...HMCS Corner Brook’s grounding should not be trivialized. It was a serious incident and had the potential to be a tragedy. However, commentators should not overstate the accident and ignore the important contributions which Canada’s submarines make to training, sovereignty and prevention of drug trafficking...” see WHOLE CANADIAN ARTICLE
ADVICE FROM "S" ON DAMAGE TO THE PRESSURE HULL
Based on a cross section [this diagram] and pictures of the damaged HMCS Corner Books, relevant issues may include:
This is especially if the collided-with tubes act as levers.
or invisible (electronic sensors can detect "microcracks" especially around the hull-tube
These repair activities may have caused a slight inconsistency between the new part and the undamaged parts of the pressure hull leading to a reduction in maximum submerge depth capability.
It is fortunate that the grounding only occurred 45 metres down. If the grounding was 250 metres down this might have caused catastrophic failures to the torpedo tube seals and to the pressure hull - sinking the sub.
By current Japanese standards high yield HY-80 steel is not that strong. [Pete comment - this is noting the much more modern Soryu has HY-156 equivalent steel.] A pressure hull 38mm or 39mm thick is rather thin. A hull thickness of 45mm-65mm would be more effective for safer, deeper, diving. [Pete comment - Pressure hull tolerances are, of cause, linked to likely threats. Canadian subs monitoring drug-organised crime is not the same as monitoring Chinese facilities (with ASW forces that may kill a sub)].