As others have mentioned Q Sport Hydro (Sport 40 equivalent) is the proper class name for both organizations.
In the IMPBA, Q Sport Hydro's must be greater than 34 inches but not longer than 40 inches. (Thanks Chilli)
6S is the limit on voltage
Motor is Open
I have been running a PT SS45 for a year and a half now with the following set up:
PT SS45 Hull (old layup that was updated to the new tunnel)
NEU 1527 1Y (1250kv)
2X GrimRacer 4200mAh (6S2P) for a total of 8400mAh on 6S voltage
CastleCreations Hydra 240 speed control
Octura X455
I have this set up running every bit of low 60’s
The video below was from a race earlier this year at the Michigan Cup Race in Leonard, MI. At the start my hull is on the inside (orange). The Mid-Michigan Electric Unlimiteds Club that hosted this race is a NAMBA club and this was run on a legal measured course. The heat time was 1:17.52 (I think). This was a NAMBA heat racing record that was not turned in.
http://youtu.be/Li_KTBHzz2E
This same hull with the exact same set up was run at the IMPBA time trials in Flint, MI for a 2 lap record of 24.506 seconds. I think the boat still has some left in it. More set up and a better driving will shave more time off… I have a video of that run below.
http://youtu.be/phVPhq3uYzQ
As for Electrics go… I think 6S boats are a nice medium between cost and performance. The set up I have listed above is a very mild set up and will run all day/year long (assuming the boat is properly set up with the correct prop).
Later,
Mike Ball