You'll find the blueprint for this over on temperance which is pretty deep into the story content. Make sure you've got your crafting materials ready - specifically 10 planks, 6 ropes, 4 metal ingots, 4 bolts, and 8 titanium ingots. Once you've researched it, check your navigation tab and get ready for precise placement.

The tricky part is installing it correctly, you'll want to create a dedicated hole in your raft's floor first since the chain needs space to drop through (3x3). The positioning here is actually pretty critical, especially if you're planning to link it with engine controls later. Speaking of controls, there's a specific timing window you need to know about - the anchor responds to the e key for manual operation, but the real optimization comes with the engine control setup.

Important detail about the controls: if you've got engine controls installed, you'll need to properly link the anchor to your system, and watch out for any existing anchors since they can create some nasty conflicts. Without engine controls, you're looking at using the local switch which honestly works just fine for most situations. Maybe interesting - if you're having trouble with the controls, try removing older anchors first since they tend to cause some weird interaction issues with the new system.