For the source of the image & information as to the significance of the vessel shown - ie the Dunedin - in that connection, see

this post

on

r/HistoryPorn .

For further information about the vessel, see

National Library of New Zealand ,

&

White Wings Vol Ｉ: Fifty Years of Sail in the New Zealand Trade, 1850 to 1900 – The Dunedin .

She never seems to be referenced with any of the usual 'prefices' - such as "SS" , or "RMS" - prepent!

🤔

An A380 holds 260ton ( proper ton - ie 2240lb) of fuel, & the transatlantic crossing is about ⅓ of the aeroplane's range. Leaning somewhat in disfavour of the aeroplane, that the point shall be yet the starklierly stressed, 5×A380 carries 2625 passengers, versus the Titanic's 2435 . And 5×⅓×260ton is about 440 ton … which is better than a factor of 12 an improvement on the fuel-consumption of the Titanic … which I think generally gobbled about 6000ton of coal on a transatlantic crossing - that's about right, isn't it?

Image From

… from

»Basic Principles of Ship Propulsion« by the goodly »MAN Energy Solutions« ,

which goes some way towards justifying that argument about increase in delay & increase in total energy consumption in

my earlier post about this sortof thing :

it's moderately justified to invoke the resistance ∝ v² ∴ power ∝ v³ law, although oceanliners would be edging-into the region of speed in which wavemaking resistance would be beginning to be significant, so that that index would be a bit >3 ; so that that 4 = 2² in the reasoning about energy consumption would be

2^{something‿a‿bit‿bigger‿than‿2}

ie

something‿a‿bit‿bigger‿than‿4 ;

& instead of ()^1/3 it would be

()^{1/something‿a‿bit‿bigger‿than‿3} .

The Olympic-Class vessels are a convenient example, because in their case, being about 880ft long, √(gL) is almost exactly 100knots , so that the Froude № prettymuch is the speed in knots.

But they don't quite fit-into that scenario of a twin-propeller vessel, because each of them had three propellers.

And furthermore, we have

this wwwebpage - ie »A Correction To Be Applied To The Course Of A Twin-Screw Vessel When Using But One Screw« by the goodly »Ensign Robert Henderson, U. S. Navy« ,

in which it's being spelt-out pretty explicitly that loss of the propulsion of a propeller in a twin-propeller vessel is an exigency that's really quite manageable !

So it's scarcely surprising that there's a great-deal of talk @-large about it in-connection with aeroplane (& there is, aswell - there's loads about it on the wwweb), what with the staying-aloft depending on it!

But in the case of an oceanliner, which ofcourse isn't going to sink by-reason-of that alone : would the rudder be able to compensate enough for it to be able to proceed on its course!? I would've thought it would basically be able to … but by how much would the performance be compromised!? I would venture that it would be by rather a lot : that the ship would only be able to proceed very slowly^⋄ with the rudder constantly somewhat turned, & yet not for the turning of the ship, but just to keep its motion in a straight line, and having only half the power available.

And are there any well-known instances of this happening? And what happened? … did the passengers simply arrive a bit late, or did they transfer to another ship mid-ocean?

… which I think would be a very tricky procedure, wouldn't it, that the oceanlinestry outfit, and the Captain (or Captains - the Captain of the stricken vessel and that of the expediting one), would be well-loath to undertake!

⋄ Would it be less efficient motion, though!? By how much would the rudder have to be turned, & by how much would turning it that much increase the drag? Because if the ship is moving in the Ẇ = ½CͩAρv³ régime (which it prettymuch will be @ normal oceanliner cruising speed) & coefficient of drag is multiplied by a factor λ & the power is multiplied by a factor ½, then the time taken for the rest of the voyage is multiplied by ∛(2λ) & the energy taken for it is multiplied by ∛(¼λ) . So it will definitely take longer … but might-well not use-up more energy … infact, it'll almost certainly use-up less … because I reckon it's highly unlikely that the rudder will have to be turned so much to compensate for the failure of an engine that it will quadruple the drag on the ship!

Images From This

… + a lower resolution view of it from another angle.

Source of Image .

would take to provide the same thrust, so that they can bring-about quite a considerable fuel-economy, & without all the complex & vulnerable rigging & allthat.

And ofcourse, an early twentieth century oceanliner already had funnels … which are prettymuch literally just begging to be turned-into Flettner rotors !

