crack in side board

[mikest29]

I took my DN out for its first sail of the year and I notice a 20 inch hairline crack in a sideboard near the mast step. It is very thin. I have west epoxy and syringes. I cant use the vacuum technique as I cant get into the inside of the hull. would it be advisable to drill tiny holes in the crack and inject epoxy? any thoughts are greatly appreciated...


Mike

[TinkerSailor]

I would consider drilling a hole in the bottom skin big enough for a small vacuume hose. You could then use the entire mast step box as a suction area. Be careful not to implode the whole thing.

Leigh

[JOHN BUSHEY]

Here is another technique:

From the bottom, and using a long 3/16 drill bit, and a jig to go straight, drill into the sideboard at mid width to a depth of 1/2 or 1" past the crack.  A hole every 2" is what I have done.  Get some 3/16 hardwood dowel from the hardware store.  Make sure it an fit in the hole, full depth.  you may need to sand it down a bit by chucking it in a drill and spinning it in sandpaper.  You want a free but close fit.  If you have put some masking tape on the bottom skin before you drill, you won't have as much cleanup of epoxy later.

Mix and put about an inch worth of epoxy in each hole, making sure it runs down inside.  It helps if the sideboard is warm, and using a hypo to keep the epoxy from bridging and trapping air.   Use the dowel as a plunger to pressurize the epoxy past and into the crack in the sideboard. Twist it a turn or two to make sure it's full surface is coated too.  It may or may not ooze out the outside of the crack, and may go inside and not be seen.  Either way, some is likely injected into the crack from inside each hole.  There will be a series of shear connections as well tension, and to some extent side bending resistance due to the dowels glued across the split in the grain.

Pull off the tape, cut and sand the dowels flush and refinish the bottom skin.

I had a boat I fixed like this and sailed it for several years without a problem.