Mark: Be careful with the throughhulls. I saw one boat go down here because during a coldsnap the gatevalve (not the throughull) froze and cracked. When the weather warmed up the lake came in.... The boat was a 20+ ft powerboat and the gatevalve (bronze, unused in the engine compartment) had been closed but not protected against freezing. The much maligned lightbulb method would have prevented the disaster. The boat was in the marina, used as a liveaboard and continuously bubbled. The freezing occured from the cold air getting at the valve (top-down), not from the water (bottom-up). George of Scaramouche1, Lake Ontario, Canada As a separate attachment, just for you Mark, Im sending a picture of the cracked valve (not allowed to send enclosures on list) - Gg