The prototype fast afloat boat (right) may have superficial similarities with the Arun class, but she was the result of a 'clean-sheet' design approach.

Apart from being much latger at 17m overall and with roughly one-third as much again in volume (due to extra beam and depth) her engines are mounted aft and use V-drives which grves greater usable internal space.

As usual with prototypes the hull has been painted grey (only accepted lifeboats wear the full liveryi but the superstructure is in an experimental high-visibility yellow..