I have always believed that IOMG could (and should) slow down any decision process regarding ferry service operation, these are some of my reasons for stating so;
1. There are too many pre-conceived ideas based on 'That's the way we have always done it so ...'
2. It is very rare in any major investment decision process to have some solid, long term, certainties on which to base your core assumptions (think financial services, offshore betting, technology investments etc. etc. etc. Here today - tomorrow?) - BUT, in this case - We know where Heysham is, Liverpool is, Douglas is, the depth of the Irish sea, the tides for the next 1,000 years, the silting rates, the harbour sizes, the (rough) population limits of the IOM etc. Good, solid, investment info - Gold dust!
3. Stop thinking about 'Travelling time' (speed) - think about 'Best time to arrive at destination' and 'Onboard experience'. Design the timetable around best arrival/departure times not 3 versus 4 hour journey times.
4. Brittany ferries deliberately slow down (and indeed 'hover') their Plymouth / Roscoff overnighters so that you can have a meal / drink, get a decent sleep, and start your car journey at 7am rested - who wants to start a six hour car journey knackered at 0445?
5. Engines do NOT propel ships! Propellers propel ships, engines turn propellers. Hull displacement and waterline length are critical factors in fuel consumption - but given the limitations in Douglas, Heysham and Liverpool, as well as Irish Sea average tides and weather conditions these factors are to a large extent pre-determined or at least pre-limited.
6. What will therefore most affect fuel consumption in this case is not ship size or sea conditions (because they are already pretty much determined) but hull and propeller efficiency. Get the prop configuration correct and you can retro-fit more efficient engines in future to drive the props that drive the ships.
7. You will not achieve best propeller efficiency with pods, CPP's, VPP's, or (especially) jets - you will achieve best propeller fuel efficiency by specifying the correct props for a stable constant speed (lower is better) and then fitting well designed props with low slip, minimal cavitation, decent blade area ratio characteristics. Propellers only ever work efficiently at one speed of rotation - if a ship leaves the Gulf carrying 500,000 tons of oil on a journey to Europe - does it really matter how long it takes to accelerate to cruise speed? That's why you see large-displacement ships propellers thrashing about like egg-whisks in harbour - they are not designed to get a ship moving - they are designed to keep the ship moving. Think 6th gear / overdrive and design the timetable accordingly.
8. Speed curves are not derived on sea trials, they are derived on initial specification, calculated during design, and confirmed to be within spec on sea trials - no surprises expected!
9. The Ben has one set of engines, props, gearboxes, generators, fire fighting systems, Manannan a completely different set, Arrow yet another. Countless different spares to be stored, three different crew training regimes, no common bits to be 'rabbited' off the spare boat to keep the in-service boat running whilst awaiting a spare part - COMPLETELY, UTTERLY, BONKERS.
10. Spend money on turn around time efficiency - take IOMSP staff down to Southampton to see how Red Funnel do it - it's like comparing an F1 pit stop to to a local garage tyre change.
Three boats, identical spec, built to suit harbours that will be here in 1,000 years time, one set of common spares, spare engine in container on quay under crane with hull 'soft patches' or bolt down hatches to enable 6 hour engine changes (max) ONE IN - ONE OUT, BOAT BACK IN SERVICE - SEND KNACKERED ONE FOR REPAIR - NO MORE 'BEN OUT OF SERVICE FOR EONS AWAITING ENGINE REBUILD - BONKERS. One crew training manual, one set of dry-dock blocks and props. Life rafts, seats, galley equipment, all on 'trickle down' to stand-by boat. Same fuelling rigs, same fuel spec and loads, same newspaper layout on shop shelves, same emergency evacuation procedures, same weather go/no-go decisions...................
Dont change travelling speed - Change number of BOATS IN SERVICE AND SCHEDULE TIMES to meet demand.
STOP - THINK - You have all the info you need to make a 100 year decision not a ten year decision - that rarely happens - PAUSE - GET IT CORRECT!
DESIGN THE TIMETABLE THAT BEST SUITS THE CUSTOMERS - THEN DESIGN THE SHIPS TO BEST PROVIDE THE TIMETABLE!