Supplement 5-6 Wet Ship Design

[Timerover51]

Paul R. Tregurtha per Mongoose Supplement 5-6 Building Rules

Just as a trial, I put the Paul R. Tregurtha, currently the largest bulk carrier on the Great Lakes, into the Mongoose Supplement 5-6 rules to see how it would look. The results are quite interesting. The dimensions of the ship are as follows, in both English and Metric. The length is 1,013 feet 6 inches or 308.91 meters, beam is 105 feet even or 32.00 meters, depth of main hull body (this is not draft but the depth from the keel plating to the top of the highest continuous deck, so does not include the aft superstructure) 56 feet even or 17.07 meters, loaded draft with 68,000 tons (long tons of 2240 pounds) or 69,092 metric tons of iron ore pellets is 30 feet 1 inch or 9.17 meters, and a light displacement, i.e. empty ship, of 14,497 tons (again long tons of 2240 pounds) or 14,730 metric tons, which would be the empty weight or mass of the ship. She is powered by 2 Diesel engines with a combined horsepower of 16,080 b.h.p., and has a top speed of 15.5 miles per hour or 25 kilometers per hour. She also has a 1500 horsepower bow thruster. I am not sure what the range is, and she would have a crew of around 30 or so, per U.S. Coast Guard manning requirements. She is a self-unloader and can off-load 10,000 tons of ore pellets or 6,000 tons of coal per hour, and was christened on 25 April 1981.

Now, just taking the dimensions of the basic hull, and she has a parallel body structure for almost the entire hull, she would be, figuring a space as a 1.5 meter square and allowing for 3 meter deck height, 205 spaces long, 22 spaces beam, and 12 spaces deep. Except for length, I am rounding up, but I am also not accounting for the aft superstructure, so this should be a good approximation. Multiplying all of this out gives me a total of 54,120 spaces for the ship hull.

Now, per the large ship design rules, the cost per space is 8,000 credits, and hull and structure equal 1 point per 2 spaces. For ship mass, important in a water vessel, 1 hull space equals 2,000 kilograms or 2 metric tons of mass. For the power plant, I assume that heavy ship equates to large ship, and the requirements for that equal one-half to two-thirds of the inhabited part of the vessel. Now, this would be in addition to the already computed space of the ship.

Based on the 54,120 spaces, the cost would be 432,960,000 Credits, just for the hull. Actual cost in 1981, about $60 million. Based on the 1 Hull point equalling 2 metric tons, the empty mass of the ship should be 54,120 metric tons, and that would not include the power plant, which is included in the 54,120 spaces of the actual ship. Note, the power plant takes up a LOT less than one-half to two-thirds of the hull. Actual light ship mass is, including power plant, 14,730 metric tons. To transport the Tregurtha via star ship to another planet would require a ship with an capacity of well in excess of 54,120 spaces, as remember, I was not including the aft superstructure in the space calculation, and that would be a star ship with that large an unobstructed cargo hold. Basically, a star ship quite a bit larger than 54,120 Traveller displacement tons, as that is just the cargo hold capacity. Not sure why you would want to carry a complete ship to another planet, as 14,730 metric tons of steel and other material takes up a lot less room.

Based on how I understand the combat system, the Paul R. Tregurtha is going to be awfully hard to sink, as it looks like you first have to destroy all of the Hull points before going after the Structure points.

For those who would like to check out the actual ship, the information and a lot of photos can be found here.

http://www.boatnerd.com/pictures/fleet/prtrgrth.htm

Oh, and before someone gets upset about my using the ship that I did, there are quite a few "footers", or 1,000 foot long ships, on the Great Lakes. There are also the current crop of extremely large cruise ships of the Royal Caribbean Line, and of course, your supertankers that would make the Paul R. Tregurtha look small.

 

[Timerover51]

An added comment when it comes to wet ship design, up to circa 1950 Real World, for Battleships and similar vessels. Norm Friedman, in his book, Battleship Design and Development 1905-1945, discussed the 60-40 rule for battleship design, where 40 per cent of the weight is in the hull and superstructure, and 60 per cent of the weight is in the armor, weapons, and machinery. Machinery weights for the ships covered in the book, pretty much all battleships built from 1905 to 1950, averaged around 10 per cent for battleships, with the early British Battlecruisers going as high as 20 per cent. The 40 per cent of hull included the space for fuel, either coal, oil, or both.

One factor, little appreciated when it comes to evaluating a design, is the increase in protection accorded by coal bunkers both against shell fire and torpedoes. Two feet of coal was equal in resistance to 1 inch of steel plate, and a full coal bunker was quite effective at processing the energy of a torpedo hit. However, longitudinal bulkheads are very bad ideas if you are hit with a torpedo, especially if the bulkheads are in the boiler rooms or engine room spaces. Asymmetrical flooding tends to make a ship capsize very quickly.

