Hello there fellow skylords!
Just read the new proposed balance changes and i'm pretty happy that battleship will have some love!
I really like the idea of speed buff when shield is applied, but I also think that having to cast shield on battleship (pretty useless on T4 unless you have 2.5k shield as Avatar of Frost) to have a speed buff feel like a stretch. Basically you waste a shield card on T4 (or a unit to cast a shield) for speed buff, while the shield mechanic should have its value on the shield itself.
I tought two more elegant way to solve this issue.
One is adding a passive ability that increase speed when out of combat. Like crew focus on sailing when out of combat, and on cannons when in combat. It makes sense to me, and fix the slow issue without any other complication. I guess the same speed of Northland drake is ok (not swift but still more fast than other t4 frost units, to regain field after battleship exit from combat). Maybe a 7 seconds delay before switching from "comabat" to "sailing" mode could be added.
Another way is a bit more complex but more typical. It consists in adding "Glaciel Shield" ability to upgrade 1 of battleship, like Mountaineer card.
When out of combat:
*the battleship regenerate every 12 sec a 500 hp shield.
* While shield is active, the battleship gain increased speed.
These change will:
*Grant a better usability of the card in pve
*No spell/unit waste just to gain speed buff
*Not overlap with other fast ship (f.e. spirit ship) because when engaged it slows down
*Make more tanky balancing low dps
Now, some number work should be done. If you grant small shield, f.e. 500 points or less, it's totally useless in T4 fights but gain some advantage over lots of small units (like every T4 should have). The compensation could be keeping cost at 300 (since it's planned to lower cost to 250) or a small decrease in HP.
The battleship usually ends in second line when fights starts (unless some particular pve maps) BUT the increased speed make them to be on first line when fights starts, so having a shield could also be selfbalanced (it will take first hits and deplete shields, unless you micro them).
Hope i throw few nice ideas in the pot!