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erice

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Posts posted by erice

    Lithium v AGM

    in TechTalk

    Posted

    so the lithium iron phosphate batteries you speak of are not the lithium ion batteries that thermally ran away and caused these problems 4 years ago?

    https://www.nytimes.com/2016/09/03/technology/samsungs-recall-the-problem-with-lithium-ion-batteries.html

    https://www.cnet.com/news/why-are-hoverboards-exploding-and-catching-fire/

    some good info here

    Lithium Iron Phosphate (LiFePO4)
    Lithium iron phosphate (LFP) has a lower specific energy and lower cell voltage than other cathode materials, it has the benefit of being very stable, which gives excellent cycle life and high specific power with much lower risk of thermal runaway, even if abused. This makes it the safest of the LI cathode chemistries currently on the market.
    LFP are generally used in stationary systems. They are being used to replace lead-acid starting batteries in vehicles. Four LFP cells in series provide 12.8 volts, compared with a standard lead-acid battery 13.8 volts. There is some question as to how LFP batteries will fair in the long term as regular vehicle charging systems are designed to charge the battery at 14.4 volts continuously in operation (BU-205, 2018).

    https://www.fireandemergency.nz/assets/Documents/Files/Report_174_Lithium_Batteries_Whats_the_problem.pdf

    Lithium v AGM

    in TechTalk

    Posted

    am not a fan of lithium batteries on a boat

    this is why

    https://www.tvnz.co.nz/one-news/new-zealand/glider-pilots-battery-caught-fire-mid-flight-causing-fatal-2017-crash-in-northland

    they always blame the charging......but personally i think there is something else going on that they don't yet understand

    https://en.wikipedia.org/wiki/Boeing_787_Dreamliner_battery_problems

     The enclosure Boeing had to add is 185 lb (84 kg) heavier, negating the lighter battery potential.[61]

    Boat on Boat

    in RaceTalk

    Posted

    luna rossa seem to be suggesting they can manoeuvre pretty damn well 

    and they expect to use that to their advantage 

    "The only thing we have seen is the quality of manoeuvres and I would say for the moment that we have an advantage. Our manoeuvres are carried out perfectly," Fischer told French yachting site Tip & Shaft.

    That is very important, as if you are clear about your manoeuvres, you can afford to change tack for tactical reasons, while if you find it hard, you avoid that as much as you can.

    https://www.nzherald.co.nz/sport/2021-americas-cup-luna-rossa-reveal-key-advantage-as-world-series-looms/UPLOSH3XT5TGFK7ZY7O4JOV7G4/

    unpowered old punt

    in MarineTalk

    Posted

    1606571293831.jpg?format=pjpg&optimize=m

    How does it work? Two large cables are suspended across the fast-flowing river. The punt is attached to both wires, and once your car is onboard, the puntman turns the boat slightly with a rudder, meaning the side of the boat catches the current. Because it's attached to a wire, it can't go backwards, so instead slides across the river. No motors, just pure physics.

    https://www.stuff.co.nz/travel/destinations/nz/central-otago-lakes/300168958/the-punt-at-tuapeka-mouth-the-floating-road-that-leads-to-a-secret-chocolate-shop

    GME MT403 EPIRB

    in MarineTalk

    Posted

    afaik

    the sats are monitored all over the world

    the hex id is the easiest thing to receive and the 'emergency' is picked up by high-level sats. then passed on to the country of origin as determined by the country specific id

    (so for a product with an oz number it goes to the oz emergency centre, they then look up their registration record and try to call the registered telephone number to check if it's a false trigger) 

    hopefully by the time this initial warning has been passed on a modern epirb/plb has managed to determine an accurate lat/long, (this can take 30min? to determine as the epirb, unlike a navigation gps has no internal clock, so no almanac of sat positions on that day + time to determine a fast and accurate fix) this lat/long data is then also transmitted and hopefully quickly passed on to the country specified by the hex id 

    you can imagine how slow things can get if 1 country can't find the hex code in their database, or find they need to telephone another country's emergency services and then keep relaying the info they get  from the receiving nation

    https://oceansignal.com/how-do-epirbs-and-plbs-operate/

    1. The transmitter is activated, either automatically in a crash or after sinking, or manually by survivors of an emergency situation.
    2. At least one satellite picks up the beacon's transmission.
    3. The satellites transfer the beacon's signal to their respective ground control stations.
    4. The ground stations process the signals and forward the data, including approximate location, to a national authority.
    5. The national authority forwards the data to a rescue authority
    6. The rescue authority uses its own receiving equipment afterwards to locate the beacon and commence its own rescue or recovery operations.