 

[Vladika]

An added comment when it comes to wet ship design, up to circa 1950 Real World, for Battleships and similar vessels. Norm Friedman, in his book, Battleship Design and Development 1905-1945, discussed the 60-40 rule for battleship design, where 40 per cent of the weight is in the hull and superstructure, and 60 per cent of the weight is in the armor, weapons, and machinery. Machinery weights for the ships covered in the book, pretty much all battleships built from 1905 to 1950, averaged around 10 per cent for battleships, with the early British Battlecruisers going as high as 20 per cent. The 40 per cent of hull included the space for fuel, either coal, oil, or both.

One factor, little appreciated when it comes to evaluating a design, is the increase in protection accorded by coal bunkers both against shell fire and torpedoes. Two feet of coal was equal in resistance to 1 inch of steel plate, and a full coal bunker was quite effective at processing the energy of a torpedo hit. However, longitudinal bulkheads are very bad ideas if you are hit with a torpedo, especially if the bulkheads are in the boiler rooms or engine room spaces. Asymmetrical flooding tends to make a ship capsize very quickly.

And coal dust is explosive. Also, an HE burst ignites coal pretty well. Still it did help considerably. During WW1 U Boats often could not achieve good results with only the deck gun. Merchant machinery spaces (boilers at any rate) were fairly well protected, when coal bunkers were full.

 

[Condottiere]

Warship designs are by nature compromises; coaling was a dirty, dirty job, though one of the few where the officers took part. Oiling was just more efficient and faster, and if you can outrun submarines, you don't need to worry about them.

Also, the most beautiful and balanced battleship was probably HMS Vanguard, who unfortunately was built twenty years too late. You needed around forty five thousand tons to achieve that balance.

 

[Timerover51]

Warship designs are by nature compromises; coaling was a dirty, dirty job, though one of the few where the officers took part. Oiling was just more efficient and faster, and if you can outrun submarines, you don't need to worry about them.

The following ships could all out-run submarines: IJN Shinano, IJN Taiho, IJN Shokaku, IJN Kongo, IJN Atago, IJN Maya, IJN Ashigara, USS Wasp, USS Indianapolis, USS Juneau, HMS Barham, HMS Royal Oak, SS Lusitania, numerous British pre-Dreadnoughts, and a very long list of other cruisers and destroyers, along with several million tons of merchant shipping.

The IJN Taiho is a very interesting case, being sunk by a single torpedo hit, from a submarine, and some appalling bad damage control.

Also, the most beautiful and balanced battleship was probably HMS Vanguard, who unfortunately was built twenty years too late. You needed around forty five thousand tons to achieve that balance.

The HMS Vanguard was an excellent ship, but the 15 inch main battery did date from World War 1, although the British 15 inch gun was one of the finest large-caliber guns ever designed and built.

 

[JimMarn]

The HMS Vanguard was an excellent ship, but the 15 inch main battery did date from World War 1, although the British 15 inch gun was one of the finest large-caliber guns ever designed and built.

The 15-inch gunned warships were turned into 'monitors' in WW2. Bunker busters on the canals leading to Antwerp. Firing missions at Normandy as well.

 

[Timerover51]

The 15-inch gunned warships were turned into 'monitors' in WW2. Bunker busters on the canals leading to Antwerp. Firing missions at Normandy as well.

The turret on the HMS Abercrombie was a spare turret built for the light battlecruiser turned aircraft carrier HMS Furious in World War 1, if the 18 inch guns that she was built originally to carry proved to be failures. The turret on the HMS Roberts was the one removed from the HMS Soult, one of the four World War One 15 inch monitors. The British built four 15 inch monitors in World War One, the HMS Marshall Ney, the HMS Marshall Soult, the HMS Erebus, and the HMS Terror. The Ney was a flat-out failure, the Soult was usable to an extent, while the Erebus and Terror were built based on the lessons learned from the Ney and Soult. The Erebus and Terror were used operationally in World War 2, with the Terror being sunk in the Mediterranean off of Tobruk. The Erebus was used during the Normandy Invasion and survived World War 2.

Ian Buxton's book, Big Gun Monitors, has an outstanding description of the development, building, and use of the monitors in World War One and Two.

 

[Condottiere]

Shinano - commander made a tactical mistake that brought his speed down to eighteen knots and zig zagged into the submarine's range.

Royal Oak - sitting target at anchorage.

Barham - torpedoed at close range, without any time to take evasive action

Lusitania - three operational boilers reduced the maximum speed to 21 knots, no camouflage, and wrong place, wrong time.

Pre-dreadnoughts - operated under an obsolete doctrine, which the construction of the Dreadnought busted, and then the Queen Elizabeths.

