Small cat for Botany Bay

Hi guys, I have been spending a lot of effort working towards a 30' odd foot powercat for a project in my other home, Fiji. But in the meantime I feel like doing a small 18-20' cat for fishing around botany bay in Sydney

I will prolly make something like this yellow cat out of ply or plascore

https://www.youtube.com/watch?v=A6dDARmnctw

I really dont want to use outboards as I want rudders on each hull. One of the things I am curious about is using a pair of small industrial type engines either in longtail fashion as on that boat or wearing high pressure pumps to use as waterjets. Like this one that delivers 33000L/h

http://www.ebay.com.au/itm/NEW-PROT...692446?hash=item1e7481f39e:g:n7IAAOSwezVWvaQd

I have no idea if that much pressure will provide any usable thrust but the pumps wont be wasted as can be used on the farm in Fiji if they dont work out. I think it will be a fun project

 

That longtail cat seems to get along pretty nice.