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Pulling cores out of the ground by hand was always one of the more difficult and demanding tasks until recently.  Driven by difficult access conditions, and limited personnel and logistical support, I have generally avoided solutions such as tripods and winches because of portability.  This was also driven in part by discreteness--coring already attracts enough attention, and on uncertain foreign turf I prefer to remain as "low profile" as possible.  So, I have always ended up pulling out cores by hand...

But this can become basically  impossible when you reach 10+ meters depth with the gouge auger, or when you run through a cemented horizon. With wide, 10 cm diameter marsh cores, they have so much surface area, and suction is so great, they are often impossible to pull out by hand even after just <50 cm of penetration.

I've developed a portable and rapid solution to deal with this, and will never again worry about a coring crew straining their backs [sorry, Ugur :( ].  This solution was inspired by the coring master, Mark Abbott, who has been known to use a car jack for his lake work...

Basically, I use a Hi-Lift jack (model HL-485) to pull a core right out of the ground using just two people.  This style jack is sometimes called a "farm jack" or "Jeep jack". Note that it is not the ubiquitous scissor-style jack you see nowadays--those types just don't have enough run.  The Hi-Lift jack has a rated lifting capacity of 2115 kg (2.33 tons).  I don't know what this limits me to, but 10 cm diameter PVC tubing driven in 2-3 meters depth can be pulled out with ease (see the "Marsh coring--portable, rapid, and perfect core recovery" page).

To attach the core barrel to the jack, I use rubberized 1/4" steel cable.  I originally thought I would need some type of lip or ridge on the core tube so the cable would catch, but experimentation shows it is not necessary.  Make a simple noose-like loop in the cable. Now, with plenty of slack on the loop, double it over on itself twice so that basically the big initial loop is composed of three smaller loops.  These three smaller loops should be big enough to fit around your core tube without much slack.  By making three (or more) loops like this, the cable essentially functions as a boa constrictor--the tighter you pull on it, the tighter it pulls on itself and grips to the core tube. Then you simply attach the cable to the Hi-Lift, and start jacking it out.  At the end of a run, just slip the jack and triple loop back down to pull out another 50 cm.

To make this go faster, you can use a cable grip.  This is optional, but very helpful. The cable grip also helps keep the steel cable in good condition--otherwise it quickly becomes kinked and frayed which is brutal on your fingers. I use a Klein Tools "Haven" cable grip (model 1604-20L), and attach it to the jack with a screw pin anchor shackle.

The pictures below show this system in action on a marsh.  Because the marsh surface is relatively soft, it's helpful to to have a board or beam like a 4x4 to put under the jack itself else you'll simply succeed in driving the jack into the ground...

Clicking on the thumbnail pictures below will pop up larger versions.

Image Captions (from left to right, top to bottom):

• Hi-Lift jack (model HL-485) with a shackle and Klein Tools "Haven" cable grip (model 1604-20L); the cable grip is optional, but it speeds up the process, and saves the steel cable and your hands!
• a closeup of the cable grip
• jacking a 4 inch (10 cm) diameter core out of Belle Isle Marsh (David Besonen at left, Pierre Francus at right); keep the jack as vertical as possible
• about halfway out--no strained backs, and just a minute's work!
• make a large, noose-like loop in your 1/4" rubberized steel cable
• fold the loop over on itself twice to make three smaller loops out of the initial loop
• the triple loop functions as a boa constrictor--the tighter you pull on it, the tighter it pulls on itself and grips to the core tube
• triple loop seen from the side
• triple loop seen from the back
   

Though the above explanation is based on marsh work, this jacking technique can easily be adapted to the gouge auger, or other coring systems.  More than anything, it is a very portable solution, and much less conspicuous than other systems. If you have another system that you think is comparable, or you have suggestions for improving this technique, I'd love to hear from you.