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12-23-2017, 05:01 PM
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#1
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Senior Member
City: Eastsound
Vessel Name: Audrey Grace
Vessel Model: 2003 Camano 31
Join Date: Nov 2017
Posts: 236
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Looks like I lost my prop shaft zinc (video)
I know many people have mentioned shaft zincs can come off so I thought I'd check all my zincs with my GoPro. Sure enough, shaft zinc gone. Check those zincs!
https://youtu.be/P2qXnNg9Xyc
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12-23-2017, 05:53 PM
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#2
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Guru
City: Palm Coast
Vessel Name: Southerly
Vessel Model: 1986 Marine Trader 36' Sundeck
Join Date: Aug 2016
Posts: 1,231
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My diver checks my zincs. Replaced many but never lost one. Not yet anyway.
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12-23-2017, 06:17 PM
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#3
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Senior Member
City: Eastsound
Vessel Name: Audrey Grace
Vessel Model: 2003 Camano 31
Join Date: Nov 2017
Posts: 236
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Quote:
Originally Posted by Donna
My diver checks my zincs. Replaced many but never lost one. Not yet anyway.
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That's the thing though... if a zinc is just gone completely, especially on a shaft or thruster, it may very well have just worked itself off with all the motion.
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12-23-2017, 06:20 PM
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#4
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Guru
City: Palm Coast
Vessel Name: Southerly
Vessel Model: 1986 Marine Trader 36' Sundeck
Join Date: Aug 2016
Posts: 1,231
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I have not heard of it just working itself off from motion. I’ll have to ask my diver if that sort of thing is common.
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12-23-2017, 08:40 PM
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#5
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TF Site Team
City: Saltspring Island
Vessel Name: Retreat
Vessel Model: C&L 44
Join Date: Nov 2007
Posts: 5,663
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I changed years ago from egg shafed shaft zincs to Donut shaped, as I had never seen the egg shaped ones still there on teh annual haulout. The donut shapes held on lots better. In the last few years the egg shapes have a different attachment method that seems to work. I have had them hang on for over a year in the last three haulouts.
__________________
Keith
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12-24-2017, 06:41 AM
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#6
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Guru
City: Ft Pierce
Vessel Name: Sold
Vessel Model: Was an Albin/PSN 40
Join Date: Oct 2011
Posts: 28,143
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Quote:
Originally Posted by koliver
I changed years ago from egg shafed shaft zincs to Donut shaped, as I had never seen the egg shaped ones still there on teh annual haulout. The donut shapes held on lots better. In the last few years the egg shapes have a different attachment method that seems to work. I have had them hang on for over a year in the last three haulouts.
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12-25-2017, 02:43 PM
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#7
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Guru
City: Under a boat, in a marina in the San Francisco Bay
Join Date: Mar 2012
Posts: 615
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Quote:
Originally Posted by Donna
I have not heard of it just working itself off from motion. I’ll have to ask my diver if that sort of thing is common.
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Not particularly common but certainly possible if installed incorrectly or left on too long.
__________________
Clean bottoms are FastBottoms!
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12-26-2017, 07:09 AM
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#8
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Guru
City: Southern Maine
Vessel Model: Prairie 36 Coastal Cruiser
Join Date: Dec 2012
Posts: 2,717
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You have to bang them tight with a hammer, then re-tighten the bolts a few times when installing them. That should keep them on at least until they erode far enough to loosen up the bolts again. Not sure how that works if replacing them in the water.
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12-26-2017, 09:38 AM
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#9
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TF Site Team
City: Jacksonville
Join Date: Nov 2008
Posts: 11,680
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Quote:
Originally Posted by CaptTom
You have to bang them tight with a hammer, then re-tighten the bolts a few times when installing them. That should keep them on at least until they erode far enough to loosen up the bolts again. Not sure how that works if replacing them in the water.
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That's what we always did and in the water. We'd mount the zinc and tap with a hammer, retighten the Allen screws, turn the shaft 180 degrees and do it again and repeat. We never lost a zinc.
When we sold our ChrisCraft, the new owner changed the shaft zincs during the survey. One month later, he called and asked if the transmission ever made a funny noise in reverse. He hadn't set the shaft zinc and it slid up the shaft to the hull in reverse.
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12-26-2017, 10:46 AM
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#10
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Guru
City: LI or Fla
Join Date: Jul 2013
Posts: 1,148
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This is somewhat application specific, we cruise at 23 knots and by the end of the season to have a zinc slide down or disappear is not all that uncommon. Displacements speeds I would guess it doesn't happen much.