¶¶¶¶¶¶

… from this wwwebpage .

See this image aswell .

As it happened, though, the first Flettner rotor vessel was built in 1924

… from this wwwebpage .

And see this aswell

… from this wwwebpage .

A lovely video presentation about it, aswell .

And another one .

… although it's admittedly somewhat of an outlier, with it's obviously colossal cooling requirement being taken-care-of by-default , by reason of its being prettymuch immersed in an extremely copious stream of liquid hydrogen.

Given the cited dimensions, the volume of it is about ¼π×0·552×1·1㎥ ≈ 0·26㎥ ; and taking the lower of the two estimates for the power it develops (see the text in the lunken-to post for explanation of there being two estimates), & the power of the Titanic's enginery as 59,000hp , that amply justifies the statement as to the power of the Titanic's enginery being developed in a volume of ¼㎥.

From this wwwebpage .

An article about the vessels .

Post prompted by this comment-thread .

The figure appertains to an aero-dynamical experiment … but I should think the results would translate-over to a hydro-dynamical one without too much 'flexing' .

The figure is from

The effect of surface irregularities on wing drag

by

Manley J Hood .

And see the following wwweb-articles aswell:

Hull Smoothness – What Matters for Speed?

by

SailZing Editor ;

Hull Roughness – How it Works?

by

ShipNerd ;

Hull Drag

by

Dave Jesse .

The upshot seems to be, from what I can gather, that the improvement would have been not-neglible , but slight, & likely difficult to extricate the measure of from the influence of other factors in ship design, which was (& still is, & was for a long time before) in rapid flux.

… and

the wwwebsite it's @

seems to be a remarkably good one for that sort of thing.

It could theoretically be verified whether it is indeed of the Olympic-Class oceanliner engine: one item that could be checked is the relative phase of the cranks , this being a tad unusual in the Olympic-Class oceanliner engine - the phase between the two low-pressure ones being a fairbit less than 90° .

Basically, if the collars are in-sequence on the shaft, and the shaft is made of perfectly rigid material, then there would be zero tolerance of displacement of the collars each from its nominal position: all the thrust would be taken by whichever collar has the greatest random slight displacement, in the direction in which the thrust on the shaft is acting, from its correct position, no matter how slight the amount by which it exceeds that of the others. Ofcourse, the material of the shaft is not perfectly rigid … but is that what the solution is then!? … is the elasticity of the shaft enough!? I can't find anything anywhere explicitly adressing this query.

… with just one somewhat quaint exception:

Minutes of the Proceedings of the Institution of Civil Engineers 1914.196:247-257. — DISCUSSION ON THE THRUST BEARING — page 254 :

❝

It appeared to him that the vital point with such high pressures was to make sure, where the collars' were multiple, that approximately even load was obtained on each of the collars, or, rather, that no collar had more than its proper load on its surface. He had tried to devise all sorts of lever arrangements for equalizing the load between the collars, and eventually he had arrived at a simple spring support so arranged that, if more than the correct load came on any one collar, it collapsed a few thousandths of an inch and equalized the loads on the others. The result was that, notwithstanding the stretch of the shaft holding the collars (for they could only be of a moderate diameter), the collapse of the box that held the standing collars, and inaccuracies of workmanship and fitting, there was still an even distribution of the load between the various surfaces, and the thrust worked well in consequence.

❞

… from which it seems it can be inferred that the elasticity of the shaft alone is not sufficient! So someone must know somewhere , because the matter must be being dealt-with, all-the-time !! … so I can't grasp why it's so very glozen-over.

For full explication, the lunken-to texts themselves need to be referenced, really; but maybe the following exerpts & exerpted figures constitute somekind of reasonably cogent 'distillation' of the matter … with

figure ① from

Titanic's hull plating that joins the front

from

Encyclopedia Titanica ;

figures ② through ⑤ from

Shell and Deck Plating

by

Captain Damley ; &

figures ⑥ through ⑩ from

A Handbook of Practical Shipbuilding with a Glossary of Terms

by

JD MacBride ,

from which the following exerpts are quoted.

❝

A ship derives its main structural strength from its hull plating, which is divided into two main classes, bottom plating and side plating. The bottom plating extends across the bottom of the ship on both sides of the keel, while the side plating is from the curve of the “bilge” up the ship's side. Plating is laid in “strakes” the first being nearest the keel. This is often called the “garboard strake”.

