prop sizing

[dvpamenter]

My Express 30 a close cousin to C&C 29's and 30's, with a Yanmar 2 GM has a martec 16 d x 10p prop. Similar sized and likely powered Beneteau in the yard has a 15d x 12p prop?
Comments on the benefits of one versus the other??
Don

[Valiente]

That sounds large for a 30 footer. My 33 footer had a 12 x 6 fixed two-blade Michigan Wheel, and I traded that for an 11 x 8 Gori folder. A friend with the same boat has a 14 inch wheel (we both have Atomic 4 direct-drives on 7/8" shafts), but that's about the upper limit.

Hell, my 15-tonne steel 40 footer has just an 18 x 13 three-blader, although that's getting changed to a 19 x 15 feathering four-blader.

Benefits are variable in terms of what you want to do, the engine size and state, and the type of prop. If it's fixed, a big prop will create drag...if it's a folder (usually a touch smaller), it will lag and be weak in reverse, and won't push the boat as well...but you sail faster.

[dvpamenter]

the prop is a 2 bladed folder.