Shell Expansion Plan

• It is a two dimensional drawing of a three dimensional surface of the ship’s hull form.
• This plan is very useful for the following information:It is used for marking the location of a hull Damage on this plan by identifying the strake number , letter and frame number so that the exact location of the damage and also suggested repairs are marked in a localised copy.
• The shell expansion can be used for finding areas of painting surfaces such as topside, boot topping and bottom areas by applying Simpsons rules directly. 
• In the shell expansion the vertical scale used is different from the horizontal scale and a suitable adjustment has to be made when calculating areas.
• This becomes useful in solving disputes concerning areas of preparation and painting.
• It gives information on the thickness of the original strake which is indicated by the number in the circle shown in the strake. 
• The quality of steel used is also shown by letters A,B,D E and AH, BH,DH, EH.