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What uses all the electricity on superyachts?

Discussion in 'Generators' started by tuna_hp, Aug 4, 2023.

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  1. tuna_hp, Aug 4, 2023
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    tuna_hp

    tuna_hp New Member

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    Looking at yacht specs, I've noticed yachts often have massively powerful generators that can produce twice or more as much power as is supplied by the power grid to the largest sorts of land-based mansions. For example, in my area of the USA, a typical detached house might be supplied 48kw of power, a large mansion might be supplied 96kw of power (400A @ 240v), and extremely large 0.01% largest houses type house might be supplied 192kw of total electricity (2x 400A @ 240v).

    Charter yacht Solandge for example, is a very large yacht, but it doesnt necessarily have more square feet of space than some of the mansions I covered above. And yet its 3 main generators produce 440kw, 440kw, and 570kw each. What the hell is all that power used for? That seems like way too much. A large 5 ton AC unit uses maybe 6kw at peak. Maybe an older model from when Solandge was built might have needed 10kw. How could you possibly need enough AC to need 440kw from the generator? AC seems like it would be the biggest power draw, lighting and electronics use almost no power in comparison. Water pumps could make a dent but still it doesn't seem like enough to justify the size of those generators.

    Any insights on to what is actually using all that power on the yacht?
  2. Norseman, Aug 4, 2023
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    Norseman

    Norseman Senior Member

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    Electric pod drives maybe?
  3. tuna_hp, Aug 4, 2023
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    tuna_hp

    tuna_hp New Member

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    @Norseman I doubt it because it has a separate pair of 2000kw main engines, and also if it had pod drives, wouldn't it have a smaller generator it could run when it wasnt running the pod drives... but interested to hear that you also think its a lot of power.
  4. Pascal, Aug 4, 2023
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    Pascal

    Pascal Senior Member

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    Everything. Air con, refrigeration, etc.

    I don’t know about big superyacht but to give you an example, even my little 53 footer uses about 15kw In summer. The 110’ I captain uses about 40kw when we have a full house in summer. See the trend? Twice the size almost 3 times the power…

    also, these big boats may have 3 big gens but they’re not going to be running at the same time. On the 110, we have 2 45KW but never run them together. One is a back up. Big super yachts are less likely to spend a lot of time connected to shorepower so having a third gen is a must for redundancy and allows to service one while still having a back up.
  5. cnvsback, Aug 4, 2023
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    cnvsback

    cnvsback Member

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    Many 500 & 1000 GT plus size yachts will have very large 3 phase electric bow thruster requirements / loads. This is one large factor in determining generator sizing, redundancies, and power management system design. Also in many cases, in addition to large kW bow thruster you will also find 3 phase electric azimuthing stern thruster arrangements that can sometimes propel the yacht forward at 2 - 4 knots. While the yacht is maneuvering it requires 100% availability of the thruster(s) electric motor(s) combined kW.

    I have been on several 70M + size yachts with these type of systems. Say you have a 380kW bow thruster and 260kW stern thruster, very common on board 1000Gt and larger yachts. Whilst maneuvering the vessel requiring 640kW of available power. This is without consideration to the house load(inlcduing multiple jacuzzi arrangements and heat plants:)). The captain may not need to use all of the available thruster power but it needs to be available on the switchboard regardless should he require it.

    Another large house consumer is the laundry center you will find on these size yachts. These areas can have up to 10 machines or more. During peak hours these will be running often to keep up with the 20 + crew and 12 or more guests.

    Zero speed stabilization is also typically 3 phase driven HPU's on larger yachts, in many cases have (4) external fins which can require more then one HPU to operate. These hydraulic pumps can be 20kW or more.

    At the end of the day these boats really do not plug into shore power often(200A services are required and sometimes not enough). They are designed with redundancy to rely on their power generation plant no matter how great the load and with loss of a generator or two in emergency cases. Power management on these boats is a whole sperate topic and is something you are constantly monitoring.
  6. tuna_hp, Aug 4, 2023
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    tuna_hp

    tuna_hp New Member

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    That's great info thanks, 45kw for a 110' scales up nearly perfectly proportionally to 440kw 2,900GT Solandge, but for some reason I thought that the ratio of power to internal space wouldn't be so flat. I assumed a larger yacht would use considerably less power per square foot from better insulation/higher efficiency generators/higher efficiency AC units/not needing as much power for electronics and galley compared to the size of the ship/generally having a much higher ratio of space to people on board.

  7. tuna_hp, Aug 4, 2023
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    tuna_hp

    tuna_hp New Member

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    Thanks I appreciate this insight. Regarding the thrusters I was somewhat familiar with all those concepts, but I was thinking, when you're using thrusters you would turn a second generator on, and that the primary generator you used most of the time could be smaller.

    Do you happen to know, when you're talking about laundry and jacuzzies for example, do yachts use modern heat pump powered equipment or do they use electric resistance heat for those sorts of things? Because land based houses also have huge pools and hot tubs and laundry rooms and all this other stuff and they're able to do it with so much less energy, I'm wondering if maybe marine-certified equipment that's designed for the rigors of being on a ship might be behind the cutting edge of efficiency in terms of what people are getting on land.

    I mean it seems to me that you'd have more than enough heat to heat the hot tubs from free waste heat off the AC alone, with the correct setup.

  8. Pascal, Aug 4, 2023
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    Pascal

    Pascal Senior Member

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    Again not familiar with super yachts but on smaller boats like the 110 I run, insulation is much worst than a in a home

    also, under a home the ground is much cooler than the water boats float on esp in the Carib or med. a home basement remains fairly cool in summer… bulges on a boat are much hotter
  9. rtrafford, Aug 4, 2023
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    rtrafford

    rtrafford Senior Member

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    3 phase power production is a more efficient means of providing high load capacity. It's also a more simple manner of balancing very large loads. Multiple generators (as mentioned) provide duplicitous backup to limit the hours on any one device, long term wear and tear.

