Jet Boat(thrust) How Does it Work

Can anyone briefly tell me or show a schematic of exactly how a Jet Boat thruster works?

Just curious.

Thanks,

Larry

Re: Jet Boat(thrust) How Does it Work

I don't know much about them, but I think I can take a stab at this...
An engine driven impeller pulls water in through an opening under the boat, pressurizes it, and shoots it out the back.
The nozzle in the back is directable for steering. A typical jet pump is direct drive, with no clutches or gears. There is a cover or "gate" on the back of the jet pump nozzle that gives you forward, neutral and reverse.

In forward, the gate is all the way up, so all the water shoots out the back of the nozzle, causing forward thrust.
In reverse, the gate covers the nozzle, and directs the water thrust back under the boat.
In neutral, the gate partially covers the nozzle so that some of the thrust goes under the boat, and some of it exits the back of the boat, theoretically canceling each other out.

Any questions?

Re: Jet Boat(thrust) How Does it Work

Thanks Roger,
Those thrusters must generate some powerful pressure cause I seen them move accross the lake pretty fast.

Thanks again,

Larry

Re: Jet Boat(thrust) How Does it Work

a1nowell said:

Thanks Roger,
Those thrusters must generate some powerful pressure cause I seen them move accross the lake pretty fast.

Thanks again,

Larry

Click to expand...

From what I've been told, a properly built pump can produce up to 150 psi on the water feed to the engine alone (this is for a old school pump). That's why water pressure regulators are recommended by most guys in the know, to keep the pressure from bursting gaskets, and other parts of the cooling system. Can't imagine what the direct pressure may be coming out the nozzle.

Re: Jet Boat(thrust) How Does it Work

Here's a little animated video i found that might help too...

Motovated Design and Analysis Superboat Impeller Animation - YouTube