How does the game determine when a ship should be sunked?

[i64man]

I thought about entering my question on the feedback for version 1.06 Beta, but decided to rather open a separate threat. So, my question is just what the title says; how does the game determines when a ship should be sunked? Here is the scenario, and before I explained, this is the result of me having to leave the game before the battle was finished.

I am playing as Germany starting in 1930. February 1931, the Brits start a war. I am playing a convoy mission escorting 4x transports. My escorts include:

1x BB, 1x CA, 2x CL, 2x DD

I am facing on the Brits side:

1x BC, 2x CA, 2x CL 2x DD

So it was a pretty balance encounter, or so I thought. Started the fight keeping the transports away and my support ships. I am controlling the BB and move in range of the Brits. Eventually, they run out of torpedos, so I move my cruisers and DD closer. My BB has taken some hits, and it is only slightly damage, above 90% on both categories. 1x Brit CA is damage, the BC is sunked as well as one DD. One of my DDs is damage and I ordered it to retreat. Here is when I had to leave the game. None of my transports were damage. So I leave the game and the window opens saying that I am leaving blah blah....

So on the victory screen, shows that I sunk the 2x Brits ships, heavily damage a CA and I had no lost ship on my part, but the game says, my BB was sunked. How? At the point, I left the game, it was 90% intacted. Which brings me to my next point, I know the game is under development and under Beta testing, but why is it that there is not a more robust save option? Something that we can reload in case of such issues as described above? If part of being on Beta is to try things and identify things that could be improved or corrected, why not having the option to reload from a certain point? That way, if we try something and does not work or find a glitch, problem or issue, it can be repeated and or corrected.

I love the game, and enjoying it on its current form, but it is frustrating to lose a ship that shouldn't have been lost.