Paint coating repair  During sailing and berthing.

        The removal of corrosion spots on different ship surfaces on the early

period allows stopping the spread of corrosion spots in the future.

        Here is a simple calculations on the example of newbuilding chemical

tanker DWT-52 thousand tons of ballast tanks surfaces, where the ballast

tanks area is about 120 000 sq.m.

     In this case each company manufacturing pain materials  under coordination

of the warranty period (taken 5 years as the basis ) stipulates annually % of surface damage.

We are surely to use the averaged values which will be

The Table of damage tolerance by years

rate of frequency By years the percentage of corrosion damage,% corrodible surface, sq.m
1 0.15 180
2 0.35 420
3 1.10 1200
4 1.50 1800
5 1.90 2280
Total in 5 years 5% 5880 sq.m.

This warranty period has expired, and the corrosion process is developing.

The ballast tanks repair usually falls on the 9th year the ship operation during

he ship repair, thus it is possible to predict the future situation of corrosion

progressing in ballast tanks

Period  by years Percentage of corrosion ,%

Surface damaged by corrosion, sq.m.

6 2,0 2400
7 2,6 3120
8 3,5 4200
9 4,5 5400

progress of corrosion

on the surface in 9 years

12,6% 21000 sq.m.

       Therefore the ballast tanks shall have 21,000 square meters of corrosion

damage on the 9th year during ship repair in dry dock.

       The repair of damaged surface during the sailing and berthing with the

least costs is suitable to be done in the wing ballast tanks, which

make up about 50% of the total surface or 10,560 square meters.

       The cost of paint coating repair in the wing ballast tanks during

sailing after the expiration of warranty shall be


 by years

Duration of

Repair in months

Number of  

Ship painters

Cost per 1

 Painter, in USD


In 6 months in USD

6 6 2 3000 36000
7 6 2 3000 36000
8 6 2 3000 36000
Total 18 months 6 9000 108000

       The repair of 10560 sq.m. shall make up 108 000,00 dollars or the cols of  1 sq.m

shall be 10,28 dollars, which makes  at least 20-25 % under cost of  work performance

at the ship-repairing yards of Europe, and the most important thing is the reduction

of ship repair for 15-20 days.

The result is obvious.