Jet drive

[JimCt]

Anybody have experience with jet drives?  Opinions?

Am kicking around possibly converting to 22-2 over when I re-build it.  Engine would stay in the same place.  What limits the boat right now is the vulnerability of the prop & rudder.

[John Jones]

I have opinions on the typical operator of a jet boat but no idea about the drive itself.  

[CThomps]

I think a jet drive on an aquasport would definitely be unique.  The only problem I have with jet drives is the amount of horsepower the usually require.  Seems like you need alot more to attain the same speed.  I could be wrong.  

A jet drive would let you run really shallow to wouldn't it?

[GoneFission]

I think a jet drive 222 would be an awsome flats boat!  There was a 222 up for sale recently with a jet drive that went for something like $25K.  

Mercury has some pretty neat jets:
http://www.mercurymarine.com/engines/je ... _specs.php

If you want to stick with a standard engine block, adding a Berkeley drive is the easiest way to go:
http://cgi.ebay.com/ebaymotors/marine-j ... dZViewItem

http://cgi.ebay.com/ebaymotors/Berkeley ... dZViewItem

http://cgi.ebay.com/ebaymotors/Berkeley ... dZViewItem

If you prefer the "outboard" look, go with an outboard jet:
http://cgi.ebay.com/ebaymotors/Mercury- ... dZViewItem

Last, jet boats don't have a great reputation (see John Jones comment above), so the boats often go cheap with a solid engine and drive.  Consider buying a cheap jet boat just to get the engine/drive:

http://cgi.ebay.com/ebaymotors/1978-Tah ... enameZWDVW

http://cgi.ebay.com/ebaymotors/Jet-Boat ... enameZWDVW

Many options - any could be pretty cool!

See ya on the water!

[JimCt]

Agree about the typical jet boat operator but it's the simplicity of jet propulsion that interests me.  Just wanted to see if any of the group has ever messed around with them.

1. Nothing in the water except the hull.  No L/U, prop, rudder.  Zero drag.
2. No transmission or gearing (which eliminates those losses).
3. Shallow water capability.

Downside is ingesting debris into the pump and low speed engine efficiency.  Efficiency rises as speed increases.  Maybe other problems that I haven't heard about yet.

[JimCt]

Thanks for the info., GF!

[scott_gunn]

Here are some cool diesel jet outboards - at least they sound cool - I don't know much about them.

http://www.swordmarine.com/Products/default.htm

[JimCt]

Cool, heavy and big $.  My 230HP Mercruiser is ~600#.  A 200HP diesel is well over 900#.

From what I've been able to find out, you can use most any appropriate HP engine with jets.  Coupling I believe is by way of a drive shaft from the flywheel to the pump with maybe a dampener in-between so it doesn't necessarily have to be close-coupled.  Engine can be anywhere.  Cost for a warrantied rebuilt marinized car engine is about $1800... cheap HP.

Have to find a jet boat around here somewhere to see how the the rig is set up.

[GoneFission]

You could keep your engine, put in a driveshaft, and connect it to a Berkeley jet - it would require a cutout like a outdrive:

If you want to stick with a standard engine block, adding a Berkeley drive is the easiest way to go:
http://cgi.ebay.com/ebaymotors/marine-j ... dZViewItem

http://cgi.ebay.com/ebaymotors/Berkeley ... dZViewItem

http://cgi.ebay.com/ebaymotors/Berkeley ... dZViewItem

[Hibrass]

I owned a Yamaha Jet outboard for a few years.  It was a 90 Jet 2 stroke but it was really a 115 powerhead.

I can tell you that I ran mine from in very shallow water conditions to 4-5ft Saginaw Bay Back Breakers.  The thing to remember is that its like a jet ski.  You need to be moving to have any control at all.  There is no "slow" in windy conditions either.  You have to get up and run in order to manage them in the rough stuff.  Takes a bit of getting use to having your bow blown off 15 degrees to the side in a cross wind while your running 25 mph.  It just does not feel right.

The outboard jets themselves are very relyable.  Contrary to what people told me......they do not load up with weeds very easily.  I use to call mine "The Salad Shooter".  They are high reving and use tons of fuel though too.

If the water levels you are running in are managable with a prop - stick with the prop.  MTC of course.