Model Forum / Radio Controlled / Water Models / August 2007

I am going to finish a hydro boat...
It is 75 cm long and it's weight when it will be ready,will be between
3,4 and 3,5 Kgm(a little heavy but a very strong ship!!!)...
I want to be very fast and i thought to use an OPS .45...
What do you think??Is it a good idea??
What prop do you recomend??
Could someone tell me if i can calculate the top speed of my boat???
Or can someone tell me which will be the top speed as you know from
your expierience??
Do you suggest any other engine??
I was thinking to use a CMB .45 but it will cost almost 120$
more...It's a lot for me cause i'm student so i don't work.....
Sorry for my english but i'm from Greece!!!
Thank you??