The Brief: A "boat" refers to a quantity of 1000 ecstasy or molly pills.

DEEP DIVE
When looking to score some recreational pills from a plug, the most common quantities are a jar (100 pill count) or a boat (1000 pill count).
Surprise our special guest is a boat of ecstasy
— shlohmo (@shlohmo) December 6, 2012
The term is usually used exclusively with XTC or molly and comes from the phrase, “boat load”, meaning a large amount of something.