Paddles and Propellers - It's all about the rotation

Today we take a quick look at the final element of a ships drive-train, the bit that spins in the water to make you go forward.
Sources:
www.amazon.co....
A Treatise on the Screw Propeller: With Various Suggestions of Improvement
John Bourne
proceedings.ca...
indico.atenana...
maritimeexpert...
www.usni.org/m...
www.shippingwo...
elfarodeceuta....
Naval History books, use code 'DRACH' for 25% off - www.usni.org/p...
Free naval photos and channel posters - www.drachinifel.co.uk
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[@Drachinifel]

Pinned post for Q&A :)

[@Zeppflyer]

On the advantages of paddle wheels: I swear I read somewhere that they are more efficient than propellers at turning engine power into thrust at very low (especially zero) hull speeds. Above a few knots, this ratio reverses and the prop gains the advantage. This (along with, as you said, maneuverability) was allegedly one of the reasons that they hung around for so long on harbor tugs in the UK. Is there any truth to this?

[@Aelxi]

Have Drach answered what's the name of the Fridays intro music?

[@ReneSchickbauer]

Could you do another part of the series, concerning rudders and how the steering mechanisms evolved over time? While steering a two person sailboat with a tiller is fine, i assume using the same technology would have been a bit impractical for ships like the USS Lexington or the Yamato.

[@wolfgangkranek376]

Josef Ressel was awarded a propeller patent in 1827. He modified the steam-powered boat Civetta by 1829 and test-navigated it successful in the Trieste harbor at six knots.

[@wulfie1199]

On the subject of paddle propulsion do you have any plans to go aboard or do a small video the PS - Waverley?, Since she is the last seagoing passenger-carrying paddle steamer in the world and she is here in the uk even though she isnt a navy ship.

[@robertmutton4973]

Great video. As a professional propeller designer and amateur propeller historian it is a good brief summary of propeller development. In such a short video some people and stories are always going to get missed out, which is shame because lots of interesting people show up in the story of propellers (and a lot of them end up suing each other). You did however, include Hooke's propeller. This is an odd one, It doesn't appear that he ever suggested anything of the sort for ship propulsion. The image commonly shown as hookes propeller, Bourne admits is just a windmill taken from Emerson's Mechanics textbook, not anything Hooke ever drew himself. One of the early textbooks took what he wrote about windmills, wind speed meters, depth gauges and roman galleys and inferred that clearly Hooke must have suggested a propeller as a screw driving water and water driving a screw are essentially the same. However Hooke never seems to have made that leap, his work only has water driving screws, never the other way round and i have spent years looking for any evidence otherwise. I suspect this has more to do with an 1850's author wanting an Englishmen to be first in his book. It has then been copied verbatum down the years even to modern textbooks. The image you showed of Bushnells turtle, which appears to be the first vessel recorded as ever being driven with a screw propeller, shows an archimedian type screw, this was a later mistake and the image has been used repeatedly since. the actual screws used were two bladed and shaped like the heads of oars. Am sure there are other things i could say but don't want to write an essay, or spoil the book i am slowly trying to write on the subject.

[@diabolicwave7238]

Good lord, I do so love reading about weird little things (:P) that people are passionate about. This comment made me smile, as funny as that is.

[@brianreddeman951]

Maybe your book is ready for publication you can share it with Drach. :) And everyone because it is an interesting topic :)

[@MyMongo100]

When your book is ready I'd be very keen to read it. I'd be interested to know you opinion on CA Parsons propellers on the Turbinia. Was this the first to use multiple screws on the same shaft to overcome the propellers cavitating?

[@teaser6089]

what do you think of the MIT revolutionary propellor design ?

[@robertmutton4973]

​@@MyMongo100 Turbinia is a really interesting boat. The idea of multiple propellers on a single shaft goes right back to Bernoulli in the 1750s and had been used a few times. Parsons was a very early investigator of cavitation and actually invented the cavitation tunnel to research it. The original one is in the discovery museum with Turbinia. Larger versions are still used for propeller research. He linked cavitation to too much thrust per unit area so realised he needed to increase blade area, so came up with the multiple props per shaft to solve it. What he really needed was a geared turbine that came along 15 years later to slow the shaft rotation down.

