GPSrChive Discussion Forum

Just discovered a waterproofing fault. I use the GPSMAP 66 on a kayak, clipped into a Garmin deck bracket. I'm not a sea kayaker in rough conditions - this is from partly salt & freash water on fairly calm rivers.

Salt water has leaked into the small catch at the bottom of the battery compartment cover. It's starting to build up on the inside components of the quarter turn catch. If not constantly cleaned after every trip it will cause total corrosion of the catch. It was harder than usual to turn it to open. It needs to be cleaned with fresh water and a very small brush with stiff bristles - maybe there's an artist's brush that will get in around the tiny parts.

Can you share photos to show this next time, please?

Both before and after you open the cover.

The outside has no sign of anything. Two shots of the salt buildup on the inside components. It's difficult to get the light and camera angle to show it.



I don't know how to insert an image so had to do it linked to a couple on my home website.

Thank you for posting those images! (external hosting is the correct method)

Looking at your photos, it appears the battery cover lock is outside the actual waterproofing seal for the battery compartment, so this is not technically a failure of the waterproofing system. This does however bring to light an important issue to be aware of for those who do use these units in or around any salt water. It certainly appears these units should likely be rinsed thoroughly with fresh water frequently and then opened up for inspection and further cleaning as required. To be fair, the GPSMAP 66 is not a marine grade GPSr, like the GPSMAP 78.

Your post serves as an excellent warning to all!

The salt water must have leaked in via the shaft on the quarter turn lock. There is no sign of salt anywhere else on the back cover or inside the battery case. Yes, it's outside on the waterproof seal, but absolutely vital for sealing the battery section. If the metal parts deteriorated the lock will fail, and whether it's inside or outside of the waterproof cavity will be an inconsequential consideration. Also, leaving it unattended for two months since my last day on the water made it more difficult to unlock the battery cover. leave it longr and the lock could break in forcing it open.

It's now thorougly cleaned with fresh water and a stiff bristle toothbrush, and the last grains of salt scraped off with a tiny screwdriver. A smear of lanolin will help keep it ok, along with constant monitoring and cleaning after paddle trips.

Posted to the GPSMAP 66 > Common Issues page as Hardware Failure #2.

Thank You!