Dan, ICE Suggest you check with neighbors who have wintered aboard for recommendations. The Kasco is widely used, but I prefer a different type. With an air compressor aboard, and an air distribution weighted hose with perforations under your boat, bubbles from the bottom bring warmer water to the surface without any active electrical components underwater... In any case, also consider a thermostat control which activates the unit of your choice to cut electricity use when temperatures permit. You may also check with neighbors who have not used any and just let the water freeze... salt water ice surrounding a hull does no damage as the hull sits protected within....It's the pushing and movement and lifting of surrounding ice and crushing from waves which is of potential concern. As fresh water ice where you are is harder, local knowledge of your immediate marina area is important. If piles remain intact during the winter, you are likely safe as they are very vulnerable to ice. Also check with marina management and get their input. Storm Windows. Also, you may find it very useful to add "storm" windows over glass areas of you boat which will be heated, especially if aluminum framed. I used 40 mil transparent vinyl (same as for drop down type side curtains) inside, with a canvass button in the upper corners. I stuck on velcro strips and stapled it to the vinyl to hold the upper edge. The sides I added full velcro and along the bottom fitted the edge into a removaed plastic window channel sitting on the window sill to form a air tight pocket along the sides and bottom. These need to be sealed to keep in a barrier of air which serves as the major insulator.... You can also get tempy interior storm window stuff at Home Depot, Lowes, which sticks on and is fitted with a hair dryer (to shrink and make tight.)... good luck, Rob Brueckner Hatteras 48 Yachtfish