33 CFR 164.37: Second radar on vessels of 10,000 gross tons

Last reviewed: October 14, 2026

This section sets radar equipment rules for vessels of 10,000 gross tons or more. Each such vessel must have a second marine radar system that operates independently of the first. Tankers of 10,000 gross tons or more that are subject to 46 U.S.C. 3708 must also meet range and stabilized display requirements.

Applies toVessels of 10,000 gross tons or more, with added requirements for tankers of 10,000 gross tons or more that are subject to 46 U.S.C. 3708.

What it says

  1. Each vessel of 10,000 gross tons or more must have a second marine radar system that operates independently of the first, in addition to the radar system under § 164.35(a).

    33 CFR 164.37(a)“must have, in addition to the radar system under § 164.35(a), a second marine radar system that operates independently of the first.”

  2. The note explains that independent operation means two completely separate systems, from separate branch power supply circuits or distribution panels to antennas.

    “Independent operation means two completely separate systems, from separate branch power supply circuits or distribution panels to antennas”

  3. The note adds that failure of any component of one system must not make the other system inoperative.

    “so that failure of any component of one system will not render the other system inoperative.”

  4. On each tanker of 10,000 gross tons or more that is subject to 46 U.S.C. 3708, the dual radar system required by this part must have a short range capability and a long range capability.

    33 CFR 164.37(b)“the dual radar system required by this part must have a short range capability and a long range capability”

  5. On each tanker of 10,000 gross tons or more that is subject to 46 U.S.C. 3708, each radar must have true north features consisting of a display that is stabilized in azimuth.

    33 CFR 164.37(b)“each radar must have true north features consisting of a display that is stabilized in azimuth.”

Common questions

Do I need two radars on a vessel of 10,000 gross tons or more?

Yes. Besides the radar system under § 164.35(a), the vessel must have a second marine radar system that operates independently of the first.

“must have, in addition to the radar system under § 164.35(a), a second marine radar system that operates independently of the first.”

What does independent radar operation mean?

It means two completely separate systems, so that failure of any component of one will not make the other inoperative.

“so that failure of any component of one system will not render the other system inoperative.”

What extra radar features do tankers of 10,000 gross tons or more need?

Tankers of 10,000 gross tons or more that are subject to 46 U.S.C. 3708 must have short and long range capability in the dual radar system. Each radar must also have a display stabilized in azimuth.

“each radar must have true north features consisting of a display that is stabilized in azimuth.”

The text of 33 CFR 164.37

Electronic Code of Federal Regulations (eCFR), current as of April 16, 2026 · Read it on eCFR

Equipment: Vessels of 10,000 gross tons or more

(a) Each vessel of 10,000 gross tons or more must have, in addition to the radar system under § 164.35(a), a second marine radar system that operates independently of the first.

Note: Independent operation means two completely separate systems, from separate branch power supply circuits or distribution panels to antennas, so that failure of any component of one system will not render the other system inoperative.

(b) On each tanker of 10,000 gross tons or more that is subject to 46 U.S.C. 3708, the dual radar system required by this part must have a short range capability and a long range capability; and each radar must have true north features consisting of a display that is stabilized in azimuth.

Sections it refers to

The plain-English explanation on this page was written with AI from the regulation text above and checked automatically before publishing: every quote appears in the text, every number comes from it, and a second model confirmed each statement adds nothing the text doesn't say. Regulation text current as of April 16, 2026. The regulation text governs. RegKnot is not affiliated with the U.S. Coast Guard.