C46 rudder cracks

[Will_M]

Hello everyone,
I recently purchased a 1995 Contest 46 in Florida. We hauled the boat out ~2 months ago for various below water line jobs, including a light sand and application of fresh ablative bottom paint. Upon returning to the boat after a month or so without seeing her, two vertical cracks have formed on the port side of the rudder approximately 15cm aft of the leading edge. I do not know how deep the cracks are without grinding, but they appear to be fairly shallow. It looks as though it is possibly a sheet of laminate that is wrapped around the front of the rudder to bond the two halves, but I'm no expert on construction.

The cracks were not evident during the survey or when the yard prepped the bottom for paint. They seem to have opened up spontaneously while sitting on the hard untouched. I don't have any evidence to believe that this was caused by damage from an object (like a car) striking it.

Has anyone else experienced this? Does anyone know anything about the rudder construction on C46s?

Thank you,
Will

[pieter2]

Looks like something is 'leaking' out of the cracks? Maybe the cracks have been there before, but not noticed due to antifouling and now on the hard the cracks are transmitting liquid?
Check of there is a lot of fluid in the rudder (drill hole on bottem of the rudder to see if it starts leaking).
How does the other side of the rudder look like, any cracks as well?
Any movement in the cracks when you apply soem force to the rudder?

[Will_M]

Hi Pieter,
- no cracks on other side of rudder
- rudder is bone dry
- absolutely no movement in the crack when throwing my entire body weight against rudder

We opened up the rudder along the crack with a grinder and found that there is indeed a piece of thin laminate that is wrapped around the leading edge of the rudder. On top of it is ~2cm of filler. The aft-most edge of the laminate has dis-bonded from the primary fiberglass rudder structure, probably due to a mistake in the original preparation.

It appears to be entirely superficial, so we are simply going to grind the superficial laminate layer back 1-2cm until we get to well bonded material and then refill and paint it. The only other option would be to open up the entire vertical length of the rudder on both sides, prep, and then layer on additional fiberglass to seal the edge of the potentially problematic layer, but that’s a more drastic measure than we want to take right now. We will see over the next 1-2 years whether additional cracks form and then reassess.

The outstanding question that I have is whether this layer of laminate was original to Contest’s construction or something that was added later during a repair.

[pieter2]

Hi Will,

So it seems to be just a minor problem. Great!

I have a contest 29 from 1974. Some years ago I saw a small crack in (approx) the same location as yours. I just grinded the top surface on both sides and made some extra layers of laminated epoxy around the back of the rudder.
I don't  know what you mean with "just refill it" but I would advice to laminate it.
Remaining question is why the cracks are seen now instead of during the inspection. Perhaps a long drying period on the hard?
Good luck with your work!