Helicopters on yachts
It sounds simple enough. Helicopters can go pretty much anywhere, so why not land on my yacht? If there’s deck area that’s strong enough and big enough then why not?
It’s not that simple
I wish it was.
All the extra detail, the procedures, the crew training, the rules that seem like overkill, the owner who wonders what all the fuss is about…
But then it happens - the accident that reminds you how fragile helicopters really are, and how fragile we are as well. The internet recalls too many videos of accidents caused by stray objects weighing a few kilograms bringing down helicopters weighing tonnes.
What’s required?
It’s tempting to look at the skids/wheels of a helicopter and think about the deck space they need. Classification societies (as the authority responsible) will look rather at the main rotor diameter and weight of the aircraft. Which makes sense in hindsight - some strange and nasty aerodynamic effects can occur at rotor blade tips if they come close to ship superstructures.
Classification societies have rules for what they consider to be a ‘compliant’ helideck. These rules are a slowly adapting version of the CAP 437 rules for offshore structures (oil rigs etc). These rules ensure that when a pilot approaches the vessel in question, they can be sure of a number of factors such as the geometry of the aiming circle and where obstacles on deck may or may not be. They can also be sure of the availability of appropriate fire fighting facilities and trained crew.
The rules for the structural design of the deck allow for high loads made in emergency landing situations. These highly localised loads are very different to the distributed loads created by water on deck, and even decks designed to withstand metres of green seas may struggle to comply with the point loads generated by an aircraft in trouble.
This is why it’s risky to make assumptions about whether the deck strength is adequate for landing.
‘Touch and go helipads’
…are not actual helipads as far as class is concerned.
The theory of ‘touch-and-go’ is that the aircraft does not power down - it keeps the main rotor running in order to not place the entire weight of the aircraft on the deck. Risk factors to consider here include the impact of wind gusts and movement of the vessel. If there’s a surprising gust of wind and the aircraft moves even slightly, what does this mean for passengers who have half stepped out on to the deck?
If the boat isn’t being chartered (no paying guests on board) and the pilot and the captain think it’s safe, then the burden for safety is on the captain and the helicopter can land wherever seems fit.
Just remember that when you read about ‘touch and go’ pads, it’s industry code for a non-compliant helideck.
The detail
The details of what’s required can be found in the ‘common annexes’ section of the latest yacht code rules. These documents cover the rules from the Red Ensign flag states that are common for both smaller and large yachts. Annex ‘H’ is the current go-to for helicopter landing areas ‘HLA’s.
This annex will effectively require the shipyard to have the deck arrangement approved by an approved ‘Aviation Inspection Body’ who will sign off the deck design and construction detail on behalf of Class and the flag state. It pays to get design advice early in order to minimise the risk of expensive compliance costs. (You’d be amazed at what compliant lighting systems for night helicopter operations can cost!)
The annex also gives indicative values of weights and rotor diameters of common helicopters which are handy starting points for drawing up general arrangement plans.
Fuel handling
If you’re planning on needing to fuel or de-fuel helicopters, be prepared for more complexity. Jet A-1 (the fuel used in turbine engines - most helicopters aside from the smaller Robinsons) is prone to microbial growth (fun PDF here from Boeing) which impacts the design of any fuel storage tanks on board the vessel, as well as the ability to re-use any fuel removed from an aircraft for storage.
As is our mantra, getting ahead of these issues in the design stage can greatly minimise cost and disappointment later in the project.
The wrap
I hope you’ve found this quick look at heli ops illuminating. Like so many aspects of boat design, there’s more to it than meets the eye.
If you’ve any questions or comments at all, please don’t hesitate to get in touch.
Take care,
Nick