[C320-list] Shaft zinc?

[Allan S Field]

Just an update on the importance of zincs.  We are on the Chesapeake and stay in the water year round.  I use 2 zincs and have them changed out each August.  About 3 winters ago, another boat pumped electricity into the water.  By the end of the winter, both zincs on our boat were destroyed while the prop, shaft and strut all now all pitted.  Interestingly, the zinc on my ice eater made it through the winter OK.  Marina staff never did figure out where the problem was so we assume it came from a boat that departed at the termination of the lease - April 1st.  I haven't yet dealt with the damage and am trying to hold off as long as possible.

Allan S. Field
Sea Shadow - #808
Columbia, MD

-----Original Message-----
From: C320-list [mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of Daryl Hunt
Sent: Tuesday, April 12, 2016 4:51 PM
To: C320-List at Catalina320.com
Subject: Re: [C320-list] Shaft zinc?

Thanks to all for the excellent advice.  I just ordered the Martyr Streamlined Magnesium Anode from iBoats.com.  They were the lowest price with shipping included.

/Fair winds, Daryl Hunt s/v Believe, C320 #660 Rochester, NY - Lake Ontario/



On 4/12/16 4:10 PM, swampcreek42 wrote:
>      
> Daryl,         Rick is correct, in fresh water you should have a magnesium sacraficial anode, actually probably more than 1. At hull number 660 you should have a Yanmar 3gm30f diesel which has no engine or heat exchanger anodes due to the material the heat exchanger is made from. Our boat lives in the Chesapeake so we have 2 shaft anodes plus a cone type anode on at the end of our Flex-O-Fold prop, since we're in brackish water we use Aluminum Alloy anodes (a topic of sometimes passionate debate amongst the "zinc has worked forever" crowd). There are also different grades of anodes, some cheaper ones might not be up to par, we order ours from Boatzincs.com and simply include it as a yearly process even though the anodes could probably go 2 years if we wanted to roll the dice. You are correct that your galvanic isolator is for shore power protection.
> Bruce Hunter Nauti Time #719
>
>
> Sent from my Verizon Wireless 4G LTE smartphone
>
> -------- Original message --------
> From: Rick <rsulewski at bex.net>
> Date: 04/12/2016  2:32 PM  (GMT-05:00)
> To: C320-List at Catalina320.com
> Subject: [C320-list]  Shaft zinc?
>
>
> Daryl,
>   If I am not mistaken, stray current in your marina may also impact your hull's exposure of galvanic corrosion that may even effect your heat exchanger where there may be another anode on some engines such as my  Westerbeke.  Since I am also sailing in freshwater I use a magnesium anode from WestMarine that is more sensitive to stray currents than other metals one could use in freshwater. I located the collar anode ahead of the strut about same as the distance as between the packing nut and shaft coupler so in the event the shaft ever departed from the coupler, the shaft will not slide past the GFO packing with making a bad situation worse.  Prop shafts are interference fitted into the coupler plus driven tighter with a slotted key, but even then I learned from a marina technician that a sudden and strong reverse thrust could back-out a shaft from the coupler if there is an installation fit issue or if the coupler set screws are not adequately secured. Hence, a second reason to have a collar anode on your prop shaft.
> Rick
> 95' 320 Hull #277
>
>
> -----Original Message-----
> From: C320-list [mailto:c320-list-bounces at lists.catalina320.com] On 
> Behalf Of Daryl Hunt
> Sent: Tuesday, April 12, 2016 2:01 PM
> To: C320-List at Catalina320.com
> Subject: [C320-list] Shaft zinc?
>
> I just noticed that Believe doesn't have a sacrificial zinc on the prop shaft.  It does have a 30 amp Zinc Saver II galvanic isolator installed but I assume that applies to shore-power AC.  This is my first spring commissioning of the boat.  I've never had a boat that didn't use a sacrificial zinc between the strut and the hull.



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