Lowrance now says their GPS receivers are submersible to 2 feet for up to one hour.  Here is their statement.
Joe Mehaffey

Lowrance considers Lowrance and Eagle products to be water proof.  This
means that a unit can be submerged for a period of 1 hour at a depth of 2
static feet of clear water.  This spec was developed by Lowrance because it
was easier to perform than the Coast Guard spec* and considered more
effective for determining if a product was water tight.

*The Coast Guard definition of water proof is found in 46 CFR (Code of
Federal Regulations).  It states that a "water proof machine means a totally
enclosed machine so constructed that a stream of water from a hose with a
nozzle one inch in diameter that delivers at least 65 gallons per minute can
be played on the machine from any direction from a distance of about 10 feet
for a period of not less than 5 minutes without leakage".
 

Lowrance Engineering

For IEC 529/IP definitions used by the USCG,  see HERE.   The IPX2 definition (for instance) means that a particular equipment has NOT BEEN TESTED for potential damage from solid objects,  but has a -2- rating for water immersion.