It can therefore be seen that the envisioned framework of SGISC gives significant importance to ship-specific operational measures (operational guidance, or operational limitations)。 Actually, the framework of the SGISC can be seen as a shift of paradigm, going from the current situation where ships are regarded as safe when designed and loaded in accordance with the current stability criteria under the assumption they are operated on the basis of generic good seamanship, to a situation where ships would be designed also considering the possibility of developing ship-specific operational guidance as a means for keeping the likelihood of stability failures below an acceptable limit。 The present target date for addressing “guidelines for direct stability assessment” and “requirements for development of ship-specific operational guidance” within SGISC has been set to that of SDC 4, which is expected to be held in 2017 (IMO, 2015)。 The SGISC framework is then supposed to be initially implemented as non-mandatory regulations through the 2008 IS Code, and a possible mandatory application is therefore likely far away in time。 Under such a situation, a series of questions arise。 To what extent will these new voluntary criteria actually be used if they are not forced by a mandatory framework? How many shipping companies/ship owners will dedicate resources to fulfil these criteria if they are non-mandatory? Will the owners/designers be interested in a pro-active verification of non-mandatory criteria, in view of a possible future mandatory application, or in view of having a better understanding of the dynamic characteristics of the vessel? Will this lead to a wider, more informed, introduction of operational-oriented measures? And how could operational measures be used to increase the safety of some of existing ships that would obviously benefit from stability and safety improvements, but which will not be affected by the new criteria?

However, irrespectively of the specific regulatory framework, it is clear that efforts should be spent, in general, to introduce operational measures in the design process, as viable and accepted risk control options。 Indeed, implementing operational measures can represent a cost-effective way for increasing safety and, also, competitiveness。 An example in this respect can be found in the case of inland navigation (Bačkalov, 2015; Bačkalov et al。, 2015), where suspension of navigation is sometime introduced in case of too harsh weather conditions (strong winds, among other envir-onmental phenomena)。 In some cases, navigational limitations based on weather conditions are also introduced, on a local basis, for sea-going vessels (to avoid, e。g。, port entrance problems)。

However, a vessel able to operate safely in such harsh conditions could become more competitive, if the cost-effectiveness analysis indicates so。 Similar considerations could also apply to vessels operating in sheltered waters, on specific routes, etc。 Furthermore, in a wider perspective, the implementation of proper operational measures can reduce the risk of, e。g。, claims due to cargo loss or damage, thus improving, through better safety records, the image of the ship owner/operator as a reliable, and then more competi-tive, company。

Implementing such an approach is not free from technical and regulatory challenges, which, at this moment, have not really been sufficiently addressed。 As a result, several questions are open and more are likely to come。

Operational limitations could be introduced by changing the reference environmental conditions for the evaluation of intact stability criteria, when this is feasible according to the structure and background of the criterion (this is doable, for instance, at Level 2 vulnerability assessment in the framework of SGISC)。 The vessel should then be approved with such limitations noted。 Operational aspects are presently under responsibility of the Administrations。 In presence of operational limitation, it could be necessary for the master to demonstrate the compliance of the planned travel (loading condition, route and associated weather forecasts) before leaving the port, and such plan should be approved by the Administration。 In this phase, the unavoidable uncertainty in weather forecasts should also be appropriately taken into account, and attention should also be given to other possible sources of uncertainty (e。g。 in the parameters describing the loading condition)。 It is worth noting at this stage that operational limitations are well-known in rules for classification of vessels for combined river-sea or sea-river navigation (Bačkalov, 2012), and therefore some experience could be gathered from that field。 In the same context, approaches have also been developed to allow the extension of operation of inland vessels (with few modifications) in coastal areas up to a certain, pre-computed, significant wave height (Vantorre et al。, 2012)。 Furthermore, weather restrictions are routinely used in the current regulatory practice by Administrations and Classes (the already mentioned case of inland/coastal ships, but also, e。g。, high-speed craft, route-depending lashing of container ships, MPVs and heavy-lift carriers, etc。)。 It is however evident that having this procedure in place for a large number of sea-going vessels would require significant pro-cedural efforts and infrastructure development。