Just started another project on my new to me H31. Somehow during one of the PO's tenur the top of the water tank became cracked and had obviously leaked. The last owner installed a bladder type water tank in the original tank. I got rid of the bladder and am in the process of repairing the tank top. See photos. I have all the sealant removed, I ground the gelcoat off the damaged area and I plan to use a couple of layers of fibreglass cloth, using waxed polyester resin. I realize I will have to sand between coats to get rid of the blush but not a problem, I have a 6 inch Portercable random orbital sander which will take care of that. I will then gelcoat the whole thing on the underside and just the repair on the top side. After that I will sand and polish the gelcoat. The jury is still out on what to use for a sealer when I install the top after completing the repairs, I have no idea what the original installer used. I am leaning toward 3M 4200 but will welcome any advice/experience anyone can offer. Sorry folks, I am struggling with these photos and how to insert them but I'm sure you get the picture (pun intended) Reg .