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[billekens]

You WILL need a big winch, the sail area on my boat is about 1600 sq inches.
At the moment winches are the weak link, I am working on a Mega Winch, no idea 
when it will be finished, still got details to work out, so, watch this Space !!!.
John.

John, have you got any more info on your Mega Winch you are working on, or has that gone by the wayside?
I love the discussion about the home made winches from electric screw drivers etc.
Lets keep it going.

Bill

[JayDee]

Hello Bill,

The large winch is in a "Lay-by" at the moment, as is modelling in general, real Life has been very busy lately.
Not really had time to do much at all, but don't worry, the old brain has been working a few things out while I have been tearing around.
Just hoping inspiration will come when I least expect it !!!.

John. 

[billekens]

Ah!
The eureka moment.

I heard a story about Newton, possible myth.
He used to sit in his rocking chair holding an iron ball in his hand, by his side. At the moment he 'nodded off' the ball would slip from his fingers and the subsequent crash would wake him. The reason? He believed that many of his creative thoughts came to him in his semiconscious state. Or so the story goes.

I believe today they call this type of creative tool, 'doing a noddy'.

Maybe having a little "noddy" might help!!  For me taking a nap is not a treat anymore...it's mandatory!  Cause if I don't on my own free will...I just fall asleep where I sit! 

Bill

[Greggy1964]

This is just at the idea stage but it's food for thought

As far as sail winches are concerned I'm toying the with the idea of using a length of screw treaded rod (say m10) mounted on ball race bearings at each end as a sail winch. The threaded rod will be directly connected to an eclectic motor, or possibly via a gearbox. On the threaded rod will be mounted a nut which will be prevented from turning thus forcing it to travel up and down the thread depending on which way the motor turns the rod.

The sail sheet will be attached to a tab on the traveller, thus giving me an adjustable in-haul out-haul movement.

My boat project hull will be 59" long so there will be no shortage of space for heavy gubbins placed in the bilges, and this way I will get the gearing inherent in the rod and nut and with my sail sheet attached to this traveller I will get in in-haul and out-haul of the sails sorted. Tension on the sheet would be via a long soft coil spring or elastic to keep stuff taffling up.

Also because of their size of my ship I might use scale blocks and sheets above deck and this will give me extra gearing force in controlling the sails as well as a working scale rig.

It's all at the scribble on the corner of the table cloth stage at the moment but what do you guys think?

[tigertiger]

This is a variation on another idea (where you use an ordinary motor instead of a winch).

The only limiting factor I can see with your idea is speed of reaction of the sheets. This mechanism will increase the time needed to come about on a windy day, to prevent the ship being overcome by the wind. Especially in a gust, when you may wish to spill wind from the sails quickly.

[Greggy1964]

I've been playing

Using my Ryobi 18v battery drill and a 100mm long M8 bolt, a nut held in the fingers will travel 100mm in 4 seconds, that means a sheet pulled in at 25mm per second and there's no way your going to stop that nut moving up that thread.

I'm planning on setting up a rig so I can work out how much this setup can lift dead weight

[billekens]

I think that we are on the right track with an experiment like this. The only variables are, courser thread or some kind of device that makes it go back to to the beginning of the thread in an instant, if you reverse it. It is an easy way to sit here and come up with suggestions but I do not have the answer, sorry about that. Let's keep this forum going as I think we are on the brink of coming to a solution. My plan was to use screw driver motors as they are much slower that a drill motor as the screw driver motor have the reduction gears build in them. Will there be enough torque with a drill motor?

[tigertiger]

Drill and screw driver motors are both high torque.

The preference for the screwdirver motor comes when using a drum on the winch. The slower speeds of rotation of the screw driver motor are more controllable. However the higher speed of the drill are needed for Gregs proposed solution.

Two more things to consider are:
- the overun of the motor once you cut power. You don't want to run to the end, it might jamb.
- how to stop the 'shuttle' at different points along the bar. To allow for different points of sail.

[Greggy1964]

I agree that we have a planetary high torque gearbox on the nose of a drill but the point is these days they can be had for peanuts and coupled with the screw thread rod make a simple winch.

