Koblenz Travel Forum

when does the mossel close for services to the locks, and does it close the same time every year

I guess you mean the river Mosel (Moselle in French)
I checked with the website of the State's Waterways agency, it says all the locks on the Mosel are self-service ones, so they are always open but you have to operate them yourself. Manuals available from here, use the website as well for contatcs with the authority (just send them an english email and see if they reply -- they are not obliged to answer in English but they just might)

http://www.wsa-ko.wsv.de/service/download/infos/index.html