chengkp75

So, let's see. Okay, your ground wires are all connected to the single neutral point (actually several due to there being more than one generator), and that is connected to the hull, yes? So, when lightning strikes the hull, it flows into the ground wires via the neutral point connection and into any chassis grounds in equipment with 3-prong plugs, and also presents a high voltage on the "back side" of the surge protectors (which are now all over the ship) MOV, which are not designed to see voltage in that direction, and fail in thermal runaway, causing a fire. Now, your point that a high voltage placed into the hull of a ship, will not vary across the hull, I understand and agree, due to the low resistance of the steel. What's your point? That just means that if the ship's equipment were connected to the hull, that very high voltage, that didn't get dissipated in the hull, would flow through the ground wires and back to the electrical equipment. My house has had a near miss from lightning. It struck the yard, and the voltage flowed up through the ground wire, to the copper pipes in the house (causing them to glow green), and fried some electronics. Now, would I rather have the high resistance of the earth between that lightning and my electronics, or the zero resistance of the steel hull? But, I'm going to let this go, as I see it is only some kind of desire to use surge protectors on ships, which is a non-starter.

Please clarify for this old brain, but what will work the same way with a single ground fault, the existing floating ground system, or your earthed to hull system? Not following your logic at all, and still wondering why you are fixated on being able to use a surge protected power strip when they are not needed. Do you make or sell them?

The decision as to whether to use a helicopter for evacuation or divert the ship is made by committee. That committee consists of the ship's doctor (what condition is the patient in), the ship's Captain (what is the risk to the ship, crew, and passengers, the helicopter flight crew (are weather conditions or distance okay to make it safe), and the USCG flight surgeon (is there more risk in winching the patient off the ship and spending an hour or two with sub-optimal life support (this is a helicopter, not an ER), or is the patient stable enough with the life support systems on the ship to make the diversion). All of these decisions put together are what determine whether a helicopter evac is warranted. If the distances that the helicopter has to cover are great, USCG will deploy a fixed wing aircraft to supervise the scene, in case things go sideways, they can deploy lifesaving equipment. The helipads on cruise ships are almost never used for landing, and being on the bow, they are difficult to use for winching operations. The ship must continue to move, in order to remain as stable as possible, and so the helicopter is forced to make a "moving hover" (staying stationary over a moving spot) with the front of the ship in his face while backing away. For this reason, most winching is done from an upper deck, around midships. This presents problems as well, as the thermal updrafts from the ship's exhausts are near, and can cause problems with hovering. No commercial helicopter (certainly not a MediAir type) company trains for hovering over a moving ship, nor winching exercises, nor even landing on a moving ship (ship would still need to be moving to maintain a stable helipad), and no Captain would think of allowing a commercial helicopter anywhere near his ship. Some countries do outsource their SAR responsibilities to private companies (Holland for one, I think), but these are typically ex-military pilots who do train for these operations.

No more than you would with bringing a six pack of root beer. Go for the Dark and Stormy.

Why would a cruise line pay more for something than they needed to, particularly if the customer is "price insensitive", since that would mean the cruise line could charge a fare to cover a non-existent electrical filtering system, when they didn't pay for it in the first place?

But, if you ground the wiring to the hull, to allow the use of passenger surge protectors, then you place all of the ship's electronics in danger of power surges from say lightning strikes, and I don't mean portable surge protectors, but permanent ones for built in equipment, which are not needed now. Not sure what your investment in allowing surge protectors on ships is about.

Not sure what you mean by "designed to function properly with one ground fault"? What is designed this way? And, why replace one ground fault meter with thousands of GFCI devices?

The decision as to what frequency power the ship produces is made by the ship owner and shipyard at time of newbuilding, and no one knows what countries the ship may serve in the future. As for dry docking, the vast majority of cruise ships don't connect to shore power in dry dock. Most shipyards are not outfitted to supply either the high voltage power (10k), or the amount of power (4-6Mw or more) that a cruise ship uses for hotel load. Cruise ship will generally have two water connections for engine cooling that replaces the sea water cooling the ship uses when in the ocean, and the shipyard pumps cooling water in one connection, and it flows out the other connection into the harbor, and the cruise ship runs one of its diesel generators while in dry dock.

