Changing from I/O to outboard

[Dave Turner]

Has anyone ever pulled an old inboard/outboard out and welded a plate over the outdrive hole, then put an outboard on for power. I have not gave this a try but I found a 19 foot aluminum deep v with just the out drive still attached. The transom is a straight across design and I was thinking about a manual jack plate to get the right height for the outboard. Anybody who can help or their thoughts is much appreciated.

 

[jbcurt00]

Re: Changing from I/O to outboard

[h=1]changing from inboard/outboard to outboard[/h]
lots of good stuff in the resto section

Look around

Use the advanced search feature

NOT a simple weld the hole shut & bolt on an OB. But possible

 

[magnumdeke]

Re: Changing from I/O to outboard

Going to take more than a jack plate, may be possible with a jack plate and a splash well fabrication, or just fab a splash well and mount it conventionaly. Others like me are doing a out board bracket, your boat is a little short for that conversion or at least on the edge. Lot of stuff to consider performance wise in order to truly make it right. There are a couple conversions going on the boards right now, do a search and a lot of reading.

 

[jigngrub]

Re: Changing from I/O to outboard

So what were you thinking when you bought the I/O anyway?

I think there should be a law that forbids this practice, anyone that buys an I/O should be made to suffer with it until they buy a boat designed for an outboard!

As MD said, lots of other considerations to this kind of conversion... mainly structural. I/O transoms aren't designed for the forces an outboard will put on it. You'll need to strengthen and modify it with braces inside at the bottom and a splashwell at the top, and if you're not a marine architect/engineer you'll need to use a bunch of overkill to make sure you have enough strength... unless you don't mind the outboard motor pushing through the transom and coming inside the boat with you, or maybe a transom in the shape of a half moon.

 

[Yacht Dr.]

Re: Changing from I/O to outboard

So you want to be a rock star ? .. how ya gonna do it ?

Oh I love that.

Remember that the transom has to Push the the boat down that line with an OB.

Beef up the transom and you should be good to go.

I have done mods that do this same thing .. but you have to make sure that the power does not go out of the water and over your head.

Beef up the transom to accept the OB.

YD.

 

[Dave Turner]

Re: Changing from I/O to outboard

As my post says: I found one but have not yet bought the boat and was just asking if the changeover is possible. If I bought the boat I want to use it for lake trolling and fishing. The I/O is not there anymore, just the outdrive.

 

[jigngrub]

Re: Changing from I/O to outboard

As my post says: I found one but have not yet bought the boat and was just asking if the changeover is possible. If I bought the boat I want to use it for lake trolling and fishing. The I/O is not there anymore, just the outdrive.

How much other stuff is stripped off of it?

You may have found a "donor" boat if a lot of stuff is gone, this means the boat will probably need a lot of work because the owner didn't feel like restoring it was worth it. It doesn't mean it's a bad boat or can't be fixed, but it will need quite a bit of work.

 

[Dave Turner]

Re: Changing from I/O to outboard

The boat is deep V Spectrum 1950 and weighs about 1800lbs. or so. The hull is nice and the floor had some issues and the owner put a new floor in it and has carpet for it. I do not want anything extra but a motor of less than 100 hp., steering and fishing seats and electronics. It is going to be a Muskie fishing lake boat and I need to be able to move around freely. Heck, i would even put a tiller on it if I thought it would work out. I understand about the transom and building it up and having a splash well. The posting about the boat not performing and the other issues is what I need to know about if I would add an outboard. Simple answers on how to do the switch would be a great help.

 

[matt167]

Re: Changing from I/O to outboard

If the boat is an I/O configuration, it would be powered with at least 120hp, probably 140hp Mercruiser 3.0L. You will want at least 75% of that HP if you go outboard, and I personally would want 100% of that horsepower because you can throttle back when you don't need it, and have it when you do need it... If the outdrive is there, the I/O is there and your missing the engine. Depending on what was there, you can get a complete engine to drop in for $500-2,000 depending on where you look.

