I/O (Sterndrive) Conversion to Outboards

tpenfield · Sep 20, 2025

alldodge said:
Wonder if it has something to do with all the new electrical stuff installed

IDK . . . maybe. Not sure how I could tell. Anyway, enough changes to the boat are forthcoming, so AF protection will be at a new starting point.

redneck joe · Sep 20, 2025

When I was daydreaming of putting outboards on the Carver, the old engine area would have been mostly fuel tank. Can't remember the numbers but range would have been fantastic. Over doubled, close to triple iirc. I had dreams of doing the great loop at planing speeds in my 23 footer. I miss that boat.

tpenfield · Sep 20, 2025

The factory OB versions of this boat (CY 338) have a 230 gallon fuel tank, which stretches a little further back towards the stern than the sterndrive fuel tank (150 gallons). I'm not sure of the rationale behind the different sizes. . . I would think 150 gallons would be enough and my understanding was that the fuel consumption between the 2 models was similar.

tpenfield · Sep 20, 2025

Thinking ahead as I get ready to take things apart I am trying to figure out what components should be removed and what should stay. A lot of it depends on engine choice. Here is my instrument panel drawing . . .

If I go with Yammy or Zukes, then everything 'Mercury' related would come out.

If I go with Mercury, then maybe some of the stuff could remain (not sure though) I'd probably have to confer with the re-power shop on the details. My guess is the items TBD would be the . . .

Mercury GPS antenna,
the diagnostic port, and
the ignition switches.

I assume all the other stuff would need to be replaced (or at least should be replaced with the latest versions). Ant one with some insight on the controls and instrumentation, feel free to chime in.

Across the top of the instrument panel are a few gauges 3-1/4" and 2", IIRC. I plan of getting digital versions of these gauges from Veratron. A few of the CY-338 owners in the FB group have switched over to these gauges with good success. The new stuff will need to run on a NEMA 2000 backbone.

alldodge · Sep 20, 2025

Can loose the blower switch
I like the trim gauges close together for easier view

tpenfield · Sep 20, 2025

alldodge said:
Can loose the blower switch
I like the trim gauges close together for easier view

I tend to agree . . . I could put both trims on the port side panel and move the fuel over to the starboard side panel

or . . .

I could put the trim display on (and in addition to) the tachometer displays for closer proximity, and maybe free up a whole panel area by moving the fuel gauge to the starboard side.

I guess I'll have to decide when the time comes.

tpenfield · Oct 11, 2025

And so it begins . . .

I built the gantry over the past few days. I was initially thinking about a 10 foot tall structure, but I went with 12 feet tall just to make sure the engines would clear the deck. Doing so, I up-scaled the top beam material to 2x12's and everything else is 2x6. Of course the weight 'up-scaled' as well and I had to get creative in raising it to its upright position.

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I still have a few finishing touches, caster wheels, etc

It is a bit over-designed, but that can be a good thing. Next steps will be to take off the outdrives. Then remove the rear seat/engine bay hatch, and pull the engines.

The hardware store in town is giving away pallets, so I'll be grabbing a few to put the engines and outdrives on.

alldodge · Oct 11, 2025

Is this an illusion ?

redneck joe · Oct 11, 2025

Are you not going to need a snow cover soon?

Lou C · Oct 11, 2025

Even New England doesn’t usually get snow till mid to late December….we have not had a “real” winter here in Long Island in 7/8 years. Little snow. We do have a nor’easter coming tomorrow though….

tpenfield · Oct 11, 2025

@alldodge - temporary oak spars, part of the finishing touches will be to replace with 2x lumber when I true-up the uprights.

@redneck joe - Snow maybe in January . . .

tpenfield · Oct 12, 2025

We are forecast to have 30 mph sustained winds and 45 mph gusts, today -> Monday. I should have time to finish the upright supports this AM, as the rain will be hitting late morning.

tpenfield · Oct 12, 2025

Pretty much done . . .
I got outside early, before the wicked storm starts, and finished up the gantry.
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I'm using moving dollies as my "poor man's" casters. . . I might need another couple right under the posts, but we'll see. (1,000 lb rating each)

One critical design aspect about the gantry was the side clearance of the knee braces, since the sides of the boat come up pretty high. Looks OK.
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Now I need to find all my ratchet straps and associated gear. Probably won't have the chance to do much more until mid-week.

Scott Danforth · Oct 12, 2025

Harbor freight moving dollies?

alldodge · Oct 12, 2025

Small rocks can make rolling it a problem
Maybe 1/2 sheet of plywood would or similar

redneck joe · Oct 12, 2025

Need to hook up yer ac drip to a pipe.

Lou C · Oct 12, 2025

Very interested to see this project progress as somone who has also lived with sterndrives with a boat moored in salt water for 20+ years as well. The boat I have was actually available with outboards although probably few were sold way back then. Actually a 200 Hp 4 stroke would probably move it nicely.

tpenfield · Oct 13, 2025

alldodge said:
Small rocks can make rolling it a problem
Maybe 1/2 sheet of plywood would or similar

Yes, the driveway is not smooth by any means; it has a pea stone topping embedded into it that makes for a bumpy ride of the casters. The structure does move OK to the extent that it needs to.

I plan to move the boat forward and slide the gantry over. Then move the boat back in place. As I off-load the rear seat assembly and the engines, I'll be moving the boat in and out of the way, so the gantry can stay put.

flashback · Oct 13, 2025

Won't the engines hit the braces?

tpenfield · Oct 13, 2025

flashback said:
Won't the engines hit the braces?

No . . . They may come somewhat close to the braces, but the engines need to clear the swim deck, which is about 2 feet lower than the sides of the boat.

It is just that the braces need to clear the sides of the boat so the gantry can be positioned over the engines.

See my mock-up below as to about how high the engines will need to be lifted.. . .

I/O (Sterndrive) Conversion to Outboards

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