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August 26, 2016

Suspension Bridge from Feb 1937 Scouter magazine

I found this suspension bridge article written by L.C. Sands in the February 1937 Scouter magazine:

No special credit is claimed for having succeeded in building the bridge described here, as it involves a principle in common use, but as the writer has not seen anything similar described in any of the books on pioneering, he considers that other Scouters might possibly like to try it out, and doubtless improve upon it. Its chief advantages are that it needs only simple materials, is easy to construct, and is one which could be crossed with ease by many people who might hesitate to venture on a monkey bridge. Any measurements stated here may be altered to suit local conditions.

Two Towers were constructed of four spars about 9 ft. long, with 1 1/2–2 in. butts, and seven Scout staves 5 ft-long. First the side trestles were made by lashing two spars together as near the top as possible with a sheer lashing, and then the ledger was put on with square lashings about oft-from the bottom of the spars. These two trestles were then connected together to form the tower by lashing a strong pole across the top in the V’s made by each pair of spars, and by lashing poles adjacent to or slightly above the ledgers of the original treetles. The base of the finished tower was about 4 ft. square. About 2 ft. from the ground further poles were lashed to both back and front of the tower: the one (A in the diagram) nearest the bridge proper bore the two hawsers of the roadway, while both bore the planking.

The Roadway was made with two 2 in. ropes to which were attached twelve Scout staves at intervals of about 1 yd., by means of lever hitches a few inches from the ends of the staves. This method is probably not the best for strength, but it is quick, although about 1 ft. of the rope is used up in making each lever hitch. When this is swung into position, the ropes at one end should pass over the front pole (A) on the tower, under the back one (B), and be made fast to pickets or some convenient tree if available. The other ends should be similarly secured, but if possible block and tackle should be used to tighten them at one end, as was used in this case.

Suspension lines were made from 1 in. cord throughout, twelve in all three for each side of each half of the bridge. These lines were attached to the pole forming the road-bearers of the bridge, and to passed over the top pole of their respective towers to pickets or suitable trees. In the case of the lines attached to the two centre poles (E and F.)loops should be made in the cords about 2 feet from the ends fastened to the roadbearers. The two loops in these two lines from E and F (see diagram) were then drawn towards one another by another cord until the angles between the roadway and the portions of the cords below the loops were almost right angles, and then made fast. This other cord was then continued in either direction, taking a turn round each of the suspension lines in passing to the towers, to form a handrail. The reason for so dealing with the middle suspension cords was to increase the angle between the suspension lines and the roadway, so as to get a better suspension of the centre part of the bridge This proved the most satisfactory of several methods tried.

The other cords from C. D. G. and H go straight from these points over the top poles of the towers to their respective pickets. These suspension cords should all be fastened on to the roadbearers at D, E, F, G and H before the suspension part of the bridge is swung into position across the gap to be bridged. All that then remains to be done is to pass the cords over the top bars of the towers and fasten to the pickets. Before use the suspension cords should be adjusted so that the centre of the bridge is slightly higher the the ends. This method of suspension was found to be the most satisfactory and easiest to make as any particular cord can be readily tightened up. Of course extra strength would be gained by adding similar cords to some - the other road-bearers, e.g., those between C-10, and G. H.

To complete the bridge some form of planking should be laid across the road-bearers and lashed to them. In this case, some fifteen inches (in width) of planking put on for the whole length, and this in itself was a considerable weight. The length of the actual bridge between the towers was 38 ft.

This bridge proved very satisfactory in practice. After it had been used a number of times the drop in the centre, while an average-sized adult was standing on it in the middle, was only 9 in, and it may be added that the writer rode his bicycle across it.

August 19, 2016

Cardboard box rafts- Akela 2016

At the recent Akela 2016 camp, I was involved in running outdoor activities for the Pack Scouters, alongside the community service and crafts bases that were run. Alongside a tensegrity cube, I ran this challenge- to build a raft using staves, light cord, cardboard boxes and dustbin bags, and float a member of their team across a swimming pool (around 10 metres/ 30 feet).
Photographs courtesy Marissa Rakic

The idea is to build the cardboard boxes up, then seal them in plastic bags, and use these boouyancy 'blocks' tp build a raft. In practice, of the three teams who attempted it, only one got their 'sailor' safely across the pool. Here are the two unsuccessful teams at their moment of immersion:

The first team built a raft that had good, solid boxes, well tied together. However, they built a narrow raft which had very poor stability, and despite a few attempts, the raft was unable to remain upright.
The second team distributed the bouyancy more evenly, but one of their boxes failed around halfway through:
 The third team, pictured at the top of the post, managed to get across without any incident. I allocated 45 minutes for this, and all three teams had sufficient time, even allowing for around half the team being unfamiliar with raft building. I can recommend this as a patrol challenge if the weather is good. I would suggest having a full set of boxes for each team- in the event that a box gets wet, it is almost impossible to re-use.

August 12, 2016

Akela 2016 "Wolf" Hypar Gateway

I recently had the privilege to spend some time at the international Akela 2016 camp outside Pretoria, and this is the main gateway to the campsite - built by Harmellia Gardens Air Scouts.

The camp was held to celebrate the centenary of the establishment of Cubs, and the gateway was designed to resemble the head of a wolf- with a snout and two ears. The ears and snout are formed with sisal and eyehooks in hyperbolic paraboloid shapes. More information on how to set out the sisal to form the shapes is available here.

You can download the SketchUp 3d model here.

May 16, 2016

Kontiki 2016 Roundup and videos

KonTiki 2016 came to a close yesterday morning, after 60mm of unseasonal rain left the campsite waterlogged. The majority of rafts spent the night on the water, and the competition went ahead- congratulations to 1st Morningside who were all the overall winners!

Hennie Hamman, from Arrowe Park, has produced a series of videos summarising the weekend:
Friday night:


I'll be blogging some more about KonTiki once the full results spreadsheets are out, and once the organisers relsease some more photographs- there were a few timelapse cameras running over the weekend, and I'm looking forward to seeing them.

May 14, 2016

KonTiki 2016: Saturday- Rafts and Land activities

Saturday is the busiest day at KonTiki- rafts are completed, and after being checked for sea-worthiness, are launched and begin their competitions on the water. Meanwhile, on land, the Beaver Challenge competition has run for the Cubs and junior Scouts, campsites are being judged, and meals are competition meals are cooked.
Here are some of the rafts preparing for launch. Because of space limitations at the venue, rafts are built three rows deep from the shore. The theme for Kontiki 2016 is 'Jedi Knights', and you can see how some of the rafts have been decorated to match the theme.
Once the rafts launched,the weather (raining for most of the morning) improved briefly and I managed to get this photo of a rainbow. The organisers arranged for live GPS tracking of all the rafts this year, and this screen in the main tent shows the current location of all the rafts.
The Beaver Challenge is a series of challenge bases hosted for the Cubs and junior Scouts who visit Kontiki. Above are some of the bases from the challenge.

May 13, 2016

KonTiki 2016: Friday night raft construction

KonTiki 2016 is under way, with most teams well into building their rafts. Here are some photos of then shorefront. Teams build three rafts deep in most places, and once ready tomorrow, will help each other launch.

March 11, 2016

Bottlecutter2.0