On the control of anti-fouling properties of ship bottom paints

A technical study of no docking system

Abstract

Kawasaki Dockyard created a new ship-building method for large tankers (D. W. 38, 000 tons and above) on march 1957. Under the new method, a large stern block as much as 3, 000 tons which was previously assembled on the assembling plat form is shifted on to the adjacent berth where the remaining part of the ship is built in about 2 1/2 months and whilst the latter work is going on, almost all fitting work, installation of engine etc, are completed and then the ship is launched.
There is so short a period of time (about 1 month) from launching to delivery that the conventional docking prior to sea trials seems to be unnecessary. In order to carry out the new fitting out method without docking, the authors have planned some fundamental studies as follows : -
1) How to make the perfect protective organic coating on ship bottom whilst on berth.
2) How to minimize the damage of hull and the scratches of protective coating by any accidents during launching and whilst fitting out.
3) To protect the ship bottom against corrosion and rusting by cathodic protection (sacrificial anode system) during guarantee period.
4) How to keep ship bottom clean after launching and during service whenever she'll be launched, especially before sea trials. For this purpose we must have the special A/F paints which are properly controlled in initial leaching rate of toxics immediately after launching and have long life of anti-fouling facilities.
Having made experiments for the above mentioned 4 subjects, the authors have had the successful results for item 4. Now the authors feel no fear about fouling of ship bottoms even if we carry out the new fitting method without docking. This paper shows how we got the new special A/F paints suitable for no docking system.