Great boat! I have one- Check the hulls at the rear beam where the deck is bonded to the hull bottom- Some of the early 18's had a tendency to fail there- if caught when fairly new (as my boat was) Prindle supplied new hulls- don't know what happened to the old ones. Mast is quite heavy but quite strong- beware heavy air downwind as the original rudders are just too small for these long hulls downwind in a blow IMO- been there and the hulls just sink down and rudders rise up (even with 3 guys on the stern!) and you are going wherever you were pointed at the time! Make sure you can right it with your crew before you go out - ie "flip" it on it's side in a protected area with your crew and make sure you are capable of righting it- as mentioned it's a long, tall, fairly heavy mast. If you cannot then invest in a righting bag, system or pole (I know Rick has the pole). Would also suggest investing in trailer winch to assist in raising mast.
Great boat and actually, surprisingly, sails decent with just the mainsail-

Kirt