1974 Merc 650 - 15' Mitchell Boat

[lilmerc]

Hi all, Newbie here - I bought this boat about 2 months ago - (early 198?, 15-1/2' Mitchell Boat, 1974 Mercury 650 O/B), and thanks to this site I have learned a lot. My question here is, "is my motor too powerful?". At WOT, I hit my Merc MFG range, 5000-5500 RPM. BUT, it is scary... boat moves VERY fast... don't know the MPH's, but she moves... Planes at about 4200 RPM very nicely. When I first took her out, she did not have much power. Got manuals, and did maintenance, added one of those "fins" to the plate above the prop... Am I just too new to the power of my motor?? I have found I like to move around at about 3000 to 3200 RPM... Is this bad for the motor?? Any in put is greatly appreciated.

 

[achris]

Re: 1974 Merc 650 - 15' Mitchell Boat

KILL THE FIN!!! That's what's making the boat scary at speed. It's pushing the bow down and makes the back of the boat feel very 'light'. Cruising at 3000-4000 rpm is fine for the engine and great on the hip-pocket nerve. I wrote quite a speal on the fins in another post. This is a copy : <br /><br />

For what it's worth. I HATE those stingray things, with a passion! I know I'm probably going to upset a lot of people by saying that, but so be it. This is a forum after all.<br /><br />The problem with them is the way they work. They push the back of the boat up, hence lowering the bow, giving you a lower planing speed et al. They push the stern up by pushing the outdrive up, and loading bearings and surfaces that weren't design to take load in that direction. I have seen some pretty impressive damage caused by them. We're talking busted cav plates, hinge pins chewed up and in one extreme case, the gimbal ring broken (for all you pro-wingers, no he didn't hit something).<br /><br />As an aside, those things are considered dangerous over here. We have some pretty big swells roll through, their last landfall was Africa. When you're racing down the face of one of these, the last thing you need is some stupid piece of plastic trying to bury the nose of the boat into the bottom of the next one.

Chris.........

 

[Chris1956]

Re: 1974 Merc 650 - 15' Mitchell Boat

Lilmerc, There should be a motor capacity plate on the boat. It will state max HP. My opinion is that 65HP on a 15 1/2 foot boat is probably not too much. I had a 16 foot winner, about 525 pounds including a 85 HP Merc. That was a bit too much hoursepower, since th boat was built lightly. I was afraid i would hit a wave and break the bow clean off.<br /><br />It never happened of course. That boat's straight Vee hull design made it ride flat on the water. The faster you went the more the hull would rise straight up in the water. Kinda scary, since I am used to a trimming up the bow at high speeed!

 

[lilmerc]

Re: 1974 Merc 650 - 15' Mitchell Boat

Thanks for the replys... I feel a bit more confident, and will try without the fin...