[@pitsnipe5559]

Your video reminded me of an incident that occurred when I was in the U.S. Navy. We had been dry docked in a Greek shipyard, while backing out of the dry dock our starboard propeller stuck an old concrete bouy anchor. They had to fly in a new propeller from Pearl Harbor. When we went to sea to find out how badly damaged the propeller was, the ship shook so violently at 10 knots that I was literally bouncing off the deck plates in the boiler room. There were three big chunks missing from two of the three blades.

[@americankid7782]

One thing I find insanely cool about cavitation is that it is one of the main reasons that Screws on Submarines are classified.

[@vylbird8014]

I suspect that if all the submarine-capable nations of the world were to reveal their screws, they would discover that all their classified designs look identical - because they are all designing for the same goals in the same environment.

[@justlucky8254]

One of the reasons I loved working on those props at the navy yard. They simply look cool.

[@americankid7782]

@@vylbird8014 yeah it’s probably a similar situation that we got goo with stealth fighters. Only a few shapes work.

[@01Bouwhuis]

​@vylbird8014 hmmmzz.....i believe that the propellers are covered so the enemy cant derive its acoustic signature from its shape.

[@joshuahadams]

@@01Bouwhuismakes sense. Being able to make a miniature to work out the sound of a rival nation’s submarines and then filter that out of background noise with a hydrophone would give you an advantage with triangulating. A few hydrophones, some acoustics, and trigonometry would be able to pin down locations close enough for active detection to be useful.

[@justlucky8254]

As a machinist at a navy yard, i repaired/refurbished props for aircraft carriers and a few classes of submarines. It was amazing to see just how much damage happened to some of them, such as blades being bent out of pitch (we'd heqt them up, hang them from a bridge crane and then use an enornous hydraulic press to bend them back into pitch). The variois sumarine props and their geometry was also really cool.

[@233kosta]

The sub props in particular evolved from a need to minimise, or if possible eliminate cavitation altogether, as that's usually the biggest source of noise underwater. Iirc, NATO could use its hydrophones to hear soviet subs manoeuvring on the other side of the planet for some time, well into the '70s I think, until they developed the same type of props.

[@ostlandr]

Many, many years ago, my buddy was serving on board USS Dallas during the filming of "Hunt for Red October." When we eventually watched the film together, he said "That is NOT what Dallas' prop looks like." I innocently asked him "What does it look like?" "I could tell you, but then I'd have to kill you." 🙂

[@Shaker626]

And really classified.

[@justlucky8254]

@@ostlandr he was absolutely correct. What they showed in the movie was....not accurate.

[@justlucky8254]

@@Shaker626 basically. I mean, it takes a certain clearance just to get into the shipyard and then into the Controlled Industrial Area, but it takes even more authorization to even get into the building where we'd have the props and work in them. If not actively assigned to be in the building, your security badge won't unlock the doors to the building, regardless of whatever other special stuff you have access to. And 2 people cnt walk thru the doors during one opening. One swipe of a badge, one door opening, one person enters. Repeat for each other individual.

[@michaelpfister1283]

WOO! Shout out to Wolverine and Sable! I grew up on Lake Michigan, and have visited Navy Pier in Chicago a few times, and those two ships were early "hero" ships of mine. Many WWII naval aviators were trained in basic carrier operations using their relatively safe and secure decks. 🙂

[@Simon_Nonymous]

Ed Nash did an episode on them on his YT channel about four weeks ago - it's an amazing story!

[@markdurre2667]

You mentioned the use of counter rotating propellers to counter the torque on the steering - this is well-known with sailing yachts where it's called "prop walk" and can be a trouble at low speeds, especially when docking under motor. Knowing how it works on your boat is a pretty standard skill for a yachtman, and can be used to get out of confined spaces.

[@ulrikschackmeyer848]

' Two kinds of propulsion came into widespread CIRCULATION' . How long did it take you to come up with that little gem, Drach?

[@Wolfeson28]

This topic just has so many revolutionary developments.

[@crazypetec-130fe7]

The witticisms here make my head spin.

[@robertslugg8361]

I am sure he went round and round on it.

[@advorak8529]

@@robertslugg8361Riding it up and down and up and down on a balancing beam, like a child on the playground …

[@Arcalargo]

I bet he thought wheelie hard about it.

[@trevorashworth7307]

Charles Parsons(Turbinia fame) did many experiments to mitigate cavitation.The old museum of science and engineering in Newcastle on Tyne had his propellers he tested.The model you showed with three shafts with three screws on each shaft is a model of Turbinia.The actual vessel is in the Discovery musem,Newcastle.

