what size evinrude to buy

Eoughphily

Seaman
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Dec 29, 2014
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63
I have a 1973 Rivera 17' fiberglass boat roughly 1200 lbs 6' wide at the transom. I am not sure what size motor to buy for it to get it on plane. I can't afford a new fancy motor so I'm limited to the old school models. I'm running a 1956 evinrude 15 HP for trolling and it works great for that. I recently put on a 1963 evinrude 40 HP selectric which gets me moving about 10 mph, but definitely not on plane. I'm looking at an 1963 evinrude 75 hp selectric. Should that put me on plane or should I go bigger? I found a 1969 evinrude 115 hp selectric shift for $150, but its an 8 hour drive one way. So I'd like to avoid that if possible. Let me know what your thoughts are, thank you.
 

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gm280

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I have to say I'm a bit surprised that a 40 HP will not plane that hull out and only moved it 10mph. Are you certain it isn't water logged? Have you checked the floor and stringers and transom. Sounds like something is really heavy. Soggy old foam soaks up water and can make a hull extremely heavy, because I don't see 1200lbs sitting there in fiberglass. Just saying... JMHO!
 

racerone

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Dec 28, 2013
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I certainly would not drive 16 hrs for a 1969 model 115 hp if it was free !!!----------Nor should you have to drive more than an hr for a good motor.----What is your location ???
 

Eoughphily

Seaman
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Dec 29, 2014
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Its possible the boat is water logged. I haven't pulled the floor boards to look at it. There is only a few inches between the floor boards and the bottom of the hull.
 

batman99

Petty Officer 1st Class
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Sep 13, 2012
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393
For a 17 ft fibreglass hull boat (as shown in picture), I've be looking at 50-70 HP motor.

If one goes too big, then too much weight on its tail. If too small of motor, it won't get on plane.

With above in mind, 115 HP would be an over kill (IMO). It would be like installing a V8 454 engine inside a VW beetle.

If wondering, I recently drove 1.5 hours (each direction) to purchase a 116 HP engine. When living in remote regions, one sometimes must drive the extra mile - to get the jewels they need. LOL!
 
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Eoughphily

Seaman
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Dec 29, 2014
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Unfortunately the boat is so old and had been gutted it doesn't have one. No, not legal as it doesn't have the maximum occupancy label either. Figure I can take care of that down the road with USCG.
 

emdsapmgr

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Dec 9, 2005
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Would be helpful to us if you'd let us know your engine requirements: What is the transom height? 15"? or 20" That will be a critical factor in determining which engine will fit. Since there is no steering console, we assume you will need a tiller model engine. Some of the engines you mentioned may not have tiller handles. Electric start is optional on some models (vs. a recoil starter.)
 

racerone

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Dec 28, 2013
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Agreed a 3 cylinder OMC 70 hp from say 1980 to 1985 would work well.----Simple and easy to maintain yourself.
 

Tim Frank

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1200 pounds?
Sounds like 700 pounds of boat and 500 pounds of soaked foam.
 

nphilbro

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Dec 19, 2011
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Unless you are adding another 750# of men and gear, a good running 35hp short shaft should be enough for that boat. I wouldn't think you'd want to go much bigger than 50hp. I've been talking to a guy near Portland with a nearly identical boat that gets moving well on his 70's 35hp Evinrude. He's looking for a short shaft because the lower unit runs to deep and slows it down a bit. Any motor that requires 50:1 mix (vs 25:1) would likely qualify as new enough for the HP to be somewhat accurate to this criteria.
 

Eoughphily

Seaman
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Dec 29, 2014
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Thanks guys for the responses. My transom is 20", I can cut it down or add onto it to fit my needs. I do have a steering console that I currently utilize. I am veering away from the tiller.

The next couple of days I'm gonna start looking into pulling my floor boards and seeing how it looks underneath. I would be surprised if there even is any foam. But my curiosity is getting to me now that its been mentioned. I really like the idea of a 3 cylinder, as I looked at a v4 yesterday and dang that thing is huge!!!
 

F_R

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Jul 7, 2006
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If you get serious about either of those Selectric motors, make darn sure you get the junction box and wiring that goes with it. And the Selectric remote control also. That stuff is worth as much or more than the whole rest of the motor. For instance, the 40hp voltage regulator is about $100--IF you can even find one. Same with the shift switch, talking several hundred for a new one, if you can find one. And curses on the guys that disconnect the cable with a hacksaw.
 

Eoughphily

Seaman
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Dec 29, 2014
Messages
63
I was unfortunate on the 40 HP selectric shift Im running now. Wires hacked off, no harness, and nothing else. Found the controller for $100 on eBay and full junction box for $35 (with regulator) got it all hooked up and its not enough power and the generator doesn't work...doh!!! Did the motor test or pullerized it, and it barely moves. Haven't tried bypassing the regulator yet to test if it just might be that instead.
 
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