Question for the physics experts : Rolling load of a trailer..

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wipe_out

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I am looking to get a winch to mount in the garage to use to pull the boat up the drive way because it's too tight for my reversing skills.. Maximum weight of the boat and trailer and everything is 2300-2400kg.. Driveway is relatively level with just a slight incline at the beginning..

Approximately how much pulling force (or more accurately approximately what winch power) would I need to pull it up the driveway? :)
 
Depends on the angle of dangle of your drive. Not much if it is 3 degrees, quite a lot if it is 45 degrees. The force is weight * sine of angle from horizontal plus rolling resistance of the tyres and friction in the bearings. The first part can be calculated easily, the latter not so.
 
I tried a manual winch AKA the type used on boat trailers to tug a caravan up a steep drive. I had the winch stationary. No breaking mech on the winch, nearly lost a finger when it spun out of control and cara careered back into (empty) street.

Sold winch, learnt to reverse... (I guess a power winch just holds when you pause it? You could pull, scotch the wheels adjust the line and pull again)

I've always wanted to use scotch small 's' in a sentence...
 
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If the surface is smooth and the tyres are pumped up, the force should be quite low.
We manhandle heavyish ribs on trailers, I reckon 100lb shifts well over a ton on the flat.
Things will roll down a 1 in 10 slope with some enthusiasm, so the drag is clearly well less than 10% of the weight.
My Dad had one of those caravan movers, motorised sack truck thing with a towball? 12V battery powered, and you can grab the van brake while using it.
Worked for him, I would say his drive was a slope of about 1 in 20?
Small light van though.
 
I know you are hoping for the perfect answer from real a expert but if he doesn't pitch up, I hope this helps:

I used to use one of these: http://www.ebay.co.uk/itm/12-v-6-00...825?pt=LH_DefaultDomain_3&hash=item462b0cefc9

To pull a 1936 MG SA up a 30 degree slope into my garage. I reckon it would pull your boat, even if you had to put a block in to get up the slope for a start. Using the remote, you also have a free hand to pull and guide it but I guess you would have at least one assistant anyway.
 
A rough rule of thumb with say a max 10 degree slope would be 20% of the Gross weight so say 500kg winch. As always, a bigger capacity will last longer, especially in 12v versions.
 
two sides to the answer.

You need something mechanical to pull the trailer UP, and also you need something mechanical to let the trailer DOWN.

The little ratchet winches on ebay are fine for pulling up, but they are lethal if you take the ratchet off and don't have very firm control of the handle. If you let go, the handle whizzes round very fast and breaks fingers.


I'd be tempted to find an old sheet winch (Lewmar 8 or similar) then install it on the trailer just behind the towball/tongue. More than enough power to pull the trailer up a ramp, and importantly, you can surge the line under control to let the trailer down the ramp.
 
Thanks for all the answers.. The drive is more or less level.. At the start though there is a small incline, at a guess I would about 5 degrees.. Even at 10 degrees it sounds like I won't need all that much to pull it..

The reason for the question is that the one recommended by the online store was rated at 8000lbs which technically is enough to lift the boat and trailer vertically.. Seemed a huge overkill for what I am wanting to do.. I don't know the physics of a rolling load though so didn't have a clue what would be needed..

So by the sound of it even a small one would do the job but the limitation of the short length of rope on the small ones.. I have to pull from about 15m away.. I could obviously use a length of rope and do a couple of pulls but will be easier to do in one go.. Si I really just need to look at the rope lengths and choose one with about 15m on it..
 
wipe_out said:
Thanks for all the answers.. The drive is more or less level.. At the start though there is a small incline, at a guess I would about 5 degrees.. Even at 10 degrees it sounds like I won't need all that much to pull it..

The reason for the question is that the one recommended by the online store was rated at 8000lbs which technically is enough to lift the boat and trailer vertically.. Seemed a huge overkill for what I am wanting to do.. I don't know the physics of a rolling load though so didn't have a clue what would be needed..

