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Author Topic: Waterfall winches  (Read 5906 times)

NFMike

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Waterfall winches
« on: July 31, 2012, 11:23:12 PM »

New to model boats though I do have a nautical background from back in ... well, a long time ago  :embarrassed:

After spending several weeks dithering I've ordered a Model Slipway Aziz (couldn't decide between a Dutch Courage, Al Khubar, Tsekoa II, or a couple of others; but now I have) and decided I should find out a bit more about what the prototype boats actually do for a living. Google has been mostly my friend - I've found some useful articles and YouTube stuff on anchor handling, but Waterfall winches are proving elusive. Google finds them by the dozen - no problem - but all I see are adverts should I want to buy one, and pictures of them - including one with 4 drums :o . But what I can't find is anything about what they are and how they are used. Even Wikipedia has a hole in it just there.

I'm an engineer so I can hazard an educated guess, but I'd rather hear from someone who knows the truth, or something close. If that person is you - please speak up and thank you in advance.

/ Mike

Umi_Ryuzuki

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Re: Waterfall winches
« Reply #2 on: August 01, 2012, 02:33:58 AM »

I found this,...

Quote

If the towing winch is equipped with two drums the spare towline should preferably be stored on the winch
drum, readily available for use.
The alternative is to have a spare towline which should be in position and so arranged to ensure that
transfer to the main towing drum is easily, quickly and safely effected.
In case of two towed objects whereby two independent towlines (main and spare) are to be connected, an
extra spare towline should be on board, arranged as specified above.


http://www.scribd.com/doc/49369360/IMO-884-Towing


Also,...

Quote

An additional fact to consider is that this will be a double-drum waterfall winch, so that there will always be a standby line available in case the main line parts.


http://www.workboat.com/newsdetail.aspx?id=4294974169

.

NFMike

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Re: Waterfall winches
« Reply #3 on: August 01, 2012, 09:50:56 AM »

Thanks for those replies which certainly add a bit to my knowledge.  This is what I take from it so far.
It seems that these are effectively (usually?) a winch mechanism with two drums which can be clutched in as needed - presumably each drum has its own brake.
The second drum usually contains (a) spare cable.

So how would this work? If you have a long tow needing the extra cable length how do you get the end of the first length free to attach the second? How do you connect the two lengths? Do you tow off the second (forward) drum or transfer the cable to the aft drum? If the latter, how?
And why use a waterfall type? Wouldn't a side-by-side arrangement be simpler?

/ Mike

NickelBelter

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Re: Waterfall winches
« Reply #4 on: August 01, 2012, 07:34:45 PM »

I believe that on a waterfall winch, the cable goes from one drum to the other before passing out to the load, to increase the 'gripping' ability of the winch drums.
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I'm interested in tiny versions of regular size things.

NFMike

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Re: Waterfall winches
« Reply #5 on: August 02, 2012, 11:52:57 PM »

Found this in an article about RAmpage 5000 Class offshore support tugs:
"The main towing winch is a double drum, "waterfall" style hydraulic winch supplied by Plimsoll. One drum is set up for towing operations, with 1,000 metres of 64 mm diameter steel wire rope towline. The other drum is set up for anchor handling, also with 1,000 metres of 64 mm diameter SWR."
We're getting there slowly  O0

NFMike

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Re: Waterfall winches
« Reply #7 on: August 03, 2012, 09:32:35 AM »

Thanks for the links John but they are mostly stuff I found before - basically makers sales sheets and pictures. These presuppose I know what to do with a waterfall winch :)

However I get the impression that one way or another these are all two functional winches, not a winch with a spare reel. I've seen something about the Aziz winch being a winch plus spare cable but I wonder if that is a myth started by someone who assumed that and which has become 'fact' through repetition.

oldiron

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Re: Waterfall winches
« Reply #8 on: August 03, 2012, 10:38:27 AM »

Mike:

  I know its of limited help, but it may be a clue to their operation. See page 3 of this PDF:http://www.zicom.com.sg/UploadedImg/Anchor%20Handling%20Towing%20Winch.pdf  , it suggests the two winches can be run either separately or coupled together to increase the pulling power. I would expect the coupling would be done through hydraulically operated clutches. It doesn't indicate the cable configuration between the two drums however. The quest continues.

John
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NFMike

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Re: Waterfall winches
« Reply #9 on: August 03, 2012, 01:47:54 PM »

I think that they are fitted with two motors which can be used one on each drum to give two winches, or they can both be connected to one drum to give that winch double the power. I don't think the drums are run in series.

But you are right, it is another clue and I think I have a good idea of how they might be used.  And I did see one reference that all the manufacturers develop their own systems and designs so there may not be a definitive answer.

Umi_Ryuzuki

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Re: Waterfall winches
« Reply #10 on: August 03, 2012, 07:12:20 PM »

Thanks for the links John but they are mostly stuff I found before - basically makers sales sheets and pictures. These presuppose I know what to do with a waterfall winch :)

However I get the impression that one way or another these are all two functional winches, not a winch with a spare reel. I've seen something about the Aziz winch being a winch plus spare cable but I wonder if that is a myth started by someone who assumed that and which has become 'fact' through repetition.

The second winch on the Aziz would be a spare cable. BUT, it is also a working winch, not just a spool of cable.
If you are towing at sea, and the towing cable parts, you can't just leave the tow, and go back to port for a new cable.
The second winch, will allow the boat to run a new line to the tow, and continue on its way. (there by using it's spare cable to continue its work.)

The waterfall configuration saves space, instead of a winches two wide on the deck, they waterfall winch can be
installed on narrower profiles. Also, if an existing boat wanted to install a second winch, the waterfall style winch can
be retrofitted into the existing space with out losing as much deck space as installing an entire second winch.


 :-))

catengineman

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Re: Waterfall winches
« Reply #11 on: August 03, 2012, 07:37:23 PM »

The second winch on the Aziz would be a spare cable. BUT, it is also a working winch, not just a spool of cable.
If you are towing at sea, and the towing cable parts, you can't just leave the tow, and go back to port for a new cable.
The second winch, will allow the boat to run a new line to the tow, and continue on its way. (there by using it's spare cable to continue its work.)

The waterfall configuration saves space, instead of a winches two wide on the deck, they waterfall winch can be
installed on narrower profiles. Also, if an existing boat wanted to install a second winch, the waterfall style winch can
be retrofitted into the existing space with out losing as much deck space as installing an entire second winch.


 :-))


Though there would be a use for the second wharp the emergency tow line would be used if the main tow warp parted for any reason.
the tug would come about and take onboard the emergency tow line marker buoy, this would then have a messenger line to the tow line which would then be fixed to the secondary  tow and then the tug would resume towage, normally to the closest convenient port so that they could replace the main.
This would be because the emergency and the secondary lines would be the last to use, and would not normally be on the best bridal configuration for towing so if anything else happened there is no help so to speak.
Also in my experience the secondary is shorter and sometimes smaller so would not have the same tonnage as a main.
when "working anchors etc" it was normal to use the secondary winch (smaller cheaper to replace) and that left the main in tip top condition for towage
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NFMike

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Re: Waterfall winches
« Reply #12 on: August 04, 2012, 12:35:59 AM »

Thanks Umi and cat..man; that makes some sense.
Which would be the 'secondary' winch? I'm guessing the aft/lower one for a couple of reasons.

(My kit arrived today O0 )
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