Well maybe not relevant but, I recently read a book "117 days adrift" and these people were passed by seven ships within a mile of there position, they had flares and made smoke bombs, and all seven passed by without notice. If you are adrift it would be nice to have an electronic noise maker. Of course I would get a radio and a gps first, and rent an EPIRB. Any one know the effect of SA on the GPS feature of an EPIRB? Although I guess 300 yards is acceptable for a helicopter to see you, and maybe the USCG is not effected by it.