Rudder Skeg Corrosion

[barrylab]

I recently started the sale process on En Fin V, a 1976 Pearson 365 recently featured Chandlery section of this club. I've been eyeing 365's for about 20 years, but never took the plunge. At the going price I know there will be a great many unpleasant suprises, and untold hours of work. My first project involves some corrosion at the base of the rudder skeg, and I'm looking for some opinions.

[kevin barber]

Well-  First of all, you are going to want to take a sander to that thing and see what the metal looks like beneath all that crud.  There are two bronze brackets that are mounted on the skeg.  It looks like you've got some pretty bad corrosion.  After you sand all the paint off, if the metal looks very discolored or brital, you will have to replace the bracket.  That most likely means getting a new one fabricated.

[barrylab]

It looks like steel, by the color of the corrosion. As it's been on the hard for 6 years, the engineer in me wants to understand where the water is coming from that caused this. It's possible this was happening when it was last in the water, but that rust is wet, so there is a path for water to find it's way internally to that bracket.

Any Idea what the structure of the upper skeg looks like? I have to believe there is some serious structural support.

[kevin barber]

Thats interesting.  My boat is a 1982, and it is definately a bronze fitting.   I don't think the skeg is hollow, however I could be wrong.  My skeg feels solid as a rock.  There is no place in the bilge that I have seen where water would be able to intrude into the skeg. 

My gut feeling is that the corrosion probably occured when the boat was in the water.  It may feel damp due to rain water intrusion from the outside.  You need to sand the entire skeg clean, in order to understand what is happening here.   Perhaps there is a crack that someone painted over years ago.

[Jim S]

The skeg is hollow.  The entrance is forward of the rudderstock and is inaccessable with the fuel tank installed.

[barrylab]

It sounds like the recent rains we've had have leaked into the lazarette, run down under the fuel tank, into the skeg, and out through the hole made by the corrosion. I'll have a closer look at it tomorrow morning, as I closed tonight and have unlimited access now. If the darker area aft smells like diesel, I have a bigger problem.

[Dale Tanski]

Yup the skeg is hollow all right.  I thought it might have been solid as well until I noticed that while washing where the fuel tank used to be, the water that collected in a slight hollow disappeared.  It sounded hollow when I knocked on it.  The skeg is glassed over, however mine was porous and not completely sealed.  I drilled a hole in the skeg and it drained out approximately 5 gallons.  The water was salty so I am assuming that it came from the outside in.  I reglassed the top and have solved the problem because it now sounds hollow when you knock on it.  Had this froze when the boat got to Buffalo, it would have been a disaster.  Not a bad idea to check this and repair if you pull your fuel tank. 
Good Sailing...   Dale Tanski

[barrylab]

Well there's no diesel in it, it's all water. I started sanding back the area, and found the bracket has been bedded in what looks like 214, some bondo like fairing material, and some really rubbery latex material. I'd guess this bracket has been out a few times. The water is following the latex. I'd guess it's following what ever mounting hardware is there (lag screws, carriage bolts ... ?)

The bracket is Bronze, and has a patina of pink that comes off in the first few mills.

My question now is ... How does this mount? I see two screws coming in from starboard, and one from port, and the bottom has a cap of fiberglass. I'm guessing it's one of two scenarios:

1. The 3 screws mount to a vertical piece of bronze that is embedded in the fiberglass if the upper skeg. The water would most likely be following the vertical piece.

2. The 3 screws mount the lower piece to the upper. The upper could be attached to the skeg with lag screws, carriage bolts, or something like that. The fiberglass cap would then be attached to the bottom of the lower bracket. In this case, the water is following the screw mechanism.

Either scenario requires me to remove the 3 horizontal screws.

I climbed into the lazarette to see where the water could be coming from. Whenever it rains,  water is coming into the lazarette through several holes for hardware that has been removed. It then travels down and pools around the tank frame, and probably enters the skeg from there. It's simple to close the holes off, but the bigger issue is preventing it from getting into the skeg if it does find its' way below.

[Atavist]

good topic and lots of good info... I had a similar problem but never figured out the cause... i assumed it was just coming through where the rudder is seated on the skeg... now I know and will address the problem more thoroughly when next I go on the hard... maybe fill the skeg with epoxy to make it solid... if it won't bond to the bolts thus and make the thing incapable of beind disasembled.

[barrylab]

As I mentioned there was water pooling just ahead of the fuel tank mount box, so I'm planning on filling the low spot with fiberglass so that water can't pool there. I'll paint the area with bilge paint when the glass has cured. That will cause any water that makes it's way in, to enter the bilge ahead of the skeg. As long she stays "shiny side up", gravity should keep water away from the skeg. With the freezing temps just around the corner, it need to be done soon.

As a side note, those screws have a 1" head. I'm manufacturing a 1" screwdriver blade for my impact driver out of a 1" spade bit drill. I'll post more pictures this weekend.