Catamaran whit 2 Jet Ski pumps and 2 air cold diesel at 26 Hp?

[aixam]

Catamaran whit 2 Jet Ski pumps and 2 air cold diesel at 26 Hp?

Hi I’m having started to think how to build a trainable catamaran for easy handling.
Have start to think that I will use 2 air cold diesel engines’ at 26 hp connected to a jet ski pump each instead of ordinary propellers. Is it some big disadvantage to do so or any odder wrong thinking of me?

[johnnyv]

Disadvantage would be lower efficiency over a prop, especially at relatively low speeds and attaching two engines to a single jet pump sounds like a pain .
Outboards give more internal room and are a lot less difficult to install.

[marshmat]

I figure a catamaran would have one engine and one pump in each hull.
How big is the thing? If you're talking about a six-metre, half-tonne runabout, you may be on to something interesting. But remember that a jet ski pump is tuned for high velocity and relatively low flow at very high RPM, when compared to a normal jet pump or a propeller. That translates to a significant loss of efficiency at lower power levels.

[aixam]

My planing was one engine and pump in ecth hull. And it could be around 5 meters long and 2.50 whith. A out bord enging is not a solution for me, have to be a fixt instalation what its well sound protekted.

[northerncat]

just pull a couple of old jetskis apart and bed the engines/jets
into your cat, only engineering hasslre then is getting your jets steering right
sean

[Nordic Cat]

What diesels are you planning on using? They could be a bit heavy for a relative small boat.
How do you want to steer? Rudders or jet drives?

Regards

Alan

[aixam]

I had plan to youde KIPOR DIESEL 2 cylinder whit a wighit at 64 kg
The stering seams to be esyest whit the water jets.

[Fanie]

I'm considering a similar setup for my sailing cat - using two 4-cyl petrol jetski motors instead of outboards. Only drawback is the reverse is not very strong, but then there is nothing the fishing line can tangle on

[Fanie]

If you're considering diesel for fuel economy I guess it depends on how you want to use the cat. The 4 cyl motors has fuel injection etc and if you keep the revs down they do quite well on fuel.

[aixam]

If Im not wrong most jet ski´s have around 6500 rpm at max and the diesel 3400 rpm so I nead a gear box betwin to get the revs up. The quistion is then if the engine are strong enuf foor that task?