Matching boat with motor…..

[mr-asa]

I have a 12 foot 1967 Delhi. My first really good running motor was a ’57 7.5HP Evinrude. It wouldn’t plane me for nothing, I even tried getting a tiller extender and sitting on the middle seat. Got a couple MPH, but definitely wouldn’t get me on plane. Add in another person… no way, no how.
I found a 10HP and started working on it, but still haven’t finished it. However I found a 15HP Evinrude and that does the job nicely with myself and a passenger. It’s become my "daily driver" whenever I head out.

[westwind]

I think the general rule is that you need something close to 1HP/100lbs to plane a boat. Of course there are a lot of assumptions on how well the boat will transition to plane and how much HP the boat will make down low, getting up to speed. Generally, you need to loose weight or add HP……

It’s tough to get below 500 lbs for the boat, 100/boat, 100/motor and tank, 50/gear, 200/me. Add another person takes a couple more HP. In a low power range it makes a big difference, changing prop pitch might get you in a better RPM range. It’s usually tougher to get on plane than to stay there, one of my boats is either too slow or too fast, with an awkward transition. I’m hoping some trim tabs will help.

[auldscott]

Your boat’s weight suggests that it is not built strongly. The limiting factor may be transom strength. When I first got my 12 foot tinny (125 lb) the transom would flex alarmingly with a 7.5 hp. I owned a similar boat back in the 70s with the same problem. With both boats, I strengthened the transom and routinely ran 15 hp motors on them, even though they were rated for 10 hp. I use a tiller extension when running solo.

With due care, the Elgin 12s should be good motors for your boat. One caution: the tiller grips taper down, which means that it will be difficult to keep a clamp-on tiller extension on the motor. DON’T run an extension if there is any chance of it coming off at speed. Find a way to keep it on.

[sydinnj]

The way it is built does make a huge difference. My Mirro Craft is an older one and is 12′ and it is rated on the capacity plate for 20 hp. Do not think I will ever put that much on it.

[Mumbles]

If you want something a bit newer, OMC 9.9’s pack a lot of punch for their size.

[garry-in-michigan]

This is the formula the boat builders used – back in the late ’50s.

According to that, the boat I ran as a teenager should have been seven feet wide. . . 😆

[Pete]

Gerry

According to that graph my 10 ft x 5 ft wide hydro max Safe Hp is 12 and I use unsafe 30 Hp 😯 😆

Pete

[20mercman]

I agree that a 7.5 Scott Atwater’s store brand motors, or a golden pen would be a nice motor. They are pretty good 7.5hp motors and one of the best in the 7.5 class IMO. If you want power and light motor, it’s hard to beat a Mercury 110. At only 11 cid. they are powerful motors, and they weigh a lot less then my 15 Fastwin or FD-10’s, but like everything, need the right prop.

Steve

P.S. I have both of these if you are interested, but this post was not offered in the interest of selling a motor.

[Author]

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