This build is focused around taking advantage of Caustic Spall Station. Its effect of adding flooding damage equal to projectile speed increase makes it one of the strongest furnitures there are, even stronger than most Major furnitures.

While torpedoes and demi-cannons have furniture that synergises really well with that effect, they lack the versatility of Long Guns against Forts or Dragons etc. Thus, La Piqúre III. They're relatively easy to get pre ascended versions of which is a bonus. We'll use Amplified Flooding to increase the secondary damage from Spall Station. Overflow and Rupturing benefits from that also.

For Major Furniture, Siphon Furnace works quite well for Sloop of War which has very quick poisoned status application and basically permanent uptime of it, therefore receiving the 10% damage increase almost all the time. Furthermore, thanks to Spall Station, 12% projectile speed gets converted to 12% damage increase as flooding.

Long Gun Grinder I adds another 15% and we have a lot of secondary damage stacked up, so Long Gun Works I is another must have.

That leaves us with 2 more furniture slots, and these are more down to personal preferance and dependant on the situation. Ramrod Workshop and Plaguebringer's Ward reduces the reload of your broadsides and increases your damage for even more dps. Beam Supports or Machinist Table (Repair) I with Little Grace III can be used to increase survivability.

Armour is another situational and personal choice, but as a generalist build, Wyrmhide will be benefical in most fights. Stout is the best value first perk for dps ships and having Survivor can be a lifesaver.