This article from Canada.com discusses the difficulties involved in getting a tow line over to the stricken sub. I'm not exactly sure how the tow line works on the Upholder class, but I assume they hook on to the cleats on deck. The danger of this method, of course, is that going on deck in heavy seas is inherently dangerous. Some subs have a connection for a tow line built into the sail, which eliminates this danger. I'm still surprised at the "worsening" condition of one of the smoke inhalation casualties who was evacuated yesterday. I'm wondering the personnel transfer didn't go horribly wrong, and we'll get more information later. Until then, we can only pray for the safety of the remainder of the crew.
Update: According to this article, she's now under tow and heading towards port at about 3 knots... should be in port on Sunday.