Why Is The Propeller At The Back?

✩ABOUT THIS VIDEO✩
In this video we investigate why the propeller of ships is found at the stern and explain why it just wouldn't work as well if it was at the bow.

✩JOIN OUR COMMUNITY✩

The community is our space for anyone that wants to get even more from Casual Navigation. I am eternally grateful for all members of the community as you are the ones that help me and continue to drive this channel forward.

When you join, you’ll instantly become much closer to the channel, with a range of perks and rewards depending on the tier you select.
➼ Ad-Free
➼ Early Access
➼ Bonus Content
➼ Get Involved

✩WITH THANKS✩

✩DISCLAIMER✩
All content on this channel is provided for entertainment purposes only. Although every effort has been made to ensure the content is accurate and up to date, it remains the responsibility of the viewer to determine its accuracy and validity. The content should never be used to substitute professional advice or education.

[wadethimbey]

Older Finnish icebreakers have 4 propellers, 2 at the bow and 2 at the aft. New icebreakers have have 3 pods and one of those is located at the bow of the ship.

[RaDeus]

Just a tip: having the two sides of the propeller blade be different shades makes the 3D effects a little easier to read.
As it is now the blade just disappears when the tip is facing you.
Edit: sooo many typos

[oldtrkdrvr]

One additional factor. With the propeller at the bow, the rudder is in the way of the driveshaft, making beveled gear necessary to wrap the shaft around the rudder, reducing efficiency for all types of ships.

[Aran]

I love that your videos always start relatively simply with things that I might already know or are very intuitive. By the end you've always taught me something new or taken the discussion in a direction I hadn't anticipated! You're a great teacher.

[hadinossanosam]

I would have liked a little more contrast with the example of aircraft given in the beginning, which usually prefer tractor over pusher configurations. As it is, I think that case provides counterexamples to most of the reasons given here:
-Aircraft don't mount any control surfaces directly behind propellers, as they prefer "clean" (less turbulent) airflow over the control surfaces for predictable, consistent maneuvering. (Even rudders at the end of small aircraft are negatively affected by the rotating prop wash from a nose-mounted propeller)
-An aircraft's body does not block the thrust of the propeller mounted in front of it, as it is designed to be smooth and aerodynamic. In fact, the cleaner airflow at the front improves the propeller's overall efficiency (As far as I know, this is also the reason to commonly mount jet engines on the wings instead of at the back of the fuselage)
-Aircraft prefer tractor over pusher configurations, i.e. tension over compression in the axle/shaft and bearings. I find this intuitive, given the high tensile strength of steel (and most metals?) compared to its lower compressive strength combined with possible buckling limits.

This leaves two reasons: protection from damage, where the analogy to aircraft clearly does not apply (except for gear-up landings maybe), and easier sealing (where I'm surprised the additional pressure is significant compared to the head pressure, but my intuition may be wrong here), both of which do not apply to azipods mentioned at the end?
I don't intend to come across too negatively, I like this channel, and this is an interesting topic I had not come across, I just feel this video has not entirely answered the question in the title to me. Then again, I know much more about aircraft than about ships, so that might color my understanding here

[bideny]

I must say, The Little Captain is ridiculous adorable and reasonably priced. I want him! 🤔 Maybe a birthday gift to myself

[rayoflight]

Wow. This video makes great sense in every little detail!
Sometime ago I expressed my enthusiasm about the azipods to a friend of mine who was a mariner. He cooled me down abruptly, saying that they prefer the electric motors installed well deep into the ship, with magnetic couplers and big axles that they can actually see and service en route. If an azipod fails in the middle of the Pacific, they must limp at a quarter steam to their port of call; if a traditional power plant fails, they can always fix it - with the exception of a broken axle.
I like the compactness and manoeuvrability of the azipods nonetheless. When I was a young kid, I had a RC boat with two axles and two propellers, and a propelling pod wasn't even a concept at the time.
Thank you again for the great video.
Greetings,
Anthony

[HALLish-jlmo]

The Joint Marine Systems Ghost uses forward mounted propellers to cause supercavitation around the hulls to reduce drag

[PsRohrbaugh]

It's also worth noting that there ARE multiple airplanes with the propeller(s) at the rear, and the same with jets.

[blaxson]

Airplanes with front propeller reasons include better cooling . Prop planes with regular or diesel engines get intense airflow over the engine to cool it more than if the prop was behind. Its not always vital and turboprops can be different. Another poster also mentioned the lift benefit of the intese airflow over the wing behind the engine.

[tyrekegordon]

And on the other side of things aircraft propellers are meant to pull and on multi engine aircraft the benefit of having front propellers that are wing mounted is that it provides artificial airflow over the wings making it more resistant to stalling

[jasonreed]

The only instance i can think of where the prop is at the front is trolling motors for small bass boats.

Considering how they are used and how they can be retracted to avoid damage, they are probably more analogous to maneuvering bow thrusters than bow mounted main screws.

[MrKweezy]

Video idea - talk about how sails were phased out. SS Archimedes had steam propulsion but was also fully rigged for sails. As time went on ships (specifically navy ships) had provisions for sails but they look less and less effective over time until they eventually disappear altogether. What were the last navy ships to have the option to go under sail? How did the maritime industry in general get comfortable moving away from sail and trusting in powered propulsion?

[robertwillis]

I now know more about boats and ships listening to your videos than I knew I could even know.

The complexity of captaining a ship is far more complex than I ever thought it was. Watching the captain s on deadliest catch made me believe it was mostly point tge ship that way and go. Never understanding the complexities of cargo, ship design, control. . .

[SageThyme]

Brilliant question that I never considered and I am surprised by how much behind this question there actually is.

[shaider]

I have read that having the prop at the rear also helps energize the boundary layer on the hull, making it more efficient. This is less important for an aircraft where the air has less density. For propeller planes, the issue is for cooling of the engine.

[looneyflight]

Beechcraft Starship, AASI Jetcruzer, Piaggo P-180 all pusher propeller aircraft for anyone who is interested. I see alot of comments about the complications with push props so didn't want people to think it can't work. The 180 is one of the fastest private aircraft.
Push props are more efficient but pull props are more convenient for aircraft ease of maintenance, design, visibility.

[FranNyan]

Will say, got my brother (who is fascinated by historial sea voyages and legends of old ships) the Little Captain, and despite him being a grown man in his late 30s, his face lit up like a child when it arrived. We briefly played a game of hiding it around the house waiting to see who would find it, which was cut short when one of the cats won a round. Now the captain is setup on a cat proofed shelf in my brother's room where he can safely watch over the chaos.

[griffithwes]

The little captain is love, the little captain is life.

[Lucius_Chiaraviglio]

By the way, ship propellers do come part way out of the water during severe pitching. My father had the misfortune to get a cabin in the stern of the ship he was on to come to the US in 1948 and had to experience this first-hand when the ship got into a storm.

Also should mention bidirectional ferries -- with these, you _can't_ get away from having some propellers up front, unless you're talking about paddle wheel ferries (which also existed well into the 20th Century).