I only did the bow of my Wood Duck and had it on end for about 6 hours and it was set up.  The end pour got hot and set up fairly fast, I am guessing it was set up in 2 hours.  I mixed my end pour with about 40 percent micro balloons.

Rod

How hot is it where you are?  How humid?  How thick did you make the epoxy mix?  Too many variables to answer a question like that with any real accuracy. 

The simple answer is to just dam the end up on the first pour and it won't matter if it's set up or not.  You can do it with plain old cardboard or get more fancy if you want.

FrankP

The best and easiest way is to do your pour in the afternoon, then  end-for-end the boat the follo,wing day.  If the mixture gets to hot it will crack and that is a BAD THING.  So I suggest going easy on the filler.  The thicker the mix, the hotter it gets...   Good  luck....  ~BRUCE~

Thanks Bruce,

I just didn't know if I could do both ends in the same day, or if I did a pour in the morning, would I be able to bring the boat inside by evening to secure it.  I'm planning to thicken with microballoons.

I did the end pours in my wife's Shearwater in a morning.

Used *lots* of microballoons, limited only by the need to ensure it would pour out of the mixing cup. There's no need for weight in that mix. I only had small cups and it was a warm morning, so couldn't have mixed and poured fast enough before it got too hot to settle into the end. Multiple cups let it remain cool until it was in the boat.

Poured one end; within 45 minutes it was hot and becoming hard to the touch. I gave it another 15 minutes and did the end-for-end and did the other side. An hour later the boat was back inside getting a sanding for the next step.

You'll want the boat vertical or just beyond to ensure the ends are really filled, not just the bottom near the end. I tied mine to the outside of my shop building.