---
kind: "section"
citation: "46 C.F.R. § 171.100"
title: "46"
number: "171.100"
heading: "Shaft tunnels and stern tubes."
url: "https://uscodex.org/cfr/46/171.100"
---

# §171.100. Shaft tunnels and stern tubes.

- (a) Stern tubes in each of the following vessels must be enclosed in watertight spaces:
  - (1) **Each vessel of 100 gross tons or more on an international voyage.**
  - (2) **Each other vessel over 150 gross tons in ocean or Great Lakes service.**
  - (3) **Each vessel under 100 gross tons that carries more than 12 passengers on an international voyage.**
- (b) The watertight seal in the bulkhead between the stern tube space and the machinery space must be located in a watertight shaft tunnel. The vessel must be designed so that the margin line will not be submerged when the watertight shaft tunnel is flooded.
- (c) If a vessel has two or more shaft tunnels, they must be connected by a watertight passageway.
- (d) If a vessel has two or less shaft tunnels, only one door is permitted between them and the machinery space. If a vessel has more than two shaft tunnels, only two doors are permitted between them and the machinery space.

## Notes

### Amendments

[CGD 79-023, 48 FR 51017, Nov. 4, 1983, as amended by USCG-2014-0688, 79 FR 58287, Sept. 29, 2014]

### Authority

Authority: 46 U.S.C. 2103, 3306; E.O. 12234, 45 FR 58801, 3 CFR, 1980 Comp., p. 277; Department of Homeland Security Delegation No. 0170.1.

### Source

Source: CGD 79-023, 48 FR 51017, Nov. 4, 1983, unless otherwise noted.

### Amendments

[CGD 79-023, 48 FR 51017, Nov. 4, 1983, as amended by USCG-2014-0688, 79 FR 58287, Sept. 29, 2014]