Converting my i/o boat into a Outboard with a bracket

[formulafisher]

What would i need to do to convert my boat that is setup for a i/o to an outboard? I would be looking to put twin 150hp's on the bracket. What kind of structural supporting would be required?

 

[ddaigle]

Re: Converting my i/o boat into a Outboard with a bracket

I did one a few years back, but with a single outboard. Twins is a lot of weight but I have seen it done. I bolted steel plates to the transom inside and out(Aluminum would be better, but expensive) and then ran angle iron to the old i/o motor mounts to brace the transom. Worked for me but there are probably better ways as I did this as cheap as possible. Turned out pretty good though.

 

[Dhadley]

Re: Converting my i/o boat into a Outboard with a bracket

Generally we glass "knees" between the transom and the stringers. The transom will get some glass too when you fill in the I/O cutout.<br /><br />You also need to address the transom angle. It can be different from a I/O boat to an outboard. Most bracket manufacturers can adjust for that when you order the bracket. You just have to know what angle you have now.<br /><br />Most bracket manufacturers can supply specific instructions for a given boat, if its a popular model.

 

[Solittle]

Re: Converting my i/o boat into a Outboard with a bracket

Be thorough on the research before you commit. There have been several posts from guys who did it and found that the balence (way the boat sits in the water) was way off after the conversion.

 

[WillyBWright]

Re: Converting my i/o boat into a Outboard with a bracket

Also make sure you actually have some meat to attach the bracket to. Many I/Os only have wood in the middle. Either side of that is just fiberglass

 

[Mark42]

Re: Converting my i/o boat into a Outboard with a bracket

I know this is more work, but I would think the best way to install an ob on a io would be to notch the transom and install a splashwell with supports that transfer the load to the old motor mounts/stringers. It will keep the weight from being shifted farther away from the original location, and will not take up as much room as the io motor and cover did.<br /><br />Either way, you still have to fill in the hole in the floor from the motor, and address the space on the back of the transom that was covered by the engine cover. <br /><br />Kind of like this boat that is meant to be built from plans:<br /><br />

 

[Dhadley]

Re: Converting my i/o boat into a Outboard with a bracket

Actually closing the transom and using the bracket usually ends up with a very favorable balance. Plus it opens up a ton of room in the boat.<br /><br />Twin 150's, especially the E/J 60 degree models, Are probably lighter than a V8 I/O package.<br /><br />The problem with a cutout from a S/D boat is the transom angle is probably wrong for the outboard. Then you get into transom wedges etc. You still have to do glass work because the I/O cutout is below the waterline. So at that point you may as well go with the bracket. Its quieter, offers a great balance point, opens up more room, compensates for the correct angle and is dryier in a following sea. Plus you end up with a swim platform.

 

[phatmanmike]

Re: Converting my i/o boat into a Outboard with a bracket

Plus you end up with a swim platform

that sold me !!!!!

 

[bernieb]

Re: Converting my i/o boat into a Outboard with a bracket

In building a bracket for two 150's you first have to take a good look at the strength of your transom that you now have .You can expect to invest 700.00 in parts if you do it right.Start off by buying 3 sheets 3/4 inch fir plywood (about 50 bucks a piece)not pressure treated plywood.You will be fiberglassing as you build.Start off with 2x2 aluim angle fastened to transom with 3/8 stainless steel bolts 8 inches on center ,very important at height with relation to keel of boat.Level the keel of boat ,level the plywood platform,keep it that way throughout job.Scribe platform to boat transom for tight fit and only fasten with a couple bolts as it will be taken down several times.You will need a router to put three 3/4 inch wide groove,(rabbit)(dado)to handle three partitions that will go from new transon to old transom.Always use 2x2 aluim angle inside were it makes sence.Use a 36 inch front to back platform,it's nice to have the room to check the engine.Rabbit ,dado the outside but don't worry about the tight fit as you will be getting the strength from the fiberglass but do use brass screws .I used a 12 degree angle for my yamaha 250 mounted on 1/2 inch high strength aluim bolted to plywood.Many frustrations but it all falls in place.Use the thick cloth on the bottom but do it while it's facing the sky. Bernie

 

[phatmanmike]

Re: Converting my i/o boat into a Outboard with a bracket

you can do as it is stated just above me here, or you could just buy one of these

<br /><br />here is the link:<br /> http://www.stainlessmarine.com/twin4.html

 

[Stumpknocker]

Re: Converting my i/o boat into a Outboard with a bracket

I feel that Superglue still has merits. Much less money and time.....

 

[formulafisher]

Re: Converting my i/o boat into a Outboard with a bracket

honestly how feasable would it be to acomplish this project. Do you think i would gain any speed over a i/o that puts out 250hp?

 

[Dhadley]

Re: Converting my i/o boat into a Outboard with a bracket

Very feasable and yes, I would expect an increase in efficiency over the I/O with a 200/225 outboard. Especially if the outboard is a DFI model.

 

[formulafisher]

Re: Converting my i/o boat into a Outboard with a bracket

could i realy expect an increase in speed from only a 225? how does that work. What do u think my gains would be with twin 150's.

 

[JasonJ]

Re: Converting my i/o boat into a Outboard with a bracket

A 225 on a bracket, properly mounted, weighs at least half as much as the I/O, and the offset gets the prop in green water. The performance increase will be quite apparant. The twin 150s would probably give similar to slightly less performance compared to the 225 because you have more weight/drag. The only advantage to the twins is get-home ability if one fails.