Complex sentence: This leaves the Navy with a single destroyer, HMCS "Athabaskan", which has been plagued with engine problems, suffering multiple failures during while transiting the Atlantic Ocean, first in February 2015, then again in October.
Split into simpler sentences: This leaves the Navy with a single destroyer-HMCS "Athabaskan". However "Athabaskan" has been plagued with engine problems, suffering multiple failures during while transiting the Atlantic Ocean, first in February 2015, then again in October.