Skyline Logging

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Skyline logging systems are most often used when topography is too steep to operate ground based logging systems overland. When extensive skid road networks are required for conventional logging, skyline logging systems can often provide a more economical and environmentally friendly method of logging. The relatively recent development of small radio controlled motorized slack-kicking carriages has simplified the economics and application of skyline logging systems.

Essential to the successful implementation of a skyline logging system is planning. Lack of planning and awareness are reasons why skyline logging systems have not been implemeneted on a wider scale in the Appalachian mountains.

Strategic Plans can be developed to determine the skyline system needs, and are primarily a map based (limited recon) product. A skyline system consists of a yarder and a carriage. Questions like:

1) How far will the system have to yard?

2) What sizes of timber will the system have to handle?

3) Will the system need to yard uphill only, uphill with modest downhill, or both uphil and downhill capacity?

4) How much deflection can be expected, and what types of rigging configurations will be needed?

5) How much truck road will be needed? / acres per setting? / volume per setting? can be answered with strategic level planning to develop target costing information.

When this has been completed the search for specific skyline yarding systems can begin with confidence that the appropriate system is being sought. If you are concerned with open market stumpage purchase; strategic logging planning information and data can be developed from selecting "typical" tracts on the market and planning with them. If you are concerned with managing fee lands; selected timbersheds can be used to develop strategic plans for yarder selection.

Tactical logging plans involve the specific plans for given settings/ landings, and are a refinement of the Strategic plan. Specific on - the - ground landing location, tower sets, setting boundaries, and other site specific information are the end product. The engineered logging plan produces a "no surprises" logging plan that the side rod/ rigging slinger knows ,and has confidence in. In this fashion, the yarding crew knows and can prepare for in advance of actual operations. In order to achieve a solid tactical logging plan, field profiles need to be surveyed and analyzed for rigging requirements and payloads. This way the yarding crew knows that when they rig a corridor on azimuth xxx degrees that the tailhold will be a tailtree rigged to a 20 ft height at station 9+50. This avoids trial and error rigging as well as overrigging. There is nothing that will stop successful yarding quicker than not knowing what, where and how of slinging rigging. Logger PC is a windows based computer program dedicated to skyline analysis and is an essential tool to skyline logging and improving existing operations.

The following screen shots show the steps involved in using Logger PC

First a survey of the proposed corridor is made, generally using a hand compass and "string box". This data is entered into the Logger PC program for analysis. Only corridors which are "critical" need to be run.
Entering field profile data


Next the Yarder and Carriage information is recalled from a file. Sometimes different carriages need to be used in order to get the best performance. Logger PC makes changing equipment analized easy.
Skyline Yarder and Carriage Specifications


Next the rigging parameters are input. The yarder set and tail hold location and height be moved easily to determine the best location. This will be the combination that is easiest to rig and set up with sufficient payload to meet the production objectives.
Analysis of Yarder and Rigging Conditions


The program then reports the safe payloads and other reports will show detail on rigging requirements. In this case, the safe payload for the first 650 feet of corridor is 6700 pounds, after that it drops to 5700 pounds. Different rigging configurations will produce different safe payloads, with the idea to analize for the best combination.
Safe Payloads for Corridor


Once the critical profiles have been surveyed and analized, the setting boundary can be determined and flagged. After this the corridors and landing locations are shown on a map and labled. Each payload and rigging report is attached as well as the cost and production estimates for the setting. All this together constitutes a tactical (or harvest) skyline logging plan. This way the timber that is to be cut can be bucked to meet the analyzed payload for the corridor, the rigging slinger knows the specifics on rigging ahead, and the crew knows what the production objective is for the setting.

Skyline logging plan for Thunderbird TMY 70 yarder with Bowman Skycar carriage

Skyline logging is less sensitive to weather related production problems and more sensitive to environmental factors. By not stacking skid roads on the hillside, impacts to the soils, watershed, and visual resources of the managed forest are reduced. Skyline logging systems can, in certain situations, reduce conventional logging costs.

. . . . . . . . Skyline Logging is a tool that can produce logs from timberland that is restricted by conventional logging. As with any specialty logging system, planning is essential to it's success. . . . . . . .




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Some Skyline Logging Pictures more to come - check back to see updates
Skagit MY 50 trailer mount with 50 ft tower Skagit MY 50 3 drum trailer mounted yarder with 50 ft tower, weight approximately 35 tons. Skagit is no longer in business. This yarder was early 1970's model and was designated MY because at the time it was a "mini - yarder" for Skagit. Today this yarder would no longer be considered a "mini" yarder, but rather it is on the large size of yarders. Many Skagit yarders & drumsets are in use today.

Properly notched guyline or skyline stump anchor Properly notched guyline or skyline stump anchor. Notches made in stump anchors encircle the stump and are cut such that the line, after being anchored, has not wedged itself into the stump making removal difficult. Notches are cut deep enough to secure the line from jumping off during shocks, but not so deep as to compromise the strength of the stump anchor. The larger the line size being anchored, the larger the stump needs to be. In general 14" - 16" trees represent the smallest tree suitable for anchoring. Stump holding ability is highly variable and is dependant on how much earth is bound up by the root system. A good way to judge this is during stump excavation.

Madil 071 yarder tracksTrack mounted Madil 071 in transport position, weight approximately 45 tons. While this model is no longer in production, Madill still builds a variety of larger yarders in British Columbia. This 49.6 ft leaning tower yarder was very popular, and with 4 drums could be rigged in any cable yarding configuration, as well as fly any carriage built.

Madil 071 logging positionMadil 071 in logging position

Skidder swing away from yarder to full service landingSkidder swing away from yarder to full service landing. This swing techinque, while more expensive, adds more flexibility in yarders sets and processing timber from traditional trailer mounted loaders.

Christy Skyline CarriageChristy Skyline Carriage, manufactured in Orofino Idaho is the most popular manual slack pulling carriage made today. It's advantages are in relatively low cost, rugged durability, and mechanically simple operations. Disadvantages are the stop moving time, mailine ball wear an repair time, and lateral slackpulling being limited by manual means.

Cable Yarded CorridorCable Yarded Corridor, regeration cut. Different from other logging systems, cable logging requires corridors to be cut in order to not hang up the operating lines. When thinning or partial cutting hardwoods, these corridors will have a minimum practical width of 20 feet. Depending on the length and deflection of the skyline corridor, timber stand conditions, and other factors, these corridors may need to be wider.

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