Carver 27' Santego

Hello,
Just picked up this boat, has twin 3 liter four cylinder mercruisers, alpa drives with hydrofoils. I have a prop question, the boat comes out of the water and planes pretty quick but is basically going awfully slow at 3200 rpm. The previous owner has 17' props on, he doesn't now the pitch but said it's pretty flat (?). Anyway, this seems like an awful lot of prop to me on these, but I have never owned twins before, or four cylinders for that matter. Any help or insight would really be appreciated, thanks in advance.

Re: Carver 27' Santego

whoops sorry about that...wrong forum...haven't been on this site in awhile.

Re: Carver 27' Santego

greatsouthbaybob said:

Hello,
Just picked up this boat, has twin 3 liter four cylinder mercruisers, alpa drives with hydrofoils. I have a prop question, the boat comes out of the water and planes pretty quick but is basically going awfully slow at 3200 rpm. The previous owner has 17' props on, he doesn't now the pitch but said it's pretty flat (?). Anyway, this seems like an awful lot of prop to me on these, but I have never owned twins before, or four cylinders for that matter. Any help or insight would really be appreciated, thanks in advance.

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Re: Carver 27' Santego

Your issue sounds similar to mine. I have a 25 ft Carver Custom with twin Mercruiser 140's. Propped with 15 1/2"x 21p cupped aluminum. I can get about 32 MPH GPS with six adults on board, but WOT is only about 4100 RPM. According to Mercruiser documentation, rated WOT is 4400 to 4600 RPM. I'm going to drop down to 19" pitch props and give it a try. If your tachometers are correct, and the best you can get is 3200 RPM, you may have another issue besides prop pitch. Rule of thumb is a gain of 100 RPM for every inch of pitch. At that rate, you would have to drop down into the single digits to comply. Would make sure your throttle controls allow full throttle function, and make sure the carburetors are synchronized at WOT. Twin engines normally require a little higher pitch prop according to most of the prop charts I've reviewed, so you may be right in the slot with 17" pitch wheels. Go to Mercruiser's website and take a look under their propfinder. They take into consideration the weight and design of your boat in their recommendations.