Lets say for the sake of argument that when the skipper pushes up the stick on his transmitter energizing circuit 1 below, the winch viewed from the motor end turns anticlockwise. The screw turns anticlockwise with it and the sheet is let out, and clockwise is vise versa. The winch is so oriented that the sail sheet runs through its fairlead in the deck to the winch which pulls the sheet in away from the fairlead and vice versa. See sketch below.

The shuttle or carrier cannot be overpowered by the sail pulling on the sheet in a squall of wind. It just will not budge from the position currently set unless a command is given to wind in more sheet or go the opposite way and let the sheet out. The boat as I see it in this situation has three options, round up into the wind, heel over, or the skipper lets out the sail by reversing the winch to let the sheet back out.

The winch is made proportional by adding the old fashioned variboard speed controller or an electronic version between the battery and the winch motor. Sketch 2 gives the power circuits. Circuits 1 and 2 are energised via micros switches A alternatively via cam on the servo which are sandwiched between servo and variboard speed controller.

Over run is cured by micro switches B at each end of the threaded rod in such a away that when the shuttle comes to the end of its travel it would trip the limit switch B at that end. Power to the winch motor is switched off for that direction only. The shuttle stops it travel almost immediately and the slight overrun opens the limit switch still further.

Then the only way forward as it were, is for the skipper to pull back on his transmitter stick energising circuit 2 and reverse the winch motor allowing the shuttle to move away from the micro switch B just tripped re energising it. At this point the winch can carry on in the current direction or go back the other way until it reaches the limit switch again.

Make sense?

Because of the torque at the planetary gearbox coupled with that of the screw thread winch, high pulling power is available to the sail sheet allowing large sails to be controlled.

My 18V battery drill coupled to an M8 thread rod on full power allows the carrier nut to travel up and down at 25mm per second. How fast do you need to haul a sail sheet in or out?

[Greggy1964]

I've been playing again . . . . . . . . . .

The set up mentioned above can dead lift vertically a 50lb in weight without breaking a sweat and it still shifts it at a linear 25mm/second, in my book that equates to a in haul force on a sail sheet torque of 50lbs per linear inch per second at 18V am I right?

Can any techies here work out what that means in sail area/wind strength?

My guess is I could double that easy but the jaws on my drill chuck don't have the gripping force to hold onto the threaded rod at that weight!

I'm going to have to rethink the drill jaws rod couple first. Watch this space. 
 

[Greggy1964]

The drill motor by the way is turning at 1300 rpm at the chuck and at 1" per second the winch will haul 50 lbs at 60 inches per minute.

To compare, the Hi-tech HS785-HB does 3.5 revolutions at 1.68 seconds per 60 degrees. On a 1.38" (35mm) diameter winch drum (circumference 4.33")

3.5 x 4.33 = 15.15" of sheet

i.e. it rotates 1260 degrees (3.5 revolutions) divide by 60 degrees = 21

21 x 1.68 seconds = 35.28 seconds to haul in 15.15" of sheet at a torque of 152.75 oz/in

if my sums are correct, my winch will haul in the same sheet at 1" per sec/15.15" = 15 seconds and it will haul 50lbs at that rate

Are my sums right or am I barking up the wrong tree?

[JayDee]

Hello Greggy,

There is NO tree and you are "barking" some good music !!!,
What a good idea, the Engineer in me is quite jealous.

I don't think you really need a fast acting winch except for racing, for a scale or a semi scale boat, a winch that
 moves at a set rate is more than good enough.
Even the very expensive RMG winches run at a constant speed.

Where you attach the sheet line to the Nut needs to be pulling equally on both sides of the Nut, this will reduce the wear on
both the nut and the threaded rod.
Pulling from one side only puts  great strain on the parts.

When your winch reaches the limit switches, will  it restart the other way?.
That is an area I had trouble with on my winch.

Keep up the good work !!!, keep posting, loving it !!!


John.

[Islander1951]

These are the specs for the HS-785HB

Torque 4.8/6.0v : 11 / 13.2g.
Speed 4.8/6.0v : 1.7 / 1.4 sec. @ 360° 

So it's not quite as slow as you thought!

[Greggy1964]

 
 

Yes Islander I had spotted the error, I was using duff data gleaned from the web.

