Going from I/O to Outboard...thoughts, rules of thumb, etc.

[Prodigal Son]

Might take my 19' runabout and put a center console on it and a single outboard. It currently has a 3.0L Mercruiser mated to an Alpha I outdrive. Any rules of thumb on what height I could mount a bracket (and subsequently a motor, what length leg on the outboard, etc). Is there any rule for how horsepower translates to performance between an I/O and an Outboard?

In my head I had pictured mounting an outboard so that the prop ends up at a similar depth as compared to the I/O drive when trimmed all the way down and the deciding on the length of the motor by figuring out how high it would need to be to stay reasonably clear of the water line...that an erroneous line of thought? Putting a bracket into the equation might confuse things, but I can't see why it would change a whole lot...

If I do this, I'm likely going to use what I can find in my garage, my neighbor's garage and any other boater's garage because the other option is to trash the boat...and I don't want to do that, the thing is a 1995 model year, I just hate the I/O runabout setup and selling it wouldn't be worth the effort unless I put some effort/money into fixing it up...which I wouldn't want to do to a boat I don't like and don't have a solid idea of what I could sell it for.

Any other thoughts on what it would take to do a half-a$$ed job at this? Seriously, half to five-eighths is about all the effort that needs to go into this. The boat floats and actually runs, but the interior is shot (so I'll lose nothing by cutting what's left of it out and buying a used console to put in the middle) and the outdrive and motor both lose oil (so I'd have to pull the motor and drive anyway...but I could theoretically fix it and put it back in.)

Lay it on me, just don't say don't do it

[fishbard]

The ventilation plate on the motor can be an inch above the bottom of the boat for each foot of setback on the bracket. It will go faster with a properly set up outboard on a bracket than an I/O because it will be lighter and the bracket is a more efficient set-up. An extra long shaft (25") motor is the minimum for a bracket, motor will be living in a pretty wet place even at that. You can end up with a nice boat doing this, but it won't be cheap or easy, make sure your transom is strong enough to take the weight cantilevered off of it. I would also say to make sure you really like the boat, because you might be better off selling the one you have and buying a used outboard boat that is more to your liking.

[Prodigal Son]

I started cutting when I got home from work, so I'm at least going to have to replace the deck and glass in a new console...that's been decided by Milwaukee and Dewalt in the past 4 hours. (I'd forgotten how much I hate grinding and cutting fiberglass...my arms are freaking burning.)

I think I'm going to try to replace the seals/bellows/etc in the outdrive and see what that nets me in the motor department. The hull of the boat is getting stripped though regardless.

I've got a friend who is a small time crabber and tends to have a fleet of outboard boats in various states of disrepair and I'm hoping to just snag one of his motors in the 115-150hp range in exchange for some work or small money, but I can't put a timeline on grabbing a cheap motor, so I'm going to hopefully run what I brung so speak in the mean time...that would be a big expense that I hope to not worry about.

[Capt. Fred]

Rub some baby powder on your skin before you start working, grinding, etc. with the fiberglass. I helps keep the fibers out of your pores.