[@edwardloomis887]

Thank you for the shout-out to Wolverine and Sable @28:49, Lake Michigan's answer to the Essex class.

[@antoninuspius1747]

Absolutely fantastic. I've seen outboard motor boat propellers that were severely cavitated by running at high speed in relatively heavy seas where the prop comes out of the water, rpms go way up, then plows back in. Very damaging and happens surprisingly quickly. Any boat owners out there, never let that happen.

[@MendTheWorld]

What you are describing is not cavitation, which occurs with the propeller completely immersed in water. Cavitation occurs when there is a phase change from liquid to vapor induced by the mechanical energy of the blade. When the cavity collapses a great deal of energy is released, which can apparently damage the propeller blade. In ultrasonic cleaners, cavitation is induced by high frequency sound waves, used for cleaning fine components, commonly in laboratory settings.

[@Kieselmeister]

​​@@MendTheWorldIt definitely IS cavitation. Whether the Prop is fully submerged is completely irrelevant. Prop cavitation occurs when the speed of the blades through the water is fast enough to generate high and low pressure zones strong enough to cause the water to vaporise in the low pressure zones. The cavities then collapse and release that energy, which tends to erode the prop. (It also makes the prop much less efficient so there are multiple reasons not to overspeed a prop.) If a prop with blades spinning slowly enough to avoid cavitation comes OUT of the water, it might then spin up to a higher RPM without water resistance... Then when the now much faster spinning prop goes back INTO the water, it would immediately start cavitating. That is exactly what the first comment described. Do an image search for "cavitation" and literally half the images are of chewed up eroded boat propellers, and the other half are for a fad liposuction alternative. Prop erosion from cavitation is, in fact, how people got the idea of using cavitation to clean things in the first place.

[@augustosolari7721]

The problem of cavitation was extremely serious for ocean liners. The RMS Lusitania had to have her entire stern reinforced in order to withstand the tremendous vibrations she suffered.

[@spacecat1726]

Sounds like my neighbor. When she got into jogging she had to go through several sports bras until she found one with sufficient reinforcement. Some models she tried early on were really quite surprising in just how significant the movement and vibration was.

[@augustosolari7721]

@@spacecat1726 you need certain vibration to achieve certain speed!!!

[@theonlymadmac4771]

Sounds like resonance catastrophe (big cups are prone to it)😂

[@blgarage9519]

and that STILL didn’t fully solve the problem. I don’t think it ever was iirc

[@AsbestosMuffins]

might have been the engines doing that. Triple expansion steam engines can't be pushed too fast

[@UnshavenStatue]

Turbine cavitation is also one of the biggest threats to rocket engines. A single bubble in the wrong place can cause a rocket engine to explode, which is usually considered to be very bad for the rocket.

[@BeingFireRetardant]

Usually

[@MrSlyFox]

Holy s...i've never thought about it. Turbopumps also use fast-spinning props, moving liquid around. Yeah, space is hard

[@Flt.Hawkeye]

​@@MrSlyFoxnah it's empty

[@Flt.Hawkeye]

Depends if she reached her destination before she Exploded. The rokets that hit Moskwa definetly had some kavitation issues at the end of their Vojage

[@MrSlyFox]

@@Flt.Hawkeye The Neptune is jet-powerd tho. It's baseically the ukrainian version of the old, soviet Granit

[@r.awilliams9815]

The paddle-wheeler I'm most familiar with is the U.S.S Quaker City, which served with distinction as a blockade ship throughout the US Civil War. After the war, she was sold and recommissioned, and took Mark Twain on the cruise where he gathered his material for his book The Innocents Abroad in 1867.

[@richardmalcolm1457]

@24:35 The trials between HMS Rattler and Alecto were important for the RN, but as you say, key Navy leadership had already been moving to the conclusion that screws were superior after Rattler's initial sea trials in 1844. So much so, in fact, that even before the Rattler-Alecto "contest" in March '45, the Admiralty had already decided that screw propulsion (specifically, using two-bladed Smith type propellers) would be added to HMS Erebus and HMS Terror for Sir John Franklin's (ill-fated) Arctic expedition - albeit, alas, connected to very underpowered (20 and 25 hp) locomotive engines. Fortunately, Rattler (200hp) would end up helping tow Erebus and Terror as far as Greenland....

