Thread: how i selected my a synthetic rope

Originally Posted by twr7cx

From briefly reading this, it seemed that a fair few of you have converted your steel cable winch setup to rope? Firstly, why? Secondly, I thought there was a difference in the drum setup between a steel cable winch and a rope unit, which prevented swapping over like this?

mostly because it is getting cheaper, its light, easy and safe to handle, easy to clean and is easy to rejoin in an emergancy to get you winching again.

the suitability of the winch drum is governed by it being grooved to start the bottom layer of a wire rope or a flat drum, if you have a flat drum you're good to go. If its a drum with an in drum anchor for the winch cable you should crimp an aglet onto the end of the rope or an electrical crimp of the right size and cut the eye off of it. If its a side mount on the flange of the drum crimp on an electrical eyelet and you're good to go. in a pinch you can tie a timber hitch or choke hitch around the drum and just hold tension on it till it takes up tension on the recovery.

Originally Posted by HarryO

Mmmmmmm - If only this great thread was posted / spotted a little earlier - I have broken the rule of thumb regarding "9000lbs winch = 9000kgs rope", 10mm vrs 12mm advice, and may others....

I purchased the "Dyneema SK75 Synthetic Winch Rope, Cable 10mm x 30m, 12000lbs, Replacement" of ebay from Aussie supplier alaka_shadesail Arrived real quick, fits winch nicely but after reading this thread I am worried I may have stuffed up. Now trying to find out from him exactly what the 12000lbs rating represents .

most likely the minimum guaranteed breaking strain you should use this number and punch it through basic rigging numbers to come up with the SWL when you're using it. best guess on a single line pull you should be good to pull about 3.5t(line pull not vehicle weight) while staying within all the safety margins.

Originally Posted by Bush65

That statement is very misleading.

The fact is that with a brake inside the winch drum, winding out creates the same damaging heat whether under load or no load whatsoever. This is because the brake is applied by the drum rotating in the direction that spools the rope out.

The brake doesn't know, or care, whether the tension in the rope is 1 Newton or 100 kiloNewton, it is just a dumb mechanical device. When powering out, the motor has to supply enough torque to overcome the friction torque from the brake and that is where the heat comes from.

Because the mass of the drum has capacity to absorb some heat before the temperature rises enough to cause an issue with synthetic rope, a small number of drum rotations can be tolerated.

With winches that have an internal brake you should always engage free spool and pull the rope out manually, if you use synthetic rope. Edit: this excludes them from use when it is necessary to lower under load.

most electric winches have the brake on the drive shaft from the motor. This uses the gearbox to increase the brake torque to the drum. These are the worst for heat on wind out. and if you do electric winch out often you should check it for its ability to hold load. Some other winches have the brake on the gearbox side of the drum inside the gearbox, these are spring applied and cam released. the only time these add heat to the drum is when the brakes ability to hold the load is exceeded and the brake slips. When this happens things get really hot really fast. In either setup, in most cases when you find out the brake wont hold you're not going to be worried about the rope, or the brake or anything else other than not being anywhere near whats unfolding followed by hoping that everyone else got as far away as you did.

Originally Posted by urumax82

hey guys i just bought some 12mm-25m dyneema from a rigging store $300 they made an eyelet on one end and crimped a electrical eye to connect the other end to the drum. I ask them if i needed to put an metal eyelet on the loop they made for the hook but said there is no need ??? what you think

no need for an eyelet in synthetic rope but you do want the eyelet to be big enough to comfortably feed a very large shackle pin through.

I like to set the eyes up so they are about 40-60cms long when finished, long enough to sit over the pully of a snatch block and keep the included angle at the splice under 45 degrees. such a large eye also makes it very easy to bend other ropes onto the eye when you want to join it and gives you an easy way of grabbing the rope when you need to haul it off the drum.

I purchased three ropes, one for myself and a mate and than we cut the third one in half so they could be used as winch extensions. You could at fit 20m of 12mm to the winch than you would have a 10m extension.

I had plenty of room on the PTO drum to fit rope.