Repairing Moist Deck Core

Hi All,

Elizabeth is on the truck (finally), bound for Danvers MA. (grin)

One of my first tasks is to repair & protect some areas of elevated moisture in the deck near the cowl vent holes (in deck - no dorades) and a little bit I noticed at the mast partners. Looked like the holes were cut in the deck, but no protective barrier was made against water entering the core.

Who has done it, how did you do it and what recommendations can you make for me. Most of the sites I find describing wet core repair, involve large areas of deck removal, core replacement etc. I believe, I only have some minor work to do here.



You may want to “biopsy” the area around the cowl vent holes and the mast partner hole by drilling 1/8" to 1/4" holes into the coring where the moisture content is high. Drill the first hole at the outer boundary of the wet areas, i.e. furthest away from each hole. Look at the drill bit cuttings to determine if the wood core is wet and rotten or just wet. You should be able to determine how far the moisture or rot traveled into the coring. Another possible “biopsy” procedure, is to use a right angle drill to drill into the side of the coring where it is exposed at the perimeter of the holes. This last procedure is less invasive but limited to the length of the drill bit.

Once you have determined how much area is either rotted or just wet, you will be able to decide whether you need to replace the coring, let the coring dry or dig out the wet coring around the hole and fill the cavity with filled vinyl ester resin


Thanks Rod,

hey nice pics of your dorade and dodger. that dodger is new this year?

Thanks for the kind words about the dorade boxes and dodger.

Lenora built the dodger in the spring of 2006. The two bows were on the boat when we purchased her. We strengthened the dodger frame by adding more support struts and fabricated bronze mounting plates for each coaming. We also built wood coaming pieces for the seahood, and cabin top. The forward part of the dodge snaps to these coamings.

Fair Winds,


Before you drill try this. Wood is like a sponge,it absorbes moisture and it will give up moisture. If you have access to a small room dehumidifier you are in business. Take off your cowl vents. Duct tape a piece of plastic over the hole on the underside to seal the outside from the inside. Set the dehumidifier close to the hole and put plastic over it and the hole to form a tent and tape the plastic to the deck to seal the edges. Now you have a little room that has an area with moisture in it that you are going to get rid of. Turn on the dehumidifier and monitor closely. Any water in the core will be extracted/evaporated by the unit. I did this on a Hans Christian with keaks around the dorades and mast openings. If your dehumidifier collection tray has a drain where you can attach a hose, do that and run the hose out under the plastic and seal it as well. If there is a lot of moisture where when you press the surrounding edges of the hole water seaps out, you can pull it with a vacuum. Seal the underside of the hole with some stiff plexiglass or thin plywood. Get a rubber drain plunger, cut a hole where the handle attaches, hook up a wet/dry vac, place the plunger over the hole and draw out the water. After that do the dehumidifier thing to extract the remaining moisture. A good moisture meter will let you get an idea of how far the moisture has spread in the core without drilling. If the wood is not rotten at the hole edges it is most likely not rotten inside between the outer and inner laminates. West System Epoxy has some very good information on repairing this type of damage. Best of luck to you.

Bob& Lois

BCC Jolie Brise

Bob & Lois:

Great idea.