Give a good dose of C.P.
It's a bio-enzymatic toilet bowl, sump, and drain cleaner that "eats" grease, hair, soap scum and other stuff that clog drains (and btw, it also kills odor on contact). Available from the online store here (and from BOAT/US if you can't wait for mail order). You may have to close the seacocks and let it stand for a day or two in drain that are running slow...but a good squirt down 'em once a week will kepp 'em running free and smelling good. And as the name implies, a squirt down the drain keeps sumps clean and smelling good too. Whatever you do, do not use a chemical drain opener...it will destroy your hoses.
