Watertight bulkheads
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Guest
Re: Watertight bulkheads
The Mark Barker has clamshell gates with any type of seal. There are only 2 cargo holds with a hydraulic “watertight” door separating them. There isn’t any type of transverse watertight bulkheads in the unloading tunnel except fed and aft of course.
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GuestfromEU
- Posts: 359
- Joined: December 7, 2014, 10:33 am
Re: Watertight bulkheads
There are two related, but different aspects here. The Fitzgerald was a gearless bulk carrier fitted with screen bulkheads. While solid in design, they were not inherently structural and primarily designed for segregation of cargo by creating separated holds. Yes, they were watertight if sprayed with a hose, but they were not designed for watertight integrity in terms of stability or dynamic loading. In comparison, ocean ships have watertight bulkheads designed as part of the hull structural integrity. Most ocean bulkers utilize one or more cargo holds for ballast, as in the entire cargo hold is filled with seawater.
On the self-unloaders on the lakes, two designs are most prevalent: Individual rubber seals at each gate, inflated like a balloon to seal the space between the unloading tunnel and cargo holds (and in turn, sealing separate cargo holds from commonality); or, traditional watertight doors located in the tunnel, in bulkheads dividing cargo holds, with the belts also sealed by smaller watertight doors which "pinch" the belt flat as the doors are closed by hydraulics. The latter design is more often seen due to easier maintenance and reliability. The ships with the balloon seals at each gate rarely use the seals and they were never widely accepted as reliable in any event. The only advantage to this design is a single, wide open tunnel space (not segregated by cargo holds), thus making for easier tunnel washing and cost savings by lower steel requirements.
Can a ship be built with a watertight tunnel and watertight cargo holds? Yes, it has been this way on the ocean ships for many, many years. Since ships on the lakes are older it is likely the USCG and class did not mandate any retrofits due to complexity and cost. I would like to know which system the Mark Barker is designed with as this ship would be built to modern rules.
On the self-unloaders on the lakes, two designs are most prevalent: Individual rubber seals at each gate, inflated like a balloon to seal the space between the unloading tunnel and cargo holds (and in turn, sealing separate cargo holds from commonality); or, traditional watertight doors located in the tunnel, in bulkheads dividing cargo holds, with the belts also sealed by smaller watertight doors which "pinch" the belt flat as the doors are closed by hydraulics. The latter design is more often seen due to easier maintenance and reliability. The ships with the balloon seals at each gate rarely use the seals and they were never widely accepted as reliable in any event. The only advantage to this design is a single, wide open tunnel space (not segregated by cargo holds), thus making for easier tunnel washing and cost savings by lower steel requirements.
Can a ship be built with a watertight tunnel and watertight cargo holds? Yes, it has been this way on the ocean ships for many, many years. Since ships on the lakes are older it is likely the USCG and class did not mandate any retrofits due to complexity and cost. I would like to know which system the Mark Barker is designed with as this ship would be built to modern rules.
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Guest
Re: Watertight bulkheads
Some absolutely have watertight bulkheads, they have “doors” that basically pinch the belt creating water tight divisions. I can’t recall for sure but I believe some Interlake and GLF vessels have these. I believe some designs got around this by having inflatable rubber bladders that seal between the cargo holds and unloading tunnels.
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Guest
Watertight bulkheads
Following the sinking of the Edmund Fitzgerald the Coast Guard recommended that transverse watertight bulkheads be installed in the cargo holds of great lakes freighters. Has this recommendation been adopted?