An Interesting Propeller II

[MacolmParticipant @macolm]

Well, you have all had your oar in, so to speak, about conventional (if sophisticated) propellers. Here is something completely not the same, the Voith Schneider propeller. It has been around for decades, but is it ripe for improvement?

https://vesselstar.com/posts/2025/03/26/

[noel shelleyParticipant @noelshelley55608]

Technically rather complex but very clever and much used on modern tugs. Far to much to go wrong for my liking ! Azipods, kort nozzels, vari pitch props Etc the further you go from the coast the simpler it is the better for me ! Noel.

[Richard SimpsonParticipant @richardsimpson88330]

All propellers are variable pitch.  The pitch decreases the further you get away from the hub.

I used to sail across the North Atlantic with Controllable Pitch Propellers so you don’t get much further from the coast than that.

 

[duncan webster 1Participant @duncanwebster1]

Wrong button

[noel shelleyParticipant @noelshelley55608]

A more nauseating load of waffle I can’t recall ! Written by an eco warrior ? Told me nothing I did not already know with terms like “environmental impact”, “greener”, “Bio”,”emissions”,”efficiency”, as for the “whale like agility in the water”, X and Y may be fine but I’m worried about how it works in the Z plane, submarine ?

The additional draft and fragility if hitting the bottom or wrapping a towing hawser round it would worry me . Noel.

[noel shelley]

On noel shelley Said:

 

The additional draft and fragility if hitting the bottom or wrapping a towing hawser round it would worry me . Noel.

I’m sure they keep a pretty close eye on the depth of water below the blades.  Echo sounders and bottom mapping is pretty good nowadays.  As for wrapping anything round them, I’ve actually seen mooring ropes wrapped around propeller shafts and stern thrusters so I think the same degree of care is required with all methods of propulsion.

[FulmenParticipant @fulmen]

If you look at the image there is no additional draft, the hull is recessed. There are also models with an end plate that is probably even more rugged. As for fragility it is claimed that they retain 2. hand value due to high performance and low maintenance costs. Sounds like the diesels of propellers.

But I do agree that the article is a load of bull.

[MacolmParticipant @macolm]

The standard Voith Schneider is claimed to be self clearing of snagging. There are also versions that can retract the blades fully into the hull. And the article does indeed seem like kite flying, to mix metaphors.

[SillyOldDufferModerator @sillyoldduffer]

Lots of stuff on the web is low on technical content, and I suggest it’s fruitless to expect more than advertising!  No different in the past, where the equivalent was glossy pamphlets.

I’ve been retired too long to know if things have changed, but my employer disregarded blurb like this:

• Someone, possibly a manager, accountant, or chief would notice a new development that might be useful.  Advertising is aimed at them, and thin on how products actually work because shakers and movers are unlikely to be technically qualified.  They respond to buzzwords that match their business needs.  ‘Green’,  ‘Efficient’, or some other advantage.   Adverts rarely mention disadvantages.
• Having identified a potential technology, the techies were unleashed, either in-house or consultants. Makers, not shakers!  I was in-house.
• I’d ring up, and say summat like “Dunn and Bradstreet registered big-spender here, my team’s been tasked to evaluate your product.  Please provide technical info and contact with your subject matter experts.”  Kimonos would open and we’d write a technical report.  The management summary might say, “exactly what we need”, or “this is useless”, or – more likely – “this has value in the following circumstances”.   The body of the report would be packed with details, in case the organisation decided to procure it.  Managers never read it!

Now I’m a long retired “Man in Shed*” with a tiny budget, it’s harder to get technical detail.  I know that web-blurb is only the front-door, intended to encourage trade.  It’s not the full story, so don’t judge anything by it!  Further investigation required.

Advertising technical products isn’t that different from us being tempted to try chocolates because a man-in-black uses James Bond methods to deliver a box to a lady friend, and then leaves, love unrequited.  The advert plants the idea, and says nothing about the chocolates.  Advertising is more to do with exploiting human frailties than engineering, so no wonder we find it unsatisfactory.

Dave

* Just in case some oversensitive soul takes the hump, “Man-in-Shed” is not pejorative.  It only means an individual working with limited facilities.   I don’t have welding equipment, a forge, surface grinder, spark-eroder, CNC, liquid nitrogen, hydraulic ram, punch, furnace or power hammer.  And many other desirable tools and materials are missing.!  And insufficient space, I don’t have room for a Bridgeport.   My workshop is useful, but very limited compared with a commercial or research establishment.

[cogdobblerParticipant @cogdobbler]

Obviously written by the marketing department. As is everything else on the site it’s on, Vesselstar Free Newsletter. You get what you pay for. Free publicity blurbs.

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