4 ms·

So it's not possible to design ducting for HVAC/engine exhaust that either closes automatically at a certain angle, or has some mechanism that lets out gases wi

by rwmj 2y ago

So it's not possible to design ducting for HVAC/engine exhaust that either closes automatically at a certain angle, or has some mechanism that lets out gases without letting in water? I assume people have thought about this, but from the outside it doesn't seem like too hard of a problem.

trhway 2y ago
All these classical smoke stacks and ventilation tubes sticking out vertically wouldn't look great on a sleek superyacht :)
- rwmj 2y ago
  That would work, but I was thinking some kind of ballcock (https://en.wikipedia.org/wiki/Ballcock https://en.wikipedia.org/wiki/Ballcock) built into the ducts.
closewith 2y ago
More or less any clever tricks at sea have been tried and tested and found unsuitable. In particular, almost any non-positively actuated mechanical valve exposed to sea air will seize in days.
krisoft 2y ago
I’m sure it is possible. One surprising thing i hear about yachts (or not surprising I guess, depending on how you look at it) is that money is not a limit when it comes to guest accomodation but they are very much pinching every penny when it comes to anything else. So the question is not “is it possible to design automatically closing ducting” but “what is the cost of doing it”. And in general everything the guests interact with or experience will be exactly how the owner wants it, while everything else will be done to the minimum quality required by the classification rules.
- short_sells_poo 2y ago
  It's not (just) cost saving. Having owned a yacht, everything breaks all the time. The environment is extremely harsh on everything. Seawater is corrosive. Even high quality stainless steel (expensive!) will corrode. Sealife is invasive. Every nook and cranny is under constant assault from all sorts of weird little critters. The most robust solution is to keep things as simple as possible. Any bells and whistles you add will become liabilities very quickly, and if crucial systems depend on these bells and whistles, you can quickly get cascading failures. I learned in about 2 months that you want the most crude, easy to repair and reliable solution to important parts and you want them cheap - because you'll be replacing them regularly. Expensive solutions will provide very little relief from this (if any at all). If the TVs in the guest rooms break regularly because of constant vibrations, that'll annoy the guests, but the ship will float and go forward. If your fancy fly by wire engine controls corrode and you are out at sea, it's mayday time. A lot of smaller boats still use mechanical wire actuation because it can be mended literally with a string.
  - krisoft 2y ago
    I agree with everything you are saying, but I posit that even with that it is really "just cost". If the simple valve is not reliable enough you can design a more reliable one. It will cost you a lot. Maintenance is a cost too. (It costs you in crew time, crew training, materials, and tools.) And when it predictably goes wrong and that causes the ship downtime, and they have to cancel a guest visit because of it that is a cost too. So all of the things you list there (very good points each!) can be either mitigated by spending more on the initial cost of the valves, or by spending more on maintenance, or paying the price when it breaks. And I also agree with you that it very well might be the case that the benefits are not worth the costs. (Especially since when you are designing the yacth you can't know what kind of disaster will strike it. We could, in an alternative reality, very well be sitting here and talking about how they should have installed more automatic fire-extinguishers, or more redundant navigation, or protection from prop-fouling.) Engineering is hard.
    - short_sells_poo 2y ago
      I think I phrased that badly. What I meant to convey is that a cheap and cheerful solution will need replacement at interval X, and a much more expensive solution will need replacement at 1.2X. At least in my experience, the relationship between the money spent and reliability tended to be logarithmic. In other words, spending more on fancier equipment didn't really minimize the main pain point of failures: the ship being unavailable for sailing due to maintenance. It was worse in fact, because more expensive equipment wasn't more reliable usually. Shiny lcd touch panels looked great but were a ballache to use when there was a swell. I had chunky 800hp mercury engines fitted to crack that magical 100mph barrier, but because they were fly by wire, we had constant issues with electrical contacts that were difficult to diagnose out at sea (unlike the older mechanically actuated throttles). Even worse, the more "over-engineered" a piece of equipment becomes, the more difficult it tends to be to reason about it's boundary conditions. More moving parts, heavier weight, more exotic materials - these all add further unknowns to an already very chaotic system that is seafaring. To come back to my electronic vs simple mechanical throttle system, the former is difficult to repair with a set of pliers, the other is trivial. Even though the former may have redundancies and fancy recovery modes, if it does fail, you are SOL. So you are right, ultimately it's a cost question in the sense that if the more expensive components aren't more reliable, why spend money on them. I was keen to make the point that I'd have gladly spent more money on said equipment to make it more reliable, but there seemed to be no correlation between the two aspects :D
- closewith 2y ago
  No, the question is whether an active or passive system can be designed (at any cost) which will satisfy each of SOLAS, the flag state and the insurers, and remain operational for more than a few days. Automatically closing vents must be considered down-flooding points, so when calculation the down-flooding angle, you must consider them to be open (for SOLAS purposes). The only exception (which is rarely granted) is for ball-type automatic closing air vents, which are not suitable for cabin ventilation as they close with negative pressure.