    When one of the COSPAS-SARSAT satellites detects a beacon, the detection is passed to one of the program's approximately 30 Mission Control Centers, such as USMCC (in Suitland, Maryland), where the detected location and beacon details are used to determine which Rescue Coordination Center (for example, the U.S. Coast Guard's PACAREA RCC, in Alameda, California) to pass the alert to.[10]

     

    • A country code, which lets the worldwide COSPAS/SARSAT central authority identify the national authority responsible for the beacon.
    • Embedded 15-Hex ID or 15-hex transmitted distress message, for example, 2024F72524FFBFF The hex ID is printed or stamped on the outside of the beacon and is hard-coded into its firmware. The 15-hex ID can only be reprogrammed by certified distress radiobeacon technicians. The national authority uses this number to look up phone numbers and other contact information for the beacon. This is crucial to handle the large number of false alarms generated by beacons.
    •  
    • https://en.wikipedia.org/wiki/Emergency_position-indicating_radiobeacon_station

    GME MT403 EPIRB

    in MarineTalk

    Posted

    afaik there are 3 differences design differences that differentiate between plb + epirb

    1. epirb must float antenna up..........so is 2x? as large as plb to contain sufficient air volume....my gme mt410 is still pocket-able which is great as it can be carried in a lifejacket pocket or any jacket pocket when taken on land beyond phone coverage  

    2. epirb must have 48hrs battery life on continuous transmit, plb 24hrs

    3. epirb must have strobe

    https://www.gme.net.au/us/news/epirb-vs-plb/

    Etnz boat 2

    in RaceTalk

    Posted

    yes it's a dead sexy boat and the very low foiling height must help aerodynamics and probably ground-effect

    as alinghi used to do they seem to have been able to launch last with a mk2.5 boat containing enough subtle improvements for that all important 1sec lead 1st mark 

    and as always it seems quite possible there are even bigger improvements in the soft-wing sail and its control

    GME MT403 EPIRB

    in MarineTalk

    Posted

    because they charge more to replace the battery pack, seals and test in nz than it costs to buy a new epirb

    i think a friend paid $550? to get his old batteries replaced and i don't think the epirb even has a gps chip, he was annoyed when he went to pick it up and they sort of said they shouldn't have done the work without telling him it would cost more than buying a new and better(gps) unit  

    some people do a diy battery replacement but you wouldn't bother if it wasn't a gps epirb

    http://battery.com.sg/our-products/3990-gme-mt401-mt403-epirb-battery.html

    https://www.marinepanservice.com/accessorio/mt403svc

    what GME  has to say about battery replacement

    https://www.gme.net.au/us/news/warning-unauthorised-battery-replacements-on-epirbs/

    when its time for my gme mt410 will be opening as these kayakers have and may now ziplock mine in the pdf pocket if the sealing is suspect

    https://gnarlydognews.blogspot.com/2010/08/plb-problem-and-modification.html

     

    This is a bit scary

    in MarineTalk

    Posted

    under xi

    all chinese companies need to further integrate 'the party' into their business structure + governance

    and if that means handing over the data on their servers for some targeted asymmetric warfare, it'll happen

    The notice requests all regions and departments to implement the new policies and “encourage private enterprises to participate in the reform of mixed ownership”. Companies are also being urged to bolster their own internal Communist Party committees, which can influence commercial decisions.

    “Party committees at all levels must strengthen their leadership over the united front work of the private economy, fully implement the party's guidelines and policies, and do a good job in implementing the various decisions and deployments of the Party Central Committee,” the notice said.

    “Guide private enterprises to improve their corporate governance structure and explore the establishment of a modern corporate system with Chinese characteristics.”

    https://www.stuff.co.nz/world/australia/300112308/chinese-drones-swarming-australian-skies-raises-security-concerns

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