Not being familiar with that specific product, I encourage you to look up the MSDS form that should be available at the manufacturer's website, or at least at the place you bought the stuff.

Wood 'brighteners' are usually oxalic acid though, so if the product label hints at that we're farther along than when you posted your query.

Oxalic acid is water-soluble so thorough rinsing after application should render the wood just fine for epoxy once again. Be SURE to let the bleached wood/plywood dry thoroughly! You don't want even a hint of water remaining in the bleached wood when it comes time to do a little sanding for grain smoothing or getting a protective coating of epoxy back onto those organic wood fibers holding the water back....

   My vote is the same as spclark - Of course you can experiment with your log cleaner, but by definition experiments sometimes have unforeseen results.

Oxalic acid is readily available at your local big box home store or hardware store, usually powder form that you need to mix up prior to use, and sometimes liquid.  Sometimes grouped with the paints and finishes, sometimes with concrete and porch cleaners.  Just follow directions, scrub on liberally with a green pad, give it some dwell time for a half-hour or so (even if that means a few re-applications to keep things wet), rinse well and let dry completely. The one hint/step I'll add is a full day in bright sunshine after the acid & rinse treatment tends to really help further bleach the wood (and dry it too). You still might have some light gray color left, and can see if any judicial sanding helps.  You might never get back to a complete color match with the adjacent protected wood.  Then do your new coats of epoxy and varnish.

Finally, there is nothing wrong with boats that show a little use and age, in my opinion, so long as they keep your feet dry. So if you get the wood back to being well protected from further damage, that's the big thing. And if all else fails and you want a new and shiny (but different) look, there is always paint.

Good luck.

I appreciate the responses.  CPR Log cleaner is sodium percarbonate and disodium carbonate. I bought a used boat so that we could use it and I would not stress about every little detail.  I will use the cpr log cleaner because it is not hard and then go from there. 

https://www.loghelp.com/images/MSDS_CPR.pdf

Know what precautions to take with both the leftover, unused product as well as what you use for your project.

These and similar compounds are typically grouped with strong oxidiers and carry a hefty fee when you go to dispose of the leftover product at a suitable hazardous materials facility.

The water solutions used for your endeavor will kill pretty much any vegetation they come in contact with. And allowing runoff to enter most any sewer system is fround upon.

Use plenty of clean, fresh water to rinse away both the working solution as well as any debris that get's lifted from the surfaces you'll be working to clean up.

Being alkaline, once the rinse water's well-dried away the cleaned surface you've revealed will readily accept epoxy or suitable varnish / primer / paint.

Theoretically, diluting the waste solutions and neutralizing them with an acid will take care of most, if not all, of the hazards. The acid can even be something like vinegar or citric acid rather than a high strength industrial one.

The oxidizer/fire hazard is for the dry powder at high temperatures and pressures.

Check with a real chemist before doing any of this yourself to make sure of the correct types, strengths and amounts of acid to use and the type of personal protective equipmet to wear.

Be safe,

Laszlo

 Whenever you get a question like that you can do a test on a similar piece of wood.