Hi Rich,
I recommend you take a look at this other forum topic. The general consensus is that you need a much more powerful thruster to properly propel a foil board, on the order of 1-2kW.
The speed you will achieve with a thruster depends heavily on the size, weight, and drag characteristics of the vehicle it is mounted on. The T200 is designed for high static thrust, not speed, and the drag of the nozzle would likely be the limiting factor on the speed of a thruster alone. Hypothetically, with the prop pitch of 27.5° and maximum rotational speed of about 3800rpm, a T200 could reach a speed of up to 5m/s (11mph) in a drag-less mass-less environment. Realistically, we he have had other customers reach speeds of about 5-6mph with a single T200 on a stand up paddle-board with a human occupant. Even with many thrusters, I believe the operational RPM of the T200 will not allow for any speed above 10mph or so at the very most.
-Adam