UWL “Helgoland” - an underwater laboratory for rough sea conditions

Kurzfassung

Die rauhen Seebedingungen in der Deutschen Bucht (südliche Nordsee) (Wellenperiode bis 8 sec, Wellenhöhe bis 8 m, Tidenstrom bis 1 m/sec und Sichtweite um 1 m), haben die technische Konzeption von UWL „Helgoland“ und alle Betriebsabläufe (z. B. Transport, Absenken, Überwachung und Dekompression) maßgeblich beeinflußt. Das UWL unterscheidet sich daher wesentlich von anderen bisher eingesetzten Systemen ähnlicher Größenordnung. Spezielle Probleme und Problemlösungen werden erläutert.

Summary

1. The UWL “Helgoland” system has been built with the rough sea conditions in the Southern North Sea in mind: wave periods up to 8 sec, wave heights up to 8 m, tidal currents up to 1 m/sec.

2. The main body can be towed at a velocity of up to 5 knots, and be lowered without the assistance of a floating crane. The system has a high degree of flexibility.

3. In order to withstand the oscillating forces caused by sea movements, a horizontal cylinder was chosen as main body. The main body is ballasted to a negative buoyancy of 16 t (more than for other comparable UWL systems). Four swords stabilize the UWL against horizontal forces. The main body acts as a self-righting body.

4. Emergency supply of food and energy allows complete surface independence for 10 days.

5. Rough surface conditions and poor underwater visibilities do not allow aquanaut activities on the sea bottom to be observed from the surface. A wireless system is used for diver communication on the sea bottom. Three communication systems connect the UWL main body to the supervising station on land: one TV and two radio systems. One radio system is used to transmit alarms to the land base, the other will be used in 1973 as transmission system for oceanological data.

6. Aquanauts cannot be transported from the habitat to the deck decompression chamber (DDC) during rough weather. Hence one room in the UWL main body serves as decompression chamber.

7. The surface energy station, a floating buoy, is a world first. The station operates automatically; it is controlled by aquanauts in the UWL. Electricity, compressed respiratory gases and fresh water are transported from the buoy to the UWL via an umbilical line. Due to tide and wave motion, the umbilical line is shaped in goose-neck fashion. Other suplies such as food and mail are brought to the UWL by supply containers without assistance from surface divers. Supplementary respiratory gas for the semi-closed diving apparatus is stored on the sea bottom; the same applies for nitrogen.

8. The first manned test period in August, 1969, and the subsequent 9-month unmanned period proved that the system is able to withstand rough sea conditions.

9. As a research base, UWL “Helgoland” has met the expectations. It is possible to work and to conduct research in the sea, even under the adverse conditions prevailing in the North Sea. In 1973, UWL “Helgoland” will operate again on the sea bottom near Helgoland.