Is there a particular reason for wanting war priest instead of inquisitor for this? A pirate ship is not the most optimal place to be wearing full plate. I’m not saying you can’t do it but be sure you are really wanting to do it.
One of my favorite war priest archetypes is the Calamity Caller, available only to elves (half-elves too, which I recommend if only to get access to alternate racial features available to them). An at-will area of effect ability that scales with level is more than sufficient price to pay for losing the sacred weapon and bonus feats. One of your blessings has to be a specific disaster blessing but your other one if whatever you want. You can still build for a combat oriented build, you just have to do so with your normal feats.
Here is a stat block for a level 1 character with the above archetype:
Half-elf (Spireborn) warpriest (calamity caller) of Besmara 1
N Medium humanoid (elf, human)
Init 3; Senses Perception +3
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Defense
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AC 18, touch 13, flat-footed 15 (+4 armor, +3 Dex, +1 shield)
hp 10 (1d8+2)
Fort +5, Ref +3, Will 4; +2 bonus vs. negative levels
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Offense
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Speed 30 ft.
Melee rapier +3 (1d6+1 P/18+) [+1 vs aquatic creatures]
Ranged underwater light crossbow +3 (1d8 P/19+) [+1 vs aquatic creatures]
Warpriest (Calamity Caller) Spells Prepared (CL 1st; concentration +3)
1st—cure light wounds, divine favor
0 (at will)—create water (at will), light (at will), mending (at will)
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Statistics
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Str 12, Dex 16, Con 14, Int 13, Wis 15, Cha 8 [[20point buy, +2 Dex from racial]]
Base Atk +0; CMB 1; CMD 14
Feats Weapon Finesse
Traits fate's favored, peg leg (campaign)
Skills Acrobatics +4 (+0 to jump), Climb +2 (+5 -3 ACP), Disguise -1 (+3 to appear human), Perception +3, Profession (sailor) +6, Swim +2 (+5 -3 ACP)
Languages Azlanti, Aquan, Common, Elven
Other Gear lamellar (leather) armor[UC], buckler, rapier, underwater light crossbow[ARG], backpack, bedroll, belt pouch, flint and steel, hemp rope (50 ft.), holy text[UE], mess kit[UE], pot, soap, spell component pouch, torch (10), trail rations (5), waterskin, wooden holy symbol, 29 gp [[assumes 200gp starting gold]]
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Special Abilities
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Blessings (3/day) (Su) Pool of power used to activate Blessing abilities. [[FLOOD/WAR]]
Lasting Breath (Su) You can touch an ally to bless it with an extra reserve of breath
War Mind (Su) you can touch an ally and grant it a tactical advantage for 1 minute
Calamity (1d6 *damage varies*, At will, DC 12) (Su) Stnd act, 5-ft square within 30 ft, call down force of nature for variety of damage and effects.
Crossbow Training Reload proficient crossbows 1 step faster.
Elf Blood
Round Ears +4 to disguise to appear human.
Shadowhunter Attacks affect incorp foes as though use magic weapon, 2x phys ab heal from undead, +2 to save vs. neg levels.
Tongue of the Sea begin play speaking Azlanti and Elven
Sourcebooks:
• Advanced Class Guide - Warpriest (class)
• Advanced Race Guide / Ranged Tactics Toolbox / Ultimate Equipment - Underwater light crossbow (weapon)
• Bastards of Golarion / Heroes from the Fringe - Spireborn (race option)
• Blood of Shadows - Shadowhunter (alternate racial trait)
• Heroes from the Fringe - Calamity Caller (archetype) • Heroes of the Wild - Fey Thoughts (alternate racial trait)
• Horror Adventures - Round Ears (alternate racial trait) • Inner Sea Races / Inner Sea World Guide - Azlanti (language)
• Ruins of Azlant - Crossbow Training (alternate racial trait); Tongue of the Sea (alternate racial trait)
• Skull & Shackles - Peg Leg (trait)
• Ultimate Campaign - Fate's Favored (trait)
• Ultimate Combat / Ultimate Equipment - Lamellar (leather) armor (armor)
• Ultimate Equipment - Holy text (equipment); Mess kit (equipment)
• Ultimate Wilderness - Flood Blessing (special ability)
The character has all the tools it needs to survive, and do well, as a member of a sailing crew. They appear to be human for all intents and purposes. They have means to deal with swarms (the calamities), melee combat, ranged combat, underwater combat, well rounded saving throws and ability scores. Leveling up, you want your 4th level ability point in wisdom and all the rest can go to dexterity. Intelligence is intended to be 13, to qualify for combat feats and to open up more skill points for you. If you don't intend to take Combat Expertise, swap the strength and intelligence scores so you can nab power attack to open up other feat chains.
So, we're in book 3 of that campaign right now, what I have noticed so far:
1. Spend points on Profession: sailing
2. Make sure someone in the party has a good Charisma/diplomacy skill.
3. Make sure you can swim, and figure out someway to breathe underwater
4. Avoid Heavy Armor, Dex builds will have an easier time of some of the challenges
5. the AP seems to have less combat that all the previous AP's I have played, and leans a little more heavy into roleplay.
That's why I was suggesting inquisitor for this. It has a focus on skills and uses lighter armor while being a holy warrior type. The warpriest is mostly the better tank, using heavier armor while being able to swift action heal. Both do about the same damage when using all of their abilities, but the inquisitor is way ahead on skills having way more skill points and then bonuses to various relevant skills.
A DEX based inquisitor is actually incredibly effective. They already get good Fort and Will saves so focusing on DEX boosts their weak save. This also gives them a good AC while avoiding heavy armor. They have proficiency with decent ranged weapons and their deities favored weapon.
Take the reformation inquisition to allow you to be the party face while dumping CHA. Stern gaze combined with using WIS for intimidate and sense motive means those skills are through the roof. Being able to roll twice on diplomacy and intimidate (at 4th level) boost that up even more. When you are 8th level you can use charm person a number of times per day equal to your WIS modifier is going to be very useful in a roleplay focused AP.
As Melkiador pointed out inquisitors are much better at skills then a warpriest.
Their spell list is also well suited for a pirate. Things like disguise self, invisibility and heroism are not on the cleric/warpriest list.
