This is how I see it from a professionals point of veiw. You may be able to get away without using a sealer coat, but why risk it? the purpose of the sealer coat is to fill the voids, and seal the wood. If you dont do this you run the risk of having the wood soak up more of the epoxy than you can anticipate, drawing it form the glass even after you got it on. this would leave weak spots, voids and sections where you can see the glass. Is it worth the risk of ruining all the work youv'e done to save one step? On the other hand if you put enough epoxy on that the wod won't soak it all up, youv'e probably made your boat heavier than it has to be. If you put an even coat, not real heavy, but just even, on the hull as a sealer, and let it harden, your boat won't soak up nearly as much when you put the glass on and you will actually end up with a lighter boat with all the glass well attached, and every bit as strong as it needs to be. On top of all that, the glass job will probably look better. AL