Coverting my outboard into an inboard jet boat

[Lyle Seratt]

I have a 1973 Ceebee Avenger. It has a 115 hp outboard and I would like to change it over to a v8 jet boat. If I do the work all myself what would it cost for the jet drive and also what do I need to do to the stringers and transom of the boat?

 

[Chris1956]

Re: Coverting my outboard into an inboard jet boat

Lyle, There was a V8 Jet Drive model Avenger made back in the 70's. I found a brochure on the internet which described all the models. it ran a Olds 442/ Berkeley Jet. I am not sure what the performance was, or where you could find such a beast, today.
I run an Avenger very similar to yours, with a Merc 135HPV6, on a jackplate. That set up is plenty fast and plenty dangerous.

What are you looking for in the conversion? Uniqueness? Speed? Suicide?

 

[sschefer]

Re: Coverting my outboard into an inboard jet boat

Lyle, There was a V8 Jet Drive model Avenger made back in the 70's. I found a brochure on the internet which described all the models. it ran a Olds 442/ Berkeley Jet. I am not sure what the performance was, or where you could find such a beast, today.
I run an Avenger very similar to yours, with a Merc 135HPV6, on a jackplate. That set up is plenty fast and plenty dangerous.

What are you looking for in the conversion? Uniqueness? Speed? Suicide?

Oh come on Chris, don't tell me you don't like flying the hull.. Avengers love to fly.

 

[emoney]

Re: Coverting my outboard into an inboard jet boat

Chris has already asked, but it deserves to be repeated.....why?

 

[sschefer]

Re: Coverting my outboard into an inboard jet boat

Chris has already asked, but it deserves to be repeated.....why?

Seriously, you have to ask...LOL... It's a speed boat and when it comes to speed we all wonder "What if"... Then we do something incredibly stupid sounding and end up either saying "WOW" or "SH....." Either way we have a blast figuring it all out because... Well, that's what trips our triggers.

 

[RogersJetboat454]

Re: Coverting my outboard into an inboard jet boat

I don't think anybody could tell you definitively what you would need to do to the boat to make it accept an engine or drive. With a standard outboard splash well, you may not have a high enough transom to install a drive shield for any number of drives such as a Berkelely. You would possibly need to do both a transom, and re-glass the whole top rear of the boat. A boat of that age, unless religiously covered and stored in doors may have mush for stringers. You would need to check the condition and possibly replace them before mounting an iron lump to them.

As for the drive, Berkeley still sells new drives at the tune of $3200-$3500 dollars. Not including engine, engine mounts, etc.
Honestly you would be best served getting a donor boat with a complete drive system. Then again you would be best served finding a boat meant to have a jet drive, and going from there.

If you do get a donor boat, one with a Berkeley 12JC or better would be your best bet. Parts are still readily available for short money. Probably also best to go with a Chevrolet engine. Olds 455, and Pontiac 400/455 jet parts are scarce, pricey, or NLA. May have a bit more luck with a Ford, but still not as cheap as a SBC or BBC.

 

[Lyle Seratt]

Re: Coverting my outboard into an inboard jet boat

I was going for a HOLY EDIT look at that beast and I like the thump but most of all I love the hands on and custom look. I think Im just going to give it some paint and new seats. I will try to find a doner boat with a good hull but till then Ill just work out the bugs in this ride.....

 

[Chinewalker]

Re: Coverting my outboard into an inboard jet boat

I would look for a similar style/era jet boat that already has what you want. I recently passed on an old Allison racing hull because someone had butchered the decks. If you want looks and a cool sound, it sounds like you've already got it. Not much out there that looks and sounds cooler than an old Merc stack six singing along at 6500 rpm...

 

[JB]

Re: Coverting my outboard into an inboard jet boat

This doesn't strike me as a thread about outboard motors. It is about boat modification.

I will move it to boat building.

 

[Chris1956]

Re: Coverting my outboard into an inboard jet boat

Lyle, A couple of things. I had a Merc 1500 IL6 on my Avenger for years, until some of the inner parts found a new, custom way to exit the crankcase. I then put a 2.0L 135HPV6 on it. The V6 motor is about 150 pounds heavier than the IL6, and she sits a bit low, for my taste. The low speed performance with the V6 is superior to the IL6, as the power band is much flatter on the V6. Top speed is about the same, in the mid-sixties. At that speed, most of the boat is mostly clear of the water and you want to go straight as the hull just slides sideways, but doesn't really change direction, as you turn the motor. Take off speed is about 50MPH, if you hit a wave, so if you are going much faster than that, don't hit a wave....

Whereas the stringers are encapsolated with fiberglass, I would be concerned with the stength of the transom, if I were you. My hull has a 3/8" piece of aluminum bolted over most of the transom, which is why my boat is still in one piece, IMHO. I would recommend you test the transom, and shore it up, if necessary.

 

[d.boat]

Re: Coverting my outboard into an inboard jet boat

I know nothing of modifying the hull, nor your purposes for the mod. But I'll chip in one guy's experience.

I used to own a V8 jet. I boat a lot with a friend who has a Merc Sport Jet. A couple of observations.

My V8 jet was VERY heavy. You'll have serious balance considerations to take into account. My boat was a good quality manufacturer (Jetcraft from the 90's before Harbor Craft merge/buyout ... still good hulls, just different now). The thing porpoised and also moved side to side (there's a word for that, but I can't remember it). It actually was pretty dangerous at WOT w/ a light load. Keep that in mind.

My friends Sport Jet is an extremely well running and economical engine, with lots of power and maneuverability. It's much, much lighter than my V8 was. HP? I have no idea, but I believe they make Merc SportJets at anything from 150(maybe even smaller?) through 225 or 250. An Optimax Sportjet would be an excellent, lightweight, reliable rig.

Just some thoughts. I don't think it's a trivial building / design challenge at all the weight w/ a V8 is a big consideration. A Sportjet would be less so.

 

[Chris1956]

Re: Coverting my outboard into an inboard jet boat

Lyle, As D.boat said, a V8 powerplant is about 800# at least. I do not know what the jet drive unit weighs, but I would be concerned that the transom would be low in the water, or worse, with all that weight in the stern.

If you are still willing to drop an I/B engine into that beast, you will need some stringer motor mounts. it makes sense to heighten the current stringers, if they are in the right place or to add the correct stringers. So you would need to cut out the floor and dig out some foam to add new stringers, or build up the old stringers. If it were me and it was feasible, I would thru bolt them to whatever stringers were available as well as figerglass them to the hull and anything else I could find. You likely would need to make a bilge under the motor to accomodate the oil pan.