Just as the Queen Elizabeth 2,in 1969,was regarded by almost all as the last large passenger ship...now numerous larger ones up to twice the size are building...so the speed record is generally regarded as forever to be held by the SS United States,unless one counts small craft never designed for carrying passengers across oceans.
Technology has not stood still since the SS US set its formal record in 1952,nor is there any reason that it should be considered the monopoly of short-haul ferries.It is time the task of engineers was set to rewriting the record book.
Length in feet Hull speed(Kn) Actual speed(Kn) 477.7(Aries) 29.2 45 882.7(Titanic) 39.8 22 963(Queen Elizabeth 2) 41.5 28.5(peak service,32 claimed top) 990(SS US) 42.1 35.59 and higher 1019(Queen Mary) 42.7 31.69 1029(Normandie) 42.9 29.98 1100 44.4 ? 1150 45.4 ? 1200 46.4 ? 1250 47.3 ? 1300 48.3 ?As you can see,it's not quite that simple.A ship with a poor design like Titanic can fall well short of hull speed.A ship like Aries,a new Italian monohull fast ferry,can exceed its hull speed through planing,like a speedboat,which is also how the Destriero,222 feet with a hull speed of 19.9 knots,managed to grab the Atlantic absolute speed record with a crossing at 53.09 knots.Hull speed is supposed to be for a "displacement monohull",hence a catamaran like Catalonia(whose 299' length would give it a hull speed of 23.1 knots,but which crossed the Atlantic at 38.77) or its identical sister Cat-Link V(39.9 knots point to point,41.284 with detour) or a hydrofoil or hovercraft does not come under this formula.Further,the formula is fudgy...the length for the Queen Mary above is its overall length,but hull speed applies strictly to its waterline length,somewhere between that and its 975' length between perpendiculars.
Within displacement monohulls design is still a major factor.Although the Normandie was slower with a higher hull speed than the Queen Mary, the Queen Mary had 25% more power needed to produce its superior speed... its hull was actually a slower,fatter,deeper-displacing design.The SS United States,with a lower hull speed but more power(240,000 HP) than either,reportedly *used* less power than either(150,000 vs. 160,000 for Normandie and 200,000 for Queen Mary) to break their records.On its trials it officially did 38.23 knots,but unofficially is understood,at full power, to have reached 43 knots with a theoretical top of 44(officially it was 41.75)...in other words,it exceeded its supposed hull speed.
Hull speed is not a strictly limiting factor,but is usually a practically limiting one.Power offers less and less of a return per unit added when you reach hull speed.Various factors in the shape of the hull optimize performance,including high length-to-beam ratios,planing tendencies,and more.
Given the opportunity to apply new technology to the design of the hull, a new engine technology that makes higher power easier to obtain than ever before,and the will to build a new vessel of heroic size,records can be shattered.
From the table above,one can tell that a ship of the size under consideration would have a hull speed of roughly 45 to 47 knots.To do a better job of performing relative to hull speed than the SS United States is a reasonable design goal.
41.3 knots is the current minimum goal for a routine service speed, in order to provide Blue Riband level service as a norm.However, this is only a starting point.A record barely set is a record prone to being re-broken.
The speed attainable would of course influence the schedule. A logical service goal is weekly round trips,with excess speed over the minimum needed for this enabling additional stops.
The shortest navigable distance between New York and Southampton is about 3169 nautical miles,so allowing for non-ideal routes in practice a *pier-to-pier* average speed of 40 knots would yield a crossing time of 80 hours and allow 4 hours turnaround...a little bit more than the QE2's record,but uncomfortably less than its scheduled interval (over 9 hours).(A Gigantic turnaround would differ from a QE2 turnaround in needing to handle more passengers,but fewer provisions per passenger).Of course,the crossing could not all take place at a set high speed...if one assumes 10% must take place at an average of 20 knots,42 knots on the remaining 90% would give an average of 39.8 knots,43 knots on 90% would give an average of 40.7 knots, 44 knots on 90% would give an average of 41.6 knots,and 45 knots on 90% would give an average of 42.5 knots for the whole voyage.
44 knots on the high-speed 90% of the crossing and 20 knots on the rest,then,would enable a crossing time of 3 days 5 hours to be scheduled,with 7-hour turnarounds,and 45 knots on the high-speed portion would cut the crossing by over an hour more.This range would be within hull speed,and within the engineering capability of the ship,though not very easy to sustain.To go higher would be desirable if it could be made reliable,but effectiveness at the margin would bear serious scrutiny.
Averaging 42.5 knots en route would cut a New York-Cape Town or Cape Town-Melbourne crossing to six and a half to seven days,and Melbourne-Vancouver to seven and a half...recall that the QE2 takes fourteen weeks or more for a world cruise,and even though we are talking about a ship that would have to go around Cape Horn,you can see that this could be cut in half if desired and multiple scenic stops still added.(Like the QE2,there would likely be one world cruise a year,but ocean-crossing would be more predominant...see itineraries).
Any who wish are welcome to offer feedback.