Here's a description of the problem as posted on the Forum by Roger Lee, Fram #71, 22 May 2014
Noticed a transverse crack in the fiberglass at the point at which the skeg piece supporting the rudder joins the hull. Very rusty water seemed to ooze out of the crack, particularly if encouraged with some compressed air. This suggests to my boatyard guys that an iron or steel member within the skeg is rusting from exposure to salt water. Their fear, and mine now, is that, over time such rusting could enlarge the iron/steel member causing the skeg to crack open. My boatyard guys think it might be sensible to grind down the fiberglass, let everything dry out, remove the rust from the iron/steel member, treat its surface to resist corrosion, and reapply the fiberglass covering. So FIRST QUESTIONS: Anybody experience this before? Is it something needing immediate attention? Any attention? Should I just wait for things to get bad before bothering to do a repair?
The boat yard fears that the water may have penetrated a long distance, making it challenging (or at least time-consuming) to dry out the iron/steel member. Penetration of water might be a lot greater if the iron/steel member was first coated with a porous fairing compound before the glass fabric layers were applied. In that case, the water might have wicked a long distance into the fairing compound. So SECOND QUESTION: Is there a layer of porous fairing compound between the fiberglass and the iron/steel, and, if so, is the porosity of the fairing compound likely to wick water over long distances?
Pithy, on-target answers preferred, but any ideas, experiences, thoughts, opinions welcome.
Noticed a transverse crack in the fiberglass at the point at which the skeg piece supporting the rudder joins the hull. Very rusty water seemed to ooze out of the crack, particularly if encouraged with some compressed air. This suggests to my boatyard guys that an iron or steel member within the skeg is rusting from exposure to salt water. Their fear, and mine now, is that, over time such rusting could enlarge the iron/steel member causing the skeg to crack open. My boatyard guys think it might be sensible to grind down the fiberglass, let everything dry out, remove the rust from the iron/steel member, treat its surface to resist corrosion, and reapply the fiberglass covering. So FIRST QUESTIONS: Anybody experience this before? Is it something needing immediate attention? Any attention? Should I just wait for things to get bad before bothering to do a repair?
The boat yard fears that the water may have penetrated a long distance, making it challenging (or at least time-consuming) to dry out the iron/steel member. Penetration of water might be a lot greater if the iron/steel member was first coated with a porous fairing compound before the glass fabric layers were applied. In that case, the water might have wicked a long distance into the fairing compound. So SECOND QUESTION: Is there a layer of porous fairing compound between the fiberglass and the iron/steel, and, if so, is the porosity of the fairing compound likely to wick water over long distances?
Pithy, on-target answers preferred, but any ideas, experiences, thoughts, opinions welcome.
Oozing rusty water leaks in the rudder shoe are not uncommon. The rust is coming from the keel's 3000 pounds of pig iron ballast.
Knowing how the shoe is constructed helps explain what's happening. Below is a picture of a hull right after it came out of the mold. Note the hollow fiberglass shoe. One of the next steps during construction was for a worker, standing inside the hull, to slide a big (1-1/2" thick by 3" wide) stainless shoe into the fiberglass shoe. Voids between the fiberglass and stainless were filled with sand-impregnated resin. Then the iron ballast was placed in the keel and it too was encapsulated with sand-impregnated resin.
Under pressure, voids in the sand-impregnated resin allow small amounts of water to wick from the shoe to the ballast. Remove the pressure, by pulling the tug out of the water, and the process reverses itself. Here's the good news. It's cosmetic not structural.
I suspect Fram's transverse crack is small and you found it only because it was oozing. If so, you have two choices. Slap some bottom paint on and go cruising. A more conservative choice would be to grind out the crack and fill it with a few layers of glass. While this fixes this spot, don't be surprised if another oozing area is found when you next haul.
Not so pithy but hopefully on-target, Dave (Nellie D. #63)
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