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Zinc problems.

rene_m

rene_m

Rene Marin
So, when i got my boat there were no zinc's anywhere and the prop paid the price for it.
I have been doing research but not with any luck. The collar type does not leave enough room between the cutlass bearing and the prop for good flow and the prop shaft is close to the rudder.

I made this set up but it was a stop gap. I had to reshape the tail end to get it to fit.
The guys at the boat yard were impressed when i came back with a milled zinc and installed it. but its getting eaten up quick.
Any suggestions on zinc's or how to slow the process?
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This is an old pitcher but one can see the football zinc. I have since replaced it with 2 collar type zincs up snug against the prop. There is still plenty of clearance between the zincs and cutlass. I think my cutlass bearing housing is shorter than yours which gives me more room.

David Smith
 
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Yes it is. there was talk of cutting mine down along with a new prop shaft but some of my time on a lathe seemed like a more cost effective path.

At least till i run out of my special cut zinc's i made. =)
 
Rene -

Thankfully, I've never had a problem with zincs, but I was told by a very knowledgeable mechanic what can cause problems. the first three are mistakes the owner can modify, and the last two might be the owner's mistake (or the marina's, or a neighbor's).

1) painting the shaft prior to installing the zinc
2) painting the zinc itself, before or after it has been installed
3) having the wrong-sized zinc, or too-loosely attached zinc.
4) improperly wired and grounded boat
5) stray current - often caused by keeping the boat dockside with AC power attached, and stray current entering in the water.
 
I would guess that the cutlass bearing was not inserted enough. Inserting further would allow zinc to be placed on the shaft.
 
I was there with the cutlass but its a big old thick sucker.. That's as far as it goes im afraid. I did find a thinner metric collar type and trimmed it down a bit more " once again on the lathe". So, now i have two on on the shaft and one at the end.

I also was on a dock with a lot of ,lets say derelict boats and the power boxes looked rough. i wonder if that had something to do with it as well?
 
I suspect the dock wiring, or one of your neighbors. It's very easy to test both the shore power for correct polarity using a $5 tester you can get at Home Depot. Insert it in a three-prong outlet, and the two lights should be green. If they're yellow or red, the wiring for the shore power is bad.

You can also use a multi-meter to see if there's stray current in the water.

And whatever you do, do NOT go swimming off the docks where there's stray current. It does not take much stray current to paralyze your muscles (including your diaphram), which will lead to drowning. And anyone on shore can't go in after you, lest they also drown.
 
I again refer reference to Nigel Calder's "Boatowner's Mechanical and Electrical Manual, How to Maintain, Repair, and Improve Your Boat's Essential Systems". If there is any book you should reference, it is this ONE!
 
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