inboard/outboard for wood john boat

[shannon andis]

I built a 14 foot flat bottom john boat for the river last summer and had a blast with it. the 9.9 OB wasnt enough as I built her a little heavy,(800 lbs or so)due to the fact I am a pretty big guy and my river buddys are about the same. we used a 25 HP johnson for the last couple river trips ,but it's not mine and I need another engine. a guy I work with has an '83 model fiberglass boat with a 2.5 GM engine and omc outdrive that he is willing to give me. I am contemplating using this set up,unless someone convinces me not to.
I figure that the weight of the I/O will about equal the 25 horse and myself.if i build a steering console on the front 3/4 of the boat,me and my partner will be in the middle. so in thery it should be ok,except the large amount of HP that I dont need. 120 vs 25. 0bviously I will need to re design the transom and supporting structure for the extra weight hanging on it.
the hot rod guy in me says go for it ,but the reasonable one says to think twice about it.
Idealy I would like to build a flatbottom sharpie type boat around 20' and use this engine combo,but I cant find any that are set up I/O and I dont think I can design my own.
if someone knows of such a design and would pass it on I would appreciate it. and I really need the flatbottom as the river gets pretty low in aug.thanks

[Gary E]

Hi Shannon,

Well... since you are a "doit yourselfer", I agree, that ought to turn out just fine, but to make sure I'd do an experiment.

First of all, and I am also not small, 6'6" and 270 ish..so I know what you mean.. Get the weight of that intire engine and out drive, then you and who ever else you need to make up that much wgt PLUS YOUR WGT AND ONE MORE HELPER, then all of you stand back there where it will be mounted, if you run outa standing room, use sandbags. If you think you need more freeboard, now is the time to find out, you can probably add a plank or 2 so you dont sink first trip out.

WHat is a GM 2.5? not a Chevy V8 ehh?

Reminds me of stuffing big Detroit iron in little cars.. then later in life stuffing big Diesels where normal gas V8's used to be.

G

[shannon andis]

yeh,the 2.5 is a 4 cyl 151 cubic inches. I have been stuffing 350's in s-10 's for years and even did a 6.2 diesel last year for a guy with a 4wd s-10.
I like the idea of calculating the weight of everything and then adding more. my inlaws live on an old strip mine lake, so it should be pretty easy to figure out if it will work or not.
as for free board,I made it 24 " deep and back when I was around 400# I could stand on the corners and still have around 16" left.when I sat in the rear seat,with the 25 horse and 2 tanks of fuel it drafts about 6 inches. the bow stands up a little but if you put a buddy up front and a good load of firewood and campimg gear(about1100 lbs total) we still only run about 6 " deep front to back. if its not deep enough it'll be a little hard since I made it out of plywood. thanks for the reply.at least someone else thinks it could work

[Gary E]

Sure, it oughta work, and even if you need another 6" of freeboard, a strake on the outside of what you have now could work and may even look good. Be sure to beef up the transom and good beefy stringers to mount the engine on, and you should haul@ss across the lake.

Good luck
G

[Donn]

Shannon...good to see another Hoosier on the forum. I was born in your fine city.

I'd think twice. The extra horses that you won't be able to use, will cause you to run the engine below it's optimal rev range, which will burn far more fuel than you need to. You'll also give up interior space with the IO setup.

How about this? Take the gift from your friend, sell it, and buy an appropriate outboard.

[shannon andis]

i thought about that.but I want to build a bigger boat and I think I have found one. a 22 foot flatbottom working garvey that I found in a book at the local library.it is based on a shortened version of henry chapelle's 26 foot new jersey garvey as presented to the FAO in 1953.
I was also worried about the engine running in its rpm range ,but figured with the proliferation of this engine in so many applications, I should be able to custom tune it to a lower rpm range if need be.differant prop,cam change, timing curves,etc. I am used to doing this in many land applications,so I dont think doing it in a boat will be much differant. just a little more research and personal testing to figure out what will work and what wont.
we have decided to keep the gift boat intact this year while I start on the larger boat. my first one was a quick and dirty little boat that works great but I would like to build something a little more "fine". or at least pretty to look at!

[ 02-08-2004, 02:09 PM: Message edited by: shannon andis ]