Waterproof white-balance stickers?

I do a lot of photography on the water from my kayak and frequently include the bow of my boat in the shot.

It is not uncommon for some otherwise good photos to not turn out well because of incorrect white balance. If I have a “true white” and/or a “true black” in a shot, it is very easy to correct this however in post-processing.

Does anybody know if there are water-proof white balance stickers that you could apply to the top of your kayak to achieve a proper reference point for doing corrections with levels and curves?

Check B&H
They have most everything, reliable dealer, good prices. I found this waterproof card, but there may be more:


I have a small piece of stick on laminate floor backslash in my camera case lid. It’s plastic laminate so it should hold up to the water. It was .30 cents at lowes.

I’ve used white clothing on many occasions to set wb. Maybe carry an extra T-shirt until you figure it out? A sticker with white?

I can set manual wb off contrasting colors and it picks out the white; for example, an American flag… maybe give it a try.