Equipment Blueprint: Blast Furnace

If you can buy these, but don't have credit for Naval Mechanics, then you can now open a ticket via this help article: https://us.battle.net/support/en/article/19029

Regarding the Naval Mechanics achievement.

I can confirm. The Blast Furnace part of this achievement is bugged (9.2.5). I wrote a support ticket and a GM rewarded me with the achievement.

How do you know it is bugged for you? If you go to your vendor at the shipyard (Salty Jorren for Alliance) and you can buy the item, then you've already unlocked that part, but it is bugged.

The equipment from this blueprint counters the naval threat [threat=81]. The trait [garrisonability=269] is first provided to you for the quest A True Naval Commander (A) / A True Naval Commander (H).

Afterward, [garrisonability=269] 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. 
   

Additional traits: 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.

The blueprints for [garrisonability=278], [garrisonability=277], [garrisonability=279], [garrisonability=281], & [garrisonability=280] are not obtainable and are no longer required for the achievement.
*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.

* Credit to Skeeve2010 for this improved Tomtom code suggestion.