Dictionaries like 《Xiandai Hanyu Cidian》, 《Xuesheng Xiandai Hanyu Cidian》 do not include the term "Youhai", on the contrary other dictionaries like 《Jinming Zhonghan Dacidian》, 《Zhongchao Cidian》 take on the word "Youhai".
《Jinming Zhonghan Dacidian》 argues that "Youhai" is a verb, but 《Zhongchao Cidian》 describes that "Youhai" is an adjective. So I think that it is worthing to study the word classification of the "Youhai".
"Youhai" is consisted of the morphemes of "You" and "Hai". So I need to consult with the similar constructure "Youyi".
According to a lot of dictionaries published in China, "Youyi" is an adjective. And in Modern Chinese the structure of the "You+abstract noun" has the meaning of an adjective, though it is the structure of "Verb+Noun", so "Youyi", "Youli", "Youxiao" and so on are adjectives. So I argue that "Youhai" is also an adjective.
The adjective "Youhai" can be followed by the function word "Yu", and the structure of "Youhaiyu" roles as a predicate and takes an object.
But now the morpheme "Yu" of the "Youhaiyu" can be easily dropped, and the result, "Youhai" can take objects directly. So I argue that in this case, "Youhai" has the word classification of a transitive verb.