Converting sterndrive to outboard

[patmilstead]

I have two force 125's I am going repower with. I have Seabird 23ft with chevy 350 and omc sterndrive being removed.
I need all the information on transit beef up also should I go with one force 125 or two. Information on mounting brackets.
I would like to know if transit can be cut to accomadate engine or engines for salt water use.
I need all the info I can get, hual is in good shape no rot.
The work is no problem my concern is the strucual stress. (like to keep the boat in one piece)
patmilstead

 

[slasmith1]

Re: Converting sterndrive to outboard

This is a bad idea that has been tried and done many times for the following reasons.
1) the boat was designed for an i/o switching to outboards will drastically change the weight distribution.
2) boat will not handle the same (see above)
3) why are you changing from an obsolete i/o from an out of business company to an obsolete outboard from an out of business company? That is just trading one set of problems for another.

I am sure that others will chime in with many more reasons so I will stop there for now.

 

[patmilstead]

Re: Converting sterndrive to outboard

I expected your reply as stated.

Lets for a moment say the two engines I have were just rebuilt.
they weigh 300 lb each.
Between the chevy 350 and out drive I am removing are about the same weight.
The last and most important thing is money I am 68 years old and retired with minimun income but love to be on the water.
If one engine will do the job that just means I have a spare in case one craps out.
I live less then 10 miles from the ocean Orange County Ca.

 

[Stachi]

Re: Converting sterndrive to outboard

you will need to rebuild your transom.... it wasn't designed or built for an outboard and its stress...your hull is where the engine was mounted for I/ O ...thats where the structural strength is...not to mention the gaping hole in the transom from the outdrive...with enough time and dineros, I'm sure it could be done but......why not look for a hull to fit one of your engines on ? I bet you could find something that would cost less then what it would cost you to do the job properly on this hull , or, if you really love the boat...maybe sell the outboards for a good rebuilt I/O ??

 

[slasmith1]

Re: Converting sterndrive to outboard

I expected your reply as stated.

Lets for a moment say the two engines I have were just rebuilt.
they weigh 300 lb each.
Between the chevy 350 and out drive I am removing are about the same weight.

Read 1&2 in my first post they may weigh the same but you are moving the weight from inside the boat to hanging off the stern. This will cause the boat to handle very differently than designed and could be downright dangerous in some situations (heavy or following seas).

 

[Stachi]

Re: Converting sterndrive to outboard

I agree slasmith...not to mention how the hull is configured for the torque , vs. what the stern was built for...add in the opening for the outdrive....

 

[patmilstead]

Re: Converting sterndrive to outboard

Ok where do I look for just a used haul.

 

[Stachi]

Re: Converting sterndrive to outboard

try craigs list, or ebay...

 

[jeeperman]

Re: Converting sterndrive to outboard

or boatangel.org http://www.boatangel.org/
Most have questionable power plants but only need cosmetic work on the rest.
Thus they often sell cheap.

 

[JoLin]

Re: Converting sterndrive to outboard

Read 1&2 in my first post they may weigh the same but you are moving the weight from inside the boat to hanging off the stern. This will cause the boat to handle very differently than designed and could be downright dangerous in some situations (heavy or following seas).

I don't want to start an argument here, but I think there's room for debate.

If that Seabird was offered in more than one configuration (outboard, or inboard, or I/O), then I'm betting that the boats were identical, the only differences being those necessary to install one drive type instead of the other.

That said, I would also look for an outboard model due to the amount of work involved in swapping from one to the other. From what I've read on the forums here, rebuilding a transom is a big job that I don't think I'd want to tackle. But, hey, some folks have a lot of time on their hands and like to "tinker."

 

[dingbat]

Re: Converting sterndrive to outboard

I find the arguments against the transition odd since the hull probably came out of the exact same mold as the outboard model.

Up until a few years ago you could order my boat with outboards, I/O or a bracket. The hull of all three boats came out of the exact same mold. They have since discontinued production of the I/O, but the only difference bwteeen the three was the configuration of the liner and the location of the fuel tank/s.

If you had a transom mounted outboard you got a liner with a splash well. If you had a bracket mounted outboard the space is used for the bait tank. If I/O equipped the area was used to mount the motor and they moved the fuel tank forward 16 - 18? to make room for it.

It all comes down to is it cheaper to make the modification or to sell the boat and buy it in the configuration you want?

Here is a Seabird I/O conversion in process to give you an idea of what you are in for.
http://www.thehulltruth.com/boating...69-23-seabird-project-boat-south-florida.html

 

[Tacklewasher]

Re: Converting sterndrive to outboard

You say you have an OMC that you are pulling out.

I tired something similar with a Starcraft a few years back. Pulled out an old stringer drive (120hp) and tried to hang a 115 Evinrude in it's place. After two seasons of using it I found the hull had hooked badly. Ended up buying a similar boat but an outboard model.

The Stringer drive has zero weight on the transom. As a result, there was no bracing of any kind and this caused the hull to deform. All the weight and power was supported by the boats stringers and the transom was there.