But the error did get me thinking how I could match the speed, because I realised that the drill motor is primarily providing the turning force only for the screw thread winch, a bit like an ARCO prop to hold up a house during renovations. That's why the drill motor had no difficultly hauling 50lbs on a dead lift.

The thread on the prop holds up the house, the builder only has to provide a turning force to jack up the prop to where he wants it.

OK to refresh.

Hi-Tech winch turns 360 degrees in 1.68 seconds and hauls in 119mm of sheet on a standard 38mm dia. drum

i.e. 35 rpm hauls in 4250mm of sheet ( 60/1.68 x 119 = 4250).

To compare :-

Screw thread winch, 360 degrees moves the nut 1.2mm and the drill motor turns the shaft at 1300 rpm through the planetary gear box and hauls in 1560 mm

ie 1300rpm hauls in 1560mm of sheet. (1300 x 1.2 = 1560)

To match the Hi-tech, the Screwthread winch has to turn at 4250/1560 = 2.7 times faster

i.e. 1300 x 2.7 = 3542 rpm therefore 3542 x 1.2 = 4250mm of sheet in 60 seconds.

An RS 540 motor on 12V turns at 16800 rpm unload speed, since the screw thread is taking all the pulling force from the sheet and hence the sail  . . . . . . .

why can't the RS 540 drive the screw thread?

Hmmmmm!

To gear down the RS540 to 3542 rmp we need a 1: 5 reduction gearbox (16800/3542 = 4.7)

You can see where I'm going I hope.

[roycv]

Hi all, This system should work but may I suggest that the 2 ends of the screwed shaft be turned down so that they are plain rods.
 
A compression spring can fitted at each end, then when the nut comes off the end thread it simply rotates but the compression spring will force it back on to the thread when the screw thread is reversed. 

You don't really need any micro switches.  I would love to say I thought of this but it is the way that the old Ripmax (mighty midget) rudder servos worked.  Thats before we had proportional control.

I enclose a photo of this 50+ year old servo.

I took a similar screwed rod set up out of a yacht some years ago as it did bind occasionally apart from being slow.
If you look carefully at the servo picture you can see that the moving nut has a loose guide to run along, I think this enables the nut to get back on the thread every time.  The Ripmax servo works every time and is quiet.
regards to all Roy

[roycv]

Hi all, on further thoughts to the above I think I would make a relatively short screwed thread section and have it working an arm with a 2 : 1 multiplication of the effort..
best of luck though.
Roy

[roycv]

Hi again just reading the bit about strength of wind.  A 20 mph wind has a force of 1 pound per square foot of sail area.  20 mph is when the water surface starts to break.  I would think 50lb pull might be overkill!!
regards Roy

[Greggy1964]

Hello Roy thanks for the info

The grand plan is to be able to make a strong but serviceable winch that can be built from the scrap box which means if you break it you can fix it.

The sail area on my ship will be 1500 square inches and while I agree 50lbs might be just a tad over kill (I'm going to need about 1/5th that) it does demonstrate that we have the makings of a STRONG winch.

Big sail boats need big winches and they also need lots of ballast so why not put some of it to work!

On a personal note I like the challenge of using my noodle to come up with something I can build myself.

[roycv]

Hi Greggy, I like your sentiments and I used to make every thing myself, that includes sail winches the radio Tx and rx (Micron) and assembled (kit) servo electronics, my own design electronic speed controllers, boiler water level controllers.

I agree if you have made it you can probably fix it.  However you can buy a sail winch (Hitec) to control 1500 sq. inches of sail for about £25 and it will give excellent service.  I think you have to throw in your 'hourly rate' and speed with which you want to get a model up and working as well.

In the mean time I will always admire the d.i.y. approach.
good luck and let us know how you get on.
regards Roy

[Landlocked]

If you're building really big, a 12V system using alarm system batteries powering a car window motor provides plenty of power.

The big Hitech servos can be "hacked" to be continuously turning (speed control instead of position control) to provide the extra turns needed for the large boat sheeting lengths.  The robot building web sites have hacking directions.

Speed control allows thumbs off once your have things trimmed right as well as very fine control with the slider instead of the stick.

Landlocked.