3 ms·

> Is this covered under warranty? According to one of the links I cited earlier [1] Royal Caribbean won $65 million from Rolls Royce concerning RR's Mermaid th

> Is this covered under warranty? According to one of the links I cited earlier [1] Royal Caribbean won $65 million from Rolls Royce concerning RR's Mermaid thrusters which are very similar to Azipods, on the Celebrity Lines' 4 Millenium-class ships. And Cunard subsidiary of Carnival won $24 million for Queen Mary II's Mermaids. I think the warranty is more of a contract issue. In newer builds the bearings may be more accessible. [1] https://www.travelweekly.com/Cruise-Travel/Insights/Vista-just-latest-example-of-azipod-blues https://www.travelweekly.com/Cruise-Travel/Insights/Vista-ju...

Animats 7y ago
It's a hard problem. The bearings that rotate the azipods are huge, carry the entire propulsive force of the ship as an angled side load on the bearing, are below the water line, and are holding something that goes through the hull. Look at one of those things, think about the stresses, and wince. Bearings with huge side loads are rarely used, because they wear badly. Ordinary ship screws are on a straight shaft through the stern, with a thrust bearing and seal. Far simpler, and solved a century ago. On the other hand, if you haven't solved the bearing and seal problems of propulsion pods, you shouldn't be selling propulsion pods. "Ship early, ship often" gives you a terrible reputation in the heavy machinery business. There was once a saying in the railroad equipment business - "Never buy equipment from somebody in a better climate than yours." The good railway equipment manufacturers were in upstate New York, and over-designed everything. Which is what you want when a snowplow has to force the ice off the tracks, and devices in the trackway need to survive that. That's why you see railroad equipment packaged in half inch thick cast iron boxes.[1] That's from General Railway Signal in Rochester, NY. [1] https://www.trainboard.com/railimages/data/541/sintonswitch.jpg https://www.trainboard.com/railimages/data/541/sintonswitch....
- cardiffspaceman 7y ago
  I hadn't thought about the load on the strut that the pod hangs from. When in working order, cruise ships can spin slowly in place so that all the passengers can see some scenery (e.g. the glacier at the head of an Alaskan fjord) from their own balconies. And they drive up to the dock without the aid of tugboats. But pods aren't the enabling technology for this maneuverability, bow thrusters, screws and rudders can do it, too. I think the fuel efficiency is the tempting advantage of azimuth pods.

Animats 7y ago

It's a hard problem. The bearings that rotate the azipods are huge, carry the entire propulsive force of the ship as an angled side load on the bearing, are below the water line, and are holding something that goes through the hull. Look at one of those things, think about the stresses, and wince. Bearings with huge side loads are rarely used, because they wear badly. Ordinary ship screws are on a straight shaft through the stern, with a thrust bearing and seal. Far simpler, and solved a century ago. On the other hand, if you haven't solved the bearing and seal problems of propulsion pods, you shouldn't be selling propulsion pods. "Ship early, ship often" gives you a terrible reputation in the heavy machinery business. There was once a saying in the railroad equipment business - "Never buy equipment from somebody in a better climate than yours." The good railway equipment manufacturers were in upstate New York, and over-designed everything. Which is what you want when a snowplow has to force the ice off the tracks, and devices in the trackway need to survive that. That's why you see railroad equipment packaged in half inch thick cast iron boxes.[1] That's from General Railway Signal in Rochester, NY. [1] https://www.trainboard.com/railimages/data/541/sintonswitch.jpg https://www.trainboard.com/railimages/data/541/sintonswitch....

cardiffspaceman 7y ago
I hadn't thought about the load on the strut that the pod hangs from. When in working order, cruise ships can spin slowly in place so that all the passengers can see some scenery (e.g. the glacier at the head of an Alaskan fjord) from their own balconies. And they drive up to the dock without the aid of tugboats. But pods aren't the enabling technology for this maneuverability, bow thrusters, screws and rudders can do it, too. I think the fuel efficiency is the tempting advantage of azimuth pods.