[C320-list] Propeller Shaft

[Jack Brennan]

Troy:

You don’t want to deal with a ripped stuffing box hose. Mine went on a previous boat, and I spent a long night on a cabin settee with one foot on the floor, hoping the rising water would wake me up when it all went to hell.

Luckily, my two bilge pumps ran properly all night, until I got to a boatyard the next morning.

Your dockmate’s experience describes crevice corrosion to a T on a SS prop shaft. Water stagnates inside the stuffing box, which prevents SS from getting the oxygen it needs to ward off corrosion, especially in warm water. The solution: sail every week to replenish the oxygen.

Manufacturers such as Catalina used naval bronze prop shafts at least until the late ‘90s, when my boat was built, because it resisted corrosion much better than the SS of that era. This is why you don’t have SS through hulls.

Supposedly, the new SS prop shafts resist corrosion better and bronze shafts are hard to find. I suppose we shall see. My naval bronze shaft ended up being cut by an incompetent boatyard that couldn’t disconnect it from the diesel, so I now have a SS prop shaft myself. 

Jack Brennan
Sonas, 1998 Caalina 320, no. 528
Tierra Verde, Fl.
Dolphin Cruising Club of Tampa Bay



Sent from Mail for Windows 10

From: Troy Dunn
Sent: Tuesday, February 12, 2019 8:04 PM
To: C320-List at catalina320.com
Subject: Re: [C320-list] Propeller Shaft

Jeff H

You lost me at shaft log... is that a common thing to replace?  It would
seem to me that unless there is a visible crack or something in the log,
it's not a wear item.  I suppose if your shaft is so far out of alignment
that load induced shaft whip is actually striking the log maybe that's the
thing?.   I can't even imagine how horrifying that must sound when you are
running in heavy seas and hoping to make it to safe harbor.  “What was
that?”  “Oh no worries just the prop shaft trying to rip a hole in the
shaft log...don't worry, we should make it to port before that happens....”

Hoping to push this whole propshaft, bearing, etc. project out another year
or so but it is coming.  I have to admit I get a kick out of folks that ooo
and aww at the bronze prop shaft.

On the topic of crevice corrosion, our dockmates lost propulsion last year
when their shaft broke inside the stuffing box.  They dove the prop and
couldn’t solve the mystery until they got the boat hauled.  They are very
lucky they didn’t lose the Gori (sp?) prop.   Not a cheap prop.  I guess
the stuffing held the back half of the shaft in place on the ride home.

T