"Jeff Morris" wrote in message
...
Bil Hansen wrote:
"Jeff Morris" wrote ...

Don White wrote:

For a smaller sailboat like mine, I'd buy...
http://ca.binnacle.com/online/produc...dept%5Fid=5120

The first item, a Davis Radar reflector, is a good item. I keep one
folding up as a reserve to the Firdell mounted high on the mast. The
second, a Mobri, is considered by many to be useless. "Essential
invisible" according to the US Sailing test.

http://www.ussailing.org/safety/Stud...ector_test.htm

US Sailing and West Marine have given the Mobri bad press.

Don't forget Practical Sailor and Practical Boat Owner. And you'll find
dealer sites that advise "best suited for powerboats," presumably
because they don't work well when heeled.

So if the Mobri
reflectors are 'essentially invisible', why does the USCG specify them
(since 1998) as the internal radar reflectors for unlighted buoys?

See http://www.uscg.mil/systems/gse/gse2...ions/450-D.pdf and
note

Interesting reading. However, the M3 and M4 are considerably larger
than the S2 commonly seen on small boats, and the buoys use three of
them. Also, I found no other mention of Mobri on the CG site, including
in the detailed specs for the buoys. I wonder if they are actually
used, since there are other vendors of reflectors for this purpose?

And remember, these are small, foam buoys used in inland waters. Even
the largest size only cost $5000, the smaller sizes are under $500.
These are not the steel buoys found in the ocean.

The USCG Ocean Engineering Division didn't specify the less expensive
Davis
reflector. Funny that, eh?

Hilarious. However, I'm guessing you've never actually sailed on the
ocean, because if you had, you'd appreciated that most ocean buoys
incorporate the same design as the Davis into their fabrication. And
several sizes of the foam buoys you mention incorporate aluminum corner
reflectors instead of the cylindrical type.

Thanks for the gratuitous swipe at my ocean experience! Nicest thing anyone
has said to me all day!

As it turns out, I have a Mobri near my masthead (you're right: I've only
sailed from California to Malaysia, from where I now reply to you, on my
current voyage. I've heaps more ocean to cross and things to learn from more
experience sailors) and I do more or less agree with PBO etc that Mobri
reflectors do not return much of a signal at any angle of heel (I base that
on talking to cargo ships that could not locate me by radar). Because of
that, I don't rely on other ships seeing me: I watch out for them and use a
radar detector when I'm not running my radar.

I thought that the PBO tests were more meaningful than the West Marine
tests; PBO also noted that adding extra radar reflectors was not necessarily
the best thing to do, because of possible cancellation effects due to phase
differences. I note also that Nova Marine (www.novamarine.ca) concluded
Davis Echo Master radar reflectors were not that good (compared to the ISO
standard) either. But I've not heard of the Big Dot reflector ever going
into production.

Bil