Sebastian Ring gave Town the lead with a well-taken strike, before Moses Ogbu doubled the lead just before half-time with a coolly taken penalty.
James Walshaw pulled one back as the hosts piled on the pressure after the break, but it was the Mariners who would go on to regain control and record another deserved friendly victory.
Town: Battersby, Starbuck, Pollock, Gibson, Ring, Curran, Clifton, Hewitt, Wright, Rose, Ogbu.
Subs - Idehen, Davey, Buckley, Owoeye.
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