Yes, it probably can be fixed.  It will take some work.  I'm quite sure the reason your surface appears lighter is that the gooey epoxy didn't penetrate the wood, so nothing you do "on top" of that interface is going to change the color tone.  Best to get a heat gun (the $20-$50 if you have to go buy one. it is worth it in saved effort and extra sandpaper).  Or you can just sand.  But back to the heat gun. Use it to soften the epoxy without burning the wood, and scrape while it is soft.  You'll need a disposable rag to wipe your scraper, or wiping it across a hard edge like an old #10 tin can edge can work.  Scrape away as much as possible.  If you have an extra person to run the heat gun while the other scrapes, that is a bonus. Then let enrything get good and hard again, then sand down to bare wood without going throught the first layer of the plywood.  Then re-coat with nice fresh epoxy.  Hopefully the color matches adjacent areas, but even if not quite perfect, at least you know you've got a well-bonded first layer of epoxy.  And if all else fails you might end up wanting to paint the boat, writing this off to experience.  

Another couple of notes/hints:

Use a flatter epoxy container - the more surface to volume ratio the less likely the cook-off and the more working time you get.

There is even less room for error when you start fiberglassing.  Epoxy that is even beginning to become slightly viscous will not properly wet out the cloth.  That's where I learned my lesson, and the reason I can offer the recovery hints above.  "Every day, in every way, I'm getting better and better." - Inspector Dryfus from one of the Pink Panther movies!

   Thanks Bubblehead. My problem is I already had glass on when I put on the epoxy. I didn't do a sealer coat. So I guess if the epoxy hasn't soaked into the timber, I probably need to sand right back to timber and then to a big patch and reglass? It is a big area. And it is a strip built kayak

   Make sure you wear a tight fitting dust mask when sanding off the fiberglass.  Fiberglass dust is very cancerous.  Ideally,  borrow a sander with an integrated vacuum system such as a Festool.f.  Best to do this job outside

   Make sure you wear a tight fitting dust mask when sanding off the fiberglass.  Fiberglass dust is very cancerous.  Ideally,  borrow a sander with an integrated vacuum system such as a Festool.f.  Best to do this job outside

Hi Antho, 

i have a lot of experience with strip builds....and you can fix this. 

first, it sounds like this happened when you were attempting to wet out the the deck glass....so it was the first coat of epoxy.   

when the epoxy starts to thicken/kick, it will not wet out the glass and you will get a whitish finish and be able to see the glass. 

to the extent that this is just an area of the glass and the rest of the work went off fine, then you just have to remove the glass/epoxy from this area.  the easiest way to do this is to put blue tape around the area you want to remove to form an easy-to-see perimeter.  then you are going to use a heat gun on the bad/epoxy glass area to heat it up so that it begins to form a blister....then you are basically going to start to peel it back to your perimeter.....then use a sharp blade to cuts the soft epoxy/glass just inside your perimeter.

once it cools, you will then sand your perimeter edge to fare it into the wood....then layover a new piece of glass, and wet it out and fare it into the sanded edge.

basically this work is like any 'patch' repair that you do.  but if the area is anything more that a couple square inches...you want a heat gun to help you pull off the bad glass/epoxy.....trying to sand it all off is a lot of work and likely to create a depression/lack of fareness.

h

   Thanks for the tips hspira. I've bitten the bullet and removed the glass and epoxy and am back to the bare timber. With the heat gun, it wasn't actually as hard as I thought it was going to be. Hopefully it's not too noticeable once I reglass it.

thats great news.

i have been there...having to pull glass off....it's a pain but way easier than sanding.  

the heat gun is a good friend of any strip builder.  in the stripping phase it can also be used to soften up wood glue and remove/repair a strip.  it, as already seen, can also undo a lot of epoxy mistakes.  

i was once told that the mark of a master builder is not the lack of mistakes, but the skill to artfully correct them and move forward.   even the masters often overpainted or undid some poorly conceived brush strokes.

h

Fumes released by heating cured epoxy can be particularly harmful. I wouldn't use any heat on epoxy without wearing an organic vapor mask. I forgot where I read this so can't offer a source.   From West System: dust from partially cured epoxy gets lodged in the lungs and will cause serious health problems.
Years ago I didn’t bother but now I always wear a VOC + particulate respirator when doing any epoxy work. I never get a good enough seal with a dust mask.
I might be overly cautious so assess your own level of risk acceptance.

Cheers,

e