A consideration of Skyline Extraction

The feasibility study has numerous tentacles concerning the supply of woodfuel. Being surrounded by timber does not necessarily mean that it will be a doddle getting it to people. A primary consideration for me at the start of the project was how to obtain enough timber to maintain a constant and hopefully growing supply of fuel for people changing from oil to wood as their primary heatsource. It was obviously important that this would be done in a sustainable fashion and there are various forest harvesting or production techniques that lend themselves to this.
But how to do it? The big how to here is called extraction by the way, and it has been challenging foresters for a long time. In the case of GWI it is all intrinsically linked to the type of boilers being used, (wood)chip or log boilers being the options available.The fuel for both of these can come from the same tree which is good, but how do you get the tree out of the woods? How much of it can you get out?What infrastructure needs to be in place for that to happen?, How much will it cost per ton and because we are short of space for drying; how dry could it be when it came out?
A further complication in Glenlyon is obviously terrain, in particular steep sided slopes. I am sure that some boffin somewhere will have worked out a table calculating economic loss in forestry plantations per degree of slope and I don't think its hard to see how that could be the case. Cost and conservation are the watchwords in this case.
For example: lots of forest harvesting and extraction these days is done very efficiently by machines such as harvesters and forwarders.

 A Forest Harvester can cut up to 60,000 tons of timber per year.
However these machines can only work on a certain degree of steepness, beyond that, more roading must be put in at more cost and that of course, can only happen following approval from various bodies, which creates a time delay, which costs more money. Remember all this timber you are harvesting has very probably not been thinned and due to elevation, exposure, and thin mountain soils is consequentially likely to be of low quality and thus low value.
I have been quoted between £350 and £500 per day for the hire of a forwarder and Operator in Glenlyon, so you can see from that how quickly costs could add up. Particularly because depending on the type of harvesting you are doing, you may not have the option of stopping an uneconomic operation without rendering the half felled site liable to potentially disastrous and even more uneconomically viable windblow.
Given that there is very likely to be a demand for chips, lets look at one option we considered earlier on in the project for supplying them from the steep slopes no one else wants. Whole tree extraction by Skyline.

A skyline or cable Crane is best thought of in terms of being like a cable car or gondola that people going skiing might use.

The same principles of cables going up and down a slope carrying a weight can be used to extract timber from slopes with a spar tree being used as a top anchor point for the cables. Around 1910 in the early days of forestry in British Columbia, a skyline system called "High lead" was developed which kept the logs off the ground, by suspending them in the air for their whole journey down the slope. Back then it saved power and was swift, today it makes Skylines a good option for reduced ground pressure from extraction. The high lead system involves a high spar tree for the cable to run to and from. The felling of these makes for some of the most incredible photos of Canadian logging.

Yes, the picture on the right really does show a man  (Big Bill Moraski) standing on top of a spar tree with his arms out. These pictures are from a time before Photoshop.

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You can the feller hanging on as the tree top is felled. This could apparently "set the spar tree lashing back and forth in a 20-foot arc". 
So was this our plan, to stand on top of big trees with our arms out, then axe blades whirling produce enough timber to meet the needs of the glen?
Err not quite, the plan was to buy a 2nd hand converted excavator cablecrane for a bargain price locally, use it to produce a large stockpile of fuelwood timber over a few months , process and start drying the timber, repeat as needed . The option was particularly tempting given that the machine could still perform large excavator duties, such as making forest roads or loading bays. It could also potentially be fitted with a log grapple or processor head making it a multi-purpose machine that would be useful not just to us, but could probably be hired to others in the glen for digger jobs.

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What a beauty eh'

A lovely cab for the operator, note the all important winches at the back and skyline boom extension at the front. 

There could have been great advantages for GWI from doing whole tree harvesting for chip production. An approximate third more produce comes from harvesting the foliage and you also leave a tidy forest floor for replanting or for safe future operations. Unfortunately someone else spotted what a bargain the machine was and unlike us could just buy it on the spot, whereas we would probably still be applying for grant funding for it as I write.
It was good though, having the experience of considering using such a machine, thinking it through and consulting with a very experienced skyline operator on it. He gave me lots of interesting thoughts and advice and said of the project " With all the timber here, how could you fail" which was really encouraging.
I am now looking at a totally different machine which is a little dearer, but new. I shall write of this at another time.
Note; The Canada photos come from the excellent book " The Lumberjacks" by Donald Mackay.