PDA

View Full Version : Who knows stuff about Jet Drives?



Last Tango
12-16-2004, 12:44 PM
I've done a very short search in our archives and on the internet about jet drives. Is Berkeley still making NEW drives? Who else is out there with state of the art new jet drives? I know from my first boat that jet drives are a little hard to use when docking (just takes practice) and have a speed loss compared to outdrives with props. However, I'm curious as to who makes them new today, can it be retro fitted to a 2001 18 Classic with a 377, and how much would a change like this cost?

Yes, I AM concerned about Manatees in my area, but also with stuff (branches) hidden just below the surface in some creeks I want to explore on the St. Johns River, and some very shallow areas I would like to run across. My Bravo One outdrive and Mirage 23 prop could easily be damaged by these.

Other than having to give up the 70mph runs I now enjoy, what other "penalties" will I incur (other than all you guys razzing me about thinking about making this change)?
When I first ordered my boat a few years ago, I asked then about a jet drive and all I got was expressions of amazement that I would want one. Of course nobody questions them on jet skis and SEADOO's.

boxy
12-16-2004, 12:54 PM
Mark, I don't know much, but I do know that these crazy mother f#@&ers www.eagleracing.ca use these guys' pumps www.americanturbine.com on their race boats.

Ranman
12-16-2004, 01:02 PM
A couple of things come to mind. To install a jet you will have to move the engine a significant distance forward. Though I've seen 18 jets, there may not be enough room in YOUR boat to do this.

Also it is a misnomer that jets can run in shallow water. Though a jet will draft much less than an IO, a jet drive has enough suction to disturb a lake bottom that is over 10' below when under full thrust. Sure you can idle in shallow water (still somewhat dangerous), but there is no safe way to run on plane in shallow water without sucking up depris into the pump damaging the impeller and wear ring.

john445
12-16-2004, 01:25 PM
To answer your question, most new jet drives are made by Mercrury. They are called the Mercury Sportjet, they come in a 175hp and a 240hp version and probably some others that I am not familiar with. I have driven a boat with the 240hp jet, it is an experience to remember. I think I went 0 to 60 in 8 seconds, faster than most cars. One of the benefits of the jet was being able to slam it into reverse at speed and come to a screeching halt. Before I would put one in an 18 classic I would check the specs on say a Seadoo Speedster for comparison. Or maybe a Seadoo Challenger 18 might be more similar. The engine, from what I understand is nothing more than an outboard powerhead connected to the Sportjet pump. Good luck!!


John H

apollo24
12-16-2004, 02:01 PM
How would one install the water intake on a deep-vee hull? A lot of jetdrives are flat-bottom or close to it; it would seem to take substantial structural modification to install the "cut-out." :confused:

gcarter
12-16-2004, 02:59 PM
It wouldn't be too difficult to install one in a classic by installing an extension box on the transom similar to the ones you see with Arnison drives to provide room for a transmission.
The real problem with a jet is there is insufficient room for a multi-stage pump.
In the early '80's, I spent some time designing multi-stage (maybe 400-600 stage) centrifugal pumps for oil wells. When testing you would never build a test pump with less than five to six stages. The reason being there are significant losses in the entry stage and the exit stage. With enough stages you might discover that you could find a "sweet spot" at which the pump would operate at 90-93% efficiency. The best you could ever expect to see with a single stage (single impellor and diffuser) is probably 35%. Well, you see where this goes. It could be done, and it would be interesting. maybe a vee hull w/ a central engine location. The pump might be three feet long.

Last Tango
12-16-2004, 04:09 PM
Thanks, everyone, for your responses so far.
A couple of boat shows back I saw a jet drive that was a complete bolt on to the transom of any boat. It was designed to be totally self-integrated except for the power controls. and fuel tank. It was in a box about 24" square and did not need any mods to the boat to install for water pick-up, particularly on V-hulls. The demo engine/jet was on a test stand, and another was installed on an 18' Zodiac to show its versatility and floatation characteristics. The "box" was all the support it needed. It was filled with floation so the boat would not sit lower in the water with the extra weight hung well off the stern. Inside this "box" was also the engine. 350hp. All of this was self-floating, even by itself. Unfortuantely, the engine in use was a diesel. Not for me.
It was never my intention to use this system. As exciting as it sounded, the "box" was ugly and would be an awkward-looking blob on the back of my boat. They joked about the original engine compartment being converted into a large beer cooler or fishing well since you wouldn't have the engine there anymore.
I am more interested in what George was talking about by putting an extension box on the boat for the transmission and then having the jet drive after that, like most jet drives, looking like I had mounted an automatic transmission back there. Just like the Donzi's that have the Berkeley drive unit.

