The Tanea towed the Jay Elaine over the Grey River bar after the larger boat experienced engine trouble recently.
It had engine trouble off Okarito a 14 hour trip away.
Fellow fishing boat Mako was nearby and towed the Jay Elaine, then the Tanea took over tow operations.
Bar conditions were calm.
The Tanea weighs close to 40 tonne while the Jay is 100 tonne, the Greymouth Star newspaper reported.