What direction in the crack running? Assuming the boat is in the water, does the crack go up and down (parallel to a rib), or left to right (parallel to a strip)?

Is just one strip damaged, or does the crack go over more than one strip.? Is the crack in the wood itself, or is a seam between two pieces of wood opening up?

Is the crack above the water line or below?

Is the boat leaking through the crack?

Is the existing fiberglass over the cracked area also cracked, or is it jsut the wood which has the crack?

If the crack is just in one strip then it can be removed and a new one inserted. That is usually an extreme case, but it always works.

For a simple crack in a single strip, the wood can be bonded by allowing epoxy resin to soak in and saturate the damged area. After the resin hardens it is stronger than the wood.

A crack in the seam between two strips means the glue, or the wood adjacent to the glue, failed. It can be reglued by letting resin soak in, as well. (Just like above)

To do this you would have to remove the fiberglass cloth and plastic resin which cover the crack, so you can apply a warm (and therefore thin and runny) coat of resin directly to the damaged wood part. After that has set up you can sand or scrape off any excess and recover the area with a fiberglass patch.

If the crack is in several strips you can try the same technique. You just have to start by removing a larger area of the fiberglass covering so you can open up a larger area.

An extra layer of fiberglass cloth on each side of the boat, sandwiching and overlapping the damaged area should strengthen the area to prevent further damage, and seal against leaks.

Hope this helps.

PGJ