Alster boat boats boats bridge dinghis germany hamburg idyll jolly-boat lake landing stage marina mast reflections river ships water wherry yacht aecurity Błyskawica destroyer dinghy launch life-boat line nautical pinnace Poland rescue safe see vessel warship work yawl yowl background blue color colour dingey frost off-season orange red sailing snow streaks sunny texture turquoise upside-down winter green purple turoise yellow