Creating a twin inboard 17ft boat

[jacobkennedy007]

So I had a Tahiti inboard boat with a Mercruiser 120 in it and that was to small. So I upgraded to a 470 (yes I know some people don’t like them but I love them, I currently own 4 rebuilt 2 of them) the 470 swap took some doing put a new transom because the old one was rotted out welded up a nice front mount and other odds and ends. Used the boat like that for a year or so now I’m bored and want to do something a little stupid so I’m thinking of putting 2 470s in. I’ve done some preliminary rough measurements and they should fit with about 3 or 4 inches clearance between them. Obviously it would take a lot of custom stuff for wiring, throttle cables, steering etc. I’m not worried about that I’m very mechanically inclined as far as that goes. I can mount shift cable assembly’s and hydro pumps elsewhere and extend the cables so those won’t be in the way. The things I’m concerned about would be having the drives that close together not sure what would happen, and the problem of having the weight of two engines in the back. Thinking about bringing a whole bunch of weights on a trip and seeing how much it would make it go down. Obviously y’all are thinking just put a 454 or something in there, but I think it would be cool to have something 1 of a kind and custom plus I got spare 470s drives and all so it would be somewhat cheap since I’m doing the labor. Just curious on thoughts about trying something like this.

 

[Chris1956]

A 17 footer doesn't usually benefit greatly from the maneuvering of twins. You would have to replace the transom to allow two OD cutouts, IMO.

Gee how about replacing your engine with a 4.3L V6 or even an SBC? The cutout is the same, but the motor mounts are a bit different, but comparing to plugging the OD hole and cutting two new ones. It makes sense.

 

[Scott Danforth]

the centers on twin 470's was as small as 32", however most installations were at 34" I do not think you have enough room, especially on a 17' tahiti

Most tahitis's (Schuster's) were jet drives, with an occasional ouboard. the I/O's were rare because of that. so you already have a sort-of low-volume custom.

If you want to build it.... go ahead. I personally would sell the 470's to the vintage hot-rodders. https://www.jalopyjournal.com/forum/threads/the-elusive-224-3-7-mercruiser-banger.256713/

 

[airshot]

Make sure you take scuba gear with you when you try it out !!

 

[cyclops222]

DIVE DIVE take her to the bottom.

Are they counter rotating props or engines ?