Cabin Top leak: Cape Dory 27

[George Hare]

Hi Board,
I am the owner a 1980 CD 27 (and a beautiful Ty). My question is about the '27. I have been searching for the source of a top cabin leak.
I became the owner a year ago, but the problem can be traced back to 2000 when a PO posted a similar Q to the board.
Here are the bullets:
Water is finding its way between the cabin top and liner immediately in the area of the mast and exactly where the mast wires enter the cabin. Yes, we have caulked the entry points for the wires. That area is very secure. Water still comes in, especially in hard blowing storms. Never in mild rain conditions or when washing the boat. Must be rain and wind. We recently had the mast removed and the mast step recaulked thinking the water is working its ways from the bolts through the core to the hole where the wires enter. (note:The original caulking by the way was shot. I suggest owners check this if you ever remove your mast removed).
Mast is back on with fresh caulk. Still leaks around the wire entry. Dorade box is secure. Sea hood is secure and dry. There is nothing else. I am working with one of the most professional boat yards in
in Oriental NC. Andy Denmark, another member the same mysterious water source on his CD 27. The boat yard staff just check on my boat after a severe storm and discover water inside the wire "liner" "sleeve" or casing (whatever you call it) for the mast wires. It suggests, absent any other explanation, that water is finding its way into the liner/sleeve from where they connect at the top of the mast and working its way down into the cabin through the inspection port in the head area Or, it suggest that residual water remains in the liner until enough new water pushes small amounts through the maze and into the boat.
With no other options at this point, we are going to operate from this theory.
My question to fellow members is whether anyone has ever heard of or had any experience with water intrusion from the sleeves of the mast wires?

[Oswego John]

George,

My question to fellow members is whether anyone has ever heard of or had any experience with water intrusion from the sleeves of the mast wires?

Yes.

There was one instance where the mast butt/mast base was caulked too well. Water accumulated in the bottom of the mast. In time, the accumulated water level rose above the connector fitting in the mast for the liquid tight, flex, plastic tubing that carries the mast wires into the cabin.

In this instance, the problem was easily solved by drilling a weep hole, vee notch, or some other way to prevent water from accumulating in the mast base.

Is this happening in your Typhoon, too?

Good luck,
O J

[George Hare]

Thanks John. I think I understand what you describe. I failed to explain earlier that my wires exit the base of the mast on the port side and enter the cabin top about 3" from the base, between the base and the dorade. The only intrusion point within the mast are the 4 bolts that secure the step which were exceptionally well caulked.
The typhoon is solid. No water intrusion at all. The prettiest girl at the dance.
Thank you

[barfwinkle]

Do you have a "drip loop" in the wiring before it exits the mast?

Fair winds.

[Andy Denmark]

I think some clarification is needed here. I have the same problem as George.

There are several wires leading down the mast from the masthead. If you were to disect these you would find small individual insulated wires encased in a common sleeve - either pairs, triples or a larger bundle such as wiring for a wind instrument. There are interstitial spaces between these smaller wires and the outer sleeve and also between the individual wires. Water seems to be entering these spaces by running down the smaller internal wires and migrating downward --- a capillary action that's aided by gravity.

Down here at "hurricane ground zero" we frequently get torrential rain that's usually wind driven. Sideways is a common direction for raindrops to travel. Yesterday morning we had almost an inch of rain in an hour with 40 mph winds. It is easy to comprehend enough raindrops impinging on the end of one of these wires that some of it runs down into the interstitial spaces, goes through these tiny spaces in and around the internal wires, and exits at the bottom where the outer insulation "sleeve" is cut away so the internal wires can terminate to something (a terminal strip for instance). What George and I are trying to explain is a wicking action where rainwater enters at the top and runs INSIDE the wire until it exits at the bottom.

I found this difficult to fathom but the two extremely competent and experienced boatyard guys both saw the same thing -- when they held the end of the wire downward water ran out from the INSIDE of the wire with a steady drip.

If you an visualize a boat in a slip where it cannot weathervane then how much water gets into the wires is largely determined by wind direction. Sometimes the top wire termination is on the windward side of the mast and sometimes the leeward. When wind blows rainwater hard against the point where the outer insulation is stripped away then a tiny amount of water enters the interstitial space, runs through the wire and exits at the bottom where the outer insulation is stripped away. The result is a steady drip as long as there is water entering at the top. If there is a drip loop at the bottom then the loop fills to overflowing - in at one end and out at the other.

In effect, this entire mechanism is simply a water column. There seem to be two solutions. (1) stop water intrusion at the top, and/or, (2) cut a hole through the outer insulation at the point where the wires exit the mast to let any water drain out before penetrating the deck. A product called Coax Seal will easily stop the intrusion at the top and I'm sure there is other stuff that will do this as well.

I am devising a test for this phenomenon at my kitchen sink to see if the theory is valid. Report to follow.

Maybe this clarifies what we're seeing down here. After decades in the boatyard business I've never seen or heard of this action but the engineer in me says it's certainly possible. Murphy's Law holds true once again.
________
List of penny stocks

[Oswego John]

George, Andy and all,

There is a method that is is commonly practiced to seal conductors that are emerging from their protective, outer sheath.

Some people paint on a plastic sealer at this point. One of the more popular products is 3M Electicote. It is a blackish colored heavy, creamy liquid. It dries to the touch in a short time. There is a built in brush in the can's cap. A half pint can will last a long time. There are other comparable brands, also.

Some people first wrap electrical black, vinyl tape between the conductors and carry the tape back over the sheath. Then they apply the electrical sealer.

Good luck,
O J

[sharkbait]

There are two types of shrink tube. One type has a very gooey center filler when heated the other doesn't. You should seal the ends of the wires with the shrink tube with the filler first and then coat with the 3M sealant.

[Andy Denmark]

This is harder to explain on paper than to see in real life. The leakage is not occurring between the metal conductor and the wire insulation but between the wire insulation and the plastic covering that holds the insulated wires together. Of course, the terminals are of the sealing variety so there's no water intrusion into the wire itself. What has not been done is to use heat shrink tubing or any kind of sealant where the insulated wires emerge from the outer covering. This is where we surmise the capillary action is taking place. Sealing here with Electricote and heat shrink will probably fix this per Sharkbait's suggestion.

[M. R. Bober]

This is harder to explain on paper than to see in real life. The leakage is not occurring between the metal conductor and the wire insulation but between the wire insulation and the plastic covering that holds the insulated wires together. Of course, the terminals are of the sealing variety so there's no water intrusion into the wire itself. What has not been done is to use heat shrink tubing or any kind of sealant where the insulated wires emerge from the outer covering. This is where we surmise the capillary action is taking place. Sealing here with Electricote and heat shrink will probably fix this per Sharkbait's suggestion.

Andy,
I understand, and can offer the following. On TIA MARI (1979 CD27) there was a recurring problem with the VHF, which required service from the manufacturer (my cost). One morning, after a squally night, I found a drop of water on the counter top below the radio. Long story made short: the antenna lead had a nick in the insulation near the masthead below the drip loop, and under certain conditions rain entered the cable and traveled down the braided portion of the co-axial directly to the top of the--vertically mounted--radio.

If I hadn't seen it, I might not have believed it.

Mitchell Bober
Sunny Lancaster (just this side of the rainbow), VA