Outboard conversion

Jgren

Jgren

Member
Apr 27, 2016
94
Plymouth
Boat Info
2001 290 Amberjack
Engines
Yamaha F250's
Has anyone converted their I/O drives on a searay to outboards. We love our 290 Amberjack minus the inboard/outboard drive system. I’d like to see what people have done, if its been done yet. I know losing the twin 5.7 mercruisers and bravo 3 drives would knock off 1000lbs easy if i went with twin 2stroke 250-275’s on a flotation bracket. The transom on our Amberjack is beefy and would be braced in four places up high direct to stringers at the engine mounts if we go this route...
 
You realize that the cost would far exceed what you would recover upon resale. the actual conversion would be somewhat of a trial and error but doable. There was a guy on another boating forum that made a conversion of an older 32ft Wellcraft St. Tropez with Suzuki 300s. He was made fun of and told by most it would not work. Well the results were impressive and he was mighty proud of him self to prove everyone wrong. Good luck.
 
I did see that on thehulltruth, the St. Tropez did turn out nice. There will always be haters in this world that want to spread the discontent negativity.
 
I guess I don't understand why you would want to go to the expense and hassle of doing this conversion. Why try to make this boat into something it's not when there are lots of boats just as nice as you AJ designed and built for/with outboards. Buying one with OB you know the boat was engineered and built for the outboards
 
You might want to explore the insurance issue with a modifies boat before you start.
 
I'll agree with NorCal on this. I love my Outboards, but doing think it's worth the expense to modify an existing I/O to outboards. You're talking about taking that 1000lb of engine weight you mentioned from the stern in front of the transom to 800ish lbs well behind the transom if a jackplate or bracket is used. My 1994 135HP 2-stroke is nearly 400lbs, (2) 250HP is probably more than that, depending on vintage. That has to have serious implications to your resting angle and defiantly your getting up on plane.
 
I agree probably not worth it but just for arguments sake there was a guy on the searay Facebook site that converted his 240 to a single 300 Yamaha, it was cool
 
I'm in the middle of doing just that! My '87 270 Amberjack is being refitted with two Suzuki D175's. We ran the Merc's IO for 10 years and really enjoyed the open rear deck. Did not enjoy the noise and vibration from down below. The cuddy cabin is big enough for the wife and I to over night, head and galley are handy too.

At this point I have cleaned all the unnecessary hardware out of the bilge. Hope to close up the transom and mount the custom Armstrong bracket in the next few weeks. Transom is solid but will be adding additional bracing just to be on the safe side. Old cable steering is out, going back with hydraulic. Instrument Panel is coming out, all glass going back in - 2 x10" touch screens - driven byRPI-3B's running linux -NMEA 2K bus along side two Suzuki display.
The economics are driven by a number of factors. Engines and outdrives were completely gone, found a good pair of used outboards. I like the older designs with some bright work. Retired with time to do most of the work myself. Progress has been slow - had to remodel the house first (first mates priorities) but will get there one day.
 
Jgren said:
Has anyone converted their I/O drives on a searay to outboards. We love our 290 Amberjack minus the inboard/outboard drive system. I’d like to see what people have done, if its been done yet. I know losing the twin 5.7 mercruisers and bravo 3 drives would knock off 1000lbs easy if i went with twin 2stroke 250-275’s on a flotation bracket. The transom on our Amberjack is beefy and would be braced in four places up high direct to stringers at the engine mounts if we go this route...
Click to expand...
In process - drop me a pm for details.
 
CNYBoater said:
I'll agree with NorCal on this. I love my Outboards, but doing think it's worth the expense to modify an existing I/O to outboards. You're talking about taking that 1000lb of engine weight you mentioned from the stern in front of the transom to 800ish lbs well behind the transom if a jackplate or bracket is used. My 1994 135HP 2-stroke is nearly 400lbs, (2) 250HP is probably more than that, depending on vintage. That has to have serious implications to your resting angle and defiantly your getting up on plane.
Click to expand...
The twin i/o 5.7’s with out drives weigh roughly 1150 each. Thats 2300 for both engines and out drives. Twin 250 outboards would weigh under 1200.
 
