"Fairhaven" Formosa 41
Join Date: Mar 2008
Location: Anacortes PNW
Thanked 19 Times in 15 Posts
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Re: hand held radio for man overboard
Here was the test of scuba divers in the water trying to signal their boat. It's a test far above and beyond anything I've seen the sailing community do. Highly recommended reading for any potential MOB.
Gear / Accessories | Scuba Diving Magazine
I disagree with the last sentance of the quoted section below. An EPIRB will be of no use, while a VHF would be of enormous help I believe.
From the article:
While signaling tubes and audible signaling devices do dramatically improve your odds of being spotted, we were surprised at the limited range they offered, even in our relatively good conditions. In general:
Size matters. All signal tubes tested were visible at one-quarter nautical mile, and about half were still visible at the half-mile mark. As expected, the longer the tube, the greater the visible range. The largest tubes in this test were visible at the three-quarter mark, and only one was still visible at almost one nautical mile.
Color matters. We also found that fluorescent yellow was very easy to spot in overcast conditions while orange stood out in bright sunlight. Lettering on tubes was not particularly helpful, and the black webbing tape that trimmed the edges of most tubes only lessens the potential visibility at greater distances.
Audible ranges are limited. Whistles were effective only to about one- quarter mile, with a few discernible at a half mile, but all were still better than yelling, which could be heard only at a tenth of a mile. Of the two air horns tested one was stellar, blasting out its call up to one mile away.
Our findings suggest that you have a fairly small window of opportunity to be seen if you're being swept away from the boat in a strong current. If you surface in a two-knot current, for example, you will drift a quarter mile in only 7.5 minutes. Think of the boat with rings around it every quarter mile. Within the first ring you have a good chance of getting noticed with most signaling devices tested here, but once you pass the half-mile mark, the ability to be seen or heard drops off significantly. If you surface already a quarter-mile downcurrent from the boat, you only have a few minutes to deploy your signal tube, sound the alert and get noticed before you pass that second ring.
Your odds are better with a very tall signal tube (eight to 10 feet), which, based on our test, could make you visible up to nearly a mile away. The higher the boat deck or point from which the searcher is looking will also improve your odds of being spotted. If the searcher is using binoculars (7 x 50 is standard for marine use), your chances of being spotted double. But once you are out of visual and audible range, it's a big ocean-an electronic beacon or EPIRB (see "Electronic Devices") may be the only way to get found.
"True, your boat will outperform mine to windward, but my boat will always outperform yours at anchor." --MedSailor