[C320-list] prop shaft zincs?

[Louis Friedman via C320-list]

Hey all,

Two novice questions -

do you replace prop shaft zincs annually - I don't remember having the yard
do this for me in the past but seems like I should have - or maybe simple
enough to do myself?.

also, if I change the fuel filters and top off engine fluids/check impeller
for the spring - is there really anything left for the yard to do on the
engine or just drop it in the water - from a preventive maintenance
standpoint.? changed oil in the fall.

Lou F.
s/v MissAdventure
#632

[kspir4 via C320-list]

Hi Lou,Replace the zinc when they show signs of mounting corrosion (before they are totally corroded).  Usually once a year depending on your boat and environment.  Highly recommend before splash that way you are more likely to have them last through the season.  ~$25 at West Marine.  Simple to install with an allen wrench.  You may need a screw driver to pry the halves apart if they have corroded together.I recommend changing the impellor in the spring also.  I found out (the hard way) they are prone to drying out over the winter when the system is drained.  The vanes can become brittle (even after just 9 months of use).  If you are opening to inspect anyway, might as well replace it to avoid interruption at the worst time during the season.Just my opinionsKenMoonDancer #1089

[Dave Hupe via C320-list]

I use a magnesium 1-inch diameter shaft anode (best in freshwater, but zinc if you are in saltwater) and replace every year before launch.  It is a very cheap preventative item and very easy do-it-yourself. Just clean the shaft off well first before installing the new one so that it makes good metal contact. Install it close to the strut but not any closer than about an inch so water flows freely thru the cutlass bearing. 
Is your cutlass bearing in good shape?  I have replaced mine several times myself using the association loaner tool. Can save a lot of cost versus the yard doing it, but this is a little harder activity. 
Also consider your shaft packing age/condition before splashing.  Simple packing replacement also is easy to do yourself. But don't overtighten when you first install it and know that it will leak pretty heavily as you launch. You will then tighten down to a reasonable drip just after splashing the boat and tighten again later after motoring for a while. 
Dave Hupe
1994 C320 #32
Holland, MI

[Laura Gwinn via C320-list]

I replace my prop anodes when my diver tells me. I thought in Sept they
would have to be replaced since had been on for just over a year (and did
not haul over that winter) but diver said I still had 90pct so no need.
Ditto on the impeller. I replace every 2 years whether it needs it ir
not (I think the Yanmar engine manual recommends something like 5 years or
more; I believe in prevention tho).

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[Dave Hupe via C320-list]

Impeller replacement every 5+ years does not sound right at all. This is a cheap preventative measure that should not be stretched (and you get "caught"). 

Dave Hupe
1994 C320 #32
Holland, MI

[Louis Friedman via C320-list]

thanks for the input everyone! looks like I'll be replacing it this spring.

Lou

--
Louis Friedman, DO, FACP
Woodbridge Medical Associates
www.woodbridgemed.com
732-634-0036

[Louis Friedman via C320-list]

looking now for the size. Catalina Direct says the shaft is 1 inch but
sizes online of zinc anodes are slightly larger at 1.375. can anyone
confirm the shaft diameter?

[Dave Hupe via C320-list]

I inch for sure and you can do better for price than Catalina Direct ... available numerous places ..... just Google 1 inch shaft anode (magnesium if in freshwater). I just got one for $13.77. 
Yahoo Mail: Search, Organize, Conquer

On Mon, Mar 16, 2026 at 8:53 PM, Louis Friedman via C320-list<c320...@lists.catalina320.com> wrote: looking now for the size.  Catalina Direct says the shaft is 1 inch but

[Greg Flanagan via C320-list]

The shaft is 1”. I buy 1” zincs. They fit perfectly. Note when you install after tightening the hex bolts, bang them with a serious hammer and tighten again. You will find there is lot of slack to take up. The banging melds the zinc to the shaft. They will not fall off revolving on the shaft.

Cheers,

Greg
Hoop Dancer #1076
Sidney, BC

> On Mar 16, 2026, at 6:27 PM, Dave Hupe via C320-list <c320...@lists.catalina320.com> wrote:
>
> I inch for sure and you can do better for price than Catalina Direct ... available numerous places ..... just Google 1 inch shaft anode (magnesium if in freshwater). I just got one for $13.77.

[Mark Seyler via C320-list]

Mine are 1 inch, also. And Dave Hupe is correct that the material depends on where you sail. I'm in brackish water and use aluminum. Zinc for salt water and magnesium for pure fresh water.

Mark Seyler
S/V Reality,
Catalina 320, #232
New Orleans, LA

[ART HARDEN via C320-list]

I have a small plastic ammunition box that is waterproof and I keep in the engine compartment area. It has a zinc “magnesium anode”, packing gland material, picks for removing packing gland, material, lubricant, wrenches, alternator, belt, and new pump impeller. I also keep a special pair of vice grips that help me remove the impeller in the box. I replaced the zinc in the box every year as I put the older one on the shaft.

Sent from my iPhone

Art Harden
Catalina 320 "Tortuga" 243
E-42
937.885.9380 (o)
937.477.5544 (m)

> On Mar 16, 2026, at 10:40 PM, Mark Seyler via C320-list <c320...@lists.catalina320.com> wrote:
>
> Mine are 1 inch, also. And Dave Hupe is correct that the material depends on where you sail. I'm in brackish water and use aluminum. Zinc for salt water and magnesium for pure fresh water.

[Dave Hupe via C320-list]

$15.92 for a 1 inch ID (magnesium) shaft  anode https://powerboatsupply.com/boat-supplies-accessories/paint-maintenance/anodes/anodes-zincs/martyr-anodes-1-magnesium-shaft-anode-cmx03m/   I am able to take an ad like this into West Marine and they will price match it without question. However, as has been discussed, make sure to get magnesium if you are in freshwater, zinc if in saltwater, aluminum if in brackish water. 

Dave Hupe 
1994 C320 #32

Holland MI 

Yahoo Mail: Search, Organize, Conquer

On Mon, Mar 16, 2026 at 9:57 PM, Greg Flanagan via C320-list<c320...@lists.catalina320.com> wrote: The shaft is 1”.  I buy 1” zincs. They fit perfectly. Note when you install after tightening the hex bolts, bang them with a serious hammer and tighten again. You will find there is lot of slack to take up. The banging melds the zinc to the shaft. They will not fall off revolving on the shaft.

[ART HARDEN via C320-list]

Buy two and keep one on the boat for next year. That way you don’t have to make a special trip to the Marine store or worried about the order coming in before you splash your boat.

Sent from my iPhone

Art Harden
Catalina 320 "Tortuga" 243
E-42
937.885.9380 (o)
937.477.5544 (m)

> On Mar 17, 2026, at 8:52 AM, Dave Hupe via C320-list <c320...@lists.catalina320.com> wrote:
>
> $15.92 for a 1 inch ID (magnesium) shaft anode https://powerboatsupply.com/boat-supplies-accessories/paint-maintenance/anodes/anodes-zincs/martyr-anodes-1-magnesium-shaft-anode-cmx03m/ I am able to take an ad like this into West Marine and they will price match it without question. However, as has been discussed, make sure to get magnesium if you are in freshwater, zinc if in saltwater, aluminum if in brackish water.