Why should the shipping industry move to change a whole system of electrical distribution, for something that is not needed. What savings do they get from buying something that has a surge protector, when they don't need the surge protector? Doing it your way would require the ships to outfit all of their electronics with surge protection, at vast cost. So, your reasoning is that they need to spend money to allow something that is not needed, when they can simply ban the item, and it doesn't cost them a dime? The only benefit of doing it your way is to the passengers, there is no benefit to the cruise industry.

I assume by "form factor" you are referring to the ship's hull shape, or block coefficient? What would that have to do with how a ship is wired? Are there different standards for wiring small, single engine airplanes or jumbo jets? Are they built by different professions? All ships have the same wiring systems. The major difference between cruise ships and the cargo ships that represent 95% of the ships in the world, is that cruise ships use electric propulsion, while cargo ships use diesel propulsion.

No, it uses 60Hz. There are never different frequency power on a ship, unless it is from a frequency drive to vary motor speed. The frequency of power is not changed when a ship moves from one area of the world to another.

You are very obviously new to Cruise Critic, or you would know that bitching about the price of the cruise is topic #1 here. They do, but they don't always work completely. And the voltage converters are to change 60Hz AC to DC, and then back to variable frequency AC to allow AC motors (driving the propellers and thrusters) to operate at various speeds. And, lets say that I have a 20Mw frequency drive connected to even a 1Gw power grid, and change the load on that frequency drive from zero to maximum in a minute? The noise from that frequency drive represents 2% of the power grid's capacity, so 98% of the power can help to filter out the noise, even without RLC circuits. Now, let's say that 20Mw frequency drive is connected to a 90Mw "grid" on a cruise ship. That frequency drive accounts for 22% of the grids capacity, leaving far less "clean" power to filter, so you would need huge RLC filters. And, that is not counting that a ship with 90Mw of generators would have typically 2 20Mw frequency drives, so the noisy power now amount to nearly half of the capacity.

The real question is why do you feel that surge protectors are needed on ships? What are the most common sources for power surges? Lightning strikes. Because the ship's wiring is not connected to the hull, lightning that strikes the ship passes harmlessly through the hull to the sea, and doesn't interact with the ship's wiring at all. I've been on several ships that have taken direct lightning strikes, and have never had any electronics (either personal or the ship's equipment) damaged by it. Transformer failure. The transformers on telephone poles takes the 12,000v from the substation, and reduces it in a single step to 220v for distribution to homes. If this transformer fails, it can send the full 12,000v to your house in a power surge. On a ship, the 10,000v main power is stepped down to 480v in a transformer, that 480v is then stepped down to 220v in a different transformer, and finally the 220v is stepped down to 120v in a third transformer. Now, most consumer surge protected power strips have a VPN (voltage protection number, or the voltage where the surge protector dumps the power to ground) of about 500-600v. So, for your device plugged into a 120v outlet in your cruise ship cabin outlet, in order to get a voltage surge large enough for the surge protector to even start protecting, would require failure of 3 separate transformers. Finally, if surge protectors were needed, why is it that none, zero, zilch of the ship's electronics (valued far higher than the aggregate of all the passenger's electronics), from navigation, communication, propulsion control, engine room automation, all the way to POS sales registers, and the multitude of desktop computers used around the ship, do not have any surge protection whatsoever.

Because, if a motor were to experience a ground failure, i.e. provide 480v power to the hull, then the neutral point on the generators would provide a return path for current, and you would have galvanic corrosion. If, however, the neutral point is not connected to the hull, that same motor going to ground would have no path for current, and would not cause corrosion. It also allows for the use of ground fault meters which are connected to the hull, to detect when these ground faults happen.

Again, do you mean that the ship is "home ported" as cruisers tend to use the phrase "it's where the ship embarks and disembarks passengers at the beginning and end of cruises"? If so, many cruise ships do not have permanent "home ports", but will change home ports with the seasons, or as demographics change the demand for cruises in other areas. Or, do you mean the "home port" as a mariner knows the term, "what is the port name on the back of the ship"? That is the "port of registry", and many ships never even call once at the port of registry, it is merely a legal "domicile". Finally, shipyards doing overhauls of cruise ships are generally not in the "home port" (either definition). Witness the Oasis class ships that do not have a drydock large enough to take them anywhere in the Western Hemisphere, where most of them routinely cruise, and have to transit to Europe for dry dockings.