Paint Film Thickness Control for Ship's Hull

Abstract

Dry film thickness on hull outside of two mammoth oil tankers which were built in two representative shipyards of Japan were measured in the numerous points. Intending to establish rational coating of hull outside which gives minimum variation of film thickness, these data were analyzed to make clear the relation of the dry film thickness and its variation with various factors in coating.
The fifteen factors which influence upon film thickness were picked up, including “Ships”, “Shipyards”, “Painting schemes”, “Port and starboard”, “Blocks”, “Painting workers”, “Atmospheric temperature in coating” and “Checkers of dryfilm thickness”.
Dry film thickness data of 13,000 were collected and an electronic computer was used to analyze them. Factors in coating and film thickness data were coded. The analysis programs were punched to paper cards and HITAC 8,400 was used for the analysis.
The results were as follows;
(1) Average paint film thickness x which was controlled by the minimum for B ship in its contract was greater than that for A ship which was controlled by the mean in its contract.
(2) Variation of film thickness data from small blocks was larger than that from big blocks.
(3) With regard to chlorinated rubber paint film, the high temperature in coating make both x and σ bigger than the low temperature in coating. While as to tar-epoxy paint, no tendency was observed.
(4) The x value from two paint sprayers were nearly equal to contract film thickness and the σ value from these workers were not so large. Where as x from another paint sprayer was much higher than the contract film thickness, and σ was also large.
(5) As to the bottom and the topside part, both x and σ from parallel body were smaller than those from the bow part and the stern part composed of many curved surfaces. As to the boot top part, there was no tendency of this kind.