Junk inboard/outboard repower with outboard?

I have a 1988 Fairbanks 28' Sportfisher. It has twin Mercruiser 470's with alpha one outdrives. The boat is kept in saltwater and has not been hauled out in 3 years. One engine is frozen, the other runs but the leg is in need of maintenance soon. Hauling out is expensive in Hawaii, $1000 or so, and I was thinking to haul, remove outdrives, seal holes, and put on an outboard. I know it will not be doing its original 27knts or maybe not even the 7knts it was doing with one engine, any suggestions? I'm happy with a 5 or 6 knot boat. Has swim platform, teleflex steering all good for outdrives. Thank you very much for suggestions.

 

The transom will not have the proper shape for an outboard, so the best way to proceed is make a support that is bolted to it. And you probably have to modify the swim platform as well.

 

A 15 deg angle is standard for the transom or the pod you intend to fit ...how many HP are you proposing to use

 

a 28' foot sport fisher will need at least 75 hp to push it, and probably 400hp minimally to get it on plane. The problem is boat was design for inboards not outboards. I would go with something like rebuilding drives and engines. as best cheapest option. Believe it or not it can be done on the boat while in the water. Get yourself and old hydrohoist type device and jack the rear out of the water. There are companys that will take your old drive and exchange or you can rebuild them yourself.

 

Thanks

Thanks for the suggestions. I had been planning to use a johnson 50 because it is considerably lighter than the 60-90. Was thinking I may have to re-prop it to get any pull agains the wind and waves but the more I think about it the more it makes sense to keep it inboard. Funny thing is. its working just fine with one inboard, have stripped the other down to the block, so now I have all kinds of spare parts!!! I know it sonds like I'm running a janky operation here but maintaining 2 engines and outdrives in salt life isnt the cheapest thing to do. And I just want to putter out and dive/party. I will look into the hydro hoist idea. At this point I think it makes sense for me to haul out, remove old block and outdrive, plug it. Then overhaul the working outdrive and just run it with one. Thanks fellas, my brain was a hurten yesterday thinking about the direction to go in. Aloha

 

If you're content with displacement speeds the power requirement is minimal. One or two small Kubota type diesels may be the answer. You might want to keep both legs in the water to stabilize the boat and keep it from wallowing at low speeds. Kubotas are used to power refrigeration machinery on freezer containers and frigocamions and used ones can be had cheap in this part of the world.

Dino

 

Stick a 115 hp Yamaha 2 stroke on the back and stop pisssssing about . If you can get it over 15 mph you will be on the plane and power requiements drop....nothing worse than trying to go at a speed between hull speed and planing speed

 

you fish in the ocean so swells and the like the plateform will stick the outboard to far out so need to get a little closer to the back of the boat , You can simply buy a bracket all ready made to bolt and plate straight to you transome and cut the plateform away and have it reglassed again where the out board will be . trying to attach to the plateform is a total waste of time and money . A 250 yamaha would be nice and comfortable and make sure its a 25 inch shaft not a 20 !! get the motor up away from and out of the water and keep it dry !!. Boat got trim tabs ?? if not you will need them for sure !!
Buy yourself a hat with a chin strap or you will loose it !!

gETTING SHOT OF TWO CLANKER INBOARDS AND THE JUNK THAT GOES WITH IT WILL GIVE THA 28 FOOTER A WHOLE NEW LEASE ON LIFE !! THAT WEIGHT WOULD BE 5 TIMES THAT OF ONE OUTBOARD EVEN A 250 HP . WHY SETTLE FOR PADDLE POWER WHEN YOU CAN FLY !! YOU JUST GO AS FAST AS YOU WANT TO AND SAVE THOSE OTHER PONYS FOR THE DAY YOU FEEL ADVENTUROUS AND WANT TO LET LOOSE AND GO !!.
i GET SICK OF WATCHING THE BACKS OF EVERYONE ELSES BOATS SO HAVE A 115 YAMAHA ON MY 14FOOT 6 BOAT . LOST 2 HATS SO FAR AND STILL HAVE 4 MORE SPARES .

 

1000 dollars for haul out!!! well make a trailer for half that. haul it out -tow it home - repair the original.

A chevy 350 long block is cheap. Where you are, second hand parts must be cheap and plentiful. Do you know Dog the bounty hunter?

 

send thoes heavy gasguzzlers to the tip along with all of its attachments make the boat lighter and a much better boat out of it !!.

 

By doing what?

 

This is such a common situation with older boats that the solution has already been well vetted. Pull the engines and outdrives, glass up the holes in the transom, install a mount bracket suitable for one or two large outboards and go. Just about everyone I've talked to in the last few months agree that Yamaha makes the most reliable engines, with Honda a close second. Keeping or modifing the swim platform depends on the bracket you install for the outboards.

MM

 

older boat were made in the days when big motor and loads of junk got used and little care . those day have gone never to return . think light and dump anything and everything thats of no use . brackets come in all sizes the further back the motor the more you will have problems out in the waves , the motor will come completely out of the water so keep it closer one foot is good but dont go to much further . use a 25 inch motor and keep it high out of the water , motors last longer give less trouble and lot less corrosion . its worth the effort and when ts finished you will wonder why you didnt do it long time ago !!dont underpower the boat , its false ecconamy as the little motor is always struggling fromthe mment you put it in gear . get some horses and use them . 250 hp vee 6 yamaha 25 inch is a nice motor . my son has one and it gets a lot of use .

 

good posts tunnels but i would go for an ultra long 30 inch leg on a boat that size. they have saved a lot of engines from getting drowned on shark cats.

 

Yip i totally agree !!:!: