I have a Catalina 30 with an inboard diesel that I launched in May of
this yr- this weekend while swimming off the back of the boat I took a
swim below with a mask to check out the bottom. I noticed the zinc I
just put on the brass prop shaft 3 months ago was missing. I put it
on myself and remember how tight I made the screws- is it possible for
it to either fall off from vibration or deteriorate that fast? The
rudder zinc is still there. I keep my boat at a private dock in a
creek- the closest boat to mine is about 100 yards away. I have shore
power- is the AC ground possibly doing something to speed up the
galvanic process? Any ideas on how to replace the zinc without
shelling out for a short haul?

Thanks-
Rob

Rob wrote:

.... Any ideas on how to replace the zinc without
shelling out for a short haul?

Sounds like you're comfortable in the water so I'd try getting the zink
ready to slip on, then hypervenelate, dive, and get it on with at least
one screw. Finish in subsequent dives. Alterantely, look up somebody
with scuba (or equivalent) gear to do it for you. Good Luck.

Hey, Rob--

Prop shaft zincs are easy to install--incorrectly. I suspect yours has
fallen off, not withered away from electrolysis, not in just three months.
And I don't think you can install one properly underwater. Here's why: the
vibration from the engine turning the shaft loosens the setscrews, and
eventually the zinc flies off. I've had this happen repeatedly, until I hit
on my current technique. With the boat out of the water, screw down the
zinc as tightly as you can on the shaft, and be sure to use some LocTite on
the threads. Now begin tapping it with a hammer, and retightening the
screws as the zinc fits more and perfectly around the shaft. Eventually you
will not be able to take up any more on the screws, but you'll be surprised
at how much slack you've created by the hammer-tapping. Unless you have
truly big league biceps, you won't be able to tap with sufficient vigor
underwater. I suppose you can try it, but if so, check frequently to see
you haven't lost the zinc to vibration.

Cheers and fair winds,

Dick Behan
Westsail 32 CAPER
San Juan Islands, Washington


"Rob" wrote in message
om...
I have a Catalina 30 with an inboard diesel that I launched in May of
this yr- this weekend while swimming off the back of the boat I took a
swim below with a mask to check out the bottom. I noticed the zinc I
just put on the brass prop shaft 3 months ago was missing. I put it
on myself and remember how tight I made the screws- is it possible for
it to either fall off from vibration or deteriorate that fast? The
rudder zinc is still there. I keep my boat at a private dock in a
creek- the closest boat to mine is about 100 yards away. I have shore
power- is the AC ground possibly doing something to speed up the
galvanic process? Any ideas on how to replace the zinc without
shelling out for a short haul?

Thanks-
Rob

Yep hammer tapping.

Rob wrote:
--

Employed by Muller Marine Annapolis Md. Marine Worker, Composer, Artist
http://www.toad.net/~crm Check out my Galleries
and http://www.toad.net/~crm/neighborhood/index.htm "Peek into my
neighborhood"
Jeeper! [Nelly Belle] [0||||0] YJ 93 Bob's your Uncle.

Unlikely it dissolved off due to electrolysis.
Most likely you did not put it on correctly?
Put another on and dive on it once a week.
Brass prop shaft - I have never seen one - only SS.

stu



"Rob" wrote in message
om...
I have a Catalina 30 with an inboard diesel that I launched in May of
this yr- this weekend while swimming off the back of the boat I took a
swim below with a mask to check out the bottom. I noticed the zinc I
just put on the brass prop shaft 3 months ago was missing. I put it
on myself and remember how tight I made the screws- is it possible for
it to either fall off from vibration or deteriorate that fast? The
rudder zinc is still there. I keep my boat at a private dock in a
creek- the closest boat to mine is about 100 yards away. I have shore
power- is the AC ground possibly doing something to speed up the
galvanic process? Any ideas on how to replace the zinc without
shelling out for a short haul?

Thanks-
Rob

Without bending the shaft .. Of course.

DP
"Bob" wrote in message ...
Yep hammer tapping.

Rob wrote:
--

Employed by Muller Marine Annapolis Md. Marine Worker, Composer, Artist
http://www.toad.net/~crm Check out my Galleries
and http://www.toad.net/~crm/neighborhood/index.htm "Peek into my
neighborhood"
Jeeper! [Nelly Belle] [0||||0] YJ 93 Bob's your Uncle.

More likely bronze than brass.

DP
wrote in message
...
Unlikely it dissolved off due to electrolysis.
Most likely you did not put it on correctly?
Put another on and dive on it once a week.
Brass prop shaft - I have never seen one - only SS.

stu



"Rob" wrote in message
om...
I have a Catalina 30 with an inboard diesel that I launched in May of
this yr- this weekend while swimming off the back of the boat I took a
swim below with a mask to check out the bottom. I noticed the zinc I
just put on the brass prop shaft 3 months ago was missing. I put it
on myself and remember how tight I made the screws- is it possible for
it to either fall off from vibration or deteriorate that fast? The
rudder zinc is still there. I keep my boat at a private dock in a
creek- the closest boat to mine is about 100 yards away. I have shore
power- is the AC ground possibly doing something to speed up the
galvanic process? Any ideas on how to replace the zinc without
shelling out for a short haul?

Thanks-
Rob

Answer for Rob

Yes the AC grounding probably has something to do with the speed of
disappearance.
As the anode gets worn away often the fastenings themselves are weakened
and the anode spins off the shaft before it is all gone.
If you have access to scuba gear there is no reason you can't fit a new
shaft anode while the boat is in the water.


Rob wrote:

I have a Catalina 30 with an inboard diesel that I launched in May of
this yr- this weekend while swimming off the back of the boat I took a
swim below with a mask to check out the bottom. I noticed the zinc I
just put on the brass prop shaft 3 months ago was missing. I put it
on myself and remember how tight I made the screws- is it possible for
it to either fall off from vibration or deteriorate that fast? The
rudder zinc is still there. I keep my boat at a private dock in a
creek- the closest boat to mine is about 100 yards away. I have shore
power- is the AC ground possibly doing something to speed up the
galvanic process? Any ideas on how to replace the zinc without
shelling out for a short haul?

Thanks-
Rob

Thanks everyone- looks like I'll be taking a swim this weekend!


Andy Warner wrote in message ...
Answer for Rob

Yes the AC grounding probably has something to do with the speed of
disappearance.
As the anode gets worn away often the fastenings themselves are weakened
and the anode spins off the shaft before it is all gone.
If you have access to scuba gear there is no reason you can't fit a new
shaft anode while the boat is in the water.


Rob wrote:

I have a Catalina 30 with an inboard diesel that I launched in May of
this yr- this weekend while swimming off the back of the boat I took a
swim below with a mask to check out the bottom. I noticed the zinc I
just put on the brass prop shaft 3 months ago was missing. I put it
on myself and remember how tight I made the screws- is it possible for
it to either fall off from vibration or deteriorate that fast? The
rudder zinc is still there. I keep my boat at a private dock in a
creek- the closest boat to mine is about 100 yards away. I have shore
power- is the AC ground possibly doing something to speed up the
galvanic process? Any ideas on how to replace the zinc without
shelling out for a short haul?

Thanks-
Rob

An alternate method includes Rum drinks and a large "C" clamp. Tighten the
set screws as far as you can, attach the "C" Clamp and tighten it. Then
alternatively recheck the zinc set screws until done.
Less likely you'll knock the strut out of alignment and you don't need to be
any stronger than the clamp screw. The Rum is meant as an advanced reward
for a job well done.

"Bob" wrote in message ...
Yep hammer tapping.

Rob wrote:
--

Employed by Muller Marine Annapolis Md. Marine Worker, Composer, Artist
http://www.toad.net/~crm Check out my Galleries
and http://www.toad.net/~crm/neighborhood/index.htm "Peek into my
neighborhood"
Jeeper! [Nelly Belle] [0||||0] YJ 93 Bob's your Uncle.