46 CFR § 170.285 - Free surface correction for intact stability calculations.

---
identifier: "/us/cfr/t46/s170.285"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "46 CFR § 170.285 - Free surface correction for intact stability calculations."
title_number: 46
title_name: "Shipping"
section_number: "170.285"
section_name: "Free surface correction for intact stability calculations."
chapter_name: "COAST GUARD, DEPARTMENT OF HOMELAND SECURITY"
subchapter_number: "S"
subchapter_name: "SUBDIVISION AND STABILITY"
part_number: "170"
part_name: "STABILITY REQUIREMENTS FOR ALL INSPECTED VESSELS"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "43 U.S.C. 1333; 46 U.S.C. 2103, 3306, 3703; E.O. 12234, 45 FR 58801, 3 CFR, 1980 Comp., p. 277; Department of Homeland Security Delegation No. 0170.1."
regulatory_source: "CGD 79-023, 48 FR 51010, Nov. 4, 1983, unless otherwise noted."
cfr_part: "170"
---


# 170.285 Free surface correction for intact stability calculations.

(a) When doing the intact stability calculations required by this subchapter, the virtual increase in the vessel's vertical center of gravity due to liquids in tanks must be determined by calculating—

(1) For each type of consumable liquid, the maximum free surface effect of at least one transverse pair of wing tanks or a single centerline tank; and

(2) The maximum free surface effect of each partially filled tank containing non-consumable liquids.

(b) For the purpose of paragraph (a)(1) of this section, the tank or combination of tanks selected must be those having the greatest free surface effect.