Dimir Pirates is a tempo deck that I've been playing on stream to much success in Competitive Constructed.  Additionally its NEARLY rotation proof (lose an unnecessary The Scarab God, Cartouche of Ambition and deserts.  Let's see what these guys bring to the table!

Creature Package:

4x Siren Stormtamer is the only 1 drop creature in the list.  It protects our buffed up, go wide boards from single target removal and fights against Settle the Wreckage

4x Warkite Marauder is the centerpiece of the list.  It's a great 2/1 flyer for 2 that can turn our opponent's creatures into 0/1 abilityless creatures!  Combo it with a -1/-1 effect and we have a near endless supply of single target removal!  (Unless they have hexproof...)

4x Kitesail Freebooter is a great tempo play.  It steals key cards from our opponents and allows us to play around their removal and answers.  Also...its a pirate... ARGHH!

3x Fathom Fleet Captain  This is our go wide strategy and helps us put power at the board without risking too many of the cards from our hand.

2x Dire Fleet Poisoner This is our answer to hexproof creatures and larger creatures when we don't have a Warkite Maruader in play.  Flash adds to its flexibility, allowing us to hold up mana to answer our opponent's cards, and then if the mana is unneeded, cast a creature onto the board.

2x Hostage Taker This is our pirate Ravenous Chupacabra with upside.  If you don't own any, Ravenous Chupacabra is a fine replacement.

1x  The Scarab God  We are running Dimir, did you really think he wasn't making the list?

Spells:

4x Curious Obsession This is our primary form of card draw and let's us boost important pirates up to x/2's to avoid Goblin Chainwhirler

3x Dive Down Our screw you to removal, also good as a combat trick against more aggressive lists.

2x Spell Pierce  More protection for our board, can usually answer board wipes on curve, and Spell Pierce is notorious for gobbling up Teferi, Hero of Dominaria, Karn, Scion of Urza and the rest of their planeswalker friends!

2x Fatal Push  This card exemplifies our strategy!  Cheap, potent, removal!

1x Fungal Infection  Becomes another 1 mana kill spell in the hands of Warkite Marauder

1x Cast Out Another flexible cheap kill spell.  

3x Cartouche of Ambition Lifelink is relevant for aggro matchups, and the -1/-1 pairs well with Warkite Marauder

Mana Base:

6x Island

4x Swamp

4x Drowned Catacomb

4x Fetid Pools

2x Grasping Dunes allows us to turn our lands into removal with Warkite Marauder

2x Unclaimed Territory Of course, always name pirates, 2 is the right number.  Remember, this doesn't work for colored mana for our noncreature (or The Scarab God) spells

1x Ifnir Deadlands is our 3rd copy of Grasping Dunes, but helps smooth the mana out by providing a black source when in a pinch.

1x Field of Ruin Don't leave home without it!

Sideboard:

3x Ruin Raider Standard's verison of Dark Confidant great vs control, terrible vs aggro.

4x Lookout's Dispersal Priemer counterspell for Pirates

1x Fell Flagship Great to up our clock vs control and to rid them of cards in their hand.

2x Vraska's Contempt I'm looking at you Teferi, Hero of Dominaria

1x Detection Tower Necessary evil vs Mono Green

1x Scavenger Grounds to combat The Scarab God decks.

1x Cast Down

1x Spell Pierce

1x Dive Down  

All for the same reasons as above!