You might want to check this thread:
You'll hear a lot of "sailing is a great workout I'm always tired!", but being exhausted doesn't necessarily mean you gained an ounce of lean body mass, are calorie balanced, or increased your aerobic capacity.
For me the key is take the real world of strength training
, conditioning, and diet, and bend it to fit around the boat. You're not going to build bone density cranking a winch and the worst storm in the world isn't going to do beans to improve your cardiovascular system.
If you could get a kick ass workout by just sailing, trust me, every body builder
and marathon runner would be sailing.