Another trick someone mentioned is to wear brighter things or put bright stickers on the helmet. I check the "ropes" on the equipment and put a good length in my pocket - if i remember. i do still go out on my own :-( At this time of year - there are NO boats in the water either - so, you/i am out on my own !!!
When I am on-call I carry a cell phone in a water pak. Perhaps I should do that at all times ...
Other readings have suggested whistles...
The crazy dudes should even wear impact vests !!
This study shows and I quote: http://bjsm.bmj.com/content/40/4/346.abstract
Conclusion: The injury incidence was 1.5/person/year with a high incidence of new and recurrent muscular strain. Lower back muscular strain was prevalent, indicating the need for preventive measures. Wave/slalom was associated with more new and recurrent injuries and the need for head protection.
AND it does look like some people actually manage to crack open the helmet!!
Here's another study with some interesting numbers: http://www.mendeley.com/research/mechanisms-prevention-windsurfing-injuries/
Aim of this study was to analyse the mechanisms of windsurfing injuries. For this purpose we performed a internet based survey among 327 windsurfers in Germany. Overall 630 accidents have been registered among all 327 athletes during the 2000 season. The majority of injuries were classified as minor injury. The most common injury was the bruise. 70 participants reported fractures, 26 participants ruptured a ligament. 280 injuries required medical treatment; in 67 cases even surgical treatment was necessary. The majority of accidents happened at wind power of 5-6 Beaufort after 2 hour exercise. A technical mistake was the most frequent cause for the accident. The most dangerous manoeuvres were difficult jumps (e. g. front loop, backward loop, 70 injuries). In 46 cases the weather conditions were underestimated. Only 10 windsurfers reported about broken material as cause for the injury. One half of the injuries happened in wave conditions. The analysis of injury mechanisms allows conclusions regarding injury prevention. A longer break after 60 minutes windsurfing might help to prevent injuries due to poor physical fitness. After one hour windsurfing without a break training of difficult manoeuvres should not be performed. The use of a helmet might prevent head injuries during training of difficult jumps. "Overpower situations" should be prevented by choosing the right board and sail size.
One thing I always overlook is energy food. I have seen and heard that people eat bananas and yogurt. Other athletes I know stress water (one bottle per hour) regardless of sport - in order not to dehydrate, and they all recommend breaks - same as above, one per hour. I will say it again - I always forget sunscreen :-(