Depth The third principal dimension is depth, which varies along the length of the ship but is usually measured ant amidships. This depth is known as the ' depth moulded and is measured from the underside of the plating of the deck at side amidships to the base line. It is shown in Figure 2(a). It is sometimes quoted as a depth moulded to upper deck'or 'depth moulded to second deck,, etc. Where no deck is specified it can be taken the depth is measured to the uppermost continuous deck. In some modern ships there is a rounded gunwale as shown in Figure 2(b). In such cases the depth moulded is measured from the intersection of the deck line continued with the breadth moulded line The three principal dimensions give a general idea of the size of a ship but there are several other features which have to be considered and which could be different in two ships having the same length, breadth and depth The more important of these will now be defined Sheer is the height of the deck at side above a line drawn parallel to the base and tangent to the length of the ship and is usually greatest at the ends. In modern ships the deck line at side often has a variety of shapes: it may be flat with zero sheer over some distance on either side of amidships and then rise as a straight line towards the ends; on the other hand there may be no sheer at all on the deck, which will then be parallel to the base over the entire length. In older ships the deck at side line was parabolic in profile and the sheer was quoted as its value the forward and after perpendiculars as shown in Figure 1. So called'standard sheer was given by the formulae Sheer forward (in)=0.2Lf+20 (in)=0.Ln+10 These two formulae in terms of metric units would give Sheer forward (cm)=1.666Lm+50.8 (cm)=0.833Lm+254 It will be seen that the sheer forward is twice as much as the sheer aft in these standard formulae. It was often the case. however that considerable variation was made from these standard values. sometimes the sheer forward was increased while the sheer after was reduced. Occasionally the lowest point of the upper deck was some distance aft of amidships and sometimes departures were made from the parabolic sheer profile. The value of sheer and particularly the sheer forward was to increase the height of the deck above water (the height of platform'as it was called )and this helped to prevent water being shipped when the vessel was moving through rough sea. The reason for the abolition of sheer in some modern ships is that their depths are so great that additional height of the deck above water at the fore end is unnecessary from a seakeeping point of view Deletion of sheer also tends to make the ship easier to construct, but on the other hand it could be said that the appearance of the ship suffers in consequence Camber or round of beam is beam is defined as the rise of the deck of the ship in going from the side to the centre as shown in Figure 3(a). The camber curve used to be parabolic but here again often nowadays straight line camber curves are used or there may be no camber at all on decks. Camber is useful on the weather deck of a ship from a drainage point of view, but this may not be very important since the ship is very rarely upright and at rest. Often, if the weather deck of a ship is cambered, the lower decks particularly in passenger ships may have no camber at all. as this makes for horizontal decks in accommodation which is an advantage Camber is usually stated as its value on the moulded breadth of the ship and standard camber was taken one-fiftieth of the breadth. The camber on the deck diminishes towards the ends of the ship as the deck breadths ecome smaller Bilge radius An outline of the midship section of a ship is shown in Figure 3(a). In many full'cargo ships the section is virtually a rectangle with the lower corners rounded off. This part of the section is referred to as the bilge and the shape is often circular at this position. The radius of the circular arc foming the bilge is called the 'bilge radiusDepth The third principal dimension is depth, which varies along the length of the ship but is usually measured ant amidships. This depth is known as the ‘depth moulded and is measured from the underside of the plating of the deck at side amidships to the base line. It is shown in Figure 2(a). It is sometimes quoted as a ‘depth moulded to upper deck’ or ‘depth moulded to second deck’, etc. Where no deck is specified it can be taken the depth is measured to the uppermost continuous deck. In some modern ships there is a rounded gunwale as shown in Figure 2(b). In such cases the depth moulded is measured from the intersection of the deck line continued with the breadth moulded line. Other features The three principal dimensions give a general idea of the size of a ship but there are several other features which have to be considered and which could be different in two ships having the same length, breadth and depth. The more important of these will now be defined. Sheer Sheer is the height of the deck at side above a line drawn parallel to the base and tangent to the length of the ship and is usually greatest at the ends. In modern ships the deck line at side often has a variety of shapes: it may be flat with zero sheer over some distance on either side of amidships and then rise as a straight line towards the ends; on the other hand there may be no sheer at all on the deck, which will then be parallel to the base over the entire length. In older ships the deck at side line was parabolic in profile and the sheer was quoted as its value on the forward and after perpendiculars as shown in Figure 1. So called ‘standard’ sheer was given by the formulae: Sheer forward (in) =0.2Lft+20 Sheer aft (in) =0.1Lft+10 These two formulae in terms of metric units would give: Sheer forward (cm) =1.666Lm+50.8 Sheer aft (cm) =0.833Lm+25.4 It will be seen that the sheer forward is twice as much as the sheer aft in these standard formulae. It was often the case, however, that considerable variation was made from these standard values. Sometimes the sheer forward was increased while the sheer after was reduced. Occasionally the lowest point of the upper deck was some distance aft of amidships and sometimes departures were made from the parabolic sheer profile. The value of sheer and particularly the sheer forward was to increase the height of the deck above water (the ‘height of platform’ as it was called ) and this helped to prevent water being shipped when the vessel was moving through rough sea. The reason for the abolition of sheer in some modern ships is that their depths are so great that additional height of the deck above water at the fore end is unnecessary from a seakeeping point of view. Deletion of sheer also tends to make the ship easier to construct, but on the other hand it could be said that the appearance of the ship suffers in consequence. Camber Camber or round of beam is beam is defined as the rise of the deck of the ship in going from the side to the centre as shown in Figure 3(a). The camber curve used to be parabolic but here again often nowadays straight line camber curves are used or there may be no camber at all on decks. Camber is useful on the weather deck of a ship from a drainage point of view, but this may not be very important since the ship is very rarely upright and at rest. Often, if the weather deck of a ship is cambered, the lower decks particularly in passenger ships may have no camber at all, as this makes for horizontal decks in accommodation which is an advantage. Camber is usually stated as its value on the moulded breadth of the ship and standard camber was taken as one-fiftieth of the breadth. The camber on the deck diminishes towards the ends of the ship as the deck breadths become smaller. Bilge radius An outline of the midship section of a ship is shown in Figure 3(a). In many ‘full’ cargo ships the section is virtually a rectangle with the lower corners rounded off. This part of the section is referred to as the ‘bilge’ and the shape is often circular at this position. The radius of the circular arc forming the bilge is called the ‘bilge radius’