Words we take for granted

No room to swing a cat . I believe is referring to a time when corporal punishment was still used. The cat is a type of whip. Cat of 9 tails. So yes very probably nautical. My Grandad told me about that & he was Royal Navy.

I’m guessing 3 sheets to the wind, is something to do with navy rum rations

Hand over fist...pulling the ropes on a ship?

Here are a few more phrases of probably nautical origin.

3 sheets to the wind.
No room to swing a cat
Swinging the lead
Hand over fist
Brass monkeys
At a loose end
Give a wide berth

3 sheets to the wind, is that a reference to sails not being tied down
Swing a cat, as has been said, referring to a whip
Swinging the lead, had that originally been to do with taking depth readings, where they drop the lead weighted rope?
Hand over fist, again as said connected to pulling on a rope ie. pulling on a rope to pull a boat into the pier
Brass monkeys, not sure where it came from but wonder if brass becomes brittle in the cold
At a loose end, again not sure but wonder if it has to do with a sail not secured
Give a wide berth, possibly connected to sailing well away from a dangerous area or ship

Well played Spec, you're pretty much there on em all. I'll leave everyone some more time to have a think.

The usually cited story is that cold as brass monkeys related to "monkeys" being the name of the brass cannonball racks on ships. When it got really cold, the brass would crack and the cannonballs would fall off. Hence, being cold as brass monkeys is when it is "cold enough to freeze your balls off".

However, when I've looked into this in the past, it appeared this was not true and was just a good story. Sadly, I don't recall the real origin of the term!

You're right Pros, the supposed other origin is a variation on cold enough to freeze the nose/tail etc off a brass monkey. The brass monkeys in question are probably the 3 wise monkeys sold to tourists.

Since we're sticking to the nautical theme, there is
a square meal - ships wooden plates were square
the bitter end - the very end of a rope that was secured around the bitts or bollards on a ship.