Equipment Blueprint: Extra Quarters

The blueprints for [garrisonability=278], [garrisonability=277], [garrisonability=279], [garrisonability=281], & [garrisonability=280] are not obtainable and are no longer required for the achievement Naval Mechanics.
*Source: Patch 6.2 Hotfixes: July 27 - July 29

However, each of these 5 pieces of equipment has a chance to be provided automatically when upgrading or building new ships.

The trait from this blueprint can be acquired 3 ways:

1. 
   
2. Automatically, as the native trait of a new or upgraded rare or epic ship,
3. 
   
4. Looted, from a mission that has a ship with the [garrisonability=287] / [garrisonability=290] buff, or
5. 
   
6. Purchased, from [npc=93812] / [npc=94801] after it has been unlocked by learning the blueprint.
7. 
   

There are 7 Tanaan Jungle bosses who are guaranteed to drop specific Equipment Blueprints needed for the achievement Naval Mechanics.

Macro code for Tomtom users:
/way Tanaan Jungle 35.4 46.8 Belgork - Bilge Pump (Counters: Stormy Weather)
/way Tanaan Jungle 37.5 76.0 Captain Ironbeard (cave entrance) - Ghostly Spyglass (Counters: Cursed Crew)
/way Tanaan Jungle 44.6 37.8 Cindral the Wildfire - Ice Cutter (Counters: Icy Water)
/way Tanaan Jungle 45.8 47.0 Felsmith Damorka - Felsmoke Launcher (Counters: First Strike)
/way Tanaan Jungle 38.0 30.0 Savage Whale Shark - Trained Shark Tank (Counters: Minelayer)
/way Tanaan Jungle 60.2 21.0 Xanzith the Everlasting - High Intensity Fog Lights (Counters: Dense Fog)
/way Tanaan Jungle 37.0 33.0 Zoug the Heavy - True Iron Rudder (Counters: Evasive)
Additionally:

All rare creatures and NPCs in Tanaan now have a chance to drop a number of equipment blueprints for ships.
Source: Patch 6.2 Hotfixes: July 27

Protip 1: I use Macro Toolkit to avoid having to split macros into smaller parts. There are other addons that also allow this.

Protip 2: Want an easy way to reset your Tomtom arrow to the nearest boss on the list? Just type
/cway and voila! *

Note: An 8th boss, [npc=90284], (second boss in [zone=7545]) drops [item=128256] which counters [threat=80]. The blueprint drops on all levels of raid difficulty.

Note 2: What about the rest of them? Only 3 other blueprints are available in 6.2.0. They come from various sources. Equipment Blueprint: Blast Furnace ([garrisonability=269] for [threat=81]), is a quest item. [item=128264] ([garrisonability=275]) and [item=128265] ([garrisonability=305]) are vendor rep items.

* Credit to Skeeve2010 for this improved Tomtom code suggestion.

Patch 6.2.2 update:

As of 09/01/2015, Blueprints are now learned account-wide*.

Source: https://twitter.com/WarcraftDevs/status/639942093520027649

* Except for the blueprints that require reputation ([garrisonability=275] & [garrisonability=305]), any of the blueprints that you have learned on your alts will be unlocked at [npc=93812] / [npc=94801] once you have completed A True Naval Commander / A True Naval Commander.

Thank you Blizz!