Changing shaft angle on 28' Crown

[Cheranadine]

Hello all,
I need some advice. I have an older ( 1970's) slow - average planing hull. Inboard V drive. I want to repower with a new high speed diesel, new tranny and vdrive, shaft strut and prop. The current shaft angle is too low, I can only fit a 16" prop. Volvo says I need a 24x24 prop. So, I have the shop and hope the abilities, and want to fix the problem. I am asking, is it an acceptable practice to increase the shaft angle to where I need it, which may change the location of the stuffing box. Or, I'm hoping, stuffing box holes are generic, and the new stuffing box will fit with the increased angle. If not, I assume I can fill in the old hole cut a new one and do it that way. Is there some thing I'm missing? Any advice would be appreciated.

Thank you

[Jango]

Yes you can increase angle to probably 15 or 16 deg. However, if you have space behind the prop to the rudder, you might be able to use a "Lower Drop" Strut, moved back with little or no other changes. If this still does not give you enough space, then shaft location (stuffing box) will also need to be changed -moved forward.
Keep in mind, you should have 15% of prop dia. clearence, prop tip to bottom - 3 1/2 " and enough space between end of drive shaft and rudder to install prop.

[Jango]

Just realized, a 24" Dia prop seems awful big for a 28 footer. You might want to check this. How heavy is the Boat and how much HP? Gear ratio?

[gonzo]

Changing the angle of the shaft will open a whole can of worms. The thrust from the shaft is supposed to be aligned with a calculated point that takes into account center of gravity, resistance of the hull, dynamic lift, etc.