NorCal Boater said:
I guess I don't understand why you would want to go to the expense and hassle of doing this conversion. Why try to make this boat into something it's not when there are lots of boats just as nice as you AJ designed and built for/with outboards. Buying one with OB you know the boat was engineered and built for the outboards
Click to expand...
The reason why is simple, we like this boat and it would be better as an outboard powered vessel for what we do.
 
Strecker25 said:
I agree probably not worth it but just for arguments sake there was a guy on the searay Facebook site that converted his 240 to a single 300 Yamaha, it was cool
Click to expand...
”
Thank you, ill check that out.
 
Didn't realize the 1100lbs you were talking about was net, thought we meant you were removing 1100lbs of engine.

If you're going with twin outboards, are you going with early 2000s, are twin 4-stroke in your budget? Love my outboard, but I wish it was new enough to be a 4-stroke. I see the newer outboards at the docks all the time, and they don't produce the massive cloud of exhaust my old blackmax does at cold start and my former Johnson did same thing. I probably wouldn't mind the fuel efficiency gains of the newer outboards either. cruising speed I'm getting 1.2 - 1.5mpg.
 
FYI my DF175's weigh 485 lbs each. Considering the Zukes also have an offset drive shaft, the cg of the engine is a little bit forward compared to others. The net change in weight and balance is not what you would think. My props will be only 6" to 8" further astern of the original out drives. Added fresh water and black water tanks up front more than offset it.
 
Sorry guys....I'm never going to get this one. There are soooo many outboard-powered boats out there for sale already set up as you want them to justify the expense but, not my money.

Just one guy's opinion but then again.... I am not, never have been, nor will I ever be, an outboard guy. I like my motors inside the boat.

Best of luck to you guys....hope it works for you
 
CNYBoater said:
I'll agree with NorCal on this. I love my Outboards, but doing think it's worth the expense to modify an existing I/O to outboards. You're talking about taking that 1000lb of engine weight you mentioned from the stern in front of the transom to 800ish lbs well behind the transom if a jackplate or bracket is used. My 1994 135HP 2-stroke is nearly 400lbs, (2) 250HP is probably more than that, depending on vintage. That has to have serious implications to your resting angle and defiantly your getting up on plane.
Click to expand...
CNYBoater said:
Didn't realize the 1100lbs you were talking about was net, thought we meant you were removing 1100lbs of engine.

If you're going with twin outboards, are you going with early 2000s, are twin 4-stroke in your budget? Love my outboard, but I wish it was new enough to be a 4-stroke. I see the newer outboards at the docks all the time, and they don't produce the massive cloud of exhaust my old blackmax does at cold start and my former Johnson did same thing. I probably wouldn't mind the fuel efficiency gains of the newer outboards either. cruising speed I'm getting 1.2 - 1.5mpg.
Click to expand...

We are looking to go with lightly used motors for this project. Twin four strokes are in the budget, however the low end torque of two strokes are attractive plus the power to weight, two strokes have the upper hand. We had outboards before this boat and that smoke cloud for the first start up of the day was hideous. They call them two smokes for good reason. That puff is only insurance making sure everything is getting oil including the environment. I had a 97 Johnson ocean runner 150 and 04 Merc 225 EFI. Both motors were bomb proof and the maintenance was simple. So I'll be going back down that road. Prob low hours white motors this time like a set of E-tecs.
 
NorCal Boater said:
Sorry guys....I'm never going to get this one. There are soooo many outboard-powered boats out there for sale already set up as you want them to justify the expense but, not my money.

Just one guy's opinion but then again.... I am not, never have been, nor will I ever be, an outboard guy. I like my motors inside the boat.

Best of luck to you guys....hope it works for you
Click to expand...
Are there any similar boats to the amberjack that have outboards and aren't walk arounds? Everything I've found are walk around styles and more geared towards fishing. we like cruising more and enjoy the space down below that the walk arounds cut into.
 
518CED64-7D8B-459E-9A54-D1E8F0A169B0.png
 
A local light hearted TV fishing show did a conversion on a 23 ft Bertram. Removed the single 5.7 merc, podded the transom to create buoyancy and lift and fitted a single 350 Yammy. They did before and after tests - it flew compared to the merc, but the Yammy still didn't mind a drink.

Google "Unleash the beast Yamaha conversion" and you should find a 9 part YouTube history of the conversion.

Link:

http://www.hooklinesinker.tv/unleash-the-beast-project-boat-2009/
 
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