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Keel Bolts corroding fast Hunter 22' ('81)

Jan 29, 2007
85
Hunter 22 Pelham Manor, NY (1981 H22)
My SS keel boats on my 1981 Hunter 22 are corroding. Is this caused by some stray current in the water? Maybe a bad reaction to the ablative paint? Should I coat them first, put zinc somewhere? Why is this happening? I feel it should not happen at all. Hasnt happened like this before. I have had keel bolts corrode and break before, but not 3/4 of them in less than one summer. Thoughts? See photos. The heads are basically dissolving off.
 

Attachments

Jan 19, 2010
9,519
Hunter 26 Charleston
That is CRAZY! I assume you have the fixed keel version.

Stray current is usually only an issue if you are at a marina AND plugged into shore power. I doubt that is the case on a 22' sailboat but if it is true for you, then yes! That could be stray current but it seems like your keel bolts would have to somehow complete a circuit with your shore power... so even if you are connected to shore power, you would have to have a ground connected in your bilge.

What is your keel made of? You could have a dissimilar metal issue.... but that really does not seem likely either.
 
Jan 19, 2010
9,519
Hunter 26 Charleston
Any chance you had something acidic in your bilge. That seem far more likely than electrolysis.
 
Jan 29, 2007
85
Hunter 22 Pelham Manor, NY (1981 H22)
I don't have acid in my bilge that I know of but I'm certainly going to rinse everything and wash everything out. it's not a fixed keel. these are the four bolts that hold my swing keel bracket. it's not a very heavy keell this is not the one with all kinds of lead in it. it's just a foam keel that weighs about 100 lbs. Anyway yeah it's totally nuts, right?
 
Jan 1, 2006
5,548
Slickcraft 26 Greenport, NY
What material are they? To me it looks like the majority of the bolt is not corroded. It's primarily the head. I'm going with a manufacturing defect.
 
Jan 1, 2006
5,548
Slickcraft 26 Greenport, NY
These are big bolts but they say all are made the same way:
 
Jan 19, 2010
9,519
Hunter 26 Charleston
Okay so I thought on this some more. What is the bracket made of? Is it SS or aluminum? If aluminum, then you have a dissimilar metal problem and you should use aluminum bolts.

If your bracket is SS andyour bolts are below the water line, there seems to be a consensus that SS has to be a very high quaility since SS does needs exposure to air to remain stainless. If the SS is to be submerged it will be starved of oxygen it can be suseptable to crevis pitting.

Brass seems to be the metal recommended on this thread.... but I would stick with whatever your bracket is made from to avoid dissimilar metal issues.




... and here is a good source to buy

 

SeaTR

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Jan 24, 2009
377
Hunter 22 Groton
Newsailor130, After reading your thread, freaky is what comes to mind. Why would the bolts fail ONLY at the shaft of the flat head (FH)? I have the same boat as you (H22, 1981), and have been using similar SS bolts (4ea) with the SS keel brackets, washers and nuts for the past 14 years at a mooring with no problems. Your picture 20210308_112933 shows what appears to me to be shear failure due to poor manufacturing with the hollowed FH interiors. Were these as-bought bolts / hardware from the previous owner (PO)? It shouldn't cost much to replace ALL hardware. Going with a reputable supplier like Grainger would help. Yes, there are a number of types of SS available....
1617833774768.png


How long have you been sailing this boat? Maintenance history? Information from the PO?
 
Last edited:
Jun 8, 2004
8,579
-na -NA Anywhere USA
swing keel is cast iron. do you have shore power? ANy thru hulls and type of material. Are you in a marina. Has anyone checked for electroylisis in the water which you can buy a sacrificial anode overboard to see if it corrodes. If so then there is a stray current in the water which needs to be fixed by the marina fast to avoid any injury. Can you take a photo or two of the bracket inside the boat?
 

SeaTR

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Jan 24, 2009
377
Hunter 22 Groton
BTW--The swing keel on this boat is NOT cast iron. I have the exact same configuration swing keel (1981, H22). It's weighted foam (~80#) with a fiberglass shell and a rigid urethane core (Foss Foam). There is about 1300# of lead epoxied into the bilge on both sides of the swing keel housing that's used for counterbalance...no iron or lead in the keel itself.

Your problem is still mystifying !