# Subs (DD-149)

> A submarine controls its buoyancy with ballast tanks. Flooding the main ballast tanks with seawater makes the boat heavier than the water it displaces, so it submerges; blowing the water out with compressed air makes it lighter, so it surfaces. Smaller trim tanks and the boat's diving planes fine-tune its depth and balance underwater. Submarines are used by navies for patrol, reconnaissance and deterrence, and research submersibles explore the deep sea. The first submarine to sink an enemy warship was the Confederate H. L. Hunley, in 1864. The footage shows submarines surfacing and underway, with the presenter.

- Department: Military (also Tech, Science)
- First published: 2023-12-29
- Last updated: 2023-12-29
- Permalink: https://detailenjoyer.com/case/subs/
- Author: Marcus Easterling (DetailEnjoyer), The Detail Department

## On the timeline

- **1864**: The H. L. Hunley becomes the first submarine to sink an enemy warship

Full timeline: https://detailenjoyer.com/timeline/?case=subs

## Quick facts

- **DD-149-F01**: Submarines dive by flooding ballast tanks. _(Write-up · Exhibit A (Ballast tanks))_
- **DD-149-F02**: Blowing the tanks with air brings them up. _(Write-up · Exhibit B (Compressed air))_

## Write-up

A submarine dives by flooding its ballast tanks. Blowing the water out with air brings it back up.

1. **Ballast tanks**: Submarines dive by flooding ballast tanks.
2. **Compressed air**: Blowing the tanks with air brings them up.
3. **Trim and planes**: Trim tanks and diving planes fine-tune depth.
4. **Uses**: Navies use submarines for patrol and deterrence.
5. **1864**: The H. L. Hunley sank a warship in 1864.

## Related case files

- [Ballistic Trident (DD-627)](https://detailenjoyer.com/case/ballistic-trident/): I linked the missile carried by US and UK submarines
- [Destroyer (DD-147)](https://detailenjoyer.com/case/destroyer/): I linked a warship built to find them

## Reel vs. record

- **Note**: 'Travel silently': submarines are designed to be very quiet, not completely silent.

## Video: Subs: A Submarine Dives by Flooding Its Ballast Tanks

- Duration: 31.0 s · Published: 2023-12-29
- File: https://detailenjoyer.com/assets/videos/C1cZGjEO4rL.mp4

### Transcript

Submarines are fascinating vessels capable of operating beneath the water's surface, providing stealth and strategic advantages. DID YOU KNOW? Submarines use ballast tanks to control their buoyancy. By adjusting the amount of water in these tanks, submarines can either submerge or surface. When the tanks are filled with water, the submarine becomes heavier and sinks. When the tanks are emptied, it becomes lighter and rises to the surface. Submarines have played pivotal roles in naval warfare and scientific exploration. Their ability to travel silently underwater makes them effective for surprise attacks and reconnaissance. NOW YOU KNOW!

## Questions & answers

**Q: How does a submarine dive?**  
A: It gets heavier. _(Source: Write-up · Exhibit A (Ballast tanks) · Wikipedia: Submarine; Wikipedia: Ballast tank)_

**Q: How does it surface?**  
A: It gets lighter. _(Source: Write-up · Exhibit B (Compressed air) · Wikipedia: Ballast tank)_

**Q: What fine-tunes depth?**  
A: Underwater balance. _(Source: Write-up · Exhibit C (Trim and planes) · Wikipedia: Submarine; Wikipedia: Ballast tank)_

**Q: Which submarine first sank an enemy warship?**  
A: In 1864. _(Source: Write-up · Exhibit D (Uses) · Wikipedia: Submarine)_

**Q: Besides navies, who uses submersibles?**  
A: To explore the deep sea. _(Source: Write-up · Exhibit E (1864) · Wikipedia: H. L. Hunley (submarine))_

## Sources

- [Wikipedia: Submarine](https://en.wikipedia.org/wiki/Submarine)
- [Wikipedia: Ballast tank](https://en.wikipedia.org/wiki/Ballast_tank)
- [Wikipedia: H. L. Hunley (submarine)](https://en.wikipedia.org/wiki/H._L._Hunley_(submarine))

## Cite this case file

Easterling, Marcus. "Subs." The Detail Department (DetailEnjoyer), case file DD-149, last updated Dec 29, 2023. https://detailenjoyer.com/case/subs/