[C38] Mast leak

Sat Nov 20 15:17:03 EST 2010

Hello List,

Rebuilding the mast step is a great way to "kill two birds with one stone."  In this case, it may be three birds.

When I rebuilt the mast step on the Renata, I built a new step from laid up glass and resin.  If you try this repair, make a grid on your cabin sole with tape or removable marker lines so you can find where the base of the mast should be to prevent having the mast base installed again in the wrong place.  Tape off the working area because this mast step rebuild is one messy job.

I cut the bottom out of the recess in the cabin sole leaving about 3/4" lip around the sides of the base.  This lip will be a reference when we build the new mast step to the original height.

I then proceeded to chisel out the rotten wood in the bilge which had been my mast step.  I used chisels and drills to finally get all of the material out leaving a clean hull.

My aluminum mast base was "welded" to the base of the mast by corrosion.  I was able to save the mast base but I had to remove 1/4" from the bottom of the mast to remove corrosion damage and also to compensate for a new deck plate described below.

Next I made a form in the bilge to act as a mold for the new mast step.  I then installed two 90 degree large diameter plastic electric conduit angles in the mold to route two mast ground cables to the keel.

Once those elbows were in place, I proceeded to build up the step with solid resin and glass until the new mast step was level with the original mast step.  

Then I fabricated a piece of 1/4" aluminum plate to fit into the mast base recess with holes allowing the conduit angles to protrude through the new base plate.  I bedded the new base plate to the new mast step using structural fiberglass putty but I put mold release on the bottom of the aluminum plate to allow its extraction if it ever needed to be removed.

I then cut off the protruding conduit angles flush with the top of the aluminum plate so they could act as drains for any water in the base of the mast.  I used a die grinder to actually funnel the tops of the elbows so they would funnel any standing water to the bilge.

I accomplished three things by this repair.

1.    By replacing the soft wood mast step with built up fiberglass, I made a strong, permanent repair to the mast step.

2.    I allowed a way for the water in the mast to drain to the bilge which also prevented future mast base corrosion and wet cabin sole.

3.    I allowed a large radius direct route for my two mast lightning ground cables to the keel making a low resistance lighting path.

I attached the mast end of the ground cables inside the mast before replacing the mast back into the boat so the two ground cables are totally out of sight concealed inside the mast.  When we replaced the mast, we just routed the mast ground cables into the elbows in the new mast step and pulled them into the bilge as the mast was lowered.

This is just a brief outline of the procedure but if anyone is interested in repeating it, please feel free to contact me for details.  I have some photos also.

A actually grounded the aluminum base plate to a forward keel bolt with a third cable but that requires removing the waste water tank to get to the forward keel bolt.

I made my keel connection clamps for the ground cables to attach to the keel studs which I also have photos of.  I terminated one of the two cables going aft to the engine also.

To complete the grounding system, any other large metal objects should also be bonded to the ground cables/keel to prevent secondary side flashes in the event of a lightning strike.  This includes the range/oven and any other large metal object like a microwave, etc. 

If you did take a direct hit from lightning without bonding your oven, you could become a conduit for a lightning strike trying to go from your mast to your oven.  This could ruin your whole day and also smell up the marina with the smoke of burnt flesh which could totally nauseate your guests.

Tom Troncalli
Recovering Catalina 38 owner.

----- Original Message ----- 
From: William Knowles 
To: Catalina 38 Listserve
Sent: 11/20/2010 8:55:29 AM 
Subject: Re: [C38] Mast leak

If you are planning to pull or just lift the mast the common fix is to drill a hole at an angle through the the base and the supporting block to drain water into the bilge. It may be a good idea to check the wood block , mine had rotted away and the survey did not find it we sailed for over a  year until the cabin sole cracked. On the positive side it shows how well built (heavy construction) these boats are.

Bill Flying Goose 324

On Sat, Nov 20, 2010 at 2:40 AM, Joseph Launie <jlaunie at cox.net> wrote:

Dan,
   Its not the bilge water that bothers me, it is the water that stands on the salon floor. Since the mast is hollow and rain water finds its way inside, I do not know of a fix - but then, I live in the desert. Joe Launie/Macavity

On 11/19/2010 10:18 PM, Dan Kueng wrote:

Is leaking water through the mast into the bilge a common problem?  Is there
a fix?

Thanks,
Dan

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-- 
W H Knowles
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