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Old 09-05-2010, 19:20   #1
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Challenge: Help Design Chain Transfer System

Hi, this is one for electric motor gurus!
I would like to make a unit that will drag chain along a 12 foot channel under the sole and deposit it in a bin in the keel.
I imagine that as the chain drops from the main winch into the bow locker, there will be another gypsy down in the keel that will drag the chain along the channel and into a bin there.
This secondary gypsy would have to be capable of applying constant drag on the chain when the winch is operating, but also be able to spin backwards unimpeded when the anchor is being deployed.
To make it simple, it would be preferable to run the secondary gypsy straight off the shaft of a 12volt dc motor which would be operating in a semi stalled mode. This would save me making a slip clutch.
Does anyone know of a motor that can run semi stalled without overheating?
Regards, Richard.
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Old 09-05-2010, 20:39   #2
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One hydraulic winch motor that pulls the 12 foot section below. All other turning points only need freewheeling idlers. Valve for motor has to allow motor to freewheel when in nuetral.
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Old 10-05-2010, 00:28   #3
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Quote:
Originally Posted by blgklr View Post
One hydraulic winch motor that pulls the 12 foot section below. All other turning points only need freewheeling idlers. Valve for motor has to allow motor to freewheel when in nuetral.
Agree
One motor only
may need a heavier anchor to resist the drag.

Interesting idea.
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Old 10-05-2010, 01:33   #4
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Thanks for your replies blgklr and James. I thought about one motor only, but there are two reasons why I don't want to do that. Firstly, it causes all components in the system to carry the full stress of raising the anchor, and secondly in my day to day cruising I am quite happy for the chain to run in and out of the forepeak locker. Would just transfer it to the keel bin for ocean sails.
Regards, Richard.
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Old 10-05-2010, 03:58   #5
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Would be a nice little system wouldn't it - but sounds like a lot of money for not a lot of use. As you say, you'd only really use it when going offshore.

How about dropping the chain through a hatch & into the bilge by hand? A few strategically placed blocks and I don't think the effort would be too significant - the drop to the keel is longer than the lift from the anchor locker so you have gravity on your side????
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Old 10-05-2010, 07:51   #6
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By hand is the best method. The pipes and tubes used to channel the chain aft will not last very long under motorized dragging of the change. The chain will rub/eat it way through the tube/pipe and then the whole system will cease operating.
- - Better to design a bilge area close enough and low enough to be able to hand feed the chain into it. Don't forget feeding chain from outside the boat into a well or locker inside the boat is also going to admit water so provisions for drying, ventilation, and pumping out standing water are necessary.
- - The conditions in today's oceans combined with the serious degradation in quality of the galvanizing of chain, means that within a year of "active" use chain will start to rust significantly. The chain is still strong and very usable, it is just rusty and stains the deck and any lockers used to store the chain.
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Old 10-05-2010, 22:51   #7
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I had just been contemplating a very similar idea ... have you been reading my mind ?

300' of 3/8" chain really does add to the moment arm and it sure would be nice to get some of that out of the bow. I was just thinking about letting gravity do the job to get the chain under the v-berth through a bent metal conduit of some kind. I had not thought of using a motor.

I'll be interested to see what alternatives are presented here or if there have been prior examples.



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Old 11-05-2010, 04:36   #8
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Storing the heavy chain in the bilge low down is not a bad idea... but again it depends on how much you store and typically use. If you carry 300 feet of chain but only use less than 100 for typical anchoring you would be carrying 200' in the bow for rare occasions when you need it. So perhaps a manual system with the extra chain lives in the keel and is used only in the rare occasions when needed.

Then of course you have the smelly wet chain right under the sole in the salon... YUCK.

To store chain in the bilge for off shore work or long passages will give you better buoyancy in the bow and that's a good thing. If you can do this is a simple manual way over the deck and down a hatch and into the bilge it would make it less complex... but more work.

KISS makes the most sense. Weigh your options / cost benefits.

Chain will not move through bent / sloped pipes very well. You'll regret wasting time on that concept. You need to pull it from where you want it to end up... or have it drop by gravity and pile up.
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Old 11-05-2010, 05:49   #9
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Just remembered - passing anchor chain through a hose or tubing does not work unless the tube or pipe is many multiples of the size of the chain. That is, the I.D. needs to be in the range of 4 to 6 inches in diameter.
- - The reason - chain with take on a twist when actively use for anchoring. This twisting is transmitted up to the upper section that is still in the boat. As a result when the chain is retrieved into the boat or released out of it locker, the links "double up" upon themselves making the effective O.D. of the chain twice or three times its normal O.D. You can see this by taking a length of chain in deliberately introduce a twist into it. The links with go perpendicular to each other and make a mess that resembles a "knot,"
- - About once per year I have to remove all the chain from my locker and lay it out then "untwist" all the links so it will lay flat again. Exactly why the anchor chain does this is not clearly understood except maybe the anchor spins as it is released on its way to the ocean floor combined with the tendancy of boats to circle around the anchor as winds and tides cycle.
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Old 11-05-2010, 07:23   #10
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The gypsy on a windless will retrieve the chain twist free, to go into the anchor locker. In doing so all turns or twists in the chain remain between the gypsy and the anchor, a good reason to have a high quality anchor swivel . I did have a problem with the gypsy twisting up the chain a few years ago. The anchor chain was wore out , the links were thin which made them "longer" which put them "out of time" with the gypsy. This resulted in the chain trying to jump off and twisting. bought a new chain and had the gypsy welded up , good as new.
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Old 11-05-2010, 14:30   #11
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I have and always use a windlass and chain gypsy and I don't know how it happens but maybe there are little gremlins down in my chain locker, but the chain develops twists over time that double the links back over themselves. In everything there is logic and then their is reality and sometimes the most illogical stuff happens.
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Old 11-05-2010, 19:01   #12
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Thanks very much for the inputs. I could place the chain by hand, but that would become tiresome. Was hoping that someone knew of an electric motor that could run in an almost stalled condition, but apparently no one does.
I guess I will have to make a small hydraulic slip coupling between a normal brush motor and the gypsy. Will need only a small amount of torque to slide the chain along the channel.
When done, will let you all know whether it works as designed, or is just a waste of time.
Regards, Richard.
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Old 12-05-2010, 18:31   #13
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Further to my last post, I have bought a viscous fan coupling (ex motor vehicle) to put between the motor and the gypsy. If I can adjust the slip rate , it could solve the problem. Regards, Richard.
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