[mitiempo]

You should grind to the depth of the crack and out in a 12-1 taper all around the damage. In other words if the hull is 1/2" thick grind 6" on all sides. Wipe the surface several times with acetone after grinding. As far as the kind of glass to use 1708 biaxial would be a good choice. This is a stitched roving with mat already on one side. All the rovings run in one direction. You can alternate direction with each layer. Start with the largest piece of 1708 and work progressively to the smallest. This way the integrity of the roving is not compromised during final sanding. Use only epoxy resin. You may find it easiest to wet out the 1708 and then put it in place as this is easier than working overhead or on vertical surfaces. Also inspect the interior carefully as it is rare for this much damage to occur outside without some damage inside as well. If in doubt have a surveyor or qualified person inspect it. West epoxy also has good technical help and they do answer the phone. Hope this helps.