Signal Tower


This tower was originally designed by John Thurman who suggested that it should be a substantial project some 24ft (7.3m) high. Unfortunately, few Groups or campsites have very long spars these days, as they are difficult to store and require careful handling. However, you could try a smaller version.



Equipment

- 12 x 4m (12ft) spars
- 18 x 1.8 (6ft) spars
- 4 x 1.8m (6ft) spars for the roof (optional extra)
- 8 x 1.8 (6ft) spars for sheer legs
- 14 x 4m (12ft) spars for lifting gantries
- 2 handy billies
- 65 lashing lengths
- 4 x 10m (30ft) ropes for guys
- 1 x 15m (50ft) rope for raising tower
- 4 pickets
- 1 maul
- 4 large tent pegs

Method

This is one of those towers which is easy to build in theory, but more difficult in practice. We suggest that you try building a model version before you start on the real thing.

It consists of four identical sides as shown in the diagram. Although this looks quite straightforward, do not be deceived. When it comes to lashing all the spars in place, on all four sides, it can be difficult fitting them in and some adjustments will need to be made to allow room for them. Use your own judgment and do not be afraid to experiment.

We suggest that you start by making two frames identical to the ones above, using 4 x 4m (12ft) spars and 3 x 1.8m (6ft) spars for each. The top two 1.8m (6ft) spars should be about 1m apart as they form the platform and handrail.

Build 4 pairs of sheer legs and support one of the frames on them so that it lies horizontally about 1.2m (4ft) above the ground. It would pay at this point to attach temporary guys to the corners of the frame and peg them out so that the whole thing is stable.

Now lay the second frame on the first with a few spare spars between them to act as spacers.

Stand 6 x 1.8m (6ft) spars against the frames where the 1.8m and 4m spars cross (points a1, a2 and a3 on each side) and lash them to the top frame.

Whilst is going on, other members of the team could be producing two lifting gantries. These are simply 4 large tripods, each constructed using 3 x 4m (12ft) spars and a tripod lashing. The tripods are placed two either side of the tower with a spar between them. A handy billy is attached to the centre of each cross spar.

The handy billies are attached to the top frame of the tower which is then raised until the ends of the vertical 1.8m (6ft) spars are in the correct place to lash to the lower frame of the tower.

The cross bracing on the other two sides should now be done. This is where you will need to use your initiative and fit the spars in wherever it seems most appropriate but do remember that the feet should all touch the ground when the tower is lifted upright.

Prepare a rope ladder and tie it firmly to the platform.

Lash sufficient 1.8m (6ft) spars across the 1.8m spars already in place (the middle set) to make a platform.

It might be nice to add a roof to provide some shade on the platform. A pitched roof covered with a canvas sheet, or thatched with grass or ferns would be great.

Finally, the tower should be raised to the vertical. The use of a tripod and some pulleys may be necessary. Ensure that the feet are dug into the ground. Guy it as appropriate.