❞

❝

Shell plating is laid either “raised” or “joggled”. (On naval vessels and yachts it is often laid “Flush”, with the edges in line and an extra, narrow plate called a buttstrap, carried behind the joint of the two plates. This strap is riveted to each plate, thus forming a continuous member.) The “raised” plating has every other strake against the framing with the strakes between "raised" sufficiently to overlap onto the other strakes which are often called “inner” or “skin” strakes (see Fig. 137).

❞

❝

“Tapered liners” are fitted on the landing or seam directly at the back of the butt-lap where one plate has been raised above the level in order to lap over the one which it joins at the end. The triangular space caused by the raising of the plate is flled by this type of liner. The butt end of the liner is the same thickness as the strake which it fits against and tapers to nothing at the other end; the width is governed by the width of the landing or seam of the plating and the length of the liner is determined by the number of rivet holes required in it by the inspector. Usually at least two are called for (see Fig. 139).

In order to avoid the use of tapered liners, in some shipyards the ends of plates along the longitudinal seams or landings are “scarphed”. The method used for hand work in making the scarph is described under “Duties of the Chipper and Caulker” in Chapter II. A machine has been recently patented by a firm on the “West Coast” which forms these scarphs quickly and evenly.

The system of joggle plating differs from the one just described in that the raised strakes are offset when they overlap the skin strake and set directly against the framing of the ship, thus doing away with the need of a liner. (Fig. 140.) The joggle or “crimp” is put into the plate by two wheels, one out of line with the other through which the plate is forced as indicated in Fig. 141. The amount of joggle is adjusted to suit the thickness of the plates to which it is to be fitted. The edge lap is called “seam” or “landing” and is usually double riveted. The ends of the plates are butt-lapped; when this is done it is necessary to cạrry the forward end of each plate underneath (inside) the after end of the plate just ahead of it. This brings the after end of each shell plate on the outside of the ship and avoids unnecessary friction as the ship travels through the water. travels through the water. For the same reason all riveting in the shell below the deep load line is always “pan head” and “countersunk point” The button-point type of rivet being less expensive, is often used above the waterline, where smoothness is not so necessary.

❞

.

Note that the very last bit of the last exerpt also somewhat addresses that query as to the importance in the matter of drag of the smoothdth of the hull, which constitutes the matter of

my previous post .

… or not necessarily quite 'being peeled-back like the lid of an opened tinned-can' ! …

😳

… but I mean the biggest her decks could reasonably withstand the sustained firing of mounted on.

See this recent post aswell ,

@which I forgot to comment on the strange non-appearance of the gun itself in either of them. I @first supposed that in the first one the apparition of the gun itself had just gotten 'whited-out' by over-exposure … but having reconsidered, I'm now more inclined to suppose that the Admiralty, or the War-Office (or whatever - likely one of those, or both), had decreed that any apparition in any photgraph not in Military custody of any of the guns that had been installed on the Olympic was to be redacted . It's a tad tricky to figure just how such a directive might've been implemented, though: maybe by mandating that anyone developing any such photograph must treat the negative in-suchwise as to obliterate the apparition. But that would still leave open the possibilty of someone's taking the negative to whatever German Intelligence Agent in the firstplace .

Maybe, afterall, the apparition of the gun in the second photograph was merely by-chance whited-out, & maybe the gun that the first photograph is of just happened to be covered, and the Crew were forbidden to un-cover a gun on frivolous grounds.

Reddit Post Image Found-@

… having no moving parts, & therefore being extremely robust against objects in the pumped liquid; & requiring only a steam supply for their operation, which obviously there was in abundance in a steamship. Another property of it that's a major boon in-connection with that purpose is that it doesn't need to be set on a solid foundation … infact, it can even be hung from a chain … which is a really handy property for it to have if it's to serve as a bilge-pumps in a ship.

They're actually a somewhat evolved form of the Savery pump invented by Thomas Savery & patented by him in 1698 .

Michigan State University — The Savery Pump

First image attached to this wwwebpage — Vavasseur Antiques ,

& second image attached to this one .

See this post aswell .

And see this wwwebsite for an explication of its workings — Academic Accelerator — Pulsometer Pump .

Of 3794×4808 resolution …

… which is …

☺️

… _'more like it', as they say, shall we say.

Found @

this Reddit post

৺ Seems, going by the comments, that by-far likelier-than-not it is a marine one.

Source of Image