Jet Drive vs. traditional prop propulsion

[jimbob1]

i was just curious why do people choose a jet drive versus some sort of prop driven outdrive. it seems to me that jet drives require a lot more power to propel a boat to the same speed....

[pyro]

I sometimes wonder the same thing...

except for those guys that run in quick, shallow rivers in the Northwest and Canada, jets are the only thing that will run in those waters...

[GTO GEORGE]

Simple, reliable, and nothing to tear up if the water gets shallow. Some may think they're safer, because no outside whirling blades.

[Lost In Space]

Both have advantages, but when was the last time you saw a 300hp jet boat run 100mph?

[1BadAction]

http://img367.imageshack.us/img367/2889/popcornyf5.gif

[Unchained]

i was just curious why do people choose a jet drive versus some sort of prop driven outdrive. it seems to me that jet drives require a lot more power to propel a boat to the same speed....

Here we go again.
Comparing HP #'s the prop boat will almost always win out.
It takes lots of HP to make a jet run strong.
A $3,500. 1970's vintage v bottom jetboat with a 300hp engine is never going to run with an STV with a 300hp outboard.
However if the same amount of money is spent assembling a late model tunnel hull jetboat to a tunnel hull outboard. That's a different story.
The jet boat will out accellerate the outboard but the outboard may have a higher top speed after 1/2 mile.
I like them both.
On a typical weekend boating, you'll always see more 100 mph outboards than 100 mph jetboats. In fact I can only think of a handfull of 100 mph jetboats that are lakeable in the state.
I can only think of a few v drive 100 mph flatbottoms and hydros.
It's the lakeable thing that they can't do well.

[Racemore]

Here we go again.
Comparing HP #'s the prop boat will almost always win out.
It takes lots of HP to make a jet run strong.
A $3,500. 1970's vintage v bottom jetboat with a 300hp engine is never going to run with an STV with a 300hp outboard.
However if the same amount of money is spent assembling a late model tunnel hull jetboat to a tunnel hull outboard. That's a different story.
The jet boat will out accelerate the outboard but the outboard may have a higher top speed after 1/2 mile.
I like them both.
On a typical weekend boating, you'll always see more 100 mph outboards than 100 mph jetboats. In fact I can only think of a handful of 100 mph jetboats that are lake-able in the state.
I can only think of a few v drive 100 mph flatbottoms and hydros.
It's the lakeable thing that they can't do well.

Yea what he said but since I had one in the 70-80's before the stv's I can tell you what the prop boats are not as good at.Since my boat was a 16' Tahiti I'll take on the 16'outboard's in almost every thing,Starting.stopping(I had serious brakes) turning,(OB's don't do 360's well)rough water running,(nobody wanted to run in the ocean with me)Shallow water,well everybody knows that that stump i went over and knocked the gearcase off the following outboard is another + for the jet.They are quicker and will out pull end to end any dragmota on any tunnel or V,(hook-em up).Now top speed
and economy I loose but I can sink yo azz with the quickness.But top speed which is is the ultimate hard on the Prop boat takes.Thats why the deck rise's higher on the prop boats.:D :cool: PS A jetboat is a better weapon.I have loaded the pump and discharged a burst of water that is lethal.They never found them though.:rolleyes: :cool:

[Steven]

i always though too that jets are much less weight sensative than outboards. seems like you can load them up with people and still run about the same as solo.

[Racemore]

i always though too that jets are much less weight sensative than outboards. seems like you can load them up with people and still run about the same as solo.

They carry weight better because of 450 hp and 1 rider won't make much difference but extra weight still slows the boat.What I failed to mention is just how good the brakes are.Twice playing around I almost sank my boat and could run 50,back off the throttle a second and pull it in reverse,hit the gas and sink the nose to the point that once it about knocked my azz out along with 100 gals of water.It was lucky that it had rained earlier and I had turn the scoop on the carb around so it didn't kill the motor.The amount of water to the stern down and wfo throttle held the nose up untill enough ran out along with my seat cushions,lifejacks,my cooler and paddle.I realised my limit at that point.I wish I had that toy back.:D

[drgboat]

Jet boats are the hot rod boat cross over from street rods. Tunnel rams and headers kick ass.