So by the sound of it even a small one would do the job but the limitation of the short length of rope on the small ones.. I have to pull from about 15m away.. I could obviously use a length of rope and do a couple of pulls but will be easier to do in one go.. Si I really just need to look at the rope lengths and choose one with about 15m on it..
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Bear in mind that most winch ratings (in fact all) will be based on the pull on the first row of windings - as the winch reel loads up the diameter of the wound wire increases and therefore the load capacity decreases - if your slope is at the beginning and you keep up the momentum then you can ignore this. Keep onlookers and yourself out of the way of a loaded 15m wire! I've had a 65mm dia winch wire part with 50 meters off the drum and 60 ton straight pull on it - not fun!!!
 
drumbeat said:
Bear in mind that most winch ratings (in fact all) will be based on the pull on the first row of windings - as the winch reel loads up the diameter of the wound wire increases and therefore the load capacity decreases - if your slope is at the beginning and you keep up the momentum then you can ignore this. Keep onlookers and yourself out of the way of a loaded 15m wire! I've had a 65mm dia winch wire part with 50 meters off the drum and 60 ton straight pull on it - not fun!!!
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Yes, I will make sure no-one is near the rope.. Can only imagine the damage a snapped rope would do to someone standing near it.. Is synthetic rope safer/better than wire rope if it snaps? or to they both cause serious injury/damage to anyone/anything nearby?

Sounds to me like I'll need less than 500kg of pulling force at the most.. So a winch rated at 3500lbs should be more than enough even fully wound.. As you say the incline is at the beginning where the winch would have the most pulling power and the latter part is pretty level so would need minimal force..
 
BruceK said:
This is my setup 12 onwards. http://www.ybw.com/forums/showthread.php?430999-Electric-Trailer-Mover-Gizmo&p=5302814#post5302814

A 4x4 winch with fwd and reverse and a hitch dolly. A 4x4 winch will hold at least 20m line. Mine 30m. Its a six ton winch but thats arbitrary. ... I needex 30m of line. Boat specific winches come with rather short winch ljnes 8m or so.
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Yes, seems the line length is probably what is going to determine the winch I have to get if I want to do it in one pull.. If I get a smaller winch with a shorter line I will have to do it in two pulls..
 
wipe_out said:
Yes, I will make sure no-one is near the rope.. Can only imagine the damage a snapped rope would do to someone standing near it.. Is synthetic rope safer/better than wire rope if it snaps? or to they both cause serious injury/damage to anyone/anything nearby?

Sounds to me like I'll need less than 500kg of pulling force at the most.. So a winch rated at 3500lbs should be more than enough even fully wound.. As you say the incline is at the beginning where the winch would have the most pulling power and the latter part is pretty level so would need minimal force..
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More than enough :encouragement:
 
At such a low loading even if a wire broke there would be little energy stored in it. It would probably just fall to the ground.
My brother in law, and others, used their trailer winches, reversed, to haul their various boats up the rough, stony and sometimes fairly steep shore at their landings on Ullswater. You do have a winch on the trailer?

Somewhat like I did on my clinker dinghy...... (20 seconds, onwards)


 
Lakesailor;5315990[COLOR="#0000FF" said:
]At such a low loading even if a wire broke there would be little energy stored in it. It would probably just fall to the ground.[/COLOR]
My brother in law, and others, used their trailer winches, reversed, to haul their various boats up the rough, stony and sometimes fairly steep shore at their landings on Ullswater.
Click to expand...

It's if/when they snag and the bloke on the button panics :encouragement:
 
Just four of us easily moved a 4 tonne boat on a 4 wheel dolly and that was on gravel.

I have a mains reversing winch that pulls 200kg with a 12mt wire, there is room on the drum for a bit more wire. Cost around £100 and would be perfect for you. I will dig out a link.

Here you go. http://www.shopix.fr/manutention-et-levage-auto/521-palan-electrique-100-200kg-3700194403287.html In french i'm afraid, but this is the 100kg version and comes with 17mtrs of cable. There is a brake incorporated, so it stops dead when you take your finger off the button. I use my 200kg one in a platform hoist on the house restoration.
These things must be available on UK e-bay.
 
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