Skidding and Boulder Fields

[Traveling Woodsman]

My problem may be somewhat unique to the mountains here in Virginia, not sure what other mountains in the east are like. Although there could be some similar situations in the Rockies.

A lot of the higher mountains around here, usually ones with over 1500′ of vertical displacement, have somewhat extensive boulder fields on the top third of the mountain. They are located in coves that come off the main ridges, and can range from extremely dangerous and difficult, to absolutely impossible, to cross with a team. Trees can be located in the middle of them, or they can block access to parts of a site. I’ve ran into them a number of times before, and I usually just dropped the trees close to edge and just didn’t log what I couldn’t reach from the edge.

But now there are some situations popping up with some high value timber located behind boulder fields, and it has gotten me thinking about alternatives to dozing a road across them. One idea I had is using a yarding winch to forward logs across the fields. I’m sure that’s one way that skidders would deal with it.

Maybe making a road is a good way to do it, from the perspective that it will be used again on future harvest.

[Scott G]

Ben,
We definitely have the issue with broken terrain (rock fields & talus slopes) here on the Northern Front Range. I can tell you as someone who has spent considerable time in a skidder it doesn’t get any better and in fact, if it is large rock with paths through it horses are capable of snaking stuff out where skidders can’t. You can pull the mainline out on the skidder but with minimal lift you are still getting hung up constantly even with block re-directs.

About 1/3 of my 80 acre tree farm is ~45-50% slope that is pure rock field. By default it is my ‘wilderness area’ and won’t be logged due to inaccessability.

More often than not in lodgepole I have found that just about every stem in a rockfield has butt rot which ruins the first post. You being someone who has cut p&p up north can appreciate the significance of that.

I have rigged up zip lines to shoot 4′ bolts for firewood down these nasty areas. You want to talk about a piece of wood reaching warp speed at the bottom…

I am looking at a couple of rock patches that have some really nice old-growth pondo in it that is buried in pecker pole lodgepole. MPB is starting to hit those stands hard and I have considered removing all of the lodgepole to get some light & air current in the stands to make the nice pondo less vulnerable. Some of these trees are ‘yellow bellies’ that are 350-500 yo. It would be kinda nice to keep them around.

The rock patches are small, 1/4 -3/8 acre. Staring at it, I’ve figured I could set up spars with blocks around the perimeter and get enough lift to get the stems up out of the rocks and lay them down on the outside. It would basically be the same system I use for getting material out of holes. Probably wouldn’t end up with much other than a bunch of butt rott lodgepole but at least the residual pondo would benefit.

Building roads through this stuff is expensive as the mid-sized boulders you see above ground are just the tip of the ice berg as it were. Large trackhoes and powder are the norm out here.

Small yarders are probably the most cost effective option (and yarder logging ain’t cheap) for getting enough lift to get the type of material you are describing out. You need to get above it though, which means a road or accesible terrain to get the yarder. If you can’t get the trucks to it you can always swing yard it with skidders to a loadable landing.

Yoders are a fairly recent addition to the equipment option lineup. They are simply a forestry swing-boom track loader that has been retrofitted with yarding winches (straw line, main line, and haul back line) to function as a yarder. They work well for accessing the small corners of cut units where it doesn’t make sense to lay out for a traditional larger yarder. They also can be outfitted with tongs or a cluster of chokers that are swung in an arc by the operator and hurled down the hill.

I will probably be administering a contract in the very near future where we will have to use a bird (helicopter) to log this nasty slope that is a critical fuelbreak for a community. Expensive, runs about $2,500-$3,00K/hr turnkey. Extremely productive though if the sale is layed out correctly and you have very good fellers & choker setters as well as a landing that is no more than a 1/4 mile turn away and is large enough to avoid a bottleneck.

No easy solution to get to the pumpkins you describe…

[Scott G]

@Joel 17019 wrote:

So are you thinning the doghair?

Mainly waxing it, Joel. This stuff is suppressed, runty pondo. This will be a true pondo restoration project as well as a shaded fuel break. It will be strictly a service contract with the exception that we will be whole tree chipping the stuff for our biomass boilers

@Joel 17019 wrote:

I worked under a helicopter at the landing. Very important to have a capable shovel operator that can clear the landing right now.

Absolutely, we will probably have two shovels as well as ~1 acre for a landing

@Joel 17019 wrote:

Unfortunately we had a few cowboy pilots that pruned every top on the approach to the landing

Won’t be cowboys for long. There are a few places in the hills around here that have clipped tops leading to a pile of recycled metal nobody will ever get to …

[Andy Carson]

I know next to nothing about logging, but I am fascinated by the mental image of zip lining logs. Is it possible to rig up some sort of braking system on these zip lines to make for a more controlled decent?

[Scott G]

@Countymouse 17025 wrote:

I know next to nothing about logging, but I am fascinated by the mental image of zip lining logs. Is it possible to rig up some sort of braking system on these zip lines to make for a more controlled decent?

