1980 Johnson 115hp weight compared to a 1969 Johnson 85hp

[swannysonny]

I currently have an old 16ft Larson Shark trihull boat. It originally had a 1969 Johnson 85hp motor on it. That motor is no good so I bought what I believed to be a 1981 Johnson 90hp motor to replace it. Well after I bought it I was looking up the serial number to find the proper replacement impeller and low and behold the motor is a 1980 Johnson 115hp with the wrong decals. According to the Nada guide it weighs 305lbs. Unfortunately the nada guide only goes back to 1974. What is the weight difference between the 1969 85hp and the 1980 115hp? My transom is in pretty good condition( I have tested it and drilled test holes to check for rot in the wood). I do not want to break the transom trying to use this motor. Thanks for any help or suggestions!

 

[racerone]

You will find that the 1969 model 85 was lighter.----Tipping the scales at 245 lbs as per my 1969 factory brochure.----For some folks it is hard to believe that older motors were lighter than the modern sleek motors.

 

[swannysonny]

You will find that the 1969 model 85 was lighter.----Tipping the scales at 245 lbs as per my 1969 factory brochure.----For some folks it is hard to believe that older motors were lighter than the modern sleek motors.

Thank you! For a weight difference of that much would you recommend me reinforcing the transom or getting a different motor? From what I can find, the Larson shark was rated for up to the 115hp from 1969.

 

[racerone]

In my opinion it is elegantly easy to beef up a transom.-----I am doing a 40 year old boat , all the rotten wood ( beaver puke ) came out and no wood is being used in the repairs !

 

[swannysonny]

Do you have any recommendations how to do this without ripping out the old transom? I am thinking about maybe putting in a steel plate or something.

In my opinion it is elegantly easy to beef up a transom.-----I am doing a 40 year old boat , all the rotten wood ( beaver puke ) came out and no wood is being used in the repairs !

 

[racerone]

Sorry----If i could see your boat / transom from the inside it would take just minutes to come up with a plan.----Carbon fiber / kevlar / composite material are my choice.

 

[spybot]

If your transom solid it should take the extra weight. If your worried just beef up the transom with timber/composite glassed knees.

 

[swannysonny]

Alright so here are some pictures of the transom. Over the summer I completely replaced the deck, stringers and structural/flotation foam in the boat. When I replaced the stringers I used 10 inch by 1.5inch(Originally was only 3/4 inch) Douglas fir which has been fiber glassed into place. I am thinking of maybe putting a steel L bracket on the inside of the transom attached to the stringers with a steel plate on the outside of the transom. I am definitely open to any other ideas/if this is a bad idea.

 

[racerone]

If the steering cable is long enough you can install direct to the motor and get rid of that bracket.

 

[swannysonny]

I am honestly not sure. I do have access to another boat that might have a slightly longer steering cable

If the steering cable is long enough you can install direct to the motor and get rid of that bracket.