Mac 25 Motor Question

[Gilligan and mate]

Alright.... i have a 85 Mac 25, someone gave me a 6 hp yamaha SHORT shaft motor. Needs some work. Before i start working on it, I need to know if it will work on my poor mans yacht. Thanks way in advance as everyone is always helpfull.

Gilligan

[snotnosetommy]

Pretty hard to tell without some measurements. My 85 Mac has a Merc 9.9 long shaft. It measures 22" from bottom of motor case to top of cavitation plate. That plate oughta be 3 or 4" under water when running. Unless you have a motor mount with a unusual amount of throw and mounted pretty low, it's hard for me to see how you can make it work. You might be better off trading it for one that will give you fewer headaches.

[Catigale]

Depends on venue too, Gilligan. If you are stuck on the Island and just want to visit a lake or two, you and Ginger will be fine with the short shaft.

If you and Maryann want to make it back to the mainland on the ocean, you will need a long shaft Im sure.

The Professor.

[Gilligan and mate]

thanks guys,,, Why is a long shaft needed again. We live on coastal North Carolina. Most of our sailing will be in the sound. Need to me able to motor to and from boat ramp.

[Catigale]

If you get stuck in rough stuff, the short shaft will cavitate and come out of the water, screaming like a banshee and then fly apart not pieces from running at 5000 rpm with no load.

The long shaft will do a better job staying in the water.

[Gilligan and mate]

Thanks Catigale!!! REAAAAAALY new boat people here. Im sure will there will be many more questions.

[Catigale]

One of the friendliest forums for new sailors in existence. Many (most?) are first time boat owners in the Mac world...with a few exceptions having rounded cape horn too......

[vizwhiz]

Yeah, my 26S came with a brand-new, short shaft also - so I sold the motor. About** to buy a long shaft or extry-long shaft in the next week or so.

The displacement hull sailboats like yours and mine tend to teeter-totter over the middle, as opposed to the planing hulls like the X/M which tend to keep the back end in the water better the way a regular powerboat does (unless you're rigged with two or three extra foresails). When a displacement hull sailboat pitches down, the back end tends to come up, which will pull the prop out of the water. In calm water it isn't a problem, it's when you're going over waves.


** "Aboot" to our Great Northern friends...

[Freedom77]

Longshaft 7.5 to 9 HP is ideal for Mac 25. Also torque of prop is important. If you can keep the prop in the water the 6hp should be adequate. Hey Gilligan, why don't you have the professor built a new outboard out of coconut shells Fair winds and full sails...