Steel Hull Plates

[mccollochd]

Good information. Thank you.

[GuestfromEU]

The posts on welding steel hull plates are very informative. Thank you. Roughly, how thick are hull plates? 1/4-inch? 1/2-inch? 3/4-inch? Are hull plates below the waterline thicker than plates up near the spar deck?? How thick are plates in the cargo hold? I would assume steel at the bottom of the cargo hold is thicker (to absorb the impact of cargo being loaded), but are they less thick at the top of the cargo hold?

It does depend on the era. Ships built in the early 1900s were built with different methods than 1950s, further refined into the 1960s, 70s, 80s, and still evolving somewhat today. Great Lakes ships are also different than ocean ships. It is rare to see shell plates less than 12mm (1/2") on ocean ships, and likely lakers. 13.5mm or 14.5mm is common. There are different thickness plates in different areas of the ship, the same as framing in the bow and stern is different than in the cargo section. Plating in the fore and aft sections is generally thicker, up to 18mm.

Cargo holds on a self unloader may be lined with Teflon sheets on the slopes, which will absorb impacts from loading cargo. For standard bulk carriers, the tank tops (bottom of the cargo hold) can vary in thickness, 12mm to 18mm. They will be replaced over the life of the ship. Periodic measurements by ultrasonic thickness gauging will determine what is the remaining thickness and what must be replaced by class rules. These measurements are required by classification society rules, and the scope of what is measured is determined by the type and age of the ship. As the ship becomes older, the scope of thickness measurements increase. After 15 years, the ship is subjected to more frequent full-scope surveys, including frames, supporting brackets, shell thickness, transverse bulkheads, piping, and more.

[mccollochd]

The posts on welding steel hull plates are very informative. Thank you. Roughly, how thick are hull plates? 1/4-inch? 1/2-inch? 3/4-inch? Are hull plates below the waterline thicker than plates up near the spar deck?? How thick are plates in the cargo hold? I would assume steel at the bottom of the cargo hold is thicker (to absorb the impact of cargo being loaded), but are they less thick at the top of the cargo hold?