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Old 05 September 2006, 16:30   #1
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winch for rib, what is the calculation for the approx weight up a slope?

I am thinking of getting an electric winch fitted for lowering and raising the rib up and down slipways.

I have seen a few winchs around on the web but wanted to see if others recommend a particular sort of winch or ones to steer clear of

my boat and trailer weighs at most 1800 kg but probably nearer 1500kg lets say
I am not sure what the average gradiant is on a slipway, but i wanted to calculate the approximate load on a winch if pulling the boat and trailer up an average slipway. At a guess i would expect the average slipway is between 10 and 40 degrees.

does anyone out there have a rough calculation that shows what effort or equivilent weight a 1800 kg boat and trailer would be when being dragged up a 10 20 30 and 40 degree slope

not sure what cooefficient of drag to use for the wheels but i suspect it should be minimal

schoooooooooooool seems to have been a long time ago and i think i bunked off this lesson

any guidance from experts out there would be appreciated

i am trying to gauge what size winch is suitable and calculate the winch speed at different loads to determine the suitable item
here is one i have found so far which would easily do the job i suspect

http://www.winchdirect.co.uk/dv-9000.htm
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Old 05 September 2006, 16:47   #2
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The winch you have looked at is designed for the front of a 4x4. It is probably overkill in terms of power and cost. It is a worm drive and very slow. A spur gear winch should do the job at half the cost. A general guide line: calculate 50% of the laden weight of the boat ( including fuel etc. ) choose a winch close to that figure and then go to the next size up. For your boat you are going to need one with a steel cable, not strap/rope. I would guess 2500-3500 lbs. will be suitable. If your are not worried about speed, but want more power then replace your existing winch with a 2 speed manual one. Remember you will have to rewire your vehicle to get enough electric power to the tow hitch area for an electric winch. Hope this helps.
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Old 05 September 2006, 16:56   #3
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AFAIK....

10 degree slope = 313Kg
20 degree slope = 616kg
30 degree slope = 900kg
40 degree slope = 1157kg

please remeber school was a while ago

i did test the figures with a 89 degree slope and it came out as 1799.7kg so i am fairly confident
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Old 05 September 2006, 17:56   #4
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Ignore all ratings for electric winches if you need to pull the thing any distance. A 9000lb electric winch will pull 9000lb for a very short time before getting hot and bothered and the same will be true of little ones. A 4500lb Land Rover needs a 9000lb electric winch for any sort of reasonable reserve capacity. This is the reason why I have a hydraulic winch on mine, because with those you get what it says on the tin, 10500lb all day long if you want it not for 2 minutes before something goes pop.

The general rule of thumb is take the weight you are pulling and double it.
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Old 05 September 2006, 18:22   #5
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thanks for the posts so far, got me thinking as to which to use. will fit the winch on the back of the MH as i dont fancy reversing this down some slipways!
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Old 05 September 2006, 19:31   #6
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Quote:
Originally Posted by BogMonster
Ignore all ratings for electric winches if you need to pull the thing any distance. A 9000lb electric winch will pull 9000lb for a very short time before getting hot and bothered and the same will be true of little ones. A 4500lb Land Rover needs a 9000lb electric winch for any sort of reasonable reserve capacity. This is the reason why I have a hydraulic winch on mine, because with those you get what it says on the tin, 10500lb all day long if you want it not for 2 minutes before something goes pop.

The general rule of thumb is take the weight you are pulling and double it.
Steven, you are talking about hauling vehicles out of holes, not winching a boat onto a roller trailer. Been there done that. Think you are more than a little off base here. Regards, T.
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Old 05 September 2006, 19:37   #7
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Quote:
Originally Posted by Limey Linda
Steven, you are talking about hauling vehicles out of holes, not winching a boat onto a roller trailer. Been there done that. Think you are more than a little off base here. Regards, T.
Hugh is not talking about getting the boat on the trailer he is talking about parking his "bus" at the top of the slipway (ramp to you lot) and pulling the boat and trailer up the slipway.
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Old 05 September 2006, 20:03   #8
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You'd be better off using a good sturdy peice of rope for that job, and it's cheaper than a winch.
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Old 05 September 2006, 20:04   #9
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Dah

I agree, certainly a "different kettle of fish" However same principles apply but maybe a lower powered winch ?? as trailer has nice round wheels. However, if the MH is at the top of the ramp/slip and you use any winch to get the boat trailer up it's arse end. What do you do then? Perhaps chock the trailer and reverse the MH back to hook up. Seems complicated to me.
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Old 05 September 2006, 20:37   #10
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Whilst on the subject. What happens to the jockey wheel on the trailer when winching? The wheel isn't really designed for anything other than keeping the trailer nose at the right height for the tow vehicle to connect to - isn't it???
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