“When you find someone who’s gonna make room for you on the door when the ship goes down, that’s a rose you cultivate.”
How true the quote above is. Sinking or submerging is the main cause of the loss of vessels. Grounding the second most frequent cause with one out of five accidents, followed by fire with one out of ten. Key is to design and construct a ship door that will avoid the ship to go down off course.
Ship doors are designed, not only to be waterproof or weathertight, but also for:
- interior or exterior positions on board,
- to open inwards or outwards,
- with one or two leaves and
- top- hinged or side-hinged.
External ship doors are often delivered as a unit including surrounding ship structure for efficient installation.
Side-hinged or top-hinged ship door
The selection of a side-hinged or top-hinged ship door depends on various factors. Like for example the free height that is available, or the space available at the side of the door opening.
TOP-HINGED MARINE DOOR
This type of ship door is often used on RoRo vessels. On these vessels a horizontal logistic flow is required between different levels and compartments below the main deck. The door design increases safety on board by supporting movement from one watertight compartment to another via top-hinged doors in watertight bulkheads.
Depending on the size of the door, one or two direct acting hydraulic cylinders raise the ship door by rotating upwards. The marine door is locked again by hydraulically operated wedges incorporated in the structure of the vessel.
When less clear space is available near the door, the design will allow the door to lift vertically before it opens.
To avoid the need for opening the complete door construction for movement of crew or passengers between compartments. An access door can be incorporated in the top-hinged marine door.
A top-hinged door can work also for naval vessel. Like the LST (Landing Ship for Tanks) which must not interfere with frontal weapons of the vessel.
SIDE-HINGED SHIP DOOR
The side-hinged doors are often used for the smaller door openings, but also for bow doors. Free space on the left and right side of the allows the use of bow doors. The side-hinged ship door requires space on the side of the door opening. External side-hinged doors can be arranged to open inwards or outwards, and can be built with either one or two leaves.
What to consider when picking a marine door
Doors on board must be used safely and properly to avoid endangering people on board of the vessel who are passing through the ship doors or operating them. Too bad, casualty statistics learn that safe and proper use is still not always the case.
SHIP DOOR SAFETY SYSTEMS
For example, investigations of the root cause after incidents involving power-operated watertight doors have revealed that it still is common practice on board vessels not to open watertight doors fully before passing through. The ship door safety systems have also been found not to be in full working order during inspections, and some doors were not properly maintained or tested. Most accidents involving humans occur when the doors are in bridge-controlled “doors closed” mode.
MARINE DOOR FIRE CLASSIFICATIONS
The fire classification “B” on board is used for cabin doors, and doors in fire classification “A” for the use in areas with higher fire protection requirements. For the classification the construction of the door has been tested from each side separately, using two separate specimens.
UNDERSTAND THE SHIP DOOR SYSTEMS
A marine door comprises mostly of a combination of several technical systems,like:
- structural,
- electrical
- hydraulic and
- control.
This combination brings many possible failure modes, besides the fact the doors are subject to wear and tear.
The crew needs to understand and comply with the procedures describing correct operation during regular voyages. But also in emergency situations. Regular maintenance is key to reduce risks, plus the crew and the leadership on board and onshore need to be addressed as well. They all have to be aware about the risks involved.
Get your door right!
The July Marine sales team can help you making the decision to select the proper ship door for your next maritime project. They can also help with the proper maintenance guidance for the marine doors. Contact us now.
