The chainplates on my Cruiser 37 go through the deck and are bolted to the hull inside a cavity, which is covered by a trapezoidal fibreglass panel. Water entering the cavity from the deck usually drains out through the lower edge of this panel. However, on one side of my boat, I now have nast rust stains descending from the lower edge of the panel. I'm thinking that maybe the drainage has become bunged up, water has accumulated, and rusting has occured on the fixings. So, I want to take the panel off and have a look. Has anyone done this? How is it held on? Please don't say Sikaflex....
PS The pic is the panel before the rust stains appeared!
Update! Oh no, it was Sikaflex or similar holding the cover plate on. And not just a small amount, about a 3cm wide seam of it. The only way to remove the cover is by wrecking it, and so I've ordered a replacement (not cheap!).
I can't understand why the cover was sealed at the bottom, because water can enter at deck level. Logically, it ought to be possible for that water to drain out rather than fester inside and cause rust.
Oxalic acid has removed the rust stains on the hull below the cover plate. I've removed about a quarter of the plate so far, but it's a long job involving chisels and brute force. Here's a very bad pic of what it currently looks like.
I wish there was more feedback on this.
I've been dealing with this for several years. I have a 2014 C37 since new. I flush out the cavity every Spring by blasting a hose through the lower edge of the cover and from the dexk above. I continue to flush until I only see water and no debris.