  - krisoft 2y ago
    > the question is whether an active or passive system can be designed (at any cost) which will satisfy each of SOLAS, the flag state and the insurers, and remain operational for more than a few days. We went to the moon. :) Or more pertinently we have diesel submarines with snorkel masts which automatically close (and even more importantly the diesel engine automatically shuts off) when submerged. So we know it can be done. I can't even imagine how expensive those things are on a submarine, and how expensive all the maintenance must be. I know this sounds crazy but changing regulations (or rather realistically obtaining exemptions) is "just a cost" too. A huge cost for sure. And an uncertain cost. But it can be done, especially when one does all the requires engineering work to show that the new solution is safer than the old one. I understand that most people when they say "at any cost" what they mean is "at any cost reasonable within our means for this kind of thing". But when taken literally "at any cost" is quite expansive. > Automatically closing vents must be considered down-flooding points, so when calculation the down-flooding angle, you must consider them to be open (for SOLAS purposes). Presumably the SOLAS calculations were already fine with the down-flooding angle as is. So we can still treat the vent as open (for SOLAS purposes) while at the same time have an auto-closing feature on them.
    - closewith 2y ago
      > We went to the moon. :) Or more pertinently we have diesel submarines with snorkel masts which automatically close (and even more importantly the diesel engine automatically shuts off) when submerged. What a non-sequitur. The issue isn't whether it can be built - but whether you can certify and insure it. Apollo couldn't have been run as a commercial pleasure spacecraft, either. > Presumably the SOLAS calculations were already fine with the down-flooding angle as is. So we can still treat the vent as open (for SOLAS purposes) while at the same time have an auto-closing feature on them. At anchor, but not at sea, where to achieve it's CE rating, the offending vents would be required to be closed.
mpreda 2y ago
I don't think it's the engine exhaust, neither the engine air intake. I think the exaust has possitive pressure when the engine is running which would prevent water from entering. OTOH water entering the engine air intake.. would be quite bad for the engine I guess, so there'd be protection against that. Also both of these (exhaust & intake) are not free to the inside of the vessel, but form a closed circuit with the engine, so there's no way to flood the vessel through those. So probably we're talking about the engine room *ventilation* openings that would let water in.
- bell-cot 2y ago
  > I think the exaust has possitive pressure when the engine is running which would prevent water from entering. Imagine a (say) 5cm diameter exhaust pipe, at a 45 degree angle - with exhaust gasses blowing out through the top 3cm, while water runs in through the bottom 2cm. At some point, the cold water starts hitting thicker and hotter pieces of metal. As you put it, "quite bad for the engine". But from the article, about what happens when the Bayesian heels over too far: "water will start to enter the vessel (usually through engine room or accommodation ventilation ducts)… once this starts the vessels is in serious trouble".
  - closewith 2y ago
    All luxury sailing yachts to a rounding error have wet exhausts below the waterline.
- jabl 2y ago
  > Also both of these (exhaust & intake) are not free to the inside of the vessel, but form a closed circuit with the engine, so there's no way to flood the vessel through those. Don't know about this yacht specifically, but as I understand it a common solution is for the engines to suck in ambient air from the engine room. > So probably we're talking about the engine room ventilation openings that would let water in. Likely yes. And probably(?!) there were watertight bulkheads around the engine room, so by itself the engine room flooding might not have sunk the boat (assuming doors/hatches were closed), but if combined with other downflooding into the living quarters (doors, ventilators etc.) it would have accelerated how quickly it sank.
K0balt 2y ago
From my perspective as a former captain of a 20m schooner, a traditional rigged boat much, much less liable to suffer a knockdown such as befell the Bayesian, it’s insane to me that the angle of vanishing stability was only 90 degrees on such a ridiculously tall vessel. That means that if that mast ever touches the water it’s not coming up. Period. And that mast is a huge lever , even without sails raised. This is a boat that was never designed to weather a bad storm, where unpredictable things are very likely to happen. And it starts to flood at 45 degrees while in normal operating trim? That is just nuts. It’s not that hard to put all of the ventilation on the centerline, and a diesel engine won’t flood a boat through its exhaust. So many design compromises on what could have been a real seagoing vessel you could trust to carry your family anywhere in comfort and safety, just for the sake of some misguided idea of opulence. In ships, beautiful is as beautiful does. A sleek coffin is an ugly ship indeed. I would not have felt safe sailing that vessel in anything other than well timed passages with no weather nearby. It really drives home the difference between a boat that is designed to stand up to whatever it might encounter vs a showpiece that is designed to look impressive but cannot face the kind of adversity that a working ship will be exposed to on a routine basis. Clearly these yachts are designed to be operational in pleasant conditions only and to hide in shelter when the sea shows it’s teeth. What a stupid waste of resources. A fake ship.

