Check these sites:
http://www.integratedturbine.com/index.htm

http://www.turbineboat.com/

Just a question, how do you slow boats down that have turbine motors. Turbines keep spinning a long time after you take the fuel away. Do you put a brake on the shaft?

26 Check,
Turbines can store up a lot of rotational kinetic energy, but there is no power behind the spinning once fuel supply is cut down...It's simply stored energy and they will spin for a while if free running or in thrust producing applications.

In a boat application, when the turbine output shaft is connected to a prop, it will slow down just about as fast as a reciprocating engine would.

Brakes are frequently installed on the shafts for shifting purposes, as they do idle quite fast.

I have a friend that is in the process of building a 36 Skater w/ twin turbines, surface drives, output shaft brakes, etc. The power plants, guage package, brakes, trans are a $500,000 up charge. (Thats plus boats, trailer, and interior). Plan on 700,000-1,000,000 to do the project new from scratch. Not cheap but 200mph never will be:D

shifter: lycoming t55 completely rebuilt is around 40-50k engine only.
non-rebuild start from 10k
you can also find used several engines(t55) between these two prices according to 'how much they are used'

There are a lot of ways to skin a cat. Some of the quotes I have seen and heard are very high. I will let you know at a later date what we come up with.
pat W