and after warm-up, run it at wide-
open- throttle and note the maximum RPM. Your Indmar engine is
equipped with RPM limiters to prevent over-revving.
If the WOT RPM is higher than the maximum RPM in your
engine’s WOT operating range, the boat is under- propped. Install
a higher pitched propeller to reduce WOT RPMs. An engine that is
over-revving may quickly experience catastrophic damage.
If the WOT RPM is lower than the minimum RPM in your engine’s
WOT operating range, the boat is over-propped. Install a lower
pitched propeller to increase WOT RPMs.
An engine that is under-revving is lugging. Lugging places
tremendous loads on the pistons, crankshaft and bearings and can
cause detonation, piston seizure and other engine damage. This will
not be covered under warranty.