[@pr0n5tar]

I have to have the greatest respect for this gentleman. Always wonder what topic is going to be next and I'm always pleasantly surprised

[@davidkillin8466]

Interesting video. Must admit that when I used to read about ship design and development, the evolution of paddle and propeller was quite fascinating. Thanks for (yet another) informative video, Drach

[@13lbaseball]

Thanks Drach! Definitely was wondering when Part 3 of the Boiler, Engine, Propulsion series would arrive, and you, as always, did a splendid job!

[@7891ph]

Used to work in the toolroom at a company that manufactured propellors; worked directly with engineering on a daily basis. This video is very good, but due to time constraints, very, very limited. Modern propellor design is just this side of Black Magic, and Drach is correct that this only scratches the surface.

[@jamespocelinko104]

The Liburnian ship looks like a medieval amphibious vehicle.

[@davidb6576]

Thanks, Drach, this was interesting. Especially liked the review of early paddle-type drives, both animal and human. I'd not realized how long ago serious attempts had been made to use this tech.

[@frankgulla2335]

Drach, what a marvelous video about the paddlewheels and propellers. I loved the pictures and illustrations you dug up. Great job and thank you.

[@bjorntrollgesicht1144]

I am now propelled by seeing this excellent video.

[@nathanlentner3129]

It would be great so see a video on how sails work. What the different sails do, how to work with the wind, etc.

[@MsSteelphoenix]

I haven't understood cavitation for literal decades, and five minutes of this video cleared it up. Thank you! You're great at explaining!

[@kyleheins]

Just wanted to say Drach, your Friday videos are lifesavers for me. The amount of built up stress relieved when you publish one is phenomenal, thank you.

[@abyssaljam441]

one of the most impressive CFD run I have seen is of a Cavitating propeller.

[@maxart3392]

Nice to mention the Turtle as one of the first (if not the very first) vessels to be driven by propeller, but I miss Joseph Ressel as one of the pioneers of the propeller driven ships who certainly deserves to be mentioned.

[@ajlancjc99]

I think this story just goes around and around!

[@sadwingsraging3044]

Another excellent showcase by Drach of how and why a technology was invented and the challenges to actually implementing the technology into common usage. Well done sir!

[@HeliophobicRiverman]

Paddle wheel propulsion makes periodical comebacks. Not so much in the military context anymore, but in river passenger ships. Recent examples are the Loire Princesse with side wheels and the Elbe Princess I & II with stern wheels, all operated by CroisiEurope. These floating hotels have a pretty constant draft as passengers don't weigh as much as cargo and the ships have ballast tanks, so staying at a level that works well for the wheels is pretty easy. The main reason for the revival of paddle wheel propulsion is the nature of specific waterways, both the Elbe and the Loire have a lot of shifting sands and frequent periods of shallow water. These ships aren't perfect though, vibration has been a major issue.

[@andersgrassman6583]

Very enjoyable video!😃 When I was a kid, and actually decades later building a powered balsa ship with my daughter, I did not always have a readymade model propeller at hand, and had to cut and bend ones out of tin-can sheet metal. So I actually spent a lot of time thinking about propellars, and also finding out that relatively "small" errors when making them, made a big difference. So starting from an early age, I've been aware ship/boat propellars are not trivial stuff! Then you go on to airplane propellars, turbines, different pump designs etc, and you realize the field is absolutely insanely complex. Achimedes and later followers, just didn't know what a hornets nest of technical problems they unleashed!😆

[@RobJaskula]

As someone who falls asleep to your videos every night (THANK YOU) I love the new music

[@99kitfox]

Been waiting for this video. Propulsion is a favorite subject of mine.

[@DemonSliime]

I’m not even particularly interested in boats. But god damn I love this channel.

[@maribelfarnsworth4565]

Thank you for another great video. I especially appreciate your explanation of cavitation!

[@rustyslug2943]

It really is incredible how all these people spent so much time thinking about how to move a ship, and none of them just used the obvious method. Forward thrusters.

[@murrayscott9546]

My Father, who served in the Merchant Marine appx, 38-48 still remembered dual-powered ( sail and steam ) ships. Still notta bad idea to keep your options open

[@andersgrassman6583]

Energy conservation / fuel economy is an excellent reason to combine sails and motor power. And sometimes speed isn't that crucial.

[@murrayscott9546]

@andersgrassman6583 Like said the tortoise to the hare. It's not the destination but the journey.

