“C” on Nov 23, 2022 made a
long comment on submarine hotel load power uses.
It’s a comment well worth
turning into the following article:
"Replying to Anonymous's very
interesting response [of Nov 16, 2022 here] to my Hotel load point: the comment from Fleet
Command Kobayashi [scroll down here for his photo and bio] is revealing and useful in confirming my suspicion that submarine commanders are likely judicious in what systems they run during endurance
exercises.
I would add that the Thales VELOX-M8 Intercept Sonar example I gave (which is one of the very few examples I have found in literature where the vendor has given a power value) was 400W, or 0.4Kw, which is not a lot in the bigger picture of hotel load computations, which seem to waffle between 50 and 200 KWh. This is an intercept sonar, ie. a relatively small item of kit, an adjunct auxiliary to the primary arrays mainly used for classifying a received tone (sound electronic support measures (ESM) [intelligence gathering] essentially). The processing unit takes up about 6U of rack-space, and I'm not sure the array size, but intercept sonars are typically very small, the British type 2019 "nipple" being iconic [scroll half way down the very informative "The History Of British Submarine Sonars" for "SONAR TYPE 2019 DOME"].
Nonetheless the point that
designers actively have tilted away from certain system layouts typical in nuke
boats because of power consumption is good to have confirmed.
Here's my extremely rough cut
of load for a medium-large boat with a crew of c. 60, and these are, in my
view, very generous:
ENVIRONMENT
12KW for Heating, ventilation,
and air conditioning (HVAC) (rough guide of 5 people per KW)
1KW for lighting (incandescent
lighting should be long gone, LED's are so vastly superior in sub context its
not funny)
FOOD
3Kw for refrigeration (A 30
cubic-meter cold room will draw about this)
5Kw for food preparation (this
will flux according to usage, but this will power an oven an 4 hot plates at
full tilt, but I use this number as an "average")
2Kw for misc (kettles/boilers
etc, also an average as will flux)
OPERATIONAL TECHNOLOGY (OT)
This is trickier and depends
on degree of automation on board, I work in Mining OT space so by way of
comparison, all the OT control systems of a large processing mill, with around
250 devices draws, for CONTROL purposes, between 2 and 8 Kw, depending on how
many things are in state-change at any point in time. This feels a reasonable
starting point, so...
6KW for onboard OT. (eg.
raising a mast will require a controller that draws only a few watts
constantly, but the actual Variable speed drive (VSD) which is driven by it,
that does the actual hoist, will draw mush more for the few seconds its
working)
SONAR, COMBAT, COMMUNICATIONS,
ETC
Well this is the big hole. I
don’t know. So far everything else has come in at about 30KW, which, if numbers
like 100KW for hotel are taken, leaves a ball-aching 70KW in mostly
computational activity. Its plausible, but thats roughly equivalent to around
100 mainstream IT servers, which feels excessive. Each terminal station, if it
includes a pair or large LCD screens, networking and computation will likely
draw 0.5 to 1KW, so a boat with 8 such terminals means there is 8KW up front.
I welcome
adjustments/insights/amendments to this, as at the moment its just not adding
up, unless current systems are just woefully inefficient and using 90's era or
older systems - which may very well be the case.
C”
Pete Comment
For further reading relevant to submarine propulsion and non-propulsion (hotel load) electrical uses see Marine Insight's "Different Systems on a Naval Submarine" of April 17, 2021 at https://www.marineinsight.com/naval-architecture/different-systems-on-a-naval-submarine/
Hi Pete, the Indian Scorpene Subtics sonar and related suite takes up nearly 125 kW of power from what I recall
ReplyDeleteYou want to look at this for BQQ-10 and BQG-5 plus related suite - 150 kW load will be needed
https://archive.aoe.vt.edu/brown/VTShipDesign/2006Team3T30.pdf
look at Table 11. No wonder nuclear propulsion allows for higher power in sonar active modes and with 300-500 sq.ft extra area needed for the Lockheed BQQ-10 set up vs Thales Subtics.
Prior comments very illuminating, and useful to roughly confirm my suspicion that the sonar and combat system is likely to be, by far, the biggest hog of power for diesel/electric boat. The numbers (very roughly) add up.
ReplyDeleteI'm no sonar engineer, but I'm still baffled why a sonar system in passive mode would consume upwards of 75Kw - active is different for sure - those are BIG numbers.
Still I guess the takeaway is that when we say "Hotel Load", these days what we really mean is "Sonar and Combat System".
C
Hi Pete.
ReplyDeleteThe "essential hotel load" of Yuan class and S-80A class are said to be 38 kW [1] and 50 kW [2], respectively.
By the way, as you know, I have made some information disclosure requests to the Japanese MoD.
The deliverables imply that the power consumption of Soryus' combat system (including sonar system, fire control system, consoles, intra-ship network, etc.) is about the same as above "essential hotel load" of Yuans and S-80As.
[1]http://gentleseas.blogspot.com/2016/02/chinese-yuan-submarines-to-use-lithium.html
[2]Scott, Richard (November 23, 2007). "Spain's S-80A submarine comes up to the surface". Jane's Navy International. p26-31
Regards
wispywood2344
Wispywood's comments also very interesting, as I would assume "essential" hotel load would preclude heavy-weight sonar processing and reducing the combat system use to plan positioning only. 38-50KW very broadly ties in with the numbers I came up with (c. 30KW + 10-20Kw for limited sound/combat systems).
ReplyDeleteC
Thanks GhalibKabir, C and wispywood2344 (Nov 24 - 28, 2022)
ReplyDeleteFor your comments, figures and links on hotel load needs.
It all seems to underline it is better to have much more plentiful nuclear power on tap for heavy sonar and broader combat system processing needs than far more limited power ultimately generated from diesel power.
So this is yet another reason Australia may make the right decision in choosing SSNs - not yet a done deal - pending the SSN Taskforce report, https://www.defence.gov.au/about/taskforces/nuclear-powered-submarine-task-force
in first half 2023.
Regards Pete