How to calculate the size of small a jet drive from scratch?

[Ngollins]

I am wanting to construct from scratch a small jet drive unit for a tender. I have a couple of old lawn mower engines with about 3 hp, which i am hoping to use. The tender is only 5 foot long, would only have 2 or 3 adults in. I am not after high speed, just enough to potter about my local harbour come the summer. A prop would be the obvious answer here, but my local harbour is a mud hole, and im keen to learn about jet drive systems.

Where do i begin to design the system bearing in mind all that is known is the input shaft power?

Im not asking for an answer, just some guidelines or pointers I can then research into.

Thanks in advance.

Nathan

[baeckmo]

Hi, Nathan, if you switch to the thread "Why a jet drive?", note #23, you will find an example of a simplified calculation procedure. There is a comparison with a propeller case included as well.