From Longman Dictionary of Contemporary Englishboathouseboat‧house /ˈbəʊthaʊs $ ˈboʊt-/ noun [countable] TTWDLa building beside a lake or river where boats are kept
Examples from the Corpus
boathouse• At Angle in Pembrokeshire the first new slipway and boathouse to be built for 31 years is to be constructed.• No one goes in the boathouse much and it's a high place.• Finding a rugby ball, they practised drop kicks in the boathouse, much to Jurgen's annoyance.• Although, by the time we reach the boathouse we look like refugees.• Half trotting, not thinking at all, she hurried down the slope to the boathouse. 