Explosive Barrels - can't place at enemy walls?

[Skydance 1]

What's the purpose of Explosive Barrels? It seems like they are intended for blowing through enemy walls (since Cannons and Grenades are useless at it) ... but I'm hearing you can't place Explosive Barrels on enemy-owned land. Is this working as intended? You bombard a wall with hundreds of cannon-balls or 100+ grenades, and then they slap a new wall into the hole to close it instantly?

[becker 0]

They're catapult ammo.

[AreYouReady2Die 7]

Place it on a enemy ship... it's not really good on buildings