Bib wrote:
Kind of beyond what you were asking about but my half dollar
suggestions.

Consider the "Safety Blaster Horn". Lung powered, 120dbs, 1 mile
range, $10. Do not try it out in enclosed space. I did. Could not
hear for 10 mins. Wife and I both carry one on PFD. All plastic, no
rust. URL below takes you Fogdog which sells them. Immersion in salt
water does not effect it at all - drain for 2 seconds and blow. Used
by us any number of times both on land and sea. Great for hiking if
separated by terrain.
http://www.fogdog.com/product/index....oductId=841305

I agree. This horn makes whistles seem anemic by comparison. I carry one
in my PFD.