I have had a closer look and found a crack running up the back side of the daggerboard trunk (3-4''). On the top of the hulll there seems to be a cap thats pushed down over the top of trunk tube, it's sealed with a compound.

Is it possible to remove this 12 x 12 inch. cap to repair the trunk from inside the hull. (with this cap removed I could get my hand down to the bottom of the trunk. But i don't want to start prying it off it it is not meant to be removed. - It's a NACRA Inter 18