speed line rope question

Maui Palm & Tree Care

Maui Palm & Tree Care

Location
Pukalani, Hawaii
why is it that your able to use a lower breaking strength rope for a "speed line"(ex 7/16-1/2")but need you need a bigger(5/8-3/4") for negative rigging??? is it because there is minimal shock loading on speed lines? i have a coconut removal next week and want to set up a simple speed line. the 2-3 foot cut chunks will be secured with a sling that has the quick link connected to the 7/16 zip line. all i have to do is push it on to the line and it will sail to the ground. i guess my question is, is an 8,000 lb breaking strength rope acceptable for this?
 
Joshua,

rigging speedlines is one of the most complicated systems that is used. Until you sit down and run the numbers to understand the loads you shouldn't take on a heavy rigging setup.

Have you read the ISA publication: The Art and Science of Practical Rigging? One of the 'must-reads'.
 
ok well nothing will get damaged here. it's a friends house with a big property and the coconut is in a big open field where if something went wrong nothing would be damaged. he is into boating and rigging sail boats and he thought it would be fun to try and set up a makeshift speed line for fun and he will pay me for it.

my smallest 7/16 double braid rope will handle this right? i mean wesspur sells a buzzline in their zip line kit and mine is a higher breaking strength then that. i know coconut sections are heavy so thatswhy im cutting them into 2 foot sections.
 
But...what happens if the SL anchors break? What if something does fail? Where will the energy be dissipated?

Have you calculated rope angles...stretch...loads on anchors...vector forces???

Or...are you going on a wing and a prayer?
 
wing and prayer. haha! it is for fun. i most certainly wouldent do this in a real work environment. because it is a friend who is into rigging too. we were gonna give it a shot but im not sure if my 7/16 line will break or not.i guess will see.
 
For one don't belittle yourself by saying you're "stupid for posting this". You are trying something new that you've heard people talk and write about. It's good that you're asking questions first before you possibly put yourself in a situation you weren't prepared for. They are just concerned for you. When you angle the line out and tension it up you take a lot of the natural stretch out of the rope. Now drop the chunk on it and the tree now flexes to compensate for the weight of the log. Some climbers won't do this technique because of the forces that are transfered onto the tree. Also try branches first, they're more forgiving than dropping logs onto the line.
 
I've never cut on any palms or coconuts but it seems like it would be springy. Not the ideal tree to atempt a speedline for first time. But if you're gonna try it to see how it reacts then do it lower on the trunk. There won't be as much leverage on the stem. Small pieces and be safe
 
As has been said, there are MANY variables. One of which is anchor strength, the rope will most likely be be your best known variable, the anchors - not so much, especially anchoring to the top of a spar - the force WILL be multiplied, and transferred to the stem and the root plate.

I usually cut my working loads in half or less when highlining, ie. MBS-6000# (10:1safety factor)=600# working load/2=300# potentially safe working load (don't forget the shockload). EXAMPLE ONLY of my personal speedline fear factor educational logorithmical common sensical tutorial - not to be taken as sound advise.
 
i wanted to see if it was safe and now that i have heard all of you tell me your input i may just block it down instead. but the speed line was worth a thought at first. cocopalms do move alot and i dont want anything happening pre maturley like the tree falling over. lol
 
Some thoughts...the more horizontal distance you are trying to achieve, the more the lateral force on the spar. A vertical speedline have almost no lateral force (blocks landing and bouncing sideways exerts some). Trying to travel sideways 1.5x's your height will exert a lot more force.

A pulley should allow travel at flatter angles with less force.

Tensioning with a 3:1 on the porty and dropping on the system is a ton more shocking than dropping onto the groundie pulling on a 3:1 or 2:1 or just holding the rope.

Be aware of how much each piece ways. Since you are playing around with it at a friends, you could actually bring a bathroom scale watch you weight/ 1' length increase.

Since you are not on a production basis, you can pull test the tree.

You can start with a vertical speedline, then change than angle bit by bit. Beware of the chunks bouncing toward anyone. Use a redirect pulley set at an adjustable distance from your anchor point, allowing different angles from vertical.

Start small in size and low angle.

If you want to try some larger chunks, be sure to catch them in a normal negative blocking way, then attach to speedline.

If in doubt...don't.
 
One thing that might be nice to try is block it down to a droppable spar. Then set up your speed line and SL the pieces you dropped out. That way you are in a safer possition to "play". Speed lines are nice in the right situation. Dropping big wood directly into the SL is not the right situation. If you are working with big wood you should either have the line higher and tip tie or drop it into a block then transfer it to the SL. Good luck
 
I have never dealt with coconuts. It seems like palms have little root systems compared to trees. Probably not the one for a heavy speedline. I've dealt with palms in Death Valley, very heavy, probably more so than most wood.

Dropping anything heavy on a speedline is very questionable, vertical speedlines having the least forces, as far as I can tell. This is especially true when you have the bottom end of the rope anchored with a friction device, as opposed to handheld or 2:1/3:1 where the groundie can absorb some of the shock, as I mentioned above.

Just wanted to clarify that you should be extra careful with something with weak roots such as palms or decay/ root disease.

I suppose that you know that palms seem to have very little structural integrity after they die. Can't say anything about them when "sick".
 
im pretty rounded with vertical speedlines. this is my set up. i tie my line with a running bowline cinched to the top it then runs down to the base where it goes into a figure of 8. the 8 is on a sling girth hitched to the base of the tree. it allows my ground man to pull the slack out and hold it or lock the 8 off. the 8 is really nice. but it can be substituted with a munter hitch on a carabiner. the cut pieces are attached to the line with a sling and either crabiner or screw link.
 
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