Do I want a jet boat?

[Number21]

I have a 16' outboard ski boat that I'm working on and I'm starting to think about passing it on to somebody else. I'm not flexible enough for this kind of work. :facepalm: I realized that if I sold my outboard and extra parts I would have enough to buy another boat...

I'm strongly considering a 70s "go fast" jet boat, probably 18'-20' with a big block V8. I want something fast and I've always liked this style of boat. I think a big V8 would be easier and cheaper to work on than an old outboard motor. I also feel like I might get better gas mileage than I did with my 150hp 70s 2 stroke. Am I wrong?

I'm kinda worried about how that type of ~18' low/sleek hull will ride? Obviously I'm not going out to sea with it but my 16' really didn't like any kind of choppy water, and it's got a deeper hull. Is this kind of boat going to be rough in anything besides smooth water?

I'm also really worried about finding a rotten stringer in a 30-40 year old boat, as I did with mine. (even though it looked alright from the outside) Is there any good way to check the integrity of the hull without ripping up the floor?

Is there anything else I need to know about these type of boats?

 

[90stingray]

Re: Do I want a jet boat?

The boats you are considering have potential to be rotted out. Get in and step around. Look around with a flashlight and mirror as much as you can. Gas mileage... are you kidding? A big block jet boat gets no gas mileage. Ever see those guys beached most of the day... costs a lot to be running that engine all day. Another reason is when the wind kicks up and you have a few waves, it gets rough. They look cool and sound cool for sure tho.

 

[Number21]

Re: Do I want a jet boat?

Gas mileage... are you kidding?

I know it isn't great, but my outboard has 3 carbs and dumps raw fuel out of the exhaust...not to mention the oil expense.

 

[jestor68]

Re: Do I want a jet boat?

They ride like crap on anything but smooth water.

They use 30-40 gph running fast. They use 11-18 gph cruising slow.

A friend has one with a BBC(600 HP?). He had a little sign made for the dash that reads "This boat runs on gas not friendship".

His has two 25 gal saddle tanks that last less than 1-1/2 hours running hard. He spends a lot of time at the sand bar.

 

[MH Hawker]

Re: Do I want a jet boat?

most jet boats will suck down 20 gallons in 15 minutes.

 

[ziggy]

Re: Do I want a jet boat?

i don't know about either of them style boats as i have no experience with them, but i wanna comment anywyas.. maybe ya could consider a v drive go fast boat? i suppose a bb would still suck the fuel down, but at least ya wouldn't have the loss of hp due to the jet drive.
imho, any of them boats sit low in the water, very little freeboard and w/ a flat bottom. i wouldn't think ya'd run them anything much more than a ripple for safety's sake at the very least.
fwiw, i did have a pwc for 9 years. the last one was 140hp. @ wot run time was 1.7 hours on 18 gallons. it was a 4 cyl. 4 stroke yamaha. way shy of a bb... anything yer proposing is gonna gulp the fuel down i'd think.

go watch some youtubes of vdrives and jetboats. they got a gob of them on the youtube. fun to watch.

here ya about the 2 smokes dumping raw fuel out the exhaust though. makes ya feel kinda bad to be a bad polluter don't it. my first pwc was a 2 smoke, so i contributed too. oil was a drag and expensive to buy too.

good luck in your desicion. hope ya post up a pic of your new boat when ya get it. love looking at them jet (or vdrive )go fasts.

 

[Frank Acampora]

Re: Do I want a jet boat?



Well, On good days, the California boaters would cruise the about 30 miles to Santa Catalina Island.

Do you need one? Obviously that is not the question. Do you want one? Well, If you are talking about an SK type hull, they did start out as flat bottoms but in later years they went to Vee bottoms. They were and in my eye still are very pretty boats and even though they are fuel hogs, I would buy one in a New York Minute.

As far as being easier and cheaper---NOT. You need to use explosion proof components, translate: expensive, and did you ever try to work on a massive V8 wedged into a compartment smaller than under the hood of a 70s car?

I took this one out of storage just for you! Didn't bother to clean it but think bright red and white. The jet drive is an F/M Hydro Jet that was manufactured by me for a couple of years.

 

[Number21]

Re: Do I want a jet boat?

maybe ya could consider a v drive go fast boat?

I would definitely love to have one of those, though they seem to be rather hard to find...especially in my price range.

here ya about the 2 smokes dumping raw fuel out the exhaust though. makes ya feel kinda bad to be a bad polluter don't it. my first pwc was a 2 smoke, so i contributed too. oil was a drag and expensive to buy too.

Yeah...I'm always in a hurry at the boat ramp before anybody notices the big oil slick forming around me!

Ideally I would like to find a boat that runs on 87 octane...right now I have to use premium + oil, and that adds at least $0.50/gallon. I'm not as concerned about the gas mileage as I am about the ride quality though. I drive a truck that gets about 8mpg so I'm no tree hugger.

Well, On good days, the California boaters would cruise the about 30 miles to Santa Catalina Island.

That's about what I'd want to do...there's a place I like to go on the river that's about 30 miles from my ramp.

As far as being easier and cheaper---NOT. You need to use explosion proof components, translate: expensive, and did you ever try to work on a massive V8 wedged into a compartment smaller than under the hood of a 70s car?

Do you need explosion proof components when the engine is completely exposed with no cover? Seems like an engine like that wouldn't be that hard to get to to work on? Outboards aren't exactly out in the open to work on either.

The part that's really drawing me to a jet is that there are less parts to break - no gears, no gear oil, no water pump impeller, no prop. I seem to be amassing quite a collection of torn up props.

