Unlimited with immersed propellor class world speed record

[Verytricky]

According to my information the last ratified Water World Speed Record for an immersed propellor boat was:

Date: 7 Jul 1952
Location: Lake Washington, USA Stanley Sayres USA
Boat: Slo-Mo-Shun IV
Average speed: 178.497 mph


Also possible was:
Date: unknown
Location: USA
Boat: Miss Freeon?
Speed: 205 mph


In my mind, the World Water Speed record should be from a boat that obtains propulsion from the water, not from a jet or air propellor. The 'unlimited' category allows any form or shape of boat. It is required to float unaided. the 'immersed propellor' part states that the driving part of the propellor must be immersed in water during the entire run.

Given these parameters, what would you think would be the type of craft to break the record? Something like the modern sprint boats, just de-tunned so it can last the distance? Or something totally new?

What sortof propellor? Twins or single?

What thoughs on this subject?