Work Item
ASTM WK84188

New Specification for Specification for Maximum Thermal Transmittance Values for Ship Hulls and Decks

1. Scope

This specification is for maximum allowable thermal transmittance values (i.e., U-values) for ship hulls and decks. These are differentiated by the following categories: 1. above the water line, 2. below the water line, 3. typical summer exterior temperatures with solar impingement, 4. typical winter exterior temperatures, 5. vertical orientation, and 6. horizontal orientation. This specification is intended to update the SNAME Specification 4-7 which has been in use since 1963.


thermal transmittance, U-value, hulls, decks, insulation, stiffeners, finite element analysis


SNAME Specification 4-7, titled "Thermal Insulation Report", was developed, and first published in 1963, to establish minimum acceptable thermal transmittance values for ship boundaries (i.e., hulls and decks). The purpose was to limit the use of fuel to heat and cool the air on ship interiors, much as building envelop insulation is used. Since 1963, liquid fuel prices have increased many times, even accounting for inflation, to the extent that the SNAME Specification 4-7 values are undoubtedly too high, resulting in unnecessarily high fuel use by ships. In addition, this condition also results in larger and more expensive electrical generation equipment on board and greater fuel weight carried on board, even accounting for the extra weight of insulation. It is past time for an updated thermal insulation specification.

The title and scope are in draft form and are under development within this ASTM Committee.


Developed by Subcommittee: F25.02

Committee: F25

Staff Manager: David Lee

Work Item Status

Date Initiated: 11-14-2022

Technical Contact: Gordon Hart

Item: 000