Similar to Ron except...
I also have an 11W UniSolar panel, which I secure by passing my main hatch padlock through one of its grommets when locking the boat. A piece of light line through an adjacent grommet is tied off to the teak handhold on the coachroof, and adjusted to level up the panel and lay it against the cabin bulkhead. In that position, it faces south and doesn't gather dust or bird "gifts".Flexible panels are less efficient than rigid panels but work better in real-world conditions. An 11W panel should be OK as long as you give it enough time between trips to recharge your battery.Recharge time can be surprisingly long, since a panel delivers its rated wattage only when it is clean and positioned square to bright sunshine. Dust, haze, clouds, shadows from the rig and the movement of the sun over the course of the day reduce the panel's ability to generate electricity.For example, if you ran your 75Ah battery down halfway and then tried to recharge it with an 11W panel, it would take over six days to bring the battery back to full charge. I assumed the panel was working at 60% efficiency and seeing 10 hours of usable sunshine a day (12 hours minus the hour after dawn and the hour before sunset). Your local conditions may be worse. Rain and cloudy days will also lengthen the recharge time. If you sail more frequently, get a larger panel.Regardless of panel size, the battery should not be drawn down past half its rated capacity. Repeated deep discharge shortens battery life. Calculate your total energy usage for a typical trip and compare with the capacity of the battery (I can help with this if you're not sure how). If you consistently exceed half the battery's capacity, add another battery or try to use less power. Happy sailing.PeterH23 "Raven"