Archimedes was not entirely right. For a boat to be unsinkable, not only does it have to experience the famous vertical thrust, but it also had to have - until 2006 - certain specificities.
One of these specificities was that it had to maintain a navigational capacity (notably to be manoeuvrable) once submerged. In addition, it should not be able to be completely filled with water, keeping a sufficient height of freeboard. In order to achieve this, these boats took on board, instead of storage lockers, compartments filled with aerated foam. The major disadvantage of these buoyancy reserves was the loss of space. This disadvantage was amply compensated for, as you will have understood, by the effective safety offered by this type of boat: even with a pierced hull, it could return to port by its own means.
Our new boats can no longer be approved as "unsinkable"
Should? Yes, because the administrative principle of unsinkability, which made it possible to avoid the need to have a lifeboat on board, has disappeared for modern boats. At present, this standard no longer exists and it is no longer possible in France to approve boats that meet this specificity. Today, only boats that inherit the past possibilities (and that have not been modified) can be qualified in this way, depriving these boats of any evolution.
And yet, it floats!
The fact that a boat floats and complies with the standard that has disappeared is no longer sufficient for it to have a certificate of unsinkability. A new boat (by design) can only claim this quality if its structure is identical to that of a unit that was approved before the standard was abolished. Few boat builders market unsinkable units. Indeed, to offer an unsinkable boat today is to announce to the buyer that it has not evolved structurally for some fifteen years...
A unique opportunity among boat manufacturers
In the family of motorboats, Zeppelin is proud to offer models that have been certified unsinkable within the meaning of the Order of 6 March 2000 and which have not evolved structurally since. The Narwhal brand offers the HD-580, which is certified unsinkable and guarantees, moreover, that the rest of the range is also. Please note, however, that the declaration presented only concerns the above-mentioned model, as the rest of the range is only certified by the manufacturer.
Moreover, no other brand - to our knowledge - offers this quality on its boats.
Boats that are approved as unsinkable, both new and used, carry a plate and the relevant certificate. And their ability not to sink must not only meet the strict criteria of this standard in terms of design (height of freeboard once the boat is filled with water, amount of flotation reserves ...), but above all, the boat must be used in compliance with this standard (number of passengers, weight carried, non-transformation of foam spaces ...).
Of course, it is imperative that no holes are made in these boats, whether in the foam tanks or elsewhere. The superstructure also counts for the bulkheads that isolate certain compartments. Similarly, in order to maintain the unsinkable capacity of these boats, it is necessary to respect the maximum loads, whether it is a question of the motorization or of the load, crew and accessories.
The second-hand market
The second-hand market is full of boats dating from the 2000s, some of which have been standardized and have the appropriate plate. We recommend that you inspect the boat you are considering and have it appraised by an expert in this type of boat. This is the only way to validate the "unsinkable" designation of the boat.
Life raft exemption as an additional argument
The fact that these boats cannot sink and maintain their manoeuvring capabilities means that a life raft is not required when sailing more than 6 miles from a shelter. This is a substantial saving, both in terms of acquisition and overhaul. But the argument is not limited to this. The safety offered by these boats makes them worth considering even today and examining their possibilities carefully.
