It got me intrigued too, so I looked at the site and could find nothing informative
So I rang my local dealer, clueless wasn’t the word, I quote, 'Volvo make what.....oh.... I didn’t know that'
So I rang Volvo they knew a bit more but not a lot. Full vertical stoke is 35mm
(not much) by 300 or 450 (two width sizes)
it works by inducing lift at the back of the boat, me 'do you mean lift or thrust
' Volvo '.......I’ll send you some literature'.
Volvo Couldn’t answer what effect they had on speed or what comparative work they had done
but did say (several times) that they were very good, based on what I don’t know.
I'll wait for the Info and see because if they are good I’d be interested Des.