Different types of strakes used in ship construction, hull plating material, and tests on hull steel.
- Keel strake (garboard strake): the bottom strake adjacent to the keel, which is thicker because it is subject to grounding and docking loads.
- Bottom strakes: the strakes between the keel strake and the bilge, forming the bottom of the hull.
- Bilge strake: the strake at the turn of the bilge, which is thicker and subject to the bilge keel attachment and the docking loads.
- Side strakes: the strakes on the side of the hull between the bilge and the sheer strake.
- Sheer strake: the top strake at the deck edge, which is thicker because it is the extreme fibre of the hull girder and subject to the highest bending stresses.
- Stringer strake: the strake at the deck edge (the deck stringer plate), which is thicker and connects the deck to the side.
- Deck strakes: the strakes of the deck plating, with the deck stringer plate at the edge being the thickest.
The strakes are arranged so that the thicker plates are placed where the stresses and loads are highest (keel, bilge, sheer strake, deck stringer).
- Chemical analysis: to verify the composition (carbon, manganese, sulphur, phosphorus, etc.).
- Tensile test: to verify the yield strength, ultimate tensile strength and elongation.
- Bend test: to verify the ductility and soundness of the plate.
- Impact test (Charpy V-notch): to verify the notch toughness at the specified temperature (for grades D, E and high-tensile steels).
- Ultrasonic or other non-destructive testing: to verify the internal soundness of the plate.
- Dimensional and surface inspection: to verify the thickness, flatness and freedom from defects.
The tests are carried out on samples from each cast/heat and are witnessed and certified by the classification society surveyor.