Cabin #6: Gin Pole (Boom Derrick)

A Gin What?

The cabin that we drew out on graph paper was two full stories high. Building up rather than out allowed us to minimize the expensive parts (roof and foundation) and get more space out of shorter logs. Easy to dream up on paper, hard to imagine how, exactly, we were going to hoist logs up and build while 17 feet in the air. If we were building in town or on the road system, we could have rented a boom truck or crane to lift the logs. Our remote location meant that we had to think harder and dig into some older technology. David did some research and came across an old military drawing of a gin pole. Technically, a gin pole does not have a boom. Our “Gin Pole” is actually called a “Boom Derrick”, However, the term “Gin Pole” is widely used in our area to refer to these things, plus we really like Gin and it is one less syllable. Below is the drawing that we used to build our gin pole:

This is a drawing fromUS Army Rigging Manual - - or, "How to Lift Things (the low-tech way)" http://logbuilding.org/GinPoles.ch5.pdf

Building the Gin Pole

The gin pole is made with fairly primitive construction, using White Spruce poles, steel spikes, and rope. 2 pair of block and tackle (3x3) allowed us to lift and position logs vertically from the end of the boom as well as by horizontally by increasing and decreasing the angle of the boom. We had to wear grippy gloves to pull down on the lines, and while it did work, if the logs were any heavier we would have needed 4x4 blocks at least. Pictures below show the base of the boom where it attaches to the mast. The boom angle is adjustable by using the block and tackle that goes between the top of the mast and the top of the boom.

Securing a Gin Pole

Getting a gin pole to be vertical is quite the task. We used David (pole climber) and 4 ropes tied off to trees as high as possible to allow the boom to swing under the lines.

Good Guy Lines

The above photo is of David climbing the gin pole to replace the guy lines (the original guy lines were nylon and they were too stretchy. We replaced them with 1/2" blue steel rope (6600 lb. tensile strength non-stretch). They have end loops with steel eye inserts spliced in which fit over a 5/8” rebar pin set in the top of the mast. this allows the mast to rotate 360 degrees while being supported by the 4 guy lines.

Using a Gin Pole

We started out by putting the gin pole at the bottom of the root cellar (photo above) and then moved it to the first floor, and finally outside of the cabin. We used it to lift basically every building material that we used: logs, poles, sod, tools, the scaffolding etc. David was fond of raising and lowering himself to the roof level using the gin pole and we found that it makes an excellent swing. The video below shows the basics in action.

Overall we were continually impressed with how versatile a tool the gin pole was for our cabin project. We made sure to stay out from under the things that were being lifted but never had any safety issues or injuries using it. The below photos show gin pole in the center of cabin (left) and outside of cabin (right).

Just for fun..

Here are some videos of non-building uses of a gin pole :)