What outboard is equal to OMC Stringer

[bill chisholm]

I have a 24' Tolley, 1980 Sportsfisher, Great Hull, with OMC Stringer, 350
4 barrel Rochester, and I am looking at a repower. I definitley going to keep this boat, I luv it and am willing to spend some money on it. I am on my 2nd 350 and have NEVER had much trouble with the outdrive. But I am going to put a swim platform and an outboard,

The question starts with the fact that I don't officially know the Horespower rating for my motor and outdrive combo but i do know the following. It runs at 28 mph at 3100RPM's with 100 gals of fuel onboard along with 2 fat people with big lunches. I very rarely run it past 3200 rpms and this motor has lasted for over 10 years with no problems.

What outboard would give me similar performance. I ocean fish a lot and don't need much more speed than 30 mph. Of course I don't want to spend more than I have to. There is a $5000 difference between 200hp and 250 hp.

Any thoughts, or better yet any real life, actual conversion stats would be great .

 

[Bondo]

Re: What outboard is equal to OMC Stringer

The question starts with the fact that I don't officially know the Horespower rating for my motor and outdrive combo

Ayuh,... It's rated 260hp...

Any thoughts, or better yet any real life, actual conversion stats would be great .

I've witnessed about a 1/2doz. hulls swapped to Outboard motors, from I/O drives...
None were launched the 2nd season,....
1 was refitted to a Mercruiser drive,... The rest were boned out, after the dismal results of the outboards...

 

[haulnazz15]

Re: What outboard is equal to OMC Stringer

Yeah, you can't just bolt an outboard onto the back of an I/O hull. The transom isn't cut for it, so you'd have to fab up a massive bracket. You have to remove all of the I/O stuff and fill in the giant hole in the transom and fiberglass over it. This wouldn't be a simple project by any means.

 

[bill chisholm]

Re: What outboard is equal to OMC Stringer

Yep I know about the physical changes to the boat to make it work for an outboard. I am well on my way to make that happen and there is a local company that makes the swim platform and installs it in the present transom.

I am mostly looking at the horsepower comparisons, outdrive vs outboard. I wonder how many horsepower actually get to the prop with an old OMC with all of the gears and ineffciency of 30 year old technology.

Question - Is a 260 hp OMC Stringer actually similar to a 200 hp outboard or...........?

 

[bill chisholm]

Re: What outboard is equal to OMC Stringer

Check out the attachment

 

[180shabah]

Re: What outboard is equal to OMC Stringer

How do you plan to compensate for the shift in weight?

 

[SeanMcl]

Re: What outboard is equal to OMC Stringer

I am mostly looking at the horsepower comparisons, outdrive vs outboard. I wonder how many horsepower actually get to the prop with an old OMC with all of the gears and ineffciency of 30 year old technology.

Question - Is a 260 hp OMC Stringer actually similar to a 200 hp outboard or...........?

The rated horsepower is taken from the prop shaft, so if it's rated at 260 that's what you had available to move the boat. You would need a 260 HP outboard to keep the same performance, minus a few ponies due to the lighter weight of the OB vs. the I/O. You would feel it if you went to a 200. That's a 23% reduction in power.

 

[180shabah]

Re: What outboard is equal to OMC Stringer

Modern engines are power rated at the propshaft, but in the 80's they were still crank ratings so a 200hp OB would be pretty close with the 220-230hp he actually has right now.

BUT

the bigger issue here is that he is moving all that weight from in the boat to behind it. This can have HUGE effects on performance, handeling and safety.

 

[Cpt D]

Re: What outboard is equal to OMC Stringer

You see these conversions to outboards all the time in Alaska. I don't think you need to worry about the weight issue at all. The boat will perform better with less weight at the stern. You might want to consider twin outboards. Nice to have two when you're in a storm. One breaks down, you know you can make it back. Either way, you'll love the outboard. My dad had a 24' boat in Sitka and it was converted to an outboard. He had a 175hp Yamaha and it performed very well.
Doug

 

[Don S]

Re: What outboard is equal to OMC Stringer

I have also seen a lot of IO to OB conversions when I lived in Alaska. Maybe 1 out of 100 will work out.
I used to pass most of them while going to work for 5,10.15 years. They are yard ornaments now. Never completed, or didn't work when they were.
All of the yard ornaments were 70's vintage boats, usually Glasplys, Reinells, Apollos and Fiberforms.

 

[HT32BSX115]

Re: What outboard is equal to OMC Stringer

If he absolutely positively MUST repower that boat............

I think his best choice would be to simply replace the engine and drive with rebuilt units.

Otherwise do a transom job and put a modern Volvo Penta or Mercruiser engine and drive in it.


Twin 150hp (or more) outboards might be ok I guess.... but I agree with the above.

Twin 150hp ETEC Evinrudes would cost about $20K (plus installation) the fiberglass fab-job to make them fit properly might probably cost another $5-7K?


I don't know what a transom replacement job would cost if you have to pay someone to do it.....it is not cheap....