The Port-a-Wrap is the most commonly used friction device for rigging in the arboricultural industry in New Zealand. All Port-a-Wraps are based on the same principal – a central pipe that we wrap the rope around to create friction, allowing the user to control the load being rigged.
The Port-a-Wrap is best set in hip height of the operator. To do this we tie an accessory cord in breast height to the tree using a cow hitch. The accessory cord should be of about 6m lengths with a spliced or tied eye in the end allowing for a karabiner to be attached. You can hang the Port-a-Wrap off this karabiner. It is best to use a screw-gate karabiner for this connection. All other karabiners show disadvantages for this application. Once the Port-a-Wrap is positioned it is easy to attach the load bearing sling.
For the bottom load bearing sling we recommend a dead eye sling that can be choked off to the bottom connection point. If a dead eye sling is not available a short piece of rope (6m) with a large bowline loop can also be used. This removes all connectors out of the load bearing system. After the sling is connected to the Port-a-Wrap it can be tied to the tree with a cow hitch.
The top and bottom as well as the cow hitch attachment prevent the Port-a- Wrap from working itself loose. Through using the accessory cord to set up the Port-a-Wrap it is easier to get all slack out of the anchor system. The less movement we have at our lowering device the more control we have over the load. Controlling the load will allow us to better control the forces generated while rigging.
Attaching the Port-A-Wrap to a tree:
1.The Port-A-Wrap should be attached to the tree with a piece of rope or a sling that is strong enough to withstand the generated forces of the rigging operation. When using a dead eye sling or a short piece of rope to attach the Port-A-Wrap to the tree we recommend using the cow hitch.
2.The Port-a-Wrap should be tied to the tree in hip height.
3.The Port-a-Wrap should be set tight against the tree to allow for a fast and efficient loading of the Port-a-Wrap and pre-tensioning of the rigging rope.
4.Using a top strop to position the Port-a-Wrap is recommended.
Lowering a load with a Port-A-Wrap:
1.The Port-a-Wrap should only be used with a sufficient safety factor.
2.All lowering of loads is done by the ground workers (not the climber in the tree).
3.Before lowering a load the ground worker should look for good footing and assure the rope
can run freely through the Port-a-Wrap.
4.The ground worker who is lowering the load with the rope should wear leather gloves to prevent rope burn to the hands.
5.All loads are to be lowered dynamically to minimise shock loading of the tree.
This means we let the rope run with the load and use all of the space between the last
redirecting point of the rope and the object to protect to slow down our load to a stop.
6.The ground worker on the rigging rope should leave at least 3 metres of rope between him
and the Port-a-Wrap.
7.Never wrap the lowering rope around body parts.
For more information on Rigging with the Port-a-Wrap visit our climbers’ corner page where the full Rigging with the Port-a-Wrap article can be found.