1974 jet drive

yea i remember a 74 catalog and it had a v20 with a jet drive as an engine drive, not sure were it is but i think that if it was a jet drive that it was an outboard one because the jet drive on the jetski would be alot of trouble. the only reason you would want a jet drive is if you do shallow water fishing.

[msbhammer]

Will be interesting to see a catalog with a V-20 jet drive.

They made a Scarab jet.

[msbhammer]

Is that for a inboard motor or is it an outboard. ??

[macojoe]

BS did tell me that the new Catalogs he posted were lost, and that he was going to have to rescan them and repost.

i am curious, i know i have seen other jetboats like yahamas and seadoo's but they claim that their boats with jetdrives get up on plane as soon as you hit the throttle and i have seen these on the water and they do, but my question is if you had a jet drive v-20, would it plane as soon a you hit the throttle or is it the design of the hull?

fishbonejr.

[spareparts]

I've worked on a lot of the older jet drives( Berkely, Dominator, Jacuzzi) in an odd array of boats. I had worked on a neat package in a 19 Grady that had a hi perf smallblock with a berkely drive, it worked pretty good, seen some of the Chrysler boats with their own jet pump( never worked on one). The biggest problem with the jets was they needed a lot of torque to make them work( small blocks were barely enough) most of them worked better with big blocks( the jets ski's have pumps that allow a lot of slippage at lower speeds), and got their reputation or being gas hogs because of that, they are actully the most efficiant way to push a boat( they just drive weird, they even coast). Pumps are making a comeback because of the more efficiant small *diesels available, the diesels torque curve match the loading of a pump. they use them in the Northwest on comersial boats, i had a friend in NC that built comercial boats with Kodiak and Hamilton pumps

[spareparts]

Fishbone, they accelerate faster then any other means of propulsion on the water, they just don't top end with prop boats because they have to maintain more contact with the water to keep water coming in the pump

ok but you need alot of power to do it.

another thing is that jetdrives also can get clogged and then you have no propulsion and you have no control over the v-20. enless you had the outboard then the lower unit could act as a rudder. But i think hammer and spare parts are right they had a jetdrive more like a jetski.

[spareparts]

thats giving a jet ski more credit than they deserve. the problem with jetpumps is they are too efficient, as the speed increases, the amount of water that enters the inlet increases, so the pump becomes more efficient in pumping the water out, *a prop usually slips some what, allowing the engine to keep turning up. Most jetpumps will bog an engine, they require tons of torque, unless you make them slip by using lots of clearance in the pump( jetski type), that allows the eninge to rev up to the higher rpm where it makes power. Some pumps have a rudder, but it doesnt help at low speed.

Check out a Hinkley Picnic Boat( 3/4 mil 34' dayboat), they use a Hamilton Jet pump hooked to a Yanmar Diesel. The low speed handleing on these suck so bad, they incorporated a computerized joystick hooked to the pump, engine, and bow thruster, this thing came make anyone dock a boat like a pro