Thanks for the insightful post. The 6 minute thing I was referring to was how long you had to keep the boat up for before you got a new one (I think?), I know it was reduced in later versions. I know david complains about it a lot. I also didn't realise boat hp was so high .
if youre at zakum and get 1/1'ed then the boat takes that much dmg (i believe) so if you were to have 30k hp somehow, your boat would take 29999999 dmg.
When the bosses like Zak do 1/1, you (= your boat) take higher damage since the damage is based on your Max HP. For example, having 12000 HP will deal 11999 damage, while having 5600 HP will deal only 5599 damage. This destroys your battleship faster which is detrimental for sairs, and is also the reason why they generally prefer not to have HB in non crucial situations.