Just checking

[Catbird Suite]

My catamaran at present has 2 80hp motors with 2.46:1 ratio gearboxes and swinging 25x20 three blade fixed props. I can just about pull full revs of 2500rpm and at that I get 11.6 knots. Trouble is my sailing speed is not that good and would like to change to folding props. Volvo penta recomend a 22x20 four blade folder but cant find any reviews of them. Does any one have any experiance of these and does any one have experiance of there sizing. Im dropping 3 inches of diameter but picking up one more blade!! Will also change the strut but thats another story.
Regards Andy