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12-26-2017, 10:54 AM
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#11
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Guru
City: Cary, NC
Vessel Name: Skinny Dippin'
Vessel Model: Navigator 4200 Classic
Join Date: Jul 2009
Posts: 5,841
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Quote:
Originally Posted by Marlinmike
This is somewhat application specific, we cruise at 23 knots and by the end of the season to have a zinc slide down or disappear is not all that uncommon. Displacements speeds I would guess it doesn't happen much.
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It happened to us.
__________________
2000 Navigator 4200 Classic
(NOT a trawler)
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12-26-2017, 10:55 AM
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#12
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Guru
City: Pender Harbour, BC
Vessel Name: Gwaii Haanas
Vessel Model: Custom Aluminum 52
Join Date: Sep 2013
Posts: 3,791
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After you have installed them, mask off the area where the screws are located and paint the thin area with some type of paint (I use Tremclad) so that the thin area will not deteriorate too quickly. Still plenty of exposed zinc but the zinc will not come off when it does its job and the screws have no "meat" left to hold together. They will stay on much longer and therefore do their job much longer.
If you're using a diver, paint it first.
__________________
Don't believe everything that you think.
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12-26-2017, 11:10 AM
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#13
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Guru
City: Gibsons, B.C., Canada
Vessel Name: Island Pride
Vessel Model: Palmer 32'
Join Date: Oct 2007
Posts: 4,414
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I learned years ago to do several things.
Light hammering is needed to set the zincs on the shaft. Tighten the screws as described above rotating the shaft to get them even and to set each zinc half.. The screws will not pull the zincs on to the shaft.
I might try a big C clamp to speed the initial setting.
Last but not least to ensure proper electrical contact the metal mounting surfaces are sanded bright, both zinc and the surface it is mounted to.
I also use SS flat washers under the screw heads. Sometime needs a bit of playing, Dremel, to get them to fit over the screw and then into the recess.
The screws are Allen heads and that head is small. THey were designed, the Allen heads, for use in alloy , hard steels where minimal size is needed. The larger standard hex head would be a problem and of course the sockets would make the recess even larger yet.
Zinc is a soft metal and the tension will soon be lost unless the load is spread out a bit more. I also , when needed, went and bought longer screws as some times the screws were simply not long enough to grab properly. And yes, I buy good zincs.
Between the hammering and the washers I stopped losing zincs.
I agree that a fast planing boat might be more likely to loose a zinc but it is also from my fast planing boat that I figured the above out and once sorted out even on that boat I lost NO more zincs.
Xsbank: Good tip about the paint.
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12-26-2017, 11:20 AM
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#14
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Guru
City: Pender Harbour, BC
Vessel Name: Gwaii Haanas
Vessel Model: Custom Aluminum 52
Join Date: Sep 2013
Posts: 3,791
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Thanks. Here's an old photo I took:
__________________
Don't believe everything that you think.
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12-26-2017, 11:44 AM
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#15
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Valued Technical Contributor
City: Litchfield, Ct
Join Date: Aug 2012
Posts: 6,784
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Here is a trick to extend the life of prop shaft zincs, but particularly the expensive zincs on feathering props like the MaxProp:
Before you install, take some of your wife's fingernail polish that she no longer likes (every wife goes through colors and shades ;-) and paint the area around where the screws seat. This will keep that part of the zinc from wasting and keep it from falling off prematurely.
Having said that, if the metal in your zinc is half gone, it is time to replace it.
David
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12-26-2017, 02:13 PM
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#16
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Veteran Member
City: Buffalo
Vessel Model: Sea Ray 400 DB
Join Date: Nov 2015
Posts: 44
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[QUOTE=djmarchand;620513]Before you install, take some of your wife's fingernail polish that she no longer likes (every wife goes through colors and shades ;-) and paint the area around where the screws seat. This will keep that part of the zinc from wasting and keep it from falling off prematurely.
David[/QUOTE
You are the third person I have heard that from. The other two were a diver in South Fl. and a diver in NC while we were looping.
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12-26-2017, 07:27 PM
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#17
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Guru
City: Pender Harbour, BC
Vessel Name: Gwaii Haanas
Vessel Model: Custom Aluminum 52
Join Date: Sep 2013
Posts: 3,791
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I guess not everyone reads all of the thread, either that or there is an echo in here...
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Don't believe everything that you think.
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