Hatch cover
Hatch covers are used to close hatches . The term mainly refers to lids with which the cargo hold hatches of seagoing and inland vessels are closed to prevent the ingress of water. The term also describes any type of fixed cover or maintenance hatch over smaller hatches, manholes and entrances as well as waterproof and dustproof flexible materials with which kayak seating areas are closed during transport or storage.
tasks
Hatch covers protect the ship and boat openings from the ingress of water, in particular. For this purpose, they must be constructed on seagoing vessels in such a way that, on the one hand, they are watertight and can withstand sea hammer (seaworthy locked), on the other hand, they should also be able to take a sufficient amount of deck load if required. Lighter hatch designs are generally used on inland navigation vessels, as protection against precipitation and splash water is sufficient here.
Wooden hatch cover
Until the 1950s, the standard hatch cover for both smaller seagoing and inland vessels consisted of shear sticks (called shear tree on inland vessels) with wooden hatch covers and a cover made of tarpaulin . The shear sticks act as cross members between both sides of the hatch coaming and can be pushed or lifted out of the way to open the hatch. The actual hatch cover consists of wooden hatch covers lying fore and aft, which rest on the transverse shear bars and the inner coaming. One to three layers of tarpaulin are applied as a seawater-proof cover. The protruding tarpaulin edges are folded over at the outer coaming edges and secured on the sides with slats , on the front and rear edges with locking slats and hatch wedges. In addition, it should be mentioned that wooden hatch covers on ships in general cargo transport as a cover in the intermediate decks of new buildings were still used after 1950; see photo MS Illstein ; Year of construction 1959. Otherwise, the principle of the shear sticks as transverse girders - as described above - was also given in the intermediate decks.
Steel hatch cover
Steel hatch covers have been developed since the 1920s and have been used since the 1930s. An example of a ship from the early days of such hatch covers is the Nordcoke . Steel hatch covers had been mandatory for new German seagoing ships since January 1, 1940 (special permits from the See-Berufsgenossenschaft could be applied for for smaller ships ), but steel hatch covers did not gain acceptance on a large scale until the 1950s, although until the early 1960s Wooden lids were still occasionally installed , especially on coasters . In the course of the development, the following constructions have prevailed:
Hatch panels
At the beginning of the conversion from wooden to steel hatch covers, steel hatch panels were often used. These were covers that reached transversely from hatch coaming to hatch coaming, which continued to rest on shear sticks and were quite unwieldy when opening and closing the hatches, as they could only be moved with the loading gear . The seal against the ingress of sea water was also done by applying one to three layers of tarpaulin.
Pontoon hatch cover
Since the hatch panels took up a lot of space when stowed on deck, individual pontoon hatch covers were developed that could be completely lifted out by a crane or loading gear and stored floating next to the ship. Initially, pontoon lids were sealed separately against the ingress of water, later permanently installed rubber seals were used. This system (but without a floating lid) has become the standard on medium-sized and large container ships today. The pontoon lids are usually stored on land or on a special device on the container bridge during container handling .
Sliding hatches
Rollable hatch covers, the individual roll covers of which can be shifted one above the other, have proven particularly useful in inland shipping. As a rule, no or at most only a very low deck load can be carried on them.
Large bulk carriers often have side-opening split hatches amidships.
Stacking hatches (piggy-back system)
In order to be able to operate the hatch panels better and to be able to use them on ships without their own loading gear, the hatch panels were combined into stackable hatch units that could be lifted, moved and stacked on top of one another with a so-called hatch car. Another variant are rollable hatch covers, which are raised at the hatch end with hydraulic rams so that the next cover can be moved under the first etc. For this system the name Piggy-Back-System has become established on board.
MacGregor system
In the 1920s and 1930s, brothers Robert and Joseph MacGregor of Whitley Bay, Northumberland developed the single-pull hatch cover system. It has developed into the most widely used hatch cover since the 1950s and could be considered the standard hatch cover until the introduction of the container ships, on which mostly pontoon covers or folding hatch covers were used.
The MacGregor single pull system consists of rollable steel cover parts with built-in rubber seals, which are connected to the side with a chain. To open the hatch, the distal end of the hatch cover is pulled open with a wire rope. The pulled lid part pushes all the others in front of it. The hatch parts run onto a ramp at the end of the hatch and are positioned vertically one behind the other in a so-called hatch pocket to save space. Closing is done in reverse. The wire runner is again attached to the last part of the cover. The chains pull the next cover part out of its position in the hatch pocket.
The advantages of the system lay in the simple, low-maintenance and space-saving construction as well as in the quick operation of the hatch covers. If the deck crew needed about one to two hours to open or close a hatch with a wooden hatch cover, the MacGregor system reduced this work to a few minutes.
Folding hatch cover
Folding or folding hatch covers are either unfolded with hydraulic rams, with hydraulic "power packs" integrated into the hatch cover or with cables, whereby they initially form a tent shape and finally find their rest position standing vertically with the undersides folded against each other at the hatch end. Although the folding hatch cover was one of the earliest designs when the steel hatch cover was introduced, it only became widely accepted with the beginning of containerization. Today most of the smaller seagoing vessels are equipped with a folding hatch construction.
Roll-up hatch
A seldom used type of hatch cover is the roll-up hatch cover. There, cover elements connected to one another in an articulated manner are wound up with a motor-driven spindle or reel. The "Ermanns roll hatch" is regarded as a pioneering design of this type, another construction of this type was the "MacGregor Rolltite" hatch cover.
Ships without hatch covers (open-top container ship)
In 1990, the Bell Pioneer was the world's first sea-going container ship to be built without a hatch cover . Later there were a number of other drafts of this construction principle, of which only a few feeder ship types were produced in larger numbers by the Hamburg shipyard JJ Sietas . For safety reasons, ships without hatch covers have a larger side height and effective bilge systems .
Hatch cover for kayaks
These are oval impregnated fabrics with a rubber edge that are stretched over the seat entry of the boat so that no dirt or rain can penetrate and there is less air resistance during transport. Correspondingly large tension covers can also be used for large open canoeing boats.
literature
- Wagner, Ernst: Deck work . A manual for seafarers. 6th edition. Hammerich & Lesser, Hamburg 1951.
- Detje, Peter (ed.): Shipbuilding for boaters . Eckhardt & Messtorff Verlag, Hamburg 1962.
- Helmers, Walter (ed.): Müller-Krauss, manual for ship management . Volume 3, seamanship and ship technology, part B. Springer Verlag, Berlin 1980, ISBN 3-540-10357-0 .
- Author collective: Stahlschiffbau . transpress Verlag, Berlin 1989, ISBN 3-341-00410-6 .