I cant believe that I'm reading that you dDivers dont use LORAN.
Lots of Commercials in New England still use Loran I would say meaybe 80% or more still use LORAN and any fisherman worth his salt has TD numbers in his Logbook, not Lats & Longs.
GPS is OK it wil get you in the ballpark
but you need Differential GPS to get you on the Infield and you rneed
LORAN to get you to Home Plate.
If your looking for shipwreacks to dive on I would not trust to using GPS. You will waste a lot of fuel or air that you could have saved buy using your LORAN
just look how tight these triagles are. You cant get that with GPS
POPPYCOCK! GPS w/o WAAS is about 45' accuracy. GPS with
WAAS is about 9' accuracy. I routinely drop the hook with that
sort of accuracy with WAAS GPS. And essentially all modern GPS
is WAAS. Differential GPS?? It was about 15' accuracy (I had one).
WAAS is differential GPS PLUS Ionospheric corrections, transmited
from geosynch satellites on GPS frequencies, so no HW required,
just some firmware in the GPS. Garmin issued new firmware
for my GPSMAP 162 in about 1998 that enabled WAAS. I gave my differential
receiver to a buddy who was doing trail mapping in canyons
at Henry Coe State Park. At that time, the WAAS birds were low
on the horizon, and you couldn't get them in the canyons, but the
LF USCG differential stuff bent down into the canyons.
The key thing to remember about LORAN is that while it was quite
repeatable, it wasn't all that accurate. So of you plug the LORAN
TDs into a conversion program, and plug the Lat/Lon that comes
out into your GPS, you won't do too hot. But of you take your
LORAN to the location, and punch a waypoint on your GPS, you
are in great shape.