Investigate methods to improve Ro-Ro ferry survivability, including portable bulkheads

Alternatively there are lines of investigation that should be pursued urgently with the object of finding methods of improving the survivability of Ro-Ro passenger ferries. 50.1 The vehicle deck may be subdivided transversely by permanent bulkheads with doors. This method would bring a Ro-Ro ferry into conformity with Rule 24 of the 1984 Regulations. The ship would then parallel normal passenger ship construction. However, such transverse bulkheads, if permanent, even with doors, could constitute a grave penalty against the commercial operation of a ferry for its primary purpose. It is concluded that a feasibility exercise should be carried out to investigate the practical details of such divisions and their effect upon commercial operations. In the case of train ferries this method would be prohibitive. Trains are loaded in rakes and then compressed against buffers. No transverse division whether permanent with doors or portable could be accepted. The Court heard evidence from Mr. Taggart illustrating the potential effect of transverse bulkheads on the HERALD. Three bulkheads above the bulkhead deck were envisaged. Damage was assumed alternatively in way of two of these bulkheads. Considerable improvements resulted. Undoubtedly transverse bulkheads in the vehicle deck would effect a considerable improvement in the safety of these vessels, but the thrust of any investigation must be directed towards operational practicability. 50.2 An alternative possibility for subdividing the vehicle deck would be to fit portable transverse bulkheads. In one form these could be top or side hinged doors. Such bulkheads are fitted to deep sea Ro-Ro freight vessels. However with deep sea vessels the need for a minimal turnround time is not as pressing as with short sea ferries, especially on routes such as Dover/Calais. Loading has to proceed sequentially from the far end of the ship towards the ramp and this may introduce trim problems. Portable transverse bulkheads would increase the turn-round time and result in a small loss of stowage space. Alternative types of portable bulkheads could be envisaged, perhaps vertically sliding, housing below the bulkhead deck; but these would only be possible in the event that the bulkhead deck was not a strength deck. Other possibilities, such as vertical roller shutter bulkheads or alternatively sideways rolling shutter bulkheads should be investigated. A detailed study should be made of all possible types of portable bulkheads, both structurally and in terms of their practical effects including concomitant vehicle stowing disadvantages as mentioned above. If fitted, either these or transverse bulkheads with doors could afford a major increase in the survivability of Ro-Ro passenger ferries. It is conceivable that arrangements could be developed to keep loss of space and vehicle handling time within acceptable limits. 50.3 Another possibility is to divide the vehicle deck with side longitudinal bulkheads, the space outboard of these being themselves subdivided transversely. The Court heard evidence on this proposal. This was in the context of the HERALD herself. The inboard side of the line of casings was on the B/5 line in the midships area. Bulkheads were envisaged extending fore and aft until reaching the forward and aft compartments, with three transverse bulkheads in the main length of each outboard space. Suitable access doors were postulated. On the assumption that two compartment damage did not penetrate the B/5 bulkhead, the result was a range of stability and GZ giving full compliance with all the required damage criteria. This proposal is practicable and satisfactory in the context of a vessel with twin casings. It would not be applicable to vessels with centreline casings. The arrangement would be likely to be dangerous should damage penetrate beyond the B/5 line. Mr. Rogan introduced evidence from 1974 I.M.O. Regulations on subdivision and stability concerning the statistics of damage penetration from 296 penetrations. This indicated that approximately 45% of penetrations exceeded the B/5 line. Mr. Rogan gave his opinion that this could produce a more dangerous situation than would have existed without the longitudinal bulkheads. The Court agrees with this view. However the proposal has some attractions and there is an urgent need for investigations into the effect of longitudinal bulkheads on a range of vessels. These investigations should include depth of penetration probability statistics and a definition of the risks involved with different configurations and penetrations.