    The larger the boat, the more bells and whistles, from HVAC to water making/conditioning/heating, larger crew quarters and subsequent support, refrigeration, and toy or house management. You aren't getting all of these assets of luxury and function into a house and a 200 amp breaker panel. You're also set up afloat so that every system aboard can be on and in use at the same time without concern.
    cnvsback likes this.
  10. cnvsback, Aug 4, 2023
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    cnvsback

    cnvsback Member

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    My experience has been 3 phase electric heating for laundry and jacuzzi systems. Some of these systems are more clever then others.

    I'm not terribly familiar with land based estate infrastructure and layout. Also, doesn't natural gas and solar play a large role nowadays ashore?

    Operating the generators is preference of the C/E. The PMS(power management system) system monitors hundreds of parameters real time with all sorts of thresholds, time delays etc. for each. Depending what mode the main switch board is in, the PMS it is capable of switching to another / between generator(s) automatically should the generator(s) online have a pre alarm condition(PMS systems are a whole separate in depth topic). When maneuvering in port, close quarters, or anchorage we would have all three generators in parallel. This allowed full availability of power to the bow / stern thrusters and three phase anchor windlesses. When not maneuvering you could manage between one and two generators running at a time. This of course depending on guest load, ambient air and water temps, zero speed stabilizers etc.
  11. rtrafford, Aug 5, 2023
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    rtrafford

    rtrafford Senior Member

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    Generators (and mains) often have PTO’s on them to network hydraulic systems used for stabilization and maneuvering as well as anchoring and windlasses. Requires the hydraulic pump to be operating, but doesn’t require much electricity. The best setups have redundancy in the pumping to allow for variations in operating conditions.

    Note, a boat has no ability to “spike” line voltage while off the dock. Only perhaps 80-85% of the available max should be relied upon. A 100% load is rarely a good idea beyond momentary use.
  12. rtrafford, Aug 5, 2023
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    rtrafford

    rtrafford Senior Member

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    HVAC, just the chiller system alone (and related air handlers) will consume 30 amps per 5 ton.

    Cooking, the galley with the refrigeration all in motion will consume another 100 amps, perhaps more if larger.

    Housekeeping and maintenance can consume another 100 amps at peak.

    All of these systems have to be able to run simultaneously at any hour. It all adds up. In a hurry.
  13. rtrafford, Aug 5, 2023
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    rtrafford

    rtrafford Senior Member

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    Aluminum conducts water temp quite well on a vessel, as you’ve stated. R value in comparison to a home is an absurd comparison when considered. The temp of the sea is a huge impact on a boat. Same with sun on that pretty Flag Blue hull.
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  14. rtrafford, Aug 5, 2023
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    rtrafford

    rtrafford Senior Member

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    Carrying this one step further, put that boat into cooler waters, and place a charter aboard. The boat needs to meet the whims and wants of every passenger. Water temp is 70. Wife wants a little heat in her bedroom. Husband heads to an area of the boat where he can deal with too much Sun by dropping the temp to 60. Meanwhile both are hungry and the chef is cooking. Laundry from the day is being handled. Beds and linens have been turned and the store is washing and prepping the spares for the next change. The kids are enjoying the hot tub under the stars. The various toys are being cleaned and reset for the next day. Not one of these features can hear the concept of “no”, and loads can’t be trimmed to bolster any of the peaks demands of the various functions.

    If you’re aboard your own private vessel, you don’t think twice about shutting down a chiller to clear the way for dinner prep. It’s second nature, and you’re working with what you have.
  15. Capt J, Aug 5, 2023
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    Capt J

    Capt J Senior Member

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    Yacht's need A LOT more BTUs of air conditioning, then you have items like water makers, stabilizers running while anchored, stewardesses running 3 washing machines and 3 dryers at the same time. A lot more refrigerators, freezers, ice makers spread throughout the boat, all electric appliances in the galley and a chef that's cooking almost non stop, because the crew eats at different times than the guests etc. etc. etc...... it all adds up.
  16. Pascal, Aug 5, 2023
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    Pascal

    Pascal Senior Member

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    Lol. You all missed one of the least predictable loads:

    the 6 long haired women who all fire up their 1500 watts blow dryers exactly one hour before dinner :). And if you re really unlucky, they ll also turn on their curly irons too!!

    We have 5 ice makers, 5 fridges and 4 freezers on the 110…. I can’t imagine what a 200’+ will have
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  17. wdrzal, Dec 12, 2023
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    wdrzal

    wdrzal Senior Member

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    Backup when at sea .
  18. Fishtigua, Dec 12, 2023
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    Fishtigua

    Fishtigua Senior Member

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    All the usual suspects, A/C, cooking and refro.

    On one boat we had a dry-cleaning machine in the Laundry Room. Have a guess which idiot was put in charge?:cool:

    Utterly useless hunk of junk, used maybe 3 or 4 times for waterproofing in 5 years. It sucked so much power to do one simple act. The Drycleaners were on speedial.
  19. Marblehead01945, Dec 27, 2023
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    Marblehead01945

    Marblehead01945 Member

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    Just for another point of reference- the 113 I ran had two 70KW generators. When we used the bow thrusters both generators powered up. Most of the time in the Summer we used almost the entire capacity of one generator to power the boat. As usual- YMMV.
  20. Pascal, Dec 27, 2023
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    Pascal

    Pascal Senior Member

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    Electric thruster on a boat that size? Or was that to run the hydraulic?

    Our hydraulics (BT, windlasses and stabs) normally run off the engine driven pumps. We have a third pump one one of the gen but that’s only for the zero speed stabs
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