You've got to have pretty deep pockets to afford offshore, voyaging insurance. Third party is the best to have (but astonishingly hard to get) with so many people sailing these days, who do not understand the give and take of the cruising community. Time was when an offer to make good any damage you incurred would have been accepted, but the new breed of sabbatical sailors just ask for your insurance company's name. However, the money you will have to shell out on full cover, would probably be better spent on really good ground tackle, etc, with the residue put aside in a high return (Hah!) investment. In fact the premium might be as much as your cruising budget. Effectively, it makes sense to self insure.
In spite of Gerry's good experiences, chances are they won't pay out anyway :-(