Among inexpensive sound signal devices, gas-powered horns are hard to beat—and darn near all the same. Whistles are better left clipped to life jackets, as Practical Sailor found out in our last test, published Sept. 1, 2002.

Gas-powered air horns offer the loudest signal with the best range, but gas refills are a must.

Collisions are among the most devastating problems that can occur at sea. Collision avoidance is the fundamental rationale for keeping a watch. An aid to the human eye is radar, which has line-of-sight range to the horizon, and even can "see" through fog and the darkness of night. Other devices include the CARD (collision avoidance radar detector), which alerts you, on your small boat, that a vessel with radar is around. …