TOPIC: 1968 G3 Restoration Underway - Motor Options

Quick backstory: I was gifted a 1967 G3 from my Uncle right before he passed away in ’99. He purchased it in 1972 from the original owner, and it was used nearly every summer until about 10 years ago. I was about 13 when I inherited it, and I kept it in great shape other than adding some dumb accessories that weren’t installed correctly and eventually led to some rot in the transom. My brother also took it out in 2008 or so and wasn’t used to turning on a plane, so when it caught an edge he crashed into the bank leaving some damage to the bow and rub rail. It’s been garaged for most of it’s life, but with the transom and fiberglass damage from the crash, I decided to do a full restoration.


Restoration: So far the transom has been replaced and built up to accommodate a 20” shaft, it’s been sanded down to gelcoat, crazing addressed, subfloor removed and replaced over foam and glassed in, etc. I plan to match original paint, seat layout, windshield, etc. with some upgrades to accommodate modern technology (transom height, trim & tilt, etc.).


Motor: It originally came with an 60HP Johnson, and when that gave out it was replaced with a new 1984 50HP Johnson 15” shaft – I guess that was the biggest motor he could get insured. The 50 HP is still in great condition, but with the restoration I’m looking to get a little more out of it. Right before the restoration, I found and bought a 1970 65HP Mercury 15” shaft locally in GREAT condition, so I bought it thinking I would swap then and there. Now with the taller transom, I’m on the fence.


The 65 HP Merc does not have factory trim and tilt, so it will be sitting on a CMC trim and tilt – I could mount the CMC unit on a jack plate and adjust to the correct height, but as I envision it, I don’t think it will look right. But, at +/-180(?) lbs. the power to weight ration seems hard to beat.


I also found a 1989 Yamaha 90HP 20” shaft that I was considering. It looks like these are approx. 260 lbs, and it comes with factory trim and tilt so in theory it could mount right to the transom. Although I’d likely get a jack plate for performance.

I don’t need a 4 stroke for the lakes/rivers I’ll be running. If I did go that route, the best option I can find is the Yamaha 70HP at 253 lbs. Anything bigger adds 100 lbs. +.


Any advice – 1970 Merc 65 HP, 15” shaft, 180 lb. mounted lower on the 20” transom, OR 1989 Yamaha 90 HP, 20” shaft, 260lb, OR something different given the new setup?


Gas Tank: Lastly, I was thinking about mounting a 12-15 gallon build in gas tank under the bow. Would that lead to performance issues with planning out? With the old 50HP Johnson setup, to get on a plane with 4 people the 2 in the back need to move the front.

Any input appreciated - long live the G3!

Thanks, Chris

IMHO the Merc 650 is gonna be a bit underwhelming. Probably top out at 35 or so and fairly thirsty fuel-wise. Plus having a short shaft hanging down on a long shaft transom, even with a jackplate, the motor is gonna be sunk by backwash I bet.

The Yamaha would give heads and heels performance above the others, and that's 90 hp at the prop not crankshaft. So if you figure 15% losses it would work out to be around 103hp at the crankshaft, in comparison to the older motors. That being said, 260lb is a pretty big Lump on the back of the boat. About 8lb more than a 4-cyl 850 or 80 hp Merc.

One engine you might consider is the JohnRude 3-cylinder family, 70hp and 75hp. Lightweight, loop-charged, very fuel efficient, these run pretty strongly. Just have to find a good one. As a caveat you must prop these to run at the higher end of their recommended rpm range, you don't want to lug by overpropping. Of course with a light hull such as the G3, it should give sparkling performance anyway!

Here's some weight info I found, it's for 1975 models but later Triples are close to the same weight.

Model: 70ES75
Motor Type: Gasoline
Volts (Electric Motors):
Thrust (Electric Motors):
Horsepower: 70
Cylinders: 3
Start Type: Electric
Dry Weight: 202
Power Tilt and Trim: No

Model: 70ESL75
Motor Type: Gasoline
Volts (Electric Motors):
Thrust (Electric Motors):
Horsepower: 70
Cylinders: 3
Start Type: Electric
Dry Weight: 215
Power Tilt and Trim: No

Model: 75ESR75
Motor Type: Gasoline
Volts (Electric Motors):
Thrust (Electric Motors):
Horsepower: 75
Cylinders: 3
Start Type: Electric
Dry Weight: 220
Power Tilt and Trim: No

Model: 75ESRL75
Motor Type: Gasoline
Volts (Electric Motors):
Thrust (Electric Motors):
Horsepower: 75
Cylinders: 3
Start Type: Electric
Dry Weight: 220
Power Tilt and Trim: No

Just a thought!

A bow tank would certainly help balance things out. IMHO a 12-gallon-or-so tank isn't gonna add any bad handling characteristics to the boat. Years ago I had an old Larson G3 with a Big Lump 75hp V4 Evinrude, it wanted to porpoise. A tank up front probably would have helped!

Hope that helps..........ed

Much appreciated, Ed. I actually prefer a John-Rude since it's been Johnson powered from the start. Thanks for listing the weight info, now I know what to look for!

The next big question is what to do with these (2) extra outboards....