Hi Paul,

Thank you.  The main use-case is that below-deck the HX851 internal
GPS does not work; thus the unit is wired up the vessel NEMA bus for
GLL/RMC from the fixed GPS.  Of course, when cradled the strobe starts
flashing.  The strobe has to be manually disabled.

Thusly, two out of the three unique features of the HX851 are
incompatible.  The user must chose one undesirable situation of:

  a. No time or geo-location source when below deck (standard DSC)
  b. No auto-strobe when outside/dropped (== pointless gimick)

This incompatible behaviour is puzzling to the user, since it is not
intuitively what is expected; viz:

  http://www.sailnet.com/forums/873796-post6.html
  "> When it's set to "strobe when wet" you can't use NMEA.
  well now you learn something new every day"

  http://forums.sailinganarchy.com/index.php?showtopic=135192
  "So I tried connecting it to my computer via DB9 female connector to
  USB-Serial cable and whenever I hook it up the strobe light starts
  blinking. I'm a computer guy so I know I got the computer side
  right, com port, 4800 8N1, etc."

  "I had mega problems with hooking my Std. Horizon VHF up to my Garmin GPS."

  "That is a pretty unacceptable bug as the strobe when dropped in the
  water was one of the reasons i bought the dam thing :(
  I hope they do a firmware update at some point "

Et cetera.  Googling will get you more, but you get the general idea:
the perception is of "some stupid bug" present in the world's top end
handheld used by everyone from James Cameron downwards.

I have to confess that 'bug' was my initial reaction too, some 18 months
ago when I first got an HX851.  From the service manual, it is plain
to see why the limitation might exist, but for mortals it is
unfathomable.  The HX851 user manual is not forthcoming:

  Page 19: "NOTE The Water Hazard LED must be turned off so the radio
  will output NMEA data to an external device (VHF Radio, PC,
  etc.).  Refer to section ''8.12 LED SETUP''"

This in itself is misleading, but also does not help the user
/understand/ the limitation.  It could be explicitly documented.

Even *better* than documenting, would be to be able to offer a
firmware fix to alleviate the perception.  What is really needed is a
dock-detect; to transparently do what the user expects:

  1. Does not flash the strobe in the cradle, but does transparently
     accept/prefer better external GPS input.
  2. And out of the cradle: does strobe when wet, and does
     automatically use the internal GPS (for distress).

Both of these are "do the obvious" (do what the user expects), and
does not force them to make a sub-optimal choice between two desirable
features (with safety-of-life benefits) that are currently rendered
incompatible soley because an implementation detail.

If the unit shipped with the proposed firmware change, by default, it:

  1. Would remove the perception of a significant 'bug'
  2. Would work below-deck and do-the-right-thing
  3. Would work above-deck and do-the-right-thing
  4. Remain locatable when dropped

The following use-case is rarer, but it would be achieved aswell:

  5. When the internal GPS is powered off (to save battery),
     the DSC and Distress functionality will still have the
     benefit of the last-known position __at the point of
     removal from the cradle__ (eg. grabbing and ditching moment).

This (5) is admittedly only a small improvement, but if the user is
unable to active the GPS (several menu layers + wait 3-5 minutes) while in
the water they will be able to transmit a good cached geo-fix, rather than
nothing.

And an even smaller unintended side-effect/advantage:

  6. When cradled, and the external power source blows
     the strobe will come on as emergency lighting.

Of course, in the ideal situation, the radio is never dropped, and the
Distress button is never plunged; the GPS never needed.  But, like the
ring-pull can, and the ejector seat: the strobe and GPS+DSC
integration are the very rationale for sale/purchase.