Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 09-01-2012, 05:50   #1
Formerly: Capt Wraun
 
Sir Rondo Normal's Avatar

Join Date: Sep 2011
Location: Port Louis, Haida Gwaii (The edge of the world)
Boat: Corbin39 CC Cutter Rig
Posts: 431
Through Bolted Zinc

Hi again people: We started into working on the Corbin over the weekend and one of the things was to prepare the hull for bottom paint. All the zincs had already been remove except one. This one is one of the bar style anodes that was bolted through the hull and to which the bonding wires from the mast were connected.
The problem was that the through bolts were brass, slotted, machine screws so both had to be removed from the hull in order to remove the zinc.

What I'm thinking is to squeeze epoxy into the holes and and insert studs with flat washers on either end, then install the zinc using a rubber o-ring underneath it to put pressure on the exterior washer and to allow water to get to the underside of the zinc.

Is this how it is normally done and which would be better for the studs/washer, stainless steel or brass?


Thanks
__________________

__________________
*** If it ain't broke... just wait! ***
Sir Rondo Normal is offline   Reply With Quote
Old 09-01-2012, 07:10   #2
Registered User

Join Date: May 2010
Location: Elsewhere on the Water
Posts: 571
Re: Through bolted zinc

My boat has stainless studs. Bonding wires attach on the inside. Nuts are placed on the studs' exterior to provide about 3/4 inch space between the hull and the zinc plates. Washers and nuts are on both sides of the zincs with no rubber involved. I do not know what type of sealant was used, but there is no leakage. The boat has been serviced by several different yards over the years, and they have all restored the installation using the same configuration.
__________________

__________________
St. Elsewhere is offline   Reply With Quote
Old 10-01-2012, 04:59   #3
Formerly: Capt Wraun
 
Sir Rondo Normal's Avatar

Join Date: Sep 2011
Location: Port Louis, Haida Gwaii (The edge of the world)
Boat: Corbin39 CC Cutter Rig
Posts: 431
Re: Through bolted zinc

Thanks St, I spoke to a fellow yesterday who suggested using 3M 5200 and stainless studs, etc. I like the idea of a nut as a spacer as I wondered how rubber would hold up over time in salt water.

Cheers!
__________________
*** If it ain't broke... just wait! ***
Sir Rondo Normal is offline   Reply With Quote
Old 10-01-2012, 05:21   #4
Registered User

Join Date: Feb 2008
Posts: 2,061
Re: Through bolted zinc

Why would anyone bond the mast to a zinc? Are you sure this wasn't a scintered bronze grounding plate (Dynaplate)?

You don't want water between the grounding plate (or a zinc) and the bottom -- it should be mounted in full contact, and I see no reason to remove a ground plate for painting unless it's to apply an epoxy barrier coat.

Also - with regard to the person who recommended 5200 that's not appropriate to use as a sealant under bolts unless it's something structural that warrants a strong adhesive in addition to sealing. I would use 4200 or 303, or other underwater-rated sealant that's not so tenacious. You only need to stop water from leaking; the bolt will handle the loads. 5200 is NEVER appropriate on a zinc, which needs to be changed as regular maintenance.
__________________
SailFastTri is offline   Reply With Quote
Old 10-01-2012, 05:59   #5
Formerly: Capt Wraun
 
Sir Rondo Normal's Avatar

Join Date: Sep 2011
Location: Port Louis, Haida Gwaii (The edge of the world)
Boat: Corbin39 CC Cutter Rig
Posts: 431
Re: Through bolted zinc

Thank-you SailFast, yes you are right. It was a grounding plate. It looked like a zinc. At any rate, I now have to either put it back or replace it with a new one. I might as well put a new one one. So the question still remains as to what I pack into the bolt holes for sealant. Wouldn't the 5200 be the best choice for in the holes?

Thanks
__________________
*** If it ain't broke... just wait! ***
Sir Rondo Normal is offline   Reply With Quote
Old 10-01-2012, 06:15   #6
Registered User

Join Date: Feb 2008
Posts: 2,061
Re: Through bolted zinc

Quote:
Originally Posted by Capt Wraun View Post
Thank-you SailFast, yes you are right. It was a grounding plate. It looked like a zinc. At any rate, I now have to either put it back or replace it with a new one. I might as well put a new one one. So the question still remains as to what I pack into the bolt holes for sealant. Wouldn't the 5200 be the best choice for in the holes?

Thanks
I would not use 5200 under the Dynaplate, because the though-bolts will hold it just fine, and all you need is some goop to stop leaks. 5200 makes a permanent bond that is very difficult to remove without collateral damage. You would need to use heat and/or debonding chemicals, or plain brute force such as an angle grinder (difficult to control precisely). Chiseling away parts bound by 5200 is likely to damage the fiberglass laminate beneath.

Sealant = gap-filling.
__________________
SailFastTri is offline   Reply With Quote
Old 10-01-2012, 06:36   #7
Registered User

Join Date: Feb 2006
Location: nyc/chesapeake
Boat: gozzard 44
Posts: 273
Re: Through bolted zinc

Don't think you meant brass bolts; most likely they were bronze.
Brass has little use on a boat.

Ronbo
__________________
ronbo1 is offline   Reply With Quote
Old 10-01-2012, 06:40   #8
Registered User

Join Date: Feb 2008
Posts: 2,061
Re: Through bolted zinc

Quote:
Originally Posted by ronbo1 View Post
Don't think you meant brass bolts; most likely they were bronze.
Brass has little use on a boat.

Ronbo
Agree -- they came with the grounding plate. If he didn't destroy the plate or bolts my bet is he'll re-use them when he finds out the replacement cost.
__________________
SailFastTri is offline   Reply With Quote
Old 10-01-2012, 07:03   #9
Registered User

Join Date: Jul 2009
Posts: 774
Re: Through bolted zinc

Quote:
Originally Posted by Capt Wraun View Post
Hi again people: We started into working on the Corbin over the weekend and one of the things was to prepare the hull for bottom paint. All the zincs had already been remove except one. This one is one of the bar style anodes that was bolted through the hull and to which the bonding wires from the mast were connected.
The problem was that the through bolts were brass, slotted, machine screws so both had to be removed from the hull in order to remove the zinc.

What I'm thinking is to squeeze epoxy into the holes and and insert studs with flat washers on either end, then install the zinc using a rubber o-ring underneath it to put pressure on the exterior washer and to allow water to get to the underside of the zinc.

Fill the holes with west system six ten, then drill out to the size of the new SS redi-rod. Bed the studs with SikaFlex or 3M 5200. Make sure you leave enough stud material inside to attach connectors and enough below for the dive plate. Use large washers inside and out and add a locking nut to both inside and outside of the studs. Do not use rubber, or similar. Do not bed the studs in epoxy, it's not waterproof and it will crack without filler. Allow the bedding material to cure.
__________________

Seahunter is offline   Reply With Quote
Old 10-01-2012, 07:26   #10
Registered User

Join Date: May 2010
Location: Elsewhere on the Water
Posts: 571
Re: Through bolted zinc

Quote:
Originally Posted by SailFastTri View Post
You don't want water between the grounding plate (or a zinc) and the bottom -- it should be mounted in full contact,
SailFast,

Why should a zinc plate be in full contact with the bottom?

On fiberglass boats the electrical contact is only through the stainless studs. The studs are held securely to the hull with nuts on both sides, and they need to remain in place to facilitate changing zincs with the boat in the water. How would you achieve full contact and maintain secure installation of the studs?
__________________
St. Elsewhere is offline   Reply With Quote
Old 10-01-2012, 07:29   #11
Registered User

Join Date: Jul 2009
Posts: 774
Re: Through bolted zinc

Quote:
Originally Posted by SailFastTri View Post
I would not use 5200 under the Dynaplate, because the though-bolts will hold it just fine, and all you need is some goop to stop leaks. 5200 makes a permanent bond that is very difficult to remove without collateral damage. You would need to use heat and/or debonding chemicals, or plain brute force such as an angle grinder (difficult to control precisely). Chiseling away parts bound by 5200 is likely to damage the fiberglass laminate beneath.

Sealant = gap-filling.
While I'm not a huge fan of 5200, this application requires a bedding agent, not a "sealant". The is a big mistake many make. Anything going through the hull to the water requires a bedding material. 3M-5200 or SikaFlex 291 will not only bed, but bond and seal any mechanical fittings used in an underwater situation. They are virtually immune to saltwater and mechanical vibration. On removal, I've found a sawsall works quite well on removing bedded fittings.
__________________

Seahunter is offline   Reply With Quote
Old 10-01-2012, 17:59   #12
Formerly: Capt Wraun
 
Sir Rondo Normal's Avatar

Join Date: Sep 2011
Location: Port Louis, Haida Gwaii (The edge of the world)
Boat: Corbin39 CC Cutter Rig
Posts: 431
Re: Through bolted zinc

Quote:
Originally Posted by SailFastTri View Post
Agree -- they came with the grounding plate. If he didn't destroy the plate or bolts my bet is he'll re-use them when he finds out the replacement cost.
Hey I'm right here eh

I'll have another look at it on the weekend and decide whether or not to re-use the block. Do they degrade over time or is it okay to re-use? It is now the same colour as a zinc. The flat head machine screws are not completely destroyed, just the slots are a little worn now.
__________________
*** If it ain't broke... just wait! ***
Sir Rondo Normal is offline   Reply With Quote
Old 10-01-2012, 18:08   #13
Formerly: Capt Wraun
 
Sir Rondo Normal's Avatar

Join Date: Sep 2011
Location: Port Louis, Haida Gwaii (The edge of the world)
Boat: Corbin39 CC Cutter Rig
Posts: 431
Re: Through bolted zinc

Quote:
Originally Posted by Seahunter View Post
Fill the holes with west system six ten, then drill out to the size of the new SS redi-rod. Bed the studs with SikaFlex or 3M 5200. Make sure you leave enough stud material inside to attach connectors and enough below for the dive plate. Use large washers inside and out and add a locking nut to both inside and outside of the studs. Do not use rubber, or similar. Do not bed the studs in epoxy, it's not waterproof and it will crack without filler. Allow the bedding material to cure.
Okay so I'll use the west system "six ten" to fill the holes but then would it be best to drill new holes or drill through the six ten?
By "bedding" the new bronze bolts, you mean coat the threads with the 3M 5200 or Sikaflex and thread them through the holes?

Cheers, your expertise is appreciated.
__________________
*** If it ain't broke... just wait! ***
Sir Rondo Normal is offline   Reply With Quote
Old 10-01-2012, 18:12   #14
Registered User

Join Date: Feb 2008
Posts: 2,061
Re: Through bolted zinc

Quote:
Originally Posted by Capt Wraun View Post
Hey I'm right here eh

I'll have another look at it on the weekend and decide whether or not to re-use the block. Do they degrade over time or is it okay to re-use? It is now the same colour as a zinc. The flat head machine screws are not completely destroyed, just the slots are a little worn now.
If pink, then the bronze has been degraded by electrolysis. Not sure what to think about silver-gray.
__________________
SailFastTri is offline   Reply With Quote
Old 10-01-2012, 20:15   #15
Senior Cruiser
 
Jim Cate's Avatar

Cruisers Forum Supporter

Join Date: May 2008
Location: cruising SW Pacific
Boat: Jon Sayer 1-off 46 ft fract rig sloop strip plank in W Red Cedar
Posts: 11,447
Re: Through bolted zinc

You might try soaking the ground plate in white vinegar for a few hours. This treatment will remove many of the strange things that grow on metal fittings in sea water. Won't hurt the plate, either. BTW, is the plate just a flat bit of solid metal, or is it made of scintered bronze, possibly with fins on the surface?

Cheers,

Jim
__________________

__________________
Jim and Ann s/v Insatiable II , lying Port Cygnet, Tasmania once again
Jim Cate is offline   Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Unfreezing the Zinc Anode Plugs Unicorn Engines and Propulsion Systems 11 28-06-2015 02:31
Seized Engine Zinc sneuman Engines and Propulsion Systems 9 01-12-2011 11:37
Zinc Anodes in Exhaust Elbow timj Engines and Propulsion Systems 4 26-09-2011 14:42
Sacrificial Zinc ? Tori Liveaboard's Forum 17 19-07-2011 12:22
For Sale: Beneteau Shaft Zinc CampDavid Classifieds Archive 0 05-07-2011 19:22



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 23:00.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.