 

[ezmobee]

Re: Do I want a jet boat?

What outboard are you running now? It sounds like it has some issues.

 

[ssobol]

Re: Do I want a jet boat?

The part that's really drawing me to a jet is that there are less parts to break - no gears, no gear oil, no water pump impeller, no prop. I seem to be amassing quite a collection of torn up props.

Most of those parts are still there. They are just arranged differently. The prop is replaced by an impeller in a housing inside the boat. If you suck something up the intake you can mess up the impeller which is something you may not be able to clear or repair on the water. The impeller is a precision part. On my outboard, if I ding my aluminum prop I can just file it out (or not) and carry on.

The engine is still water cooled. Whether this is open loop or closed loop cooling, there is still a pump somewhere.

If you are "amassing a quite a collection of torn up props" may be you should examine how/where you operate your boat. If you operate in water that has a lot of debris in it or is very shallow, a jet drive may not help. Most jet drives require a certain depth of water to avoid sucking things off the bottom.

 

[WIMUSKY]

Re: Do I want a jet boat?

I know it isn't great, but my outboard has 3 carbs and dumps raw fuel out of the exhaust...not to mention the oil expense.

Sounds like you need to pull the carbs, clean, rebuild and adjust them properly.

Outboards aren't exactly out in the open to work on either.

I don't understand that comment. You can't get more out in the open than an O/B.

My bud had an 18' jet years ago. Cool boat. At 18' on inland lakes we road on top of waves, even in a moderate chop. Kept the throttle up some and skimmed across the top...To this day I think they're very cool and wouldn't mind having one for a while......

 

[H20Rat]

Re: Do I want a jet boat?

As far as being easier and cheaper---NOT. You need to use explosion proof components, translate: expensive, and did you ever try to work on a massive V8 wedged into a compartment smaller than under the hood of a 70s car?

There is no USCG requirement for ANY marine components (ie, protected spark) for boats with fully exposed engines, like what the OP is talking about. The ones I've been on at least are 100% automotive/truck crate longblocks.

But... Try getting insurance, even just liability, one one of those. The very fact that the engine has no cover is a red flag for most insurance companies.

 

[H20Rat]

Re: Do I want a jet boat?

That's about what I'd want to do...there's a place I like to go on the river that's about 30 miles from my ramp.

30 miles and depending on how fast you want to get there, your actual mileage could be as low as 1 mpg. (cruise might put you around 2.5 mpg or so) Worst case, its going to cost you $240 to make that round trip. Best case, about $100. if there is no fuel stop on that trip, you may not even have enough fuel for a round trip.

In terms of mileage, your 175 is a couple magnitudes better.

 

[North Plains Drifter]

Re: Do I want a jet boat?

I had a 18' go fast boat many years ago, it had a Merc 175 w/power T&T that would make that thing fly! I could beat alot of V8 jet boats! I could go all day on a 18 gallon tank. It was best on lakes with not much waves as they don't ride great and hate waves, took a few over the bow and they end up in your lap! The best thing about the OB was that I could trim it WAY up to bring the bow WAY up, then I could take the big waves from the cruisers going by, those were the scariest!

 

[Number21]

Re: Do I want a jet boat?

What outboard are you running now? It sounds like it has some issues.

It's a 150hp Mercury inline 6 and it runs fine. Even when it was brand new it was a weird motor with a bad temper. Add 40 years to that...

The engine is still water cooled. Whether this is open loop or closed loop cooling, there is still a pump somewhere.

I thought the cooling water came out of the jet pump? Am I wrong?

Sounds like you need to pull the carbs, clean, rebuild and adjust them properly.

I'm not sure what that would have to do with gas mileage?

I don't understand that comment. You can't get more out in the open than an O/B.

Every outboard engine I've ever seen is under a tight cover, under a pile of wires, hoses, and parts.


Can anybody tell me why 90% of these boats seem to have a 455 Oldsmobile motor? I never see that motor in any other kind of marine use or hot rod...

 

[H20Rat]

Re: Do I want a jet boat?

I thought the cooling water came out of the jet pump? Am I wrong?

Every outboard engine I've ever seen is under a tight cover, under a pile of wires, hoses, and parts.

Correct, there is no water pump. The jet pump itself IS the water pump.

As far as outboards, they aren't considered explosion risks because the amount of air contained inside the cover is relatively minimal. At most, an explosion would just pop the cover off. With a motor mounted in the boat, the air compartment is MUCH larger. But again, most jet boats don't have any engine cover, so there isn't an explosion risk.

 

[roscoe]

Re: Do I want a jet boat?

Can anybody tell me why 90% of these boats seem to have a 455 Oldsmobile motor? I never see that motor in any other kind of marine use or hot rod...

Because the Pontiac 455's were harder to come by.

 

[Number21]

Re: Do I want a jet boat?

Because the Pontiac 455's were harder to come by.

Why would you use either instead of the standard Ford/Chevy? Why don't I ever see them in anything besides a jet boat?

 

[Lone Duck]

Re: Do I want a jet boat?

Why would you use either instead of the standard Ford/Chevy? Why don't I ever see them in anything besides a jet boat?

5 bolt main

 

[WIMUSKY]

Re: Do I want a jet boat?

I'm not sure what that would have to do with gas mileage?


Every outboard engine I've ever seen is under a tight cover, under a pile of wires, hoses, and parts.

I was commenting on the raw gas going out the exhaust not gas mileage. However, if you're not burning all the gas properly, it will have a negative effect on gas mileage...

I still think O/Bs are easier to work on. The only time I needed to be "flexible" was working on I/Os.