The current big fish targets are the American supercarriers, and their nuclear reactors can outrun modern submarines, because if the attack submarines do want to drag race, they lose their cloak of silence and get hunted in return.

 

[MongooseMatt]

The current big fish targets are the American supercarriers, and their nuclear reactors can outrun modern submarines,

Unless, of course, they make a tactical mistake and start zig-zagging, are a sitting target at anchorage, get torpedoed at close range, have their speed reduced, or operate under obsolete doctrines

 

[Condottiere]

That's what happens when the TL jumps up or goes up incrementally.

It's debatable at this moment whether a carrier would survive against a peer opponent, but the danger seems to lie more from missile attacks, which is why the Americans are keen to develop a viable energy weapons system (TL jump).

There is an attack submarine trailing every deployed carrier, there may be another cruising in the area. If you want to sink one, it probably won't be by torpedo.

 

[MongooseMatt]

There is an attack submarine trailing every deployed carrier, there may be another cruising in the area. If you want to sink one, it probably won't be by torpedo.

Unless it is air-launched

You are right about the debate, with those against citing the shift away from battleships towards airpower as having happened to carriers sometime ago - we just have not had a war to prove it yet.

I find myself in that camp, especially with some of the missiles flying about these days, though I note those who love their ships are somewhat set against it. I can wax on about the idiots in the British government who decided to build two supercarriers (and then use one), and the tragedy of the F-35. But then again, when it comes to political idiocy, there is just so much to choose from!

It is possible we have moved off-topic

 

[Timerover51]

It is possible we have moved off-topic

Somewhat, but the idea was to trigger some discussion of design sequences. I would say that you can develop a set of design sequences for water-(or other liquid)borne vessels, but not a single design sequence.

The design sets would include: muscle-powered vessels, wooden sailing vessels (with a subset for metal- or other material-hulled ships), non-combatant steam ships, ironclad and other combatant steam ships, and submarines. The steam ship category would include steam power (reciprocating engine and turbine design) and internal combustion engine design, with maybe a subset for the internal combustion engine, and fission-powered nuclear ships.

I am working on a preliminary system for wooden ships and basic steam ships, both combatant and non-combatant. The muscle-powered set is going to have to wait until I figure out where a put a couple of books on naval warfare under oars.

 

[Timerover51]

That's what happens when the TL jumps up or goes up incrementally.

It's debatable at this moment whether a carrier would survive against a peer opponent, but the danger seems to lie more from missile attacks, which is why the Americans are keen to develop a viable energy weapons system (TL jump).

There is an attack submarine trailing every deployed carrier, there may be another cruising in the area. If you want to sink one, it probably won't be by torpedo.

Based on a very detailed study done in World War 2 by the US Navy Bureau of Ships on what it took to sink WW2-era ships with airborne weapons, and applying that to the current range of US carriers, there are very few missiles that can inflict major damage on a US carrier, while the torpedo protection system is going to be fairly hard to defeat. When it comes to the now-retired battleships, there is very little of anything, except 2,000 pound deep-penetrating bombs, that would really cause damage to them, full size submarine torpedoes excepted.

The current big fish targets are the American supercarriers, and their nuclear reactors can outrun modern submarines, because if the attack submarines do want to drag race, they lose their cloak of silence and get hunted in return.

Have you ever heard of long-range wake-following torpedoes, which the former USSR developed for use against carriers? And if the seas are rough, the carriers do have to slow down a bit. Then you do have the carrier escorts as well.

 

[Condottiere]

I haven't trusted Russian maritime hardware since the Kursk, and when Putin decided he needed French expertise to build amphibious ships.

 

[JimMarn]

I remember watching a documentary some years ago on television which pointed out most navies could handle just so many attacking aircraft against a battle group. After that, the defenses become overwhelemd and the escorts cannot block all attacks headed to the aircraft carrier.

When I served aboard ship, one of the things I was told was that our ship was to absorb hits aimed at the carrier from long distance.

I was a long time out of the U.S. Navy when I heard about the Exocet missle. I think several of those could sink a super-carrier.

 

[Timerover51]

I was a long time out of the U.S. Navy when I heard about the Exocet missle. I think several of those could sink a super-carrier.

Hmmm, maybe if you hit it with about 50 of them, on the same side, you might have a chance. And that assumes that the Exocet fuze works properly. Based on combat usage, it had about a 50% failure rate.

 

[Timerover51]

I haven't trusted Russian maritime hardware since the Kursk, and when Putin decided he needed French expertise to build amphibious ships.

I would suggest that you take a look at how many navies have had trouble with hydrogen peroxide using torpedoes. The previous amphibious ships that the former USSR used were primarily built in Poland, which I suspect is not likely to be building ships for Russia.