posted 11-12-2007 10:28 AM ET (US)            

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Brand does make a difference because each of the brands measures and designates their pitch differently. For example, OMC era propellers tend to have a higher designated pitch than Mercury propellers. For example, a 19 inch pitch OMC propeller seems to have similar running characteristics to a 17 inch pitch Mercury propeller.

I suggest you try any or all of the following for starters:

OMC/BRP Viper 14 3/4 x 19
OMC/BRP SST 14 3/4 x 19 (Swept Back Design)
OMC SST II 14 1/2 x 19
OMC Raker 14 1/2 x 18 (if you can find one)

Mercury Mirage Plus 15 1/2 x 17 (you will need a Flo-Torq II hub kit for Evinrude/Johnson).

Stiletto Advantage II 14 1/4 x 17.

I'm guessing that these propellers will allow the motor to turn between 5300 and 5500 when your boat is lightly loaded (1/4 tank of fuel, 1 person, little gear). However, if the WOT RPM loaded fall below the 5300 to 5500 range under such conditions, you may want to consider using any of the same propellers but in the next available lower pitch. Conversely, if the WOT rpm hits 5500 RPM or above, you may want to move up one size in pitch for any of the above propellers. But I would start the "dial-in" process with any on the list above.

posted 11-13-2007 09:35 AM ET (US)            

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No two propeller are exactly the same not even if they share the same diameter and pitch. The best advice I can offer you is to try as many different propellers as you can get your hands on, record the performance results and pay attention to how the boat feels to you with each prop.

Ultimately, experimentation is the only way to find the best prop possible.

All the propeller that Peter has listed are good candidates for your boat. I would also recommend you consider a 14" x 17" Mercury VenSura/Offshore and a 14-1/4" x 15" Stiletto Advantage II.

posted 11-13-2007 08:36 PM ET (US)            

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Among a particular brand of propeller and within a particular style of propeller of that brand, you will find that there is a reasonably accurate rule of thumb that says that a increase in pitch of 2-inches will cause a decrease in engine speed of 450-RPM, and vice versa.

There is no universal standard for rating of pitch, so it is very likely that propellers of the same pitch but made by different manufacturers will not all produce the same results.

The propeller of choice is a propeller that allows the engine speed to advance to very close to the top of its rated maximum engine speed when the boat is lightly loaded.

There is no one style or brand of propeller which always gives the best performance. This is why there are so many choices available. If only one brand or style of propeller produced the best results in all cases, then this particular propeller would quickly establish itself as the best, and all other brands and styles would soon suffer.

posted 11-13-2007 10:39 PM ET (US)         

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Here is the universal standard for determining pitch. It appears the professional and manufacturing capabilities of the various manufacturers comes into play here, all not being equal. The reason RPM often varies is because diameter, rake, number of blades, and efficiency also effect pitch, which can't be considered by itself.

Link to good article on basics of propeller terminology

posted 11-14-2007 01:17 PM ET (US)         

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Quoting Mercury engineers:

"Pitch is the distance that a propeller would move in one revolution if it were moving through a soft solid, like a screw in wood."