[Noah1]

If you just want to go very fast buy a outboard:)
If you want to go fast & have alot of fun buy a jet:)
This has been talk about & talk about & talk about:eek:

OK, I have The one & only prototype1977 HydroStream 460 V-King jet boat. About 400 HP This boat was never put into production.

From 0 to 65 (top end) is like right now. Everyone knows what a V-king will do with a outboard.
Hydrostream V-King Jet Drive--stopping:eek: cornering:eek:
0 to 65 is faster The hole lake knows when I fire it up:D
Love that V8 sound

Hydrostream V-King prop :cool: Top End:)

If I can't beat you with the jet:D Then I get the outboard. :eek:

Jim's 1 cent + Noah's 1 cent = Our's 2 cents worth:D

[Glenn]

I'd love to see pics of that thing!

Glenn

[Steven]

I'd love to see pics of that thing!

Glenn
yeah...me also!!!

[Glenn]

Assuming you could get it going fast enough to get up on the pad, can't see how you could drive it with all that torque without a ton of ballast on the side!

Glenn

[Techno]

I could quote your statement and ask why people choose car engined inboard conventional props over OBs.


require a lot more power to propel a boat to the same speed....:D

I guess I did.


Heres a movie of how well jets maneuver http://www.hamjet.co.nz/files/Multiple%20Waterjet%20Control%20%28web%29.avi

This is how little water they can operate in.
http://www.hamjet.co.nz/files/images/Riffler%203.jpg

[Racemore]

Assuming you could get it going fast enough to get up on the pad, can't see how you could drive it with all that torque without a ton of ballast on the side!

Glenn
There is no steering torque with a Jet.Also I had a run in with 2 v-kings with 235's on them when Hydrostream's first came out and I spanked there a$$ from every angle.They were a mile per hour faster in smooth water.That would have been 77 mph. They didn't want to ride they wanted to attack me like they were they baddest thing on the river.When they eased by me and trimmed out to roost me that was the beginning of a bad day.I herded them up like sheep and plummeted their ass.2 on 1 and I made them regret that day.Don't mess with dem jets.They will hurt ya.You got to slow down some time.What got me were the people that thought they wanted to drive through my rooster tail.Those people are fools and I had a seville run onto my roost and it blew his windshield off his boat and hurt his wife.I had no idea that he was going to cross behind me.I was just cruising along and he ran up behind me.Fool.What should 16 cubic feet of water per second do.Bust yo azz.:rolleyes:

[Noah1]

Glenn & Steve here are some Pic of our jet boats.Our Sea-Doo is just a 20ft jet-ski


http://i5.photobucket.com/albums/y160/cobra041/79b02995.jpghttp://i5.photobucket.com/albums/y160/cobra041/c93a69b9.jpghttp://i5.photobucket.com/albums/y160/cobra041/2fe21083.jpghttp://i5.photobucket.com/albums/y160/cobra041/805120ad.jpghttp://i5.photobucket.com/albums/y160/cobra041/bbcea2e2.jpg

[stylishskier]

allow me to be the first so say HOLY BAD A$$ BATMAN!

[Glenn]

Holy cow! That's awesome! Guess you'd need a long tow rope to ski behind that:D

Glenn

[Steven]

very nice...beautiful and unique stream! love the color. thanks for the pics

[jimbob1]

that hydrostream is great looking

[Racemore]

I think a V king jet would be a hoot.Needs a J12 with a jetovator though.

Sweet rigs Noah.:cool:

[1BadAction]

the v-king makes the sea-goo look like humpty-dumpty. :D

[dfwx]

There is an HUGE added plus to a jet drive over a prop. The waters around here are very shallow and unpredictably so with tides. Running along at 80 hitting an underwater shell bar, log or anything with a prop can cause serious damage and injury - particularly if an outdrive. After losing numerous props and replacing more than one outdrive unit, it became clear my only real option was a jet drive. This was not just a cost factor, but a safety factor. Hitting an underwater object going even just 40 or 50 with an outdrive could seriously injury anyone aboard. A jet drive will just skid over it.
That isn't a minor consideration particularly for a family boat. Use your imagination of hitting a log at 60 with an outdrive unit... There's an underwater boulder around here they call "the million dollar rock" for all the transoms and motors it's ripped off - and that is for boats in the 30 to 40 mph range.
When family boating you aren't always in a predictable area in terms of depth and underwater objects, and depth gauges only tell you where you are, not what is ahead of you.

Just around here, every year, some people will die in 40ish mph small boats that flip when hitting a small wave or wake from another boat at the wrong angle.

The other safety factors of jet drives are obvious.

Unless you are SERIOUSLY getting into HIGH SPEED racing, a jet drive is more "fun", safer and likely less maintainance. People not familiar with performance boats don't realize how fast 90 mph is on the water or the dangers of doing so. Last month, a bunch of people were injuried and killed when a half million dollar 40+ footer hot fishing cruiser doing about 50 hit the wake of an incoming big cruiser at an angle - flipping the boat. And that was a wide beam, heavy big boat.

My jet picklefork will do about 90 and get to that plenty quick, but it is rare I will actually go that fast due to flipping dangers. Driving a boat fast isn't like driving a car fast, because a boat isn't on a flat road. It takes very little to flip a small boat or even take it airborne. And a 90 mph boat is no place for "family." For "family" keep it under 50 and then only on a very calm water day. Small boats have flipped at under 40 just hitting 1 foot whitecaps at the wrong angle. Lifejackets a must, but a boat slamming down fast on someone is a backbreaker.
Srly, you'd love a 50ish mph jet boat or maybe something like a twin jet drive family type boat. Lots of fun and plenty fast. Of performance? There will ALWAYS be someone faster than you. If you want to be the fastest on your lake or river? That's measured in tens of thousands of dollars and like cars, a super fast boat is not suited for anything but short race runs. "Performance" and "family" never go together. Risk your own life only.

I own a lot of boats. Surface drive twin diesels 40+ foot Cigarette, 32 foot twin BBC with outdrives, a couple of jet drive drag pickleforks, a Bass Master fishing boat, a few old boats back in a field, and just gave away 2 large cruisers, plus some PWCs.

You pick the boat for what you are going to do. If you want a "family" go-fast boat, pick up a cheap one - ideally a jet drive - and then make your true performance boat a different boat. Buying a used one someone else built will cost you 1/3rd to 1/4th the cost of building your own. Just the paint job if you have it done will set you back $5Kish and you'll have another $10K just in a modest performance motor not counting the drive unit. You can buy an entire set up boat for the $15K to $20K range. Shop around and you can find an 80 mph boat for $10K or less if you don't need a perfect paint job. You can pick up plenty fast 70 mph boats for under $10K.

[dfwx]

On performance differences?
A jet drive will initially hole shot (start from 0 ) quicker than it's prop counterpart. This is due to water doesn't compress within the impeller housing, while a prop from a dead stop is more challenged to "grip" the water. So even up, a prop is playing catch up - but ultimately usually will within the quarter mile.

That initial advantage then becomes the limiter on speed. Water can only be pulled into the jet drive so fast and as speed builds up the water can't be pulled thru fast enough - thus limiting the ultimate higher speed potentials. For performance, if the play is 80 mph and below, I'd go with a jet drive. To 100 it's close to even up. Beyond 100 is the world of props. That also is the real danger speeds zone for which your costs aren't just performance, but you better spend some real buck on safety features and design.

However, for fun around the lake with "ordinary" boats - meaning the typical 50-60 mph hot ski style boats, the jet boat will more quickly leave them behind because all the play is at lower speeds. And, of course, there is the rooster tail fun of a jet boat. My picklefork has an 800 horsepower water cannon for those pesky PWCs.

A jet drive must keep it's butt in the water, so as the speed gathers the prop boat can more "get up on the water." The highest top speed of true all-out race boats is significantly higher for a prop boat - with jet drives rarely good for much over 100 - though (rare) they've got up to around 150 - very rare.

Horsepower also is a real factor. If you are going into mega power, a prop is the only way to go. If you are down the scale - meaning in the world of reality for a multi-use boat rather than pure racer, a jet drive is a very viable choice with the advantages unique to them. Are you REALLY going to have a 1000 horsepower boat? Really?

If you watch drag races between similarly hulled and powered boats, the jet drive will usually jump out ahead at the start. The question is can the prop boat catch up before the finish line. If the quarter mile, usually yes.

"Top speed" potential is essentially irrelevant in a racing boat. It is easy to power a boat to have an ultimate top speed (at reduced acceleration) much faster than the hull can safely go. Its only a question of how fast before you go airborne. Going airborne is bad. LOL

[HStream1]

Wow another 4 year old thread brought back to life. :leaving:

[LaveyT]

Glenn & Steve here are some Pic of our jet boats.Our Sea-Doo is just a 20ft jet-ski


http://i5.photobucket.com/albums/y160/cobra041/79b02995.jpghttp://i5.photobucket.com/albums/y160/cobra041/c93a69b9.jpghttp://i5.photobucket.com/albums/y160/cobra041/2fe21083.jpghttp://i5.photobucket.com/albums/y160/cobra041/805120ad.jpghttp://i5.photobucket.com/albums/y160/cobra041/bbcea2e2.jpg

We need a nice You tube Video of that Hydrostream Jet running!

[speedboats]

Both have advantages, but when was the last time you saw a 300hp jet boat run 100mph?

What's your fuel consumption with that 300hp outboard?

Stock sbc's only make somewhere like 290hp, but the performance bolt-on's are cheap, and assides from impeller and nozzle insert you shouldn't need to touch the pump 'till you make over 800hp. Run something like the LS2 or LS3 motors and they'll make 440-480hp out of the box with factory warranty, aftermarket parts are still cheap, and in a modern boat you are good for 80mph+/- Compare apples with apples, not a jet from the '70's and '80's with genII sbc against the latest offering from the egg-beater crowd.

Jets will out manouver any prop at slow speed, especially when fitted with a 'bucket' type reverse because max thrust is available at zero speed (with manipulation of the bucket you can achieve max rpm and still be stationary, spin the wheel and the transom kicks HARD)

I've had guys follow me across the harbour on an outgoing tide, funny when they have to stop and lift their egg-beater to float back out to deeper water. Pulling skiiers and toys are no dramas, especially with that low end bollard pull, (could pull an outboard backwards). Nothing to macerate swimmers with, so the wife can't back over me and claim it was an accident! The pump should require little maintenance meaning that you can take the motor to any auto mechanic for servicing, so no expensive 'marine servicing' labour charges

[200VEGAS]

yea thanks for returning that old thread, i can beleibve my eyes. good looking boat. oh, and its a ford

[whipper]

yea thanks for returning that old thread, i can believe my eyes. good looking boat. oh, and its a ford

Thats OK still a good read. BTW there making 300 lb 400+hp Aluminum blacks these days for jetboats and they will do 100mph on a light 20ft hull.My Buddy's Jet boat Aluminum Tunnel hull with a tourbo Northstar engine and Race nozzle setup does just over 100 GPS and gets there mighty fast I might add. Hes geared with the impeller for top speed so the hole shot sucks until hes on plain. Then look out it accelerates like a raped ape from then on. The technology with engines and jet pumps is ever evolving and in the very near future on smaller go fast boats they will be really great combos that get better fuel consumption. I still think Surface drives are the ticket though. It would be interesting I think to mount the motor of a 300XS inboard to a smaller surface drive like a small Arnison drive. I think you will get very high top speeds and still great fuel mileage? Just always wondered about how that combo would work.:rolleyes: