39 with 700s and 6s what size props ?
 

boat came with mercury 17.25 34pitch 18rake 1200 runs about 98 but hits the limiters barrowed my dads mercury 17.5 37s 18rake 900hp boat ran 102 at 5300 rpms. anyone know what a 39 with 700s and 6s should have ?

Every boat is different so it is impossible to have a definitive answer.
The 37's are slipping a little more than I would like to see.
These drives are touchy and the boats slippery. My initial thoughts without much info is to lower the drives and retest with dads props.
Or, get the X dimension and give me a call.
I feel 17x37 900HP 18 degree are going to work with set up changes.

Brett