Posts: 3514
Location: Elk River, Minnesota | Hiya,
I would say you should probably see a bit more in both RPM and speed out of the boat. RPM's are well below max for that motor as the max RPM is 6000.
Right off, this tells me two potential areas to check: First would be the pole setting on the Tachometer as I think you are probably fairly close to your maximum speed with the boat. I would think close to 30 would be about right for that boat as it sits alone is 900 pounds alone before adding 23 gallons of gas. This is assuming you trimmed the motor up while at full speed. If you did trim up, then get the motor warm and running at idle speed. Determine what your RPMs are reading at idle and compare to the specifications for the motor. This might be a little fuzzy since I believe you can adjust the idle speed to some extent.
I am wondering, though, and am just going to throw it out there as a possibility...did you trim the motor up while on plane? If not, the 3200 RPMs would sound about right as when trimmed down, the bow is essentially being "pushed" into the water rather than being pulled up out of the water and the stern is being lifted. This would also account for the lower than expected speed. If this is the case, take the rig back out, trim in and get up on plane. Then, start trimming out until either the bow starts to porpoise or the motor does not gain any more speed, but rises in RPM. When you reach the point where either of the two scenarios happen, back the trim down just a touch and record that RPM value and the speed your boat obtains.
If the Tach is correct and you are trimming up, then I would be looking at a potential over-propped engine. If you can, take a look at the pitch and diameter of the prop as well...it is probably stamped on the side of the prop, or is located under the prop nut and washer. This can also tell a bit about the situation.
Steve
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