The guys at Rockler told you to put on a wash coat of shellac, which means about 30% shellac and 70% alcohol, to partially seal the grain. In woods like maple, cherry, and pine, this is important because they take dye and stain very unevenly, which makes it look blotchy, even with careful sanding. Mahogany isn't one of those woods- it takes dye and stain like a champ. So, throw out the advice from there, not to mention the problems with epoxy.

I did some long-term fade tests with alcohol-based TransTint dyes last summer with good results, and posted them on the forum a while ago, so check the archives.

As far as your multiple dye plans- the dyes are completely transparent. Lighter colors like yellow won't give vibrant color on a dark colored wood like mahogany, they'll mix with the mahogany's base reddish color and make it look more orange. The lighter colors can only change the tone of a wood that is darker than the dye color. If you want to really change the color and not just the tone of the existing color, you'll need to use dyes that are darker than the wood's natural color. Keep in mind that the color of the wood you got is not what you see now- it's what you'll see when you put the finish on. To see about what your wood will look like with finish on, wipe it with water or alcohol, and see if that's a color more to your liking.

I have used the red mahogany dye on cheap mahogany recovered from pallets that were used to ship plywood here from South America, and it works very well. If you tinker with the amount of dye you put in your mix and maybe add a little bit of blue you should be able to get a color like a classic Chris-Craft runabout. (They were dyed as well. You didn't really think every mahogany plank on every Chris-Craft ever manufactured was the identical color did you? )

After you choose your colors- you'll have to mix the dye really weak and add multiple coats. I have used TransTint quite a bit lately, and for my taste I only mix it at about 2/3 of the recommended "full strength" rate. Keep in mind that all of these things are subjective. Mix it at 130% if it gives you the color you want. You'll need to do tests on maybe the inside of one of the panels or something if you don't have any scrap to test on. If you do a fade, also keep in mind that where the two colors meet you don't want them to make a hideous clashing color so be sure to test what they look like when they overlap.

My only tip on applying it is to use a diluted version of your final desired color and build up the color you want in multiple coats. A kayak is a really big surface, and alcohol dries pretty quickly, so there's a good risk of getting dark streaks where you overlap on something that's already dry. That's only a problem if you plan to do it in one coat- if you do it in light coats there isn't much chance that you'll go in exactly the same place twice, so problem solved. And don't use a brush- it will probably drip and apply too much. Use a rag, and don't over-saturate.

Good Luck- Dye is cool!

m