by rwmj 2y ago

trhway 2y ago

All these classical smoke stacks and ventilation tubes sticking out vertically wouldn't look great on a sleek superyacht :)

rwmj 2y ago
That would work, but I was thinking some kind of ballcock (https://en.wikipedia.org/wiki/Ballcock https://en.wikipedia.org/wiki/Ballcock) built into the ducts.

closewith 2y ago

More or less any clever tricks at sea have been tried and tested and found unsuitable. In particular, almost any non-positively actuated mechanical valve exposed to sea air will seize in days.

krisoft 2y ago

I’m sure it is possible. One surprising thing i hear about yachts (or not surprising I guess, depending on how you look at it) is that money is not a limit when it comes to guest accomodation but they are very much pinching every penny when it comes to anything else. So the question is not “is it possible to design automatically closing ducting” but “what is the cost of doing it”. And in general everything the guests interact with or experience will be exactly how the owner wants it, while everything else will be done to the minimum quality required by the classification rules.

short_sells_poo 2y ago
It's not (just) cost saving. Having owned a yacht, everything breaks all the time. The environment is extremely harsh on everything. Seawater is corrosive. Even high quality stainless steel (expensive!) will corrode. Sealife is invasive. Every nook and cranny is under constant assault from all sorts of weird little critters. The most robust solution is to keep things as simple as possible. Any bells and whistles you add will become liabilities very quickly, and if crucial systems depend on these bells and whistles, you can quickly get cascading failures. I learned in about 2 months that you want the most crude, easy to repair and reliable solution to important parts and you want them cheap - because you'll be replacing them regularly. Expensive solutions will provide very little relief from this (if any at all). If the TVs in the guest rooms break regularly because of constant vibrations, that'll annoy the guests, but the ship will float and go forward. If your fancy fly by wire engine controls corrode and you are out at sea, it's mayday time. A lot of smaller boats still use mechanical wire actuation because it can be mended literally with a string.
- krisoft 2y ago
  I agree with everything you are saying, but I posit that even with that it is really "just cost". If the simple valve is not reliable enough you can design a more reliable one. It will cost you a lot. Maintenance is a cost too. (It costs you in crew time, crew training, materials, and tools.) And when it predictably goes wrong and that causes the ship downtime, and they have to cancel a guest visit because of it that is a cost too. So all of the things you list there (very good points each!) can be either mitigated by spending more on the initial cost of the valves, or by spending more on maintenance, or paying the price when it breaks. And I also agree with you that it very well might be the case that the benefits are not worth the costs. (Especially since when you are designing the yacth you can't know what kind of disaster will strike it. We could, in an alternative reality, very well be sitting here and talking about how they should have installed more automatic fire-extinguishers, or more redundant navigation, or protection from prop-fouling.) Engineering is hard.
  - short_sells_poo 2y ago
    I think I phrased that badly. What I meant to convey is that a cheap and cheerful solution will need replacement at interval X, and a much more expensive solution will need replacement at 1.2X. At least in my experience, the relationship between the money spent and reliability tended to be logarithmic. In other words, spending more on fancier equipment didn't really minimize the main pain point of failures: the ship being unavailable for sailing due to maintenance. It was worse in fact, because more expensive equipment wasn't more reliable usually. Shiny lcd touch panels looked great but were a ballache to use when there was a swell. I had chunky 800hp mercury engines fitted to crack that magical 100mph barrier, but because they were fly by wire, we had constant issues with electrical contacts that were difficult to diagnose out at sea (unlike the older mechanically actuated throttles). Even worse, the more "over-engineered" a piece of equipment becomes, the more difficult it tends to be to reason about it's boundary conditions. More moving parts, heavier weight, more exotic materials - these all add further unknowns to an already very chaotic system that is seafaring. To come back to my electronic vs simple mechanical throttle system, the former is difficult to repair with a set of pliers, the other is trivial. Even though the former may have redundancies and fancy recovery modes, if it does fail, you are SOL. So you are right, ultimately it's a cost question in the sense that if the more expensive components aren't more reliable, why spend money on them. I was keen to make the point that I'd have gladly spent more money on said equipment to make it more reliable, but there seemed to be no correlation between the two aspects :D
closewith 2y ago
No, the question is whether an active or passive system can be designed (at any cost) which will satisfy each of SOLAS, the flag state and the insurers, and remain operational for more than a few days. Automatically closing vents must be considered down-flooding points, so when calculation the down-flooding angle, you must consider them to be open (for SOLAS purposes). The only exception (which is rarely granted) is for ball-type automatic closing air vents, which are not suitable for cabin ventilation as they close with negative pressure.
- krisoft 2y ago
  > the question is whether an active or passive system can be designed (at any cost) which will satisfy each of SOLAS, the flag state and the insurers, and remain operational for more than a few days. We went to the moon. :) Or more pertinently we have diesel submarines with snorkel masts which automatically close (and even more importantly the diesel engine automatically shuts off) when submerged. So we know it can be done. I can't even imagine how expensive those things are on a submarine, and how expensive all the maintenance must be. I know this sounds crazy but changing regulations (or rather realistically obtaining exemptions) is "just a cost" too. A huge cost for sure. And an uncertain cost. But it can be done, especially when one does all the requires engineering work to show that the new solution is safer than the old one. I understand that most people when they say "at any cost" what they mean is "at any cost reasonable within our means for this kind of thing". But when taken literally "at any cost" is quite expansive. > Automatically closing vents must be considered down-flooding points, so when calculation the down-flooding angle, you must consider them to be open (for SOLAS purposes). Presumably the SOLAS calculations were already fine with the down-flooding angle as is. So we can still treat the vent as open (for SOLAS purposes) while at the same time have an auto-closing feature on them.
  - closewith 2y ago
    > We went to the moon. :) Or more pertinently we have diesel submarines with snorkel masts which automatically close (and even more importantly the diesel engine automatically shuts off) when submerged. What a non-sequitur. The issue isn't whether it can be built - but whether you can certify and insure it. Apollo couldn't have been run as a commercial pleasure spacecraft, either. > Presumably the SOLAS calculations were already fine with the down-flooding angle as is. So we can still treat the vent as open (for SOLAS purposes) while at the same time have an auto-closing feature on them. At anchor, but not at sea, where to achieve it's CE rating, the offending vents would be required to be closed.

