How much do the various stacked starship command skills improve a ship? It's suppose to improve the hull, speed and manuverability but I've can't seem to find any numbers.

I thought that at first too, but turns out that if I am at spacedock, or even in space, it shows no bonus. Yet when I am in a system (ex-missions) it does show the bonus. I have almost all my boxes full for my cruisers, and it has amounted to a bunch more hull and sheilds, so it seems to be worth it.