Existing technologies in the cruise ships and oil platforms industries have proven to be safe. As with anything, of course, there are risks, but seasteads will employ much of the same safety technology, such as storm warning systems, that are currently used in the ocean industry. We also expect early seasteads to be mobile and/or modular and able to move to avoid storms. Later seasteads will likely employ artificial breakwaters to protect them from rogue waves. Of course, as we continue to gather information about safe designs, risks lessen.
Our approach to hurricanes and other severe weather is threefold: 1) Avoid being in an area where severe weather hits, if possible; 2) Build structures that can withstand the worst storms expected in a seasteading area; 3) Design platforms, modules or adjunctive seacraft that can move out of the path of storms or other severe weather—whether seasonally or immediately (i.e., within a few days of advanced warning).
Can a floating platform weather typhoons and so-called “rogue waves” that can swell to more than eight stories tall?
Modern semi-submersibles are built to withstand once-in-a-hundred-years waves by locating the platform significantly higher than the water and by building a strong, resilience-engineered structure. Simulations have shown that semi-submersible platforms can survive rogue waves, but a sturdy mooring system is important. This is an important area of research The Seasteading Institute will engage in over time. We believe our research will mitigate those risks.
As for wave motion, seastead structures will be designed to reduce coupling with the surrounding waves. One way to accomplish this is by keeping the structure’s center of gravity below the waves. Wave motion can also be reduced by locating seasteads in calm areas of the ocean. As seasteads grow in size, that too will reduce wave motion. Just as passengers on large cruise ships often can’t feel the waves beneath them, neither will the residents of large seasteads. With time people will earn their “sea legs,” and become acclimated to the remaining wave motion.
Although piracy receives a lot of press, it is a relatively rare phenomenon. Pirates typically lurk off the shores of unstable regions, such as the southern coast of Africa. Seasteads can avoid most piracy risk by locating far away from these regions. Also, relative to other targets such as container ships, seasteads represent a poor risk/reward ratio to would-be pirates. Container ships carry mostly cargo and small crews. Seasteads carry relatively little valuable cargo and large (likely armed) populations. Seastead residents are likely to fight much harder than container ship crews, as they are defending their own homes and businesses, not a corporation’s insured property. Therefore, it will be wise for pirates to avoid seasteads in favor of easier prey.
Much piracy is small-scale theft—for example, of the 335 attacks reported in 2001, only 73 involved guns. Sixteen ships were hijacked, and 21 people killed (all but one in Asian waters). A sea-city will be much too large for this kind of crime. Even an individual seastead—a concrete tower—will be a much tougher target than a luxury yacht. Piracy against yachts is mainly notable for being vivid and exciting, and is rare enough that the ocean is still full of private pleasure craft. Still, we recommend that small seasteads avoid the pirate hot spots such as Southeast Asia and Somalia.
There are larger organized criminal groups involved in piracy that capture entire ships and their goods (often worth tens of millions of dollars). These groups have even been known to use forged documents to obtain a new load of cargo from legitimate shippers, and then steal it. It is worth noting that these groups specifically target container ships. This is not at all surprising, given that container ships only have a few crew and vast amounts of nicely boxed cargo. A cruise ship has fewer marketable goods, and many more people to handle. A cruise ship might have 100 times more passengers and crew per dollar of movable cargo than a container ship. A simple cost/benefit analysis suggests why pirates tend to focus on the latter.
While it is possible to escape the full force of an ocean storm by submerging beneath the waves, it is not simple or cheap. To completely escape the sub-surface pressure variations from severe waves, one would have to be more than 500 feet below the surface. A small submersible would likely be tumbled about severely at depths less than 100 feet. Even larger vessels like military submarines have to dive deeper than 100 feet to ride comfortably in stormy seas. Moreover, these pressure variations can increase the structural loads on the hull, and are particularly worrisome because of the additional loads imposed on windows and doorways that are often envisioned for submerged seasteads.
Submersible seasteads are certainly possible, but are not cheap relative to floating seasteads. Submerged vessels must have sufficiently sophisticated and reliable ballast systems that will allow them to accurately maintain their target depth. For a vessel on the surface, floating is relatively easy, because there is ‘reserve’ buoyancy in the hull; if weight is added or buoyancy is lost (due to a leak), the hull can continue to float, albeit at a deeper waterline. But for a vessel below the surface, there is no ‘reserve’ buoyancy; if it springs a leak or simply wants to return to the surface, it must eject water from its ballast tanks or otherwise increase its buoyancy.
The Institute neither encourages nor endorses the idea of building submersible seasteads for the purpose of avoiding weather hazards at sea.
See this blog post by Director of Engineering George Petrie for a longer discussion of submersible seasteads.
Posted on June 10, 2013 at 6:58 pm