Your MasterCraft boat was designed to be a high performance ski boat. You may have seen professional drivers with advanced operating skills perform high speed maneuvers and on a dime turns. DO NOT attempt to duplicate or simulate these feats. Paid, professional drivers log thousands of hours on the water and carefully choreograph every move. Plans are made in advance in the event the routine must be aborted. Maneuvers of this nature could cause serious injury or death, as well as damage to your MasterCraft that will not be covered under warranty.
For the 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 with the proper diameter and pitch. The propeller supplied with your boat was chosen for best all around performance under average operating conditions.
Load, weather, altitude and boat condition all affect WOT engine operation. If you use your boat for several different applications such as wakeboarding, bare footing and cruising, it may be necessary to have two or more propellers of different size and pitch to allow the engine to operate in the WOT range for each application.
Propping the boat should be done after the 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 example, if you are propping the boat for wakeboarding, fill the ballast tanks and add 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. EFI engines are equipped with RPM limiters to prevent over revving. Take note if the RPM limiter is activated. If the WOT RPM is higher than the maximum RPM in your engines WOT operating range, the boat is under propped.
The engine operating ranges for engines in MasterCraft boats are:
RPT 1 engine:
8.1 Liter engine:
See Crusader manual for information.
Installing a higher pitched propeller will reduce the 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 engines WOT operating range, the boat is over propped. Installing a lower pitched propeller will increase WOT RPMs. An engine that is under revving is lugging. This places a tremendous load on the pistons, crankshaft and bearings and can cause detonation, piston seizure and other engine damage.
Elevation and weather also have a very noticeable effect on the wide open throttle power of an engine. Since oxygen gets thinner as elevation increases, the engine begins to starve for air. Humidity, barometric pressure and temperature have a noticeable effect on the density of air since heat and humidity thin the air.
This phenomenon can become particularly apparent when an engine is propped out on a cool, dry day in spring and later, on a hot, humid day in summer, and does not have the same performance. Although some performance can be regained by dropping to a lower pitch propeller, the basic condition still exists. The propeller is too large in diameter for the reduced power output. An experienced marine dealer can determine how much diameter to remove from a lower pitch propeller for specific high elevation locations.
MasterCraft engine manufacturers suggest that consumers consult with the dealer from whom you purchased your boat regarding the best propeller for the application in which you expect to run your boat. However, you should be aware that changing your propeller may void your warranty. Again, working with your dealer is your best bet to ensure excellent performance.