MOP
12-16-2004, 04:29 PM
Hopefully the fellow that showed up at the 1000 run with the 18 juiced 460 chimes in. His engine did not look that far forward and is bigger than a SBC, I think he had a Berekely. There are quite a few jet manufacturers out there, back awhile I cruised a few sites. Kodiak, Berkeley, American Turbine, Hamilton, Legend, Dominator, Aggressor, Jacuzzi are the common names. We had a fellow running a parachute ride out of our marina a long time ago, he had a 455 Olds in a 21 foot what ever. He was constantly sucking stones into his pump, it was an SOB to get them out and worse changing out the impeller.

Phil

MOP
12-16-2004, 04:37 PM
There is no transmission on most jet setups, I think you will find some are quite short.

Phil

smokediver
12-16-2004, 04:40 PM
Mark , I had an 18 foot boston whaler with a 351 and an american turbine jet . the installation looked like that of an i/o . the hull had the intake on the bottom and the bowl was on the outside of the transom . with 275 hp you would have thought performance would have been good . it wasn't . maybe 45 mph on a good day . you lose so much in the jet . also there is a fine line between shallow draft and being a vacuum cleaner ! a lot is picked up and there is wear issues .

MOP
12-16-2004, 04:52 PM
Go to Events & Gatherings, post on Pre Season Planning, post #71 has pictures of Hard Candy the 18 with the 460 Ford and the Berekely.

Phil

gcarter
12-16-2004, 05:07 PM
OOOOOPS!
Mark, I wasn't saying there was a transmission, it would be similar to a transmission standoff box used w/ an Arnison.
BTW, I think a lot could be gained by going to at least three stages.

Greg K
12-16-2004, 05:27 PM
What you want is the JETPAC (http://www.jetpac.us/) check it out.

Lenny
12-16-2004, 05:45 PM
Keep in mind that this BIG BLOCK fits nicely into this JET X-18.

http://www.donzi.net/hull.cfm?id=303

http://www.donzi.net/hull/DRM180790773/5.jpg

Last Tango
12-17-2004, 03:08 PM
Jetbert sent me a nice picture this moring of Lenny's X-18 side shot in front of the brick church wall. He photo-shopped the JetPac that Greg K has linked, onto the stern of Lenny's boat. I hope he posts it here because I'm absolutely CERTAIN I would never consider it. Boat looks like it just farted a big grey bubble.
I like what I hear from George and MOP. I'll breathe deep though and keep thinking about it. But I also will heed the advice from those who say it is a virtual vacuum cleaner. We don't have many rocks to worry about here in Florida, but we have plenty of gooey sand and vegatation. And I don't want to suck up a Manatee off the bottom and onto the boat like a big drop tank.
Maybe I should go the other way and get a prop-driven fan like the airboats. Just run a big blower drive belt off the front of the motor and up to a big prop in a birdcage.
Jetbert can fix us up with one of those pictures, I'm sure.

Thanks to everyone who responded, and if you have anymore thoughts on this topic please let me know.

boxy
12-17-2004, 03:16 PM
Maybe I should go the other way and get a prop-driven fan like the airboats. Just run a big blower drive belt off the front of the motor and up to a big prop in a birdcage.

Dude I was with you on the whole jet drive thing, but you need to drop the pipe and step away from the keybaord RIGHT NOW .......... :D :D

Last Tango
12-17-2004, 03:50 PM
You are right. I don't know what came over me. I'll be better in a minute. :banghead: :bonk:

I looked at the pix of HARD CANDY and I really like what I see there. The engine does look more forward than mine. I don't want to get carried away with mods, though. I was really hoping something like the Berkeley drive (or whatever)would just sort of pop in where the outdrive stuff used to be. I have thru-hull exhasts so I don't need to worry about rerouting the exhaust system. What sort of top end does HARD CANDY experience? How much HP does the engine have to get it there? My generally stock 377 has 320 HP. I can push 72 MPH under the right condidtions.
I can see where in deep lakes with hard bottoms that the vacuum cleaner thing would be nominal. But the water here is shallow and mucky and filled with all sorts of stuff left from 3000 years of humans living next to the river.

