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  1. #31
    Join Date
    May 2007
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    Default Re: Anchoring technique

    It would be interesting to measure the current lowering the anchor, it should be quite small.
    If you measure the voltage while lowering, if it is below 12.7 then the battery is discharging, above that the alternator is providing the current. I would expect a good alternator system to be doing the bulk of the lowering, with the battery providing the starting surge.
    In the limit, it ought to be possible to recover energy from the falling anchor....

  2. #32
    Angele's Avatar
    Angele is offline Registered User
    Location : Hertfordshire
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    Default Re: Anchoring technique

    [ QUOTE ]
    Your thinking seems logical but is not in fact correct.

    [/ QUOTE ]

    I do not think I am incorrect, but I accept that numbers on both sides of the equation are smaller than the figures I quoted.

    I did not say my batteries were dead, but that they were clearly holding relatively little charge. We still spent a whole night at anchor with them. Fridge, lights and anchor light.

    The point I was trying to make is that the power coming from the engine alternator was insufficient to turn the windlass. My expeirment proves that you do need to draw power from a battery bank even if your engine is running and the anchor is being lowered.

    In terms of which battery the power comes from I disagree. I want my engine start battery to do that and that only. I want to know that my starter battery has not been run so low by lifting the anchor that if it will start the engine.

    I agree that an engine start type of battery would be more appropriate than a deep cycly sort as it can give the necessary oomph. In an ideal world we would have three banks of batteries. I don't so I am sticking with the way my (modern) boat manufacturer made it, and all other boats in its range, by using the domestic supply. I don't care if it shortens the lives of those batteries. At least I know if my engine won't start it isn't for lack of battery power.

  3. #33
    Robin's Avatar
    Robin is offline Registered User
    Location : Daytona Beach, Florida
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    May 2001
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    11,458

    Default Re: Anchoring technique

    [ QUOTE ]
    I did not say my batteries were dead, but that they were clearly holding relatively little charge. We still spent a whole night at anchor with them. Fridge, lights and anchor light.

    [/ QUOTE ]

    You said 'they were more or less knackered'.

    We run a big 200 litre fridge 24/7 and all the conveniences and even without using our wind and solar panels can last 3 days without charging or the battery volts dropping below my personal 'limit' figure of 12.4v.

    [ QUOTE ]
    The point I was trying to make is that the power coming from the engine alternator was insufficient to turn the windlass. My expeirment proves that you do need to draw power from a battery bank even if your engine is running and the anchor is being lowered.


    [/ QUOTE ]

    You missed my point. The alternator isn't running the windlass, not unless you disconnected the battery (DON'T do it, just imagine it!), the alternator is under the control of it's regulator and is trying to recharge the battery. The battery will only accept a percentage of the alternator output depending just how flat it really is and will never be likely to be asked to produce anything like it's rated output. Anyway nobody said lunch was free, the windlass will use some capacity (amps used x time used for) but this will very quickly be replaced by the alternator even at tickover whilst you are attaching a snubber and walking back to the cockpit!

    [ QUOTE ]
    In terms of which battery the power comes from I disagree. I want my engine start battery to do that and that only. I want to know that my starter battery has not been run so low by lifting the anchor that if it will start the engine.

    [/ QUOTE ]

    If your engine battery is correctly sized it loses very little capacity (again high amps but x very brief time) whilst starting the engine. If you start the engine before using the windlass you would not have a problem anyway, it is already running! In any case as you said you do have a means of linking in the domestics if push came to shove which it never should. Our engine battery in fact is 120Ah but with very high CCA, in fact we could start the engine with one under half that size.

    [ QUOTE ]
    I am sticking with the way my (modern) boat manufacturer made it, and all other boats in its range, by using the domestic supply. I don't care if it shortens the lives of those batteries. At least I know if my engine won't start it isn't for lack of battery power.

    [/ QUOTE ]

    Pity they were not modern enough to read the windlass installation instructions! [img]/forums/images/graemlins/smile.gif[/img] Who is the builder BTW? Frequently things like windlasses are options added by the dealer after delivery rather than the builder.
    Sermons from my pulpit are with tongue firmly in cheek and without any warranty!

  4. #34
    Angele's Avatar
    Angele is offline Registered User
    Location : Hertfordshire
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    Default Re: Anchoring technique

    [ QUOTE ]
    Who is the builder BTW? Frequently things like windlasses are options added by the dealer after delivery rather than the builder.

    [/ QUOTE ]
    Builder is Dufour. Windlass (and hence all associated wiring) was factory fitted - part of the basic spec and not even optional. The battery link all switch was a dealer fit option that I specified just to be safe. It is not part of the base spec.

    Sorry, but I'm sticking to my principle of one battery for the engine only. Domestics for everything else.

    In the first instance I still think that using gravity is better for dropping the hook if you have that option rather than the windlass. Even if the power consumption point is, as you maintain, immaterial it gets the anchor on the seabed in a fraction of the time that it takes the windlass to do it.

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