Tenkars Tavern was running a competition in honor of the new Razor Coast product in which I took third place. I just sort of posted the first thing that came to mind, and really wished afterwards that I’d fleshed it out a bit. Here is my original entry:
The Mad Priest of Shebaba, and his vessel, the sepulcher of Shebaba.
The mad priest was once a totally sane priest of another religion entirely, until Shebaba washed ashore, a sea monster of sorts which happened to look an awful lot like the creature of his most recent nightmares. The priest (once named Ulful, now simply known as the mad priest) became obsessed with the rotting mass he’d dubbed a she.
As his mental illness took hold, and he was being held in his quarters, the subjects of his abandoned parish made plans to cast Shebaba into the sea. Driven mad with what he calls “The essential cleansing of soul and sanity” Ulful had the strength of a hundred men, and earned his new name slaying the majority of his former flock. Enslaved by The Mad Priest the people of the small port city built a craft of strong wood and stronger sea monster bones and ichor and took to the sea with their subjugator/church father, riding the very mausoleum of their goddess.
The Sepulchre of Shebaba sets to port often, she is given wide berth by other vessels, and the port villages and cities seal their doors so as not to be taken to crew the vessel. The vessel is crewed by the enslaved, the mad, or the half demon spawn of those creatures the Priest summons to breed with the insane and the slaves.
The Mad Priest is a 8th level chaotic cleric, Shebaba is dead but her Ichor seems to have the stuff of sapience infused into its essence and her torment bleeds through into the psychic plane, leading to madness if a daily save against her forces isn’t made successfully.
As you can see it is devoid of any real details on Ulful as an NPC, or the vessel as a location. My thought is that either a group of shipwrecked PC’s could be picked up by the ship, or they could be Impressed into service. In either case a clear description of the ship, the capitain, and an overview of likely crew might be helpful.
Ulful 8th level chaotic priest of Shebaba the rotting heathen goddess.
Attributes Str: 9(18) Dex: 10(15) Con: 8(16) Int: 15 Wis: 17 Cha: 13
(those in parenthesis are supplied by the power of shebaba and are only in effect when his link to her is solid)
Weapons: 3 Highway Pistols (from the Freebooters guide) Mace (with his old godesses symbol twisted into a poor imitation of Shebaba as she lay on the beach when found)
AC 5  (chainmail)
Spells: Detect Good, Detect Magic, Hold Person, Silence 15ft radius, Cause Disease, Locate Object, Protection from Good, Cause Seriouse Wounds, Finger of Death, Insect Plague.
The Sepulcher of Shebaba!
The sepulcher is broken up into three parts, with castles at the front and rear. Built on the crude pattern of a galleon by a mad architect and slave labor the ship is not much to look at. Every part of the Sepulcher but the planks is salvaged from the rotting corpse of Shebaba herself, its ropes are her sinews, its sails are her tanned hide, and its major structural beams are her bones.
The hold is flooded with the blood, ichor, and leftover bits of Shebaba herself. If Psionics exist in your campaigne a specialist in such things will be able to detect her continued agony in death, but no clear mind as men comprehend such things. Any magic able to detect undead will also show that Shebaba does exist in a state of unlife. Ulful sacrafices heathens and the unworthy by submerginging them in the brew, and all food is simply dumped in the hold to mingle with her, the crew is fed from her continually replenishing remains.
The below deck is a series of bulkheads and jurry rigged sleepquarters for the crew, its a chaotic shanty-town where might makes right, and very few creatures truely sleep in peace. Nothing of any real value is stored here except captives awaiting ritual torture and sacrafice.
On the Deck itself there sits a forecastle and an aftcastle, the latter of which is where the Capitain stores his treasure, and also where he locks himself in occult study for weeks on end. The forecastle is a small temple to shebaba, topped with the altar where the capitain holds his darkest rituals for the crew to see.
The crew is made up of 2d6+5 insane human captives, and 1d6 abominations created by the capitain using virginal sacrafices and summoned Demons and Sea Monsters in his quest to create a Massiah of Shebaba. The stats for any low level Demon or Abomination can be used, although ideally you’ll use something like The Random Esoteric Creature Generator.