If you have a jet drive Classic 18, you can expect me to be your new best friend at any events we show up at together.

boxy
12-17-2004, 04:21 PM
Barry McLaughlin, Hard Candy's owner, has been at the 1000 Islands Run the last 2 years, and he has been to the Spring Dust Off. I'm not real sure of his top end, but he gets there real quick......
He is running a healthy BB 460. I think Tom Davis has a great picture of it running in front of Boldt Castle, throwing a huge rooster tail.
Barry's is not on the board much, but if you want I can get you a number where you could contact him.

Why not just get yourself a little 14 foot airboat, and leave your classic intact ?

Last Tango
12-17-2004, 04:28 PM
Well, the concept appeals to me simply because I don't like the idea of chopping up manatees (unlikely, but still possible), snagging crab pot lines and pots (twice already - both had lost their bobbers but the prop snatched them up off the bottom and wrapped them around the outdrive), and just generally being limited by shallow water entry to many creeks and springs along the St. Johns river.

boxy
12-17-2004, 04:31 PM
If you are running 40 mph plus and you hit a sea cow in a v bottom metal intake jet boat, are you still not going to cause him a world of hurt ? I realize that propeller strikes hurt them a lot, but would the impact hurt almost as much ?

CrackerJack
12-17-2004, 04:33 PM
Here you go Mark. :jestera:

Last Tango
12-17-2004, 05:36 PM
Thanks, Jack! That was just exactly what I needed to clear my head. Not that I thought THAT thing would ever look good on ANY boat.

Manatees are bottom feeders. They surface to breathe about every 13 minutes or so. They sleep on the bottom and during that period they breathe only once every 48 minutes. They eat mostly Eel Grass and Water Hyacinths. Eal Grass is on the bottom, Hyacinths on the surface, extremely visible from long distances, and NOT the sort of plant you want drive through with ANY sort of boat or drive.
The Manatee is normally injured during its transit times, or in shallow water with lots of boaters (read fishermen and skiers). The Manatee stays along the shoreline. In the more picturesque rivers and creeks along the St. Johns, families of Manatee will swim together and feed and mate and play. It is illegal to join them in any of these activities. However, Manatees are docile and slow. Nobody wants to hurt them. They are virtually friendly. And a beautiful and graceful and powerful animal to watch.
A jet power system would MINIMIZE not eliminate the chances of hurting one of them. And even WITHOUT Manatees, Florida waters can be fraught with hidden trees and other underwater obstructions. A 12 inch draft is better than a 40 inch draft, planing or otherwise. Many springs and creeks are shoal at their entry and deep within. Silting from the passing river settles at their mouth. Once inside these beautiful waterways, sunken trees (that fell over from land)are common despite the deep water.
So I'm still very interested in the CONCEPT of a jet drive. I just don't want to suck up the bottom and be just as problematic as a deep outdrive with low intakes and a spinning meat cleaver. My Bravo One drive is a deep intake version. If I'm going to replace an outdrive sometime, I want to have my plan in place for the jet.
If I drop into the low 60's for speed, then so be it. My wife and friends are not comfortable at any speed above 50 anyway.

Speed-Racer
12-17-2004, 05:51 PM
Boxy I have some of those bad ass pics, that's got to be one hell of a ride!! :eek!:


Jetboats(not sea doo, or yamaha though) are cool, fun to drive on twisted back rivers,but a DONZI jetboat I dunnoo...

If you turn your 18 into one, I just don't think I'd be able to call you "Uncle mark" anymore....

Phil Rheed might want to sell his :rlol:

BUIZILLA
12-17-2004, 06:38 PM
Mark, I think your making a mistake....

JH :wink:

knots2u
12-17-2004, 06:45 PM
If you follow this thread and substitute "windshield on an 18" for "jet on an 18"............ I think you get the picture. The fastest I have ever gone in a boat was in a jet boat, didn't reach top speed, driver and I both ran out of testosterone. I would take a jet over an outdrive any day. Jet boats handle like Porsche's, so don't let off the throttle! Both jets and outdrives have limitations, but in the long run the jet is more reliable. A set back pump would be easier to mount in the 18, most of it is hanging out the back. Check out Jet pumps (http://www.glen-l.com/resources/msjetsup.html) for manufacturers and types of pumps. I would suggest calling Tim Speer at Proboat in Woodstock, Ga.. Toona probably knows of him, he's in her backyard. He might even do the mod's for you.


Lenny if you read this check out Garelick 75080, I'll talk to you soon.

Merry Christmas All!