 

[jigngrub]

Re: Changing from I/O to outboard

Simple answers on how to do the switch would be a great help.

You have to ask simple questions to get simple answers, the simple question to this modification is "Can it be done?" and the simple answer is "Yes."... after that it's liable to get complicated with a project like this. Not many people have done this, nor would many people want to. It would be much easier and cheaper to buy an outboard project boat and restore it than it would be to convert an I/O to outboard and restore it too.

If you're interested in boat building/restoration/modifications my best advice to you would be to hang out on these forums and educate yourself until you become confident enough that you can undertake a project like this mainly by yourself and show us all how it's done.

 

[magnumdeke]

Re: Changing from I/O to outboard

The boat is deep V Spectrum 1950 and weighs about 1800lbs. or so. The hull is nice and the floor had some issues and the owner put a new floor in it and has carpet for it. I do not want anything extra but a motor of less than 100 hp., steering and fishing seats and electronics. It is going to be a Muskie fishing lake boat and I need to be able to move around freely. Heck, i would even put a tiller on it if I thought it would work out. I understand about the transom and building it up and having a splash well. The posting about the boat not performing and the other issues is what I need to know about if I would add an outboard. Simple answers on how to do the switch would be a great help.

Dave there is no simple answer, this mod has been tossed about by many and completed by a few on here, at least in the small aluminum boat category. Fairly common on larger big water glass tubs, repower with a swim platform out board bracket, commonly called an off shore bracket, Smaller aluminum hulls suffer from a drastic change in center of gravity shift doing this, can cause porpising or ridding bow high like a old 12' tinny with a 20 hp on the back and one guy in it, bow never comes down and makes it impossible to control at speed.
Points to overcome in my opinion are,
1. Center of gravity, move any weight you can forward, batteries, fuel tanks etc.
2. Actual mounting of outboard, jack plate by itself gives you no room to tilt motor up, cutting transom down will
make it easily swamped if you do not build in a splash well.
3.Transom forces, out board pull and push on the transom at the same time, need to transfer the forward force from
the middle of transom down to the lower hull at least to floor level, normally done with "knee braces"
As short as you are a pod prolly won't work, I would do a splash well and bracing and i believe you would be alright, that being said do you have a motor already? if not it may be easier to get a I/O motor to mate up to your drive, I did not go that way because i run in freezing temps, if i was willing to sacrifice that fishing I would probaly have an I/O set up myself.
Oh ya, put as much horse power on it as it is rated for, you will not be disapointed that way!

 

[Dave Turner]

Re: Changing from I/O to outboard

Thanks guys for all of your input and answers. I must say it sounds like it may be something that I would spend more time working on and less time fishing, LOL

 

[runninfarmer]

Re: Changing from I/O to outboard

I was in the same position as you and did the conversion on an almost Identical hull. My Blue Fin's not much different. Here's a pic of how I did it:


Here's the thread I started on it:
http://forums.iboats.com/boat-resto...-less-than-500-no-welder-required-603161.html

This should help answer some questions, granted I haven't gotten it in the water yet, but it's pretty solid.

 

[jasoutside]

Re: Changing from I/O to outboard

Thanks guys for all of your input and answers. I must say it sounds like it may be something that I would spend more time working on and less time fishing, LOL

Yup!

Yah, if you want an OB boat, you'd really be way further ahead just buying a boat built for an OB. Keep and eye out, you should see one that suites your needs in short order.

 

[bob johnson]

Re: Changing from I/O to outboard

normally finding a boat that is already set up for an outboard would be way way easier...no engineering needed!!! but there has to be something said for a 38" high transom!! guys like me that run in rough waters and back up in rough waters, will appreciate a TALL transom. Bilges are nice, and necessary, but the best thing is keeping water out of the boat! I would say that if you had to pay someone to make an outboard bracket or a splashwell, youd be better off just paying a little more for the boat already set up for an outboard.bob