Join Date: Sep 2008
Location: Victoria B.C. Canada
Thanked 106 Times in 97 Posts
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I agree it is probably cored - for some bolts if not all. Core is easy to deal with but it does take longer. Here's a link by Maine Sail - a complete how-to for dealing with core and sealing it properly.
Sealing Deck Penetrations to Prevent Core Rot Photo Gallery by Compass Marine at pbase.com
Living aboard in Victoria Harbour