Bertram31.com General Bulletin Board

Re: Are my stock shafts too small?

Posted By: Capt Patrick McCrary
Date: Sunday, 26 December 2004, at 6:06 a.m.

In Response To: Are my stock shafts too small? (Ron B)

Ron,

The 5.7 Vortec delivers 307 HP to the shaft, making the 1 1/8" shafts, (especially in standard stainless steel), marginal at the best... I'd upgrade the shaft size to at 1 3/8" if you have enough material in the strut tube to handle the over bore. 1 1/4" might be OK, but only if you went with Aquamet 22 shaft material.

Another cause of shaft breaking can come from operator error. Always bring the boat up slowly from an idle speed until you reach about 10 - 12 kts before fully advancing the throttles. Also watch your sea conditions and don't allow your wheels to come out & catch air. If the wheel isn't fully submerged, the increase of RPM coupled with bitting back into the water will put a tremendous momentary torque on the shaft.

Best regards,

Patrick

Messages In This Thread

Are my stock shafts too small?
Ron B -- Saturday, 25 December 2004, at 10:37 p.m.

Re: Are my stock shafts too small?
Capt Patrick McCrary -- Sunday, 26 December 2004, at 6:06 a.m.

Re: Are my stock shafts too small?
Jon Wagner -- Sunday, 26 December 2004, at 8:01 a.m.

Re: Are my stock shafts too small?
Bob S -- Sunday, 26 December 2004, at 5:41 p.m.