[@scrambledganglia6946]

Select the right propeller combo and you can equip your North Carolina battleship berth with a vibrating mattress at certain speeds. Certainly a plus for tired gun crews after wrestling with 16" projectiles. Those clever ship designers. Always wondered what the magazine crews thought about the experiment where they shot a full load of main armament shells to see how it worked.

[@timwerner7771]

I seem to recall that when the Bismark was dueling with HOOD her main batteries firing destroyed one of her radars as well as a range-finder

[@Sebastian262]

A very informative and entertaining video, Drach! Kudos! Yet I wish you mentioned Josef Ressel, as he is credited with the first functional propeller (patented 1827 and tested in1829) and seems pretty much unknown except to people from countries that were once part of Austria-Hungary.

[@martinnermut2582]

Czech forester :) His shape is similar to that at 23:16. But he didnt use axial bearing for carrying thrust force, just pointed shaft end, pushing on a verical plate. Unfortunately he used poor reialble modern steam engine.

[@robinmilford2426]

My first experience of propeller excited vibration was on the VT1 hovercraft when one of the (underwater) propeller blades broke off and the whole craft shook.

[@lezardvaleth2304]

4th AD naval engineers: _You can't propel a ship without wind or dozens of men rowing_ 4th century unknown author: *OBSERVE*

[@BCSJRR]

Great video fer shure! Nice job on the historical (sometimes hysterical) efforts to power paddle wheels. As for human power, I've used the modern 2 person paddle wheel boats (on a pond) where the people work pedals (like a bicycle) which are hooked the paddle wheel. One would need to be an Olympic calibre cyclist to get any degree of speed and maintain it. I served on a certain large aircraft carrier in the US Navy in the '70s and got a good look at the propellers. Talk about massive pieces of metal. I don't think they'd fit in the room where I watched your video. Thanks for your research efforts and the storyline. Very cool.

[@WesleyHarcourtSTEAMandMORE]

Interestingly, the first steam powered boat (John Fitch's steamboat 'Perservearance' of 1787) was propelled by multiple oars held vertically and operated by a steam engine coupled to the oars by a complicated mechanism. She first steamed successfully 235 years ago this last August 22nd.

[@Alex-cw3rz]

The first Ocean going Steam powered warship was the 20 gun PS Rising Star commissioned in 1822 for Thomas Cochrane when he was Admiral of the Brazilian navy, it was never used in action as the war was almost over, it had an interesting design of internal paddle wheels to protect them a bit more from cannon fire. The first Steam warship to participate in combat was the Karteria commissioned in 1826 and first saw combat in 1827 in which it was highly effective. This again involves Cohrane, he and another British naval officer Frank Abney Hastings, were employed by the Greek government in their independence movenment against the ottomans. They set out a plan to build 6 Steam warships and buy two old 74 gun ship of the lines and razee them to become heavy frigates, this plus the rest of the Greek fleet was seen as good enough to take on the ottoman navy. This was very ambitious and in the end only 1 steamship was delivered and they got two heavy Frigates built in the US rather than Razeeing a 74, but due to major corruption in the end the Greeks could only get 1 Frigate. The Steamship although only having 8 x 68 pounder guns proved to be brilliant, using the power plants Steam to create heated shot and a method developed by Hastings to stop any barrel explosions, meant that it was highly effective and destroyed quite a number of ships even when the Greek side was outnumbered in the battle.

[@jamesharding3459]

Nonense.

[@chrissouthgate4554]

@jamesharding3459 Sir, If you have proof that a lengthy entry is factually incorrect then it would be more courteous to the author & fellow readers to provide that information. A single-word reply is both churlish & uninformative. Also, a simple internet search shows loads of entries on this subject, indicating that he is not alone in his opinion whether it is correct or not!

[@chrisconnor7170]

@@chrissouthgate4554 well said, sir

[@greenseaships]

5:27- Now I want to build a radio controlled paddle steamer powered by hamsters yoked to the drive chain. Like a horizontal exercise wheel! Let's GOOOOOOOOOOO! :D

[@greenseaships]

Actually, I said 'horizontal' but a normally arranged exercise wheel could run a direct axle to the paddle wheels! But if you think it's hard to get French workers to work....

[@ebenezer1690]

Sir, if I may, you are, a man, my father would have been proud of. Your devoted senpai.

[@ph89787]

Random fact. When Enterprise (CV-6) was being converted to night operations at the end of 1944. Her centre propellers were replaced with a 5 (quintuple) blade model. That was supposed to reduce vibrations in high speed maneuvering

[@tomppeli.]

