After the second coat of expoy to the exterior of the hull (the 2nd over the glass cloth on the bottom panel and garboard and 1st on the un-glassed panels) I sanded and cleaned prior to applying the third coat of expoy.

I applied with a foam roller, but did not "tip out", resulting in a typical roller (i.e., not "smooth as glass") type finish.

I'd appreciate any thoughts as to whether I should apply a fourth coat and "tip out" or leave it as it is and deal with it via sanding, primer and paint.

Thanks in advance for your consideration.

When it is thoroughly cured, you could try sanding it smooth. If you find that you are making it more "bumpy" or digging into the glass, I would then just lightly sand the surface and add another epoxy coat that you can smooth out by tipping.
A good primer/filler of two coats can make a nice fair hull before painting.
My two cents...
Kyle

David,

My experience has been that it is best to do everything you can to get the epoxy as close to the finish you want before it dries. There's no other way to put it... sanding epoxy sucks.

Good luck.

Agreed - sand away!

Also, I know there are many different approaches and views on this. My own view is to choose the sandpaper for the job you're doing. If you're trying to remove bumps - I'd rather sand aggressively with coarse paper (60, 80, 100, depending on the task at hand). I find this makes sanding go much faster and gets you a smooth hull ready for a final build-coat of epoxy.

Save the finer stuff (150, 220) for when you have a smooth hull that just needs to be scuffed.