I built an Aeromarine 56" Apache with stock weedeater motor connected to an older Eastcraft Marine twin drive gearbox running
C/R A.M.P.S. outdrives with 52mm 2 blade alum props. GPS'd at 20.4 mph.

My question (I'm sure has been asked many times before) is I want to use 3 blade C/R props, either alum or s.s. but I don't know what size to start with or who to contact? If I drop some mph I don't mind as I want the scale look of 3 blases. The max. dia.
for the outdrives is 54mm. I can't go with a more powerful motor as the u-joints on the outdrives are made of plastic so no damage to the outdrives will occure if an object is hit (I broke 1 and was lucky enough to find a gentleman who had some).

Any help would be great.

Thanks
340cudaman