The principles of prime numbers and harmonics would like to agree with you on this one

[@maxart3392]

If I'm not mistaken United States was also built with the same configuration.

[@ph89787]

@@maxart3392 exactly

[@michaelwright2986]

Fascinating and excellent video. The information density was just right for me: non-techie, but interested in tech subjects. I learned a lot about paddle wheels. Interesting that the paddle wheel can be seen as an inverse water wheel, but the screw as an inverse windmill doesn't seem to have had much of a run after that first thought by Hooke.

[@hisdadjames4876]

You spin me right round baby right round 😵‍💫

[@joshjones3408]

I guess they got tired of paddling around an instead they would rather screw around 😆 great video 👍

[@billharm6006]

Excellent! Even relative to your high-quality output. Thanks.

[@graulus8986]

Very good, Drach! Thanks a lot for this. Seeing - or rather not ;-) - that you didn't include a visual of the raising screw of Fregatten Jylland at Ebeltoft, I reckon you have't seen her yet: this ship is such an impressive sight that you wouldn't have missed the opportunity to show the rope they used to hoist the thing when under sail! In the vein of this video, I'd b keen on having your engineers views on steering equipment over the ages, starting, e.g. , on the viking ship replicas in Roskilde (another recommendation) and their side rudders, via the Mary Rose, through Wasa and the tiller they used, a 'standard' age-of-sail pulley arrangement like on the Victory, (I'm not sure what the original system was on (HMS) Unicorn in Dundee as no one was around to explain it to me back in the day), to Jyllands' (I think early) rudder quadrant system using a chain along with a pulley system and a very 'historical' looking steering wheel on deck) as well as the further developments into the age of steam. Again, kudos for screwing us!

[@robertmatch6550]

Good morning from Anchorage. Named by Captain Cook.

[@michaelkaylor6770]

Dude travelled a lot!

[@ivoryjohnson4662]

As always…..an excellent production

[@CrystalKingdomGeneral4942]

*All about the rotation.* PERFECT ROTATION! PERFECT ROTATION!

[@bobperrine6193]

A very interesting and informative video.

[@theoccupier1652]

We still had Paddle Tugs (Forcefull & Faithfull) in Plymouth RN Servive is the 1970's/80's ... they were great Tugs and were a joy to watch working away Tugging the likes of our own ship the 50,000 ton Ark Royal lV R09

[@pierremainstone-mitchell8290]

Very well told not to mention very well researched video! Well Done!

[@johnheigis83]

As per usual... Well done. Thanks. Semper Fidelis...

[@PBGetson]

There are advancements in cavitation reduction by using toroidal propellers. That is a propeller that has a blade that curves back to the shaft. They have much greater efficiency in propelling a vessel than normal propellers. This 1895 patent is one of the earliest examples I've found that uses a type of toroidal design. US0547210A Marine Propeller.

[@robertmutton4973]

Is a variation on the Wells-Myers design of 1891,

[@PBGetson]

@@robertmutton4973 I'll have to have a look for that one. Thank you.

[@PBGetson]

Found it. patentimages.storage.googleapis.com/5d/b2/5e/f983b16c98b284/US467322.pdf

[@Slaktrax]

Great educational video Drach.Thanks. 🙂

[@malcolmtaylor518]

Very interesting exposition on the paddle wheel and propellor. It always surprised me that the Admiralty didn't armour the paddle wheel sponsoons, making a paddle wheel armoured ship more viable. Pivot guns were making broadside fire less important. Infact an armoured paddle wheeler, with its versatile manoeuvrability, would have made an interesting ramship.

[@douglasfur3808]

It takes an engineer to make a connection between paddle wheel enclosures and radar towers.

[@ralphgarrett9034]

Fascinating………..Thank You

[@rickhobson3211]

You need to do an in-depth video about the two US side-wheeler aircraft carriers in World War II.

[@AdmiralGray1911]

Agreed. They are such fascinating oddities.

[@ryanfoster9863]

Another great video! It was always my understanding that oceangoing paddle steamers sails would be trimmed to keep an even keel and to minimise rolling. Would the sail master make log entries for this to better understand operations?

[@pauldziejman]

Very very interesting! Thank you!

[@deckape714]

@:59 running with full sail. Glorious to me

[@REEbott86]

Great video, i really enjoyed the shorter style.

[@SamAlley-l9j]

Thanks Drach.

[@na3044]

There's an anecdote I heard while visiting the danish frigate "Jylland" in Ebeltoft, DK: Supposedly it suddenly increased it speed one day, and from then on was a bit faster than before. Upon examination they discovered that about half of the formerly Archimedean-type had broken off, making it more like a modern one except having just 2 blades now.

[@AdmiralGray1911]

Great video. I find Wolverine and Sable most fascinating. They are such oddities.

[@GrahamWKidd]

Thanks Drach!

[@Kim-the-Dane-1952]

Great summary. Thanks!

[@jonathanmormerod]

Just one minor flaw with that 4th century idea. In an era when ships were sunk by ramming, the moment the oxen-propelled ship strikes the enemy, all the oxen will be thrown out/through the treadmills, with ultimately fatal results. Make sure you have an army of carpenters and butchers on board and that your crew like beef 3 times a day.🤣🤣

[@sorover111]

This is great .. engineering in the context of naval history

[@johnjephcote7636]

I remember the paddlers (Buff Funnel steamers) going from pier to pier along the South coast. Irrelevant here, but I would klike to know more about a pre-war ship that had tall funnel-like masts with rotors inside them. The ship was subsequently converted into a conventional motor vessel...but how did it work? (The inventor also introduced those small rotors which one sees on van roofs).

[@johnjephcote7636]

The Flettner Rotorcraft.

[@orbitaldropshockpizza]

We finally finished a series!

[@sing4gd1]

Great video, thanks

[@Max_Flashheart]

That was super interesting especially have the accident caused the vessel to accelerate after half it the propeller fell off

[@demos113]

Interesting vid. 🙂👍

[@benchan16]

Got to love fridays

[@scrapperstacker8629]

Great video!!

[@abhoren13]

Think Drach missed a trick on the subtitle. Just begging for something like "You spin me right round....."

[@craigbinder5560]

Yay I been waiting for this one

[@luminyam6145]

That was fascinating.

[@AlRoderick]

Those animal powered paddle wheels had a more critical flaw, draft animals need to drink a lot of fresh water, which is a more critical stores concern than their fodder if you're operating at sea.

[@philliprandle9075]

Great video!!!!

[@HouseholdDog]

I didn't think a video on propellers would be so interesting.

[@BigMoTheBlackDragon]

10:53 of course they were steam powered. "Oi! You there laddie! You be running now or we dump this boiling water on yeahs!". Just having a guy with a fan waffing steam towards them must have been tremendous incentive to move.

[@David-js4wd]

May i give shoutout to the Waverley the World’s last seagoing paddle steamer, sailing around the UK for pleasure trips. A google will find her - she is currently sailing out of London to Southend and back, later to Glasgow and around the clyde. We went on her from Swanage to IOW and back, a day out on a nice hot summers day - well worth it for the views of the ship and the southcoast of the UK

[@jman2903]

Nice werk, Could you do an episode about Submarine pariscope design and evolution?

[@henrygibbons2354]

The pic of the Liburnian ship with the paddle wheels is from a 15th Century edition of the original 4-5th Century text. Really cool illumination though.

[@jarmokankaanpaa6528]

Contrary to what was said at the beginning, sail-powered merchant ships did not carry on into the early part of the 20th century because of the unavailability of fuel. The main reason why square-riggers persisted in transporting grain from Australia and guano from Peru was money: it was cheaper to carry bulk cargo that did not need to arrive quickly by sail, where the only running expenses were the (poor) salaries and food of the crew and where fuel did not take up a notable portion of the storage space and draught. Gustaf Erikson of Åland was able to buy a large number of sailing cargo vessels cheap after WW1 and he had the largest sailing cargo fleet in the world by the 1930s. He was able to make a bundle specifically by keeping expenses down and concentrating on grain and lumber; there would have been no fuel problem between Australia and Europe or between Scandinavia and Britain, where he primarily operated.

[@Goatcha_M]

The Murray Princess in Australia uses a stern wheel system, although it was built in 1986 for tourists and modelled after the Mississippi boats..

[@rpchan]

We get to fun Friday and get to remember the good old theme music days… sigh.

[@shaider1982]

I have been waiting for this for quite a while since the powerplant video was released I think a year ago.

[@TerminalConstipation]

marvelous

[@phill1009]

Check out the toroidal propeller, its a pretty cool concept and design