[Code of Federal Regulations]
[Title 46, Volume 7]
[Revised as of October 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 46CFR174.145]

[Page 175]
 
                           TITLE 46--SHIPPING
 
   CHAPTER I--COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED)
 
PART 174_SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES--Table of 
Contents
 
       Subpart E_Special Rules Pertaining to Tugboats and Towboats
 
Sec. 174.145  Intact stability requirements.

    (a) In each condition of loading and operation, each vessel must be 
shown by design calculations to meet the requirements of paragraphs (b) 
through (e) of this section.
    (b) The area under each righting arm curve must be at least 16.9 
foot-degrees (5.15 meter-degrees) up to the smallest of the following 
angles:
    (1) The angle of maximum righting arm.
    (2) The downflooding angle.
    (3) 40 degrees.
    (c) The area under each righting arm curve must be at least 5.6 
foot-degrees (1.72 meter-degrees) between the angles of 30 degrees and 
40 degrees, or between 30 degrees and the downflooding angle if this 
angle is less than 40 degrees.
    (d) The maximum righting arm shall occur at a heel of at least 25 
degrees.
    (e) The righting arm curve must be positive to at least 60 degrees.
    (f) For the purpose of this section, at each angle of heel, a 
vessel's righting arm may be calculated considering either--
    (1) The vessel is permitted to trim free until the trimming moment 
is zero; or
    (2) The vessel does not trim as it heels.

Subpart F [Reserved]