It does work well for smaller wood. Primarily post/poles and 4′ bolts for firewood/pulp. Anything over 8″ d would be too much for the small system I routinely use. You could definitely beef up the components of the system to handle much larger material, however. Arborists often use this to get larger material from removals over fences to the truck, for example. I saw an article several years back where some guys were speed-lining large sawlogs across a ravine using bull rope for the mainline and rigging blocks. I rig up 1/4″ wire rope secured at the toe of the slope to a tree and the uphill is secured to a tree as well, but with a come-along to get adequate tension of the line. The line is usually set about 6′ off the ground depending on what size of bolts/posts you are sending down the hill. For hanging the wood on the line, I know some guys who use long fence staples with one leg cut off to form a ‘j’ hook. Works OK for micro-wood but the staples pop out too often for my liking. My method is to get 1/4″ eye lags, spread the joint on the eye slightly to open it up a bit. I then tap it once into the end of the log with my felling axe and put my scrench through the eye to screw it in. Sounds involved but it only takes 15 seconds or so per piece once you get the hang of it.

As far as braking, I don’t worry about it. The tail tree is about 20-30′ up the hill from the road so that makes a pretty decent landing zone. Depending on how far you send the wood and what the grade of the hill is the stuff can fly, …literally. The wood usually comes off when it reaches the end of the line. I had one set up where I had to move the tail end back up the hill a bit as I was rocketing the wood airborne over the road and down the other side.

If you wanted braking I suppose you could create more deflection in the line plus/minus have a belay line going down to the load. That would take the entertainment value out of it for me though…

I need to start getting better about bringing a camera and getting some pictures. I usually am working in the woods by myself and it is hard to remember to take pictures (or even bring the camera along) when you are concentrating on getting the job done…

BTW, clarification on the aircraft wreckage. What I was referring to were small planes not helicopters. The mountains around here claim many amateur pilots of small planes that realize way too late they bit off more than they could chew at high altitude.

[Andy Carson]

Thanks Scott, I had somehow thought the limitation of ziplining logs was the destructive energy released by a big log flying down the mountain… I did a little math and it is very clear to me (as you seem to know) that the major limitation is the strength of the cables and the tensioning of the cable line to elevate the logs. It is amazing to me just how huge those cables have to be and how much power is required to tension them!!! The heavy machines needed to handle them seem out of reach to people doing this on a small scale… So I was thinking of other ways to zipline big logs down a slope. I hope I am not bugging people with my amateur musings… At any rate, based purely on mathmatical modelling, it seems a 2 ton log could be ziplined down a slope using two 3/8 inch cables tensioned at 4 tons each (as with a hand come-along) IF the cables are supported every 25 feet or so (at 8 feet off the ground). This would require erecting some sort of temporary support structure every 25 feet for the length of the line. Tho whole system might look something line a ski lift. Putting up the support structures might be annoying, but it seems to my amateur mind less annoying and destructive than building a road.

[Andy Carson]

More musings… If the log travelling downhill on the cableway was suspended above the ground by a 20 foot long support beam (with pulleys on either end), then the cable does not have to be near as strong. Putting a beam on the cable also allows for more deflection in the cable line without requiring steep slopes to overcome the sag prior to encountering a support… Using this kind of setup would allow a 2 ton log to travel on one 3/8 inch cable with support structures roughly 40 feet apart (4 foot maximum deflection). That’s with roughly a 1:3 safety factor, I am not sure what kind of safety factor is normal for logging applications. I would think the support structures would need to swing back and forth slightly to equalize tension as the log travels downhill. Maybe simple inverted “V’s” staked to the ground at the base. Sorry again if I am bugging people with my musings. I really don’t know much about logging, I just think designing is fun…

[Scott G]

You are now entering the realm of full blown skyline/cable yarding.

It involves a mechanical tower with multiple winches with at least three for main line, haulback line, and straw line (for pulling the other lines). A carriage is also used which may or may not be a slack pulling carriage and is radio controlled. It also uses intermediate supports like you desribe with ‘jacks’ if you are going over areas of irregular terrain that have significant convex surfaces. It is an art and science to lay one of these operations out.

Elaborate system that is the norm for logging steep ground in the NW.

Google ‘skyline cable yarding’ and you’ll find an abundance of information.

[jac]

I read somewhere that in, I think , Scandinavia, they use horses to feed the outer extremities of the skylines reach and in this way halved the number of times the rig had to be taken down and set up …
John

[Andy Carson]

I am envisioning a system where support structures could either be hauled into rough county with horses or prepared on site using pole sized trees. These structures might be as simple as two 12 foot poles attached to the cable support apparatus and staked to the ground at the base on each pole to make an inverted V and ought to be easily erected by hand. A 3/8 inch cable could also be strung by hand, and the whole cableway could then be tensioned by a hand powered cable come-along. You would probably need some way to keep the tension from exceeding some safety limit, but I am sure this could be figured out if there is interest… Once the cableway is set up, logs could either by skidded to the cableway with horses and/or winched into place using a small winch. The logs would then be winched up onto the log carriage and carried by gravity through the very rough terrain to the bottom of the hill, where I assume there is better access. I would think that you would want to have a rope to control decent and possibly another “trip rope” that you could pull the release the log from the carriage at the bottom or the trip. The carriage could then be hauled back up the hill by hand using the same rope that controlled decent. It seems to me that the limiting factor in this system is placing and erecting these support structures… There would need to be 25 placed for a 1000 foot trip. I would think this would be useful in situations where skidding for the full trip is not an option due to the terrain and the competing technology is either building a road or using a helicopter. As the initial costs for this system are tiny, it might even be competative in some situations where small operators might have been tempeted to hire a yarder. Hopefully the loggers out there can tell me whether the system I am envisioning would be helpful even IF the details can be ironed out. It might work out that the “details” are limiting to the system, but there is no sense thinking about these details if there is no interest in the concept…

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