On Mon, 19 Jul 2010 23:18:19 -0500, cavelamb
wrote:

NOTAM:

Oakland Center (Fremont CA) [ZOA]: April NOTAM #31 issued by Gps Notam OA [GPS]
Navigation GPS is unreliable and May BE unavailable WITHIN A 375 nautical miles
RADIUS of 393101N/1175659W LOVELOCK / LLC / VORTAC 141.25 DEGREE radial at 46.65
nautical miles, at FL400; decreasing in area with DECREASE in altitude to 290
nautical miles RADIUS at FL250; 220 nautical miles RADIUS at 10000 ft. mean sea
level, and 220 nautical miles RADIUS at 4000 ft. above ground level. effective
from April 09th, 2010 at 06:00 AM PST (1004091400) - April 09th, 2010 at 11:30
AM PST (1004091930)

Those ranges quoted are for aircraft thousands of feet above sea
level. The jamming range would be much shorter for boats, probably
10 miles or less.