We call this configuration the hammerhead class. We used medium cannons instead of large cannon in the front and back, with variations in the number of cannons on the front. During the Great Turnip War against the Myrmidon aggressors, these ships dominated the seas. Brigs and Galleons-- whole fleets ran from our outnumbered ships. Many Slam Whale ships of exotic designs sought their fortunes out there on the high seas, but the hammerhead is still the tip of the spear. We largely ignored brigs until the closing days of the war with Myrmidon, we only showed interest because we were annoyed that their brigs could outrun our ships.
That being said, I want to react directly to your ship design now. Your design has one major concern and an inefficiency, but there is also one thing you did that made me rethink how I design ships. Firstly the major flaw with your design is that the entire premise of large cannons as effective weaponry rests in the knowledge and ability of the designer to zero in the cannons so they all hit in one place at a given range. Not a lot of people have bothered to figure that out. If those cannons were zeroed that ship would simply delete a brig panel with every hit. Its a solid plan but it needs refining. Next... the whole idea of an airlock on a schooner, or really any walls beyond the ceiling tiles to properly close the hull is needless weight. If you are ever in a situation where a schooner needs an airlock, the ship is already a lost cause. Any weight you can shave off is a blessing. What you impressed me with was your use of the gun mount and wall. I never really thought about gun mounts and walls in that way, and i'm having a million ideas right now because of it.