Crack in rudder support arm

Dutch01527

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I have a Southerly 100. I have it out of the water for anti fouling. I have discovered a small crack running around the support that projects from the hull to house the lower rudder bearing. Below and slightly aft of the prop in the first picture below (same model boat). The second picture shows the crack. When I put lateral pressure on it there is a bit of movement and the crack opens a tiny bit - maybe 0.5 mm. The fiberglass underneath the support arm has some l damage. Clearly there is something wrong that needs fixing.

Does anyone know how the support arm is constructed, what is below the fibre glass?

Anyone had a similar issue before and how did you fix it? Would bolting steel support on to the arm be a good option?
 

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alahol2

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This is from a survey on a Southerly 100...

The lower bearing was mounted on a U-section bracket, extending aft of the GRP
skeg. This bracket was 420 mm long and constructed from 10 mm thick welded
stainless steel. This bracket was secured to the lower edge of the skeg by four
stainless steel fasteners. These were screwed into tapped holes in the bracket.
The bracket was well secured to the GRP skeg.

Don't know if this accords with what you are looking at.
Either way you need to remove the old antifouling so you can see what you are dealing with.
 

Dutch01527

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Thanks. That is very useful. Looks like the Skeg in which I have a crack is grp. I did not know if there was a steel or wood core.
 
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Lifeboater

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I have a Southerly 100. I have it out of the water for anti fouling. I have discovered a small crack running around the support that projects from the hull to house the lower rudder bearing. Below and slightly aft of the prop in the first picture below (same model boat). The second picture shows the crack. When I put lateral pressure on it there is a bit of movement and the crack opens a tiny bit - maybe 0.5 mm. The fiberglass underneath the support arm has some l damage. Clearly there is something wrong that needs fixing.

Does anyone know how the support arm is constructed, what is below the fibre glass?

Anyone had a similar issue before and how did you fix it? Would bolting steel support on to the arm be a good option?
Get a real good survey done and ask them about how it should be repaired, rather than the usual archair sailors. Use real good epoxy like West System and alas it's going to be a big job as you need to grind back to a 7 to 1 slope before laying up the glass. Use a moisture meter to make sure the area is bone dry or vacuum bag it dry. DO NOT USE FILLER AND SELL THE BOAT, as a rudder failure can be very dangerous. Forget about using stainless steel for anything serious unless it's expensive 318 Duplex that have a fatigue life and ultimate shear strength that is very similar to mild steel.
 
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