This vessel at CCG Dartmouth base April 6th, 2007.

Update:
Older tender, most of these replaced by newer versions. This one is currently used by Louis S. St-Laurent, and sisters to this have been used on older vessels. I've found photos of identical vessels on-board CCGS John A. MacDonald and I believe CCGS Labrador, along with CCGS Gannet, a former British WWII-era Landing craft purchased along with seven others between 1957 and 1961 and converted into Northern Supply Vessels. GANNET was decommissioned in 1971. This tender must be quite old.
Also note the older paint scheme, dating between 1975 and 1984.

Yet another update:
It's called an LCM Barge, and similar craft were used in WWII.