Electrolytic action on aluminum spars - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > On Board > Gear & Maintenance
 Not a Member? 
  #1  
Old 03-12-2010
Junior Member
 
Join Date: Jun 2009
Posts: 21
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
johnseattle is on a distinguished road
Electrolytic action on aluminum spars

I'm in the process of painting the aluminum mast, boom and cross trees on a 1978 Islander 28. I've removed all the standing rigging & other hardware and sanded down to bare metal which after 30 years is still in excellent condition but for some slight surface corrosion on the boom around some of the steel fittings. I believe this is the result of electrolytic action and I'm looking for advice to stop it recurring. I guess I can coat screws and pop rivets with silicone but what about other areas where steel touches aluminum? Is there a recommended insulating material, an insulating paint perhaps or perhaps just more silcone? Apart from this one question I am ready to finish the project as soon as we have the next couple of Seattle days that are dry and over 60 Fahrenheit. Thanks in advance, advice much appreciated.
Reply With Quote Quick reply to this message Share with Facebook
  #2  
Old 03-13-2010
sailingdog's Avatar
Telstar 28
 
Join Date: Mar 2006
Location: New England
Posts: 43,290
Thanks: 0
Thanked 11 Times in 11 Posts
Rep Power: 13
sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice
Using something like TefGel or LanoCote is probably better than using a silicone sealant. If the pieces are larger, say, like the base of a mounting plate or line clutch, you can use the thin plastic from the side of a translucent milk jug as a galvanic isolation washer, in conjunction with the LanoCote or TefGel.
__________________
Sailingdog

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Telstar 28
New England

You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

If you're new to the Sailnet Forums... please read this
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.

Still—DON'T READ THAT POST AGAIN.
Reply With Quote Quick reply to this message Share with Facebook
  #3  
Old 03-13-2010
Junior Member
 
Join Date: Jan 2009
Posts: 16
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
Alden44GER is on a distinguished road
Hi John,

I refurbished my corroded 62ft mast last year.

Don't use steel brushs or something to clean the aluminum. You will rub in tiny steel parts which will make your mast blossom again for no apparent reason.

Use etch primer prior applying the primer and AWL Grip. The etch primer will turn brown if applied correctly. Remove it if it does not and start again. Coat the etch primer with two-compound primer as early as possible to prevent separating.

Get rid of the steel rivets or screws wheresoever possible. Use MONEL rivets (Ni/Cu) instead. They are more expensive but it's worth it. Be careful - the load capacity of MONEL rivets is not as high as of stainless steel rivets.

If you have to use steel screws or rivets (e.g. top of mast track and points of reefing heights) insulate them with LanoCote.

RECKMANN Germany recommends "Wollwachs" (Lanolin) which is basically LanoCote. You get it as "Adeps lanae" in a good drugstore (at least in Germany) It's much cheaper. 150ml Adeps Lanae will cost you round about 4 EUR which will last for probably all the masts you will ever own (I replaced all 400 rivets and screws in my mast and the container is still full to the brim).

Concerning the material to insulate steel and aluminum opinions differ. There are some pastes to prevent corrosion. A surveyor and rigger told me that Sikaflex is the best bet you can get. But I was afraid of squeesing out the insulation when torquing the fittings. So I sticked to the more traditional way of using a special rubber tiles German snowplows have attached to edge of their shovels which appeared to work well (my mast is 30 years old).

Don't use rubber discs underneath winches. It's too soft. I used 4mm GRP tiles instead.

If you feel like having a look at some pics I will upload some of them.

Good luck!

Luis


Quote:
Originally Posted by johnseattle View Post
I'm in the process of painting the aluminum mast, boom and cross trees on a 1978 Islander 28. I've removed all the standing rigging & other hardware and sanded down to bare metal which after 30 years is still in excellent condition but for some slight surface corrosion on the boom around some of the steel fittings. I believe this is the result of electrolytic action and I'm looking for advice to stop it recurring. I guess I can coat screws and pop rivets with silicone but what about other areas where steel touches aluminum? Is there a recommended insulating material, an insulating paint perhaps or perhaps just more silcone? Apart from this one question I am ready to finish the project as soon as we have the next couple of Seattle days that are dry and over 60 Fahrenheit. Thanks in advance, advice much appreciated.
__________________
Alden44
Reply With Quote Quick reply to this message Share with Facebook
Reply

Quick Reply
Message:
Options

By choosing to post the reply above you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Register Now

In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
cleaning aluminum water tank rbtpfe9 Gear & Maintenance 18 12-27-2010 12:31 PM
Cleaning Aluminum Spars Duke 7184 Gear & Maintenance 6 09-12-2006 07:23 PM
Repainting aluminum spars andyking Gear & Maintenance 2 07-30-2006 10:42 AM
Upgrading Spars Tom Wood Gear and Maintenance Articles 0 12-01-2003 08:00 PM
Upgrading Spars Tom Wood Cruising Articles 0 12-01-2003 08:00 PM


All times are GMT -4. The time now is 07:11 AM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.