As well, the boat never did work right. It was slow out of the hole and slow at the top end. Plus I had a lot of ventilation problems. Even tried a jackplate but it did not help. Same motor on the same size and weight hull works much better.

 

[slasmith1]

Re: Converting sterndrive to outboard

I don't want to start an argument here, but I think there's room for debate.

If that Seabird was offered in more than one configuration (outboard, or inboard, or I/O), then I'm betting that the boats were identical, the only differences being those necessary to install one drive type instead of the other.

That said, I would also look for an outboard model due to the amount of work involved in swapping from one to the other. From what I've read on the forums here, rebuilding a transom is a big job that I don't think I'd want to tackle. But, hey, some folks have a lot of time on their hands and like to "tinker."

not true at all there are many differences between i/o and outboard models from the same manufacturer.
I will offer just 1 example because I was looking at 1 the other day. 2006 searay 185 both models are called the 185 but the i/o version is 2ft longer.

 

[CheapboatKev]

Re: Converting sterndrive to outboard

Ok where do I look for just a used haul.

You can look here on the Orange County craigs list for a hull..
Make sure the transom is solid on any old hull you go inspect.

Happy Hunting

http://orangecounty.craigslist.org/boa/

 

[NSBCraig]

Re: Converting sterndrive to outboard

Dingbat is right boat hulls are not made from different molds for the hull except in certain circumstances (like Skater adds a transom notch for outdrives).

Rebuilding the transom in a way like the builder did it is all that is needed, and re-rigging.

Do check your stringers and even if the builder didn't build knees think about doing it now, not much work but worth it in my mind.

(and really Force???)

 

[JoLin]

Re: Converting sterndrive to outboard

not true at all there are many differences between i/o and outboard models from the same manufacturer.
I will offer just 1 example because I was looking at 1 the other day. 2006 searay 185 both models are called the 185 but the i/o version is 2ft longer.

I went to the Searay site to check that out. Yes, the 185 I/O model's LOA is 20" longer than the outboard's. But, take a look at the photo gallery. The I/O model has a swim platform that the outboard doesn't, and that platform sticks out beyond the transom. Cut off the swim platform and notch the transom, and you're looking at the outboard model.

They're the same boat

 

[slasmith1]

Re: Converting sterndrive to outboard

I went to the Searay site to check that out. Yes, the 185 I/O model's LOA is 20" longer than the outboard's. But, take a look at the photo gallery. The I/O model has a swim platform that the outboard doesn't, and that platform sticks out beyond the transom. Cut off the swim platform and notch the transom, and you're looking at the outboard model.

They're the same boat

that is a molded in swim platform. so the mold must be different. the angles of the transom ar different under that swim step. should i go on. older models that look the same have different knees and so on to support an outboard.

The boats are also rigged differently such as fuel tank location which is why just switching motor configuration will cause weight distribution issues and potentially dangerous handling characteristics.

 

[smokeonthewater]

Re: Converting sterndrive to outboard

the intent of the guys original question was to put together a cheap rig..... seems like all this debate is a little over the top seeing as how he has disapeared..... some are molded different and some the same.... what actually matters are additional steps to make the transom more rigid... for example a splash well is not just a splash well it is a structural part of the boat which ties the top of the transom to the sides of the hull.....
Yes the conversion can be done... On some boats it works well and on some not so well...... for a first timer on a very limited budget a better choice would be to spend the winter coaming craigslist for a decent outboard hull without engine or trailer for $50 - $500 slap on their engine adjust trailer to fit and go fishing

 

[JoLin]

Re: Converting sterndrive to outboard

that is a molded in swim platform. so the mold must be different. the angles of the transom ar different under that swim step. should i go on.

These boats are assembled in 2 main parts- the hull, and the cockpit liner that is set down on top of the hull and screwed to it. The swim platform of the I/O model is molded into the cockpit liner. The hulls are the same.

older models that look the same have different knees and so on to support an outboard..

Not arguing that the transom needs to be strengthened. That's a given.

The boats are also rigged differently such as fuel tank location which is why just switching motor configuration will cause weight distribution issues and potentially dangerous handling characteristics.

There are things that need to be reworked and relocated. I never implied that one can simply switch the motor configuration and be done with it. Nor would I consider a 2006 Searay to be a good candidate for that kind of surgery. There are too many molded-in shapes in newer boats. Would take a crazy amount of fiberglass fabrication to do it. Makes no sense.

Now, take a look at a 23' Seabird. I googled it- they're around. Old, straight-up boat with square lines. It's doable if you have the time and skill, and there's no reason that it would be "dangerous" to do it. I recommended against it due to the amount of work involved. But hey, people do stuff all the time "just because", and it does make for an interesting project.

(with all respect to smokeonthewater, this debate is not "over the top". The guy wanted to know about do-ability, and there are differing opinions on whether that's the case).

Anyway, I'm done. Have a great day!

 

[smokeonthewater]

Re: Converting sterndrive to outboard

fwiw jolin.... I do agree with you on many points... I just thought maybe a couple folks might have lost sight of the o/p... def not pointing fingers