Interesting article about a father and his two adult sons' trip through Hudson Bay in a sailboat. It makes it obvious, through their log, how difficult it would be for two inexperienced mariners. The weather conditions, shallow water, water temps and storms/wind that come up quickly would be challenging to even the most experienced mariners. It's not a long article and talks about the Cree and Inuit communities along the Bay's shores and is very enlightening.
As far as hijacking a ship, the only port in Hudson Bay where Panamax (read: BIG) transoceanic vessels call is Churchill. Given that Hudson Bay is a compulsory sea pilot waterway, the idea of two teens (even armed) getting past all of the longshoremen and onto the ship and holding the pilot, Captain, officers, and crew at bay during a sea voyage are fantasies, at best. Even if they managed to both stay awake and continue holding a crew of about 20 people hostage for the entire voyage, there is the other end of the trip when a vessel has to get clearance into a port to dock and take a local pilot onboard to safely get them there, and more longshoremen are needed to tie the vessel up. The idea of doing all of this while evading detection or arrest is truly ludicrous.
If they knew one iota of what they were suggesting they would have realized it was pure fantasy to even think about it. None of this even takes into consideration the fact that the Bay is frozen and unnavigable for large AND small craft after early Autumn, so they wouldn't have had much time to "march there" and "hijack a boat".
https://www.sailmagazine.com/cruising/cruising-the-hudson-bay-canada
I know this has already been discussed, but I was poking around online looking for navigation data in Hudson Bay and thought this article was interesting.