---
kind: "section"
citation: "33 C.F.R. § 164.40"
title: "33"
number: "164.40"
heading: "Devices to indicate speed and distance."
url: "https://uscodex.org/cfr/33/164.40"
---

# §164.40. Devices to indicate speed and distance.

- (a) Each vessel required to be fitted with an Automatic Radar Plotting Aid (ARPA) under [§ 164.38](/cfr/33/164.38.md) of this part must be fitted with a device to indicate speed and distance of the vessel either through the water or over the ground.
- (b) The device must meet the following specifications:
  - (1) The display must be easily readable on the bridge by day or night.
  - (2) Errors in the indicated speed, when the vessel is operating free from shallow water effect, and from the effects of wind, current, and tide, should not exceed 5 percent of the speed of the vessel, or 0.5 knot, whichever is greater.
  - (3) Errors in the indicated distance run, when the vessel is operating free from shallow water effect, and from the effects of wind, current, and tide, should not exceed 5 percent of the distance run of the vessel in one hour or 0.5 nautical mile in each hour, whichever is greater.

## Notes

### Amendments

[CGD 83-004, 49 FR 43467, Oct. 29, 1984, as amended by USCG-1998-3799, 63 FR 35532, June 30, 1998]

### Authority

Authority: 46 U.S.C. 2103, 3703, 70034; E.O. 12234, 45 FR 58801, 3 CFR, 1980 Comp., p. 277. Sec. 164.13 also issued under 46 U.S.C. 8502. Sec. 164.46 also issued under 46 U.S.C. 70114 and Sec. 102 of Pub. L. 107-295. Sec. 164.61 also issued under 46 U.S.C. 6101. DHS Delegation No. 00170.1, Revision No. 01.4.

### Amendments

[CGD 83-004, 49 FR 43467, Oct. 29, 1984, as amended by USCG-1998-3799, 63 FR 35532, June 30, 1998]