Replacing an outboard

[enduro155]

I have a 1987 vanguard star fire. It is rated up to a 115 hp engine. Now I have a 1978 Johnson 85 hp. My question is does anyone know an approximate weight of this engine? I want to go to a 2006-2010 90 or 115 oil injected engine. What are the approximate weights of these newer motors? The boat is in mint condition and I don't think I need a new one. What other considerations would I need to look at? Any help would be appreciated.

 

[bonz_d]

From what I've been able to find the new V4 is about 35lbs heavier. Both the 90 and the 115 weighing appx. the same at 335lbs..

 

[bilge rat jim]

Your 1978 85 hp weighs in at 295-310 lbs. A new Mercury Optimax 1.5L (115 hp) is 375 lbs.

 

[enduro155]

The hull in my boat is in very good condition. Would redistributing the weight in my boat. Help with the extra 50-70 lbs? Or it that even much of a concern?

 

[pckeen]

You probably won't have to worry about redistributing weight. Think of it this way. Adding another transom to the back would be the equivalent of putting a large child in the back of the boat - I doubt any weight adjustment would be necessary. The bigger question is whether your transom can handle the additional weight. When I did something similar (putting a 400 lb motor on the back of a boat that used to have a 290lb motor), I had it inspected by the qualified installer, who said it should be fine. If your transom has any flex, you'll want to add a transom replacement to the new motor. Be aware you will have to replace your controls and likely the steering as well.

 

[bonz_d]

Must have missed something here as I was under the impression that the replacement was another OMC.

 

[crb478]

What motor are you wanting to replace it with? If its an e-tec then the weight is about the same. If your transom and boat are in excellent condition then they will probably be strong enough for a moderately heavier 4 stroke. I have a 18 foot CC that was rated for a 140 hp motor. I replaced my 115 hp Johnson 2 stroke with a 90 hp Yamaha 4 stroke. I have not had any issues in how the boat runs or handles. The transom handles the extra weight with no problem and the top speed is within 3 mph of the old motor. Fuel usage is much better at the speeds I run.

 

[pckeen]

That's funny crb, I did exactly the same motor change, also with no issues.