2005 255 CONQUEST with twin Mercury 150-HP OptiMax: Propeller Selection

[GMcCracken]

I just purchased my first Boston [Whaler boat,] a 2005 255 CONQUEST [with twin Mercury Marine] 150-HP [OptiMax two-stroke-power-cycle engines].

Q1: what propeller [should I be using for a 2005 255 CONQUEST with twin Mercury 150-HP OptiMax engines]?

I feel like the engines lack power. [Acceleration from a standing start at maximum power] is very slow to increase boat speed and to reach planing speed for the hull.

I do not know what the engine speed in RPM is a full throttle because I have not tried that yet.

[Phil T]

What props are you running, make, model and pitch.

Are you running tabs?

[GMcCracken]

The propellers are the MIRAGEplus three-bladed propellers with 15.5-inch diameter and 17-pitch, Mercury number 48-18278

The trim tabs are in up position.

[jimh]

Q1: what propeller [should I be using for a 2005 255 CONQUEST with twin Mercury 150-HP OptiMax engines]?

You should choose a propeller that allows the engines to accelerate at full throttle to the upper range of the manufacturer's recommended maximum engine speed range--or if provided by the specifications--to the upper end of the manufacturer's recommended OPTIMUM engine speed range.

If for operation at FULL-THROTTLE you provide the manufacturer's recommended maximum engine speed, or the manufacturer's recommended optimum engine speed, and you provide your actual observed engine speeds at full throttle, and details about the engine mounting heights, then a possible analysis of your present set-up can be made.

Thanks for information on the propellers. The Mercury Marine MIRAGEplus three-bladed propellers in 15.5-inch diameter and 17-pitch are very good propellers.

Now we need to know the specifications from Mercury for the engine speed ranges, your actual engine speeds at full throttle, and your actual boat speeds.

Also, give the gear ratio of the engines.

[Jefecinco]

If the engines were not surveyed at the time of purchase they may be overdue for a service and testing.