SOLAS Davit Shortcoming Left Hanging in NORSOK Standard
Striking the right balance on how strictly to apply the rules can be tricky for regulators: if the standard is too low, why bother having it? If it’s too high, inflexibility can result, or the temptation can grow to work around it.
What should be clear cut as far as maritime safety is concerned is that rules are applied with consistency, and that they are not applied to equipment or systems for which they were never envisaged. Atle Kalve, Development Director at boat handling specialist Vestdavit says that the safety rules applied to davit handling by the International Maritime Organization require adjustment.
“The lifting and lowering speeds enshrined in SOLAS are sometimes equated to davit performance standards; they are really the bare minimum considered acceptable for life-saving equipment, and a launch boat is not a lifeboat,” he says.
While davits can be called into action in an emergency, the workboats they handle routinely are not considered as life-saving equipment. Here, ‘safety’ falls under the occupational conditions faced by the workboat crew.
“SOLAS has strong views on the maximum speeds at which davits can hoist [18m/min] and lower [36 m/min] boats when working as life-saving appliances,” says Kalve. “However, it has nothing to say about the relationship between these speeds and the sea states in which boats are launched and recovered.
“A davit performing at the SOLAS minimum offers an unpleasant and potentially hazardous ride: a boat hoisted free from the water at 18m/min in a down-swell could be lifted by the following wave, causing the hoisting wires to go slack. When that wave subsides, the boat drops, and that is an injury risk.”
New rules aimed at fast rescue craft (FRC) used on ro-ro vessels were added to SOLAS after the Estonia disaster, building in wave compensation and new recommendations on davit hoisting speeds. However, Kalve says that while the amendments look good on paper, there has subsequently been no demand for ro-ro ship FRC davits with such capabilities and, if there were, their performance would be compromised because ro-ro FRCs are positioned so high up on the vessel structures, at or close to the stern/bow.
That the overall SOLAS minimum is no longer thought acceptable is demonstrated by NORSOK R-002 Standards, developed by the Norwegian petroleum industry, which came into use in 2015. These new standards offer far more considered guidance on davits and, Kalve notes, bear comparison to API 2 standards due to be introduced in US waters.
Vestdavit D-5000 davits meet NORSOK R-002 guidance and are already in use in the Norwegian sector of the North Sea for major operators. Available models include the 5-tonne capacity D-5000 fixed A-frame davit and the 6-tonne SWL PLR 6000 pivoting A-frame davit for Fast Rescue Craft, and the HN-16000 – a dual point davit designed for FPSOs and other floaters working in the Norwegian North Sea.
Kalve welcomes NORSOK R002 new guidance for HPUs, valves, control systems, electronics cabinets and back-up accumulators, and that Class verification is now recommended for FAT-testing. However, based on experience of operations at sea, he does not believe that the changes in NORSOK R-002 should be adopted slavishly by IMO when they come to updating rules on davits.
Vestdavit, for example, recommends a hoisting speed for a single point davit of 50m/min as sufficient to lift a boat out of the waves safely in sea state 5 and 6. “We need this to lift the boat up and out of the sea at the top of the wave, before the next waves comes in,” says Kalve. “You want to avoid the next wave hitting the MOB boat as this can cause a dangerous situation.”
To meet NORSOK R-002, however, the davit lifting and lowering speed is derived from a formula based on input from crane-makers. The formula results in different recommended speeds for a jack-up and an FPSO, for example, to take account of different dynamic factors. Kalve says that, in some circumstances, the NORSOK standard thus encompasses hoisting speeds to be up to 120m/min.
“Vestdavit supplies systems offering constant tension, where the boat rides the waves until the operator decides to start hoisting,” he says. “The self-tension speed is actually up to 120 m/min, but hoisting is not possible in the tension mode. The NORSOK standard essentially neglects self-tension solutions, and instead envisages lifting the boat out of the water so fast that there is no need to worry about the next wave. In this scenario, there is a real risk that such high accelerations will cause injury to the boat crew.”
NORSOK R-002 also envisages high equipment redundancy, which may in-build unnecessary costs, Kalve believes. Recommendations include dual hydraulic levers and dual brake systems, for example, in case of main winch brake failure that can take up the dynamic forces and stop a boat from lowering. Also suggested are dual HPU motors and pumps, where each motor would need to run from a different power supply. NORSOK 002 also recommends that the davit system complies with the EU machine directive, while davits located in an explosion zone on a rig should also be ATEX/EX compliant. Meeting these requirements adds significant cost.
“The paperwork also demands something approaching one man-year to produce documentation for the davit system,” Kalve observes. “In general, comparing a MOB boat davit with a capacity to handle a boat with SWL of 6 tons to a NORSOK davit with the same capacity, the price difference is 5-6 times. The NORSOK standard is useful in many respects, but meeting it is also costly.”
Summing up, he says: “The existing rules and regulations covering the use of davits at IMO need to be corrected for workboat davits and FRC/MOB davits. As we know, IMO rules are already hard to change, and change takes time. My misgiving is that, in NORSOK R-002, we have not come up with the right recipe to make the rules easier, and the steps that were supposed to address regulatory weakness are themselves flawed.”
About Vestdavit AS
Since 1975 Bergen-based Vestdavit has supplied over 1,800 davits and side and stern launch systems. We have proven ourselves over more than 30 years use in the North Sea and other harsh environments around the world. Vestdavit is a team of committed people with different backgrounds and experience that are all passionate about safe boat handling. Our key focus is on operational effectiveness, safety and the reliability of our equipment. For more information, please visit https://www.vestdavit.no.
The products and services herein described in this press release are not endorsed by The Maritime Executive.