150 MONTAUK: 60-HP with Four-blade Propeller

[Dutchman]

I finally got a four-blade propeller and did some un-scientific comparison on my 2008 Montauk 150 with Mercury 60-HP Bigfoot weighing in at about 1,275 lbs, and a Vengeance three-blade Stainless propeller. I used a stopwatch and GPS. [For these unscientific comparison tests, the boat had] 13-gallons of [fuel], my standard equipped boat, plus 270-lbs of crew for an approximate total of 1,625-lbs.

[Using a propeller with a part number] Mercury 48-17314 (13-3/8x 14) [was] a great standard setup except no [acceleration at full throttle onto plane from a standing start]. Top [boat speed was] 34.7-MPH and 9.1 second to plane.

I picked up a Mercalloy Spitfire four-blade aluminum 13 x 15 propeller (P/N 48-8M8026580 and 12.8 x 15 ), which had [acceleration at full throttle onto plane from a standing start] that was better but couldn't [allow the outboard engine to accelerate to] over 5,200-RPM, no matter how I trimmed: hence not the right propeller

I exchanged it for a the same kind 48-8M8026570 13.8 x 13 pitch and that is the right propeller.

I have to make sure the trim is all the way in and [the boat] gets on plane in 6.7 seconds. I can trim out to get [an engine speed of] 5,900 to 6,000-RPM, but [for the engine to accelerate to this speed] takes slightly longer than with the Vengeance. [The boat speed] tops out at about 31-MPH. Also [the 2008 MONTAUK 150 boat] is more prone to porpoise at the top end. But 25 [MPH] is fast enough. I'm not racing anybody. [I am] just putting around inland lakes.

I did get a better [acceleration at full throttle onto plane from a standing start] even with another 165-lbs weight, which is what I was after.

We'll find out if [the last tried combination of boat, engine, and propeller] also pulls the tow better when we get some better weekend weather.

[macfam]

Thanks for the good information.