Bob

Sorry about that link, it has been corrected, try it now. Also contains some good info on Arnesan surface drives at twindisc.com

Last Tango
12-17-2004, 09:29 PM
Well, I gotta be honest. I never expected my 2001 Classic 18 to ever be worth much as a collector boat. Originality isn't a long suit with me when it comes to my own boats and cars. I don't have a windshield, and don't want one. Got a Bimini (sorry Cuda), and I have drilled holes for this and that everywhere without regard to whether some archaeologist would someday dig up my boat and draw conclusions about what was a REAL Donzi and what isn't. There seem to be plenty of older Donzi's out there on this board that have jet drives, so obviously I'm not alone in this thought, nor did Donzi seem to think it was too quirky an idea to put on their performance boats. And I haven't seen a plethora (I just think that is a fun word to pronounce) of threads here over the years with jet drive owners looking for advice on how to convert to outdrives.
I've always had a certain atrraction to the unusual and different. Particularly if it seems like a viable option. Technically, we should all have been using Beta Max tapes rather than VHS during the 80's and 90's since Beta was actually a far superior technology. But sometimes the market doesn't want better. That is why we see lots of Chevrolets and Hundai's and not so many Mercedes.
Thanks to the folks here on this thread, I have been able to locate even more information and resources on jet drives. And for that I am truly thankful to each of you for participating. Oh, and thanks Jack and Brandon for the "artwork." I really appreciate the work and the fun. And Brandon, you don't have to dis-own me for quite some time. I only have 140 hours on the Bravo One drive. But I'll keep you in mind when I'm ready to sell it.

Lenny
12-17-2004, 11:58 PM
Bob, I read everything :D

I have gone from learning about seat sliders, to Jet Pack, to Manatee habit and their nuances. Man, talk about a twist :D

yeller
12-18-2004, 02:58 PM
Looks like I'm chiming in a little late, but I have to throw my $ 0.02 in here. I put a Berkeley in my 16 Classic and love it. The slow speed handling takes a bit of getting used to, but once you've figured it out, you can dock in places no one else can. I can rotate my boat 360 deg without moving forward/backward. The classic handles the jet beautifully. No porpoising at all:dolphin:, and because of the deep vee, you can do 180 deg turns at full speed....just warn your passengers to hang on tight or they might be going for a swim:eek:. You do lose a bit of top end but not as much as people think. I don't have any experience with multi-stage jets but if you use a single stage (as I did), I'd go with the AmericanTurbine and an 'A' impeller. With a 'B' impeller you'll turn more RPM's and pick up about 3mph but the lose in fuel economy isn't worth it imho. I did just that for 1 season then went back to the 'A'. I'm running a 300hp (estimated) 350sbc and get great fuel ecomony (with a rochester) and a conservative estimated top speed of something over 60mph. I have yet to gps it but based on my other motor, which I did gps, I know I'm doing at least 60. If I was running a newer AmericanTurbine I'd pick up close to 5mph. I run my boat in the Fraser river which is home to many saw mills and deadheads are extremely common. I've hit a few of them over the years and just kept going. If I had an outdrive I'd have been dead in the water. As far installation, you can get one that sets the majority of the drive outside the boat so you won't have to move your motor forward more than a couple inches, if at all. If you buy a new one, it'll come with templates for installation. One last thing...you can't beat the durability of a jet. I've used mine for 16yrs and I'm still on the same impeller/wear ring. I replaced the bearing/bushings/seals 3 times...at a cost of about $100 Canadian. These I replaced only because I was rebuilding the motor and thought I may as well do the jet as well.

mattyboy
12-18-2004, 08:04 PM
why not skip the jet drive, skip the turbine,
and go right to the warp drive

captain I don't think she'll take much more of this :)

beam me up Scotty ;)




Damn it Jim I'm only a doctor :smile:

Last Tango
12-19-2004, 02:38 PM
Okay,
I see some trends here. Boxy and I have been chatting and we have come up with the following recommendations for the Donzi Marine 2005 mid-year model additions to the current model line-up. Just in time for Spring.

Classic 16 with the following power plant:
http://www.mercurymarine.com/mercury_250_optimax_m2_jet_drive (awesome RIVER boat and yacht tender!)

Classic 22 Poker Run edition with TWINs of the SAME powerplant as above. (500 HP!!!!!!!)

Classic 18 MX6.2MPI with an American Turbine jet drive.