mpreda 2y ago

I don't think it's the engine exhaust, neither the engine air intake. I think the exaust has possitive pressure when the engine is running which would prevent water from entering. OTOH water entering the engine air intake.. would be quite bad for the engine I guess, so there'd be protection against that. Also both of these (exhaust & intake) are not free to the inside of the vessel, but form a closed circuit with the engine, so there's no way to flood the vessel through those. So probably we're talking about the engine room *ventilation* openings that would let water in.

bell-cot 2y ago
> I think the exaust has possitive pressure when the engine is running which would prevent water from entering. Imagine a (say) 5cm diameter exhaust pipe, at a 45 degree angle - with exhaust gasses blowing out through the top 3cm, while water runs in through the bottom 2cm. At some point, the cold water starts hitting thicker and hotter pieces of metal. As you put it, "quite bad for the engine". But from the article, about what happens when the Bayesian heels over too far: "water will start to enter the vessel (usually through engine room or accommodation ventilation ducts)… once this starts the vessels is in serious trouble".
- closewith 2y ago
  All luxury sailing yachts to a rounding error have wet exhausts below the waterline.
jabl 2y ago
> Also both of these (exhaust & intake) are not free to the inside of the vessel, but form a closed circuit with the engine, so there's no way to flood the vessel through those. Don't know about this yacht specifically, but as I understand it a common solution is for the engines to suck in ambient air from the engine room. > So probably we're talking about the engine room ventilation openings that would let water in. Likely yes. And probably(?!) there were watertight bulkheads around the engine room, so by itself the engine room flooding might not have sunk the boat (assuming doors/hatches were closed), but if combined with other downflooding into the living quarters (doors, ventilators etc.) it would have accelerated how quickly it sank.

K0balt 2y ago

From my perspective as a former captain of a 20m schooner, a traditional rigged boat much, much less liable to suffer a knockdown such as befell the Bayesian, it’s insane to me that the angle of vanishing stability was only 90 degrees on such a ridiculously tall vessel. That means that if that mast ever touches the water it’s not coming up. Period. And that mast is a huge lever , even without sails raised. This is a boat that was never designed to weather a bad storm, where unpredictable things are very likely to happen. And it starts to flood at 45 degrees while in normal operating trim? That is just nuts. It’s not that hard to put all of the ventilation on the centerline, and a diesel engine won’t flood a boat through its exhaust. So many design compromises on what could have been a real seagoing vessel you could trust to carry your family anywhere in comfort and safety, just for the sake of some misguided idea of opulence. In ships, beautiful is as beautiful does. A sleek coffin is an ugly ship indeed. I would not have felt safe sailing that vessel in anything other than well timed passages with no weather nearby. It really drives home the difference between a boat that is designed to stand up to whatever it might encounter vs a showpiece that is designed to look impressive but cannot face the kind of adversity that a working ship will be exposed to on a routine basis. Clearly these yachts are designed to be operational in pleasant conditions only and to hide in shelter when the sea shows it’s teeth. What a stupid waste of resources. A fake ship.