Most marine epoxys come in a quart minimum. They require the recomended pump system that pumps the proper amount of epoxy to hardener. It is not a 50/50 mix as most epoxys.
There are different hardeners with fast or slow cure times. You must be careful with the fast hardener if mixing large quantities as is can start to cure very fast in the pot as you are working.
Marine epoxys are very thin. You may need a thickening additive depending on the job.
GL...Bill