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Deep survey / In service, four hulls

Six kilometres down, running a survey line for forty hours without asking anything of the surface.

PLATE 91:20
Depth rating
6,000 m
Line accuracy
± 9 cm
Endurance
40 h

HALVARD-9 is the hull we build everything else against. It carries the full sensor stack to six thousand metres and holds a survey line to within nine centimetres of plan across a forty hour dive. Nothing about it is clever. It is heavy, cold-tolerant, and it comes back.

The pressure housing is a single machined titanium cylinder with two end caps. There is no bolted mid-section, because a mid-section is a seam and a seam is where the ocean gets in. Every penetrator is inspected before and after each dive and logged against the hull's own service record.

Its autonomy is deliberately narrow. It will not improvise a new survey pattern, and it will not decide that a feature is interesting. It flies the line, it records the returns, and it surfaces on schedule. Judgement happens on deck, with the data on a screen and a person accountable for the reading.

Sensor stack

  • Multibeam echosounder, 400 kHz
  • Sub-bottom profiler, 2 to 8 kHz
  • Synthetic aperture sonar
  • Conductivity, temperature, depth
  • Stills camera, 42 MP, strobe pair
  • Methane and turbidity probe

Representative return, single ping

Full specification

HALVARD-9, as built

Length5.85 m
Diameter0.72 m
Dry mass1,180 kg
HullTi-6Al-4V, single billet
Transit speed3.4 kn
Survey speed2.1 kn
Energy42 kWh, pressure tolerant
NavigationINS with DVL aiding
RecoveryAcoustic release, surface strobe
Turnaround6 h deck to deck

Other hulls

Deployment

HALVARD-9 deploys from two ports with a 6 h deck to deck turnaround. Tell us the depth and the question and we will tell you whether this is the right hull.