Converting I/O boat to outboard

[Shawn Mclaren]

Hey Guys,
I am interested in converting my 97' Eliminator 22 Daytona I/O to outboard. Are there any threads of past projects? I know the I/O hulls have thicker transoms but just want to know the best materials or methods to complete this project. I will have someone re-gel the rear of the boat but wanted to save some money and do the fiberglass myself.

[David - WI]

Why not sell it and buy an outboard that you like?

[Shawn Mclaren]

I just got this boat and bought it with intentions to switch over. Everything near me is $40-50k and I didn't like the interior or colors of the boat. I got this for a good price and I'm willing to put in the work and build it and rig it the way I want.

[David - WI]

Man, it's just a lot of work and usually ends up not performing as well as a boat designed as an outboard BUT most of the people here are smarter than I am... so take it for whatever it's worth.

[donmac]

did a 28 maverick years ago, pulled the 2 inline volvo's and put V8 fridges on the back with 26'' gil brackets, boat had good top end but porpoised badly at some speeds! really need to pay attention to c of g doing this stuff! plugging transom isn't a problem but adding tie bars from stringers to transom is good insurance, think i put 8 in because of the motor weight and setback!

[Jimboat]

Man, it's just a lot of work and usually ends up not performing as well as a boat designed as an outboard

did a 28 maverick years ago, pulled the 2 inline volvo's and put V8 fridges on the back...boat had good top end but porpoised badly at some speeds! really need to pay attention to c of g doing this stuff!

i agree that conversion of IO to outboard can dramatically change the performance of a hull. The Eliminator 22 Daytona was designed as an inboard power, so it's possible that the boat, including the bottoms, was designed for much different weight and balance. The dynamic stability may be quite changed when converted to OB. This can often show up as porpoising or other instabilities. Best be careful if trying to achieve higher speeds. Perhaps the good thing is that OB->IO is probably more difficutl than IO->OB.

[Instigator]

What Jim said!

I had two twin OB 24’ Sonic vee bottoms that’s design started as single, big block IO Donzi’s.

They both ran very well as OB’s.

In the water I ran them in, they were huge fun and ran great at all speeds.

In large swells though, they came down motors first, aggressively (!!), where the IO boats landed more evenly.

I recently did a 25’ Checkmate big block to twin OB conversion.

The factory offered these hulls both ways.

As an IO, they were great boats and handled any power you through at them (I know of one that went 126) and handled predictably.

The factory OB hulls had splashwells w/motors mounted to transom to compensate for the change in C of G and they still had a reputation for having a hop at certain speeds w/o full down tabs.

When I did my Checkmate conversion I just assumed those guys were off on set up and that mine was close enough to my previous Sonics to be safe.

I was wrong!

The Checkmate is both lighter and narrower than the Sonics.

So, like the lightweight lake rockets that we all love, the effect of weight placement has for more effect than on heavier hulls.

I pretty well have mine dialed after much weight transfer but is far different than where it started.

As a side effect, it will greatly reduce your trailers tongue weight and it’s handling.

After conversion, my (I think 4700 lbs total) tongue weight was at 135lbs!
Talking about scary towing!

It is now at 450.

But, was one more thing I didn’t expect to become a project!

[donmac]

2 maverick 28's one open deck, one closed! the open deck {ROUGHnTUMBLE} got the stock V8outboards 77mph! the closed deck {BANSHE} got a twin turbo 482BBC with ssm 86mph!
big difference in performance, but a lot of maintenance on the hyped 482, re-ring as I recall every 30hrs.

[Greg G]

Here is a thread that goes through the process .........

https://www.performanceboats.com/thr...t#post-1247607

[GETBOATS]

I just converted a 1988 Cole 24 from Merc. 502/bravo to single Yamaha 4.2l. in the 80's, 90's and beyond engineered/designed was more like what you will do, trial and error. What I did first with a good running boat was to find the balance point. From there as the conversion progressed, try to mimic that same balance point. Right now, the boats runs great with some porpoise at certain speeds, most boats do. Speed is 6-7 MPH slower than previous power. Thats with no setup/propeller changes. In the end I'd expect to be in the 82-84 range. I did not do tie bars to stringers and never have, always viewed that practice as a band aid or short cut. I build large knees, glassed to transom and existing stringers, all tied to boats bottom. Used a Bob's 14 setback with 6" lift so engine could be tilted during trailering. 20" engine running prop shaft 1-1/2 below the bottom. I too had the gel coat shot and polished by a pro and it looks new. I've done several of these both in composite and plywood. your boat is plywood, so composite might be more exotic than you need. It will be a snow ball as you will find more to fix than originally thought, but go for it.

[doug7488]

It’s not really that hard
Follow me for more boat building tips

[donmac]

fat broad boarding that,one of those things that can't be unseen!

[Shawn Mclaren]

Thanks for the info guys. I am currently doing interior, carpet, stereo and new gauges. I will run the boat as is for the summer and maybe this winter or next i will switch over.

[David - WI]

Thanks for the info guys. I am currently doing interior, carpet, stereo and new gauges. I will run the boat as is for the summer and maybe this winter or next i will switch over.

It's a good looking boat!