Like I was saying, there are already plenty of Classics with Donzi factory installed jet drives. I haven't heard a single owner of one of these pining away for an outdrive. Hmmm
To the "traditionalists", uhhhh, what exactly is a traditional Donzi Classic? We have all sorts of engine makes and outdrives and types already on this board. And it seems to me the King of the Hill Classic is Geo's with an Arneson drive and blown SBC. Another very popular boat here is painted Tangerine metalflake inside and out. Chevy, Ford, OMC, Mercury, Volvo, 4, 6, 8, carbs, FI, supercharged, turbocharged, small block, big block, bimini, no bimini, windshield, no windshield, L couch, 2+3, and a hundred different models and configurations of each. Practically no two boats exactly the same. I LOVE this diversity. We have always said it was like a custom hot rod show on water whenever Donzi's gather. I LOVE it!
So, I'm gonna do some more homework, and some more boating. And when the time comes, I'm gonna resurrect this thread for review.
Speaking of boating, I was out yesterday for a run to lunch and back. Beautiful sunshiny day, cool air, no wind (except for my own self-created wind chill factor). We didn't have to bundle up much. Sweat shirts and jeans.

ToonaFish
12-19-2004, 11:15 PM
I would suggest calling Tim Speer at Proboat in Woodstock, Ga.. Toona probably knows of him, he's in her backyard. He might even do the mod's for you.

There is a man in my backyard and I haven't been properly introduced? Tisk, tisk.

Bunches,

Celene "jetboat=roostertail=excitement"

Morgan's Cloud
12-20-2004, 01:37 PM
families of Manatee will swim together and feed and mate and play. It is illegal to join them in any of these activities.


Byjeezus that gave me a chuckle ... although I'm sure it came out the wrong way ... :smile:


Interesting thread too !

S

Last Tango
12-20-2004, 01:41 PM
NO, you got it right! I was having a bit of a chuckle when I wrote that. :biggrin:

Last Tango
12-20-2004, 01:50 PM
After reading MC's response to me, and Toona's response, these two items seemed strangely somehow appropriate at this point...: :yes:


1.
After a few years of married life, this guy finds that he is unable to get it up anymore. He goes to his doctor, his doctor tries a few things but nothing works.

Finally the doctor says to him "this is all in your mind", and refers him to a psychiatrist.

After a few visits to the shrink, the shrink confesses "I am at a loss as to how you could possibly be cured."

Finally the psychiatrist refers him to a witch doctor.

The witch doctor tells him, "I can cure this", and throws some powder on a flame, and there is a flash with billowing blue smoke....

The witch doctor says "This is powerful healing but you can only use it once a year! All you have to do is say '1 2 3' and it shall rise for as long as you wish!"

The guy then asks the witch doctor "What happens after when its over?".

The witch doctor says "all you have to say is '1 2 3 4' and it will go down". "But be warned it will not work again for 3 months!"

This guy goes home and that night is ready to surprise his wife with the good news... So he is lying in bed with her and says "1 2 3", and suddenly he gets a hard-on.

His wife turns over and says "What did you say '1 2 3' for?"


Quick Joke #2 (insert the word Manatee for Pig)

A farmer buys several pigs, hoping to breed them for ham, bacon, etc.... After several weeks, he notices that none of the pigs are getting pregnant and calls a vet for help.

The vet tells the farmer that he should try artificial insemination. The farmer doesn't have the slightest idea what this means but, not wanting to display his ignorance, he only asks the vet how he will know when the pigs are pregnant. The vet tells him that they will stop standing around and will instead, lay down & wallow in the mud when they are pregnant. The farmer hangs up & gives this some thought. He comes to the conclusion that artificial insemination means that he has to impregnate the pigs.

So, he loads the pigs into his truck, drives them out into the woods, has sex with them all, brings them back & goes to bed. Next morning, he wakes & looks out at the pigs. Seeing that they are all still standing around, he concludes that the first try didn't take, and loads them in the truck again. He drives them out to the woods, bangs each pig twice for good measure, brings them back and goes to bed. Next morning, he wakes to find the pigs still just standing around. One more try, he tells himself, and proceeds to load them up & drives them out to the woods. He spends all day shagging the pigs and, upon returning home, falls listlessly into bed.

The next morning, he cannot even raise himself from the bed to look at the pigs. He asks his wife to look out and tell him if the pigs are laying in the mud.

'No,' she says, 'they're all in the truck and one of them is honking the horn.'

Morgan's Cloud
12-20-2004, 01:59 PM
:biggrin: :biggrin: Both hysterical but #2 destined to become a classic ! :biggrin: :biggrin: