Corrosion in the compression post?

[Stephen Trapani]

Not sure what needs to be done here. Hoping for some help! I believe there may be a breach at the top of my mast letting in water. Maybe for about 6 months. There's water leaking from the bottom of the post, anyway.

As you can hopefully see in the one photo, there is some corrosion which circles about halfway around the base of the compression post near where it is glassed into a support on the keel. The corrosion is about 1/16th deep into the metal of the post. Not sure the gauge of the post.

Can it be repaired, hopefully, assuming I stop the leak?? Does it even need repair, assuming I stop the leak? Does the compression post have to be replaced? Why is it corroding from the outside of the post?

 

[Terry Cox]

Mast Step Leak

In case your situation is similar to what we experienced, we offer the following in order to help diagnose whether our solution will work in your case. Without being there it is hard to tell. Please let us know what you determine is causing the corrosion.

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While Belle-Vie was on the hard for repairs awhile ago I addressed a number of minor maintenance issues including a small leak through the mast step into the salon.

The mast step is held in place with four SS flat head through bolts with lock nuts. This step has a drain hole on the head end bottom side so that rain water entering the mast head can drain out through this small hole at the bottom. The electrical wires run through a short piece (original was two inches long) of one inch plastic PVC pipe that is inserted in a hole in the coach top. You can see this piece of pipe if you remove the covering from the top of the compression post.

The pipe is supposed to be sealed, but over time this seal failed, so water coming from the mast head would leak around this pipe and into the salon. The PO tried to use Silicone II from inside the boat but that did not work.

After cleaning the cast aluminum step plate and coach roof surface I used 3M4200 sealant to rebed the plate. The new three inch piece of PVC was placed with a liberal amount of 3M4200 around where it entered the coach roof. The PVC pipe extends about two inches above the coach roof so that any rain water pooling at the base will run out through the weep hole in the step plate. Be sure to leave a drip loop in the wires that enter the coach roof.

Each season I use a pipe cleaner to clear out any debris in the step plate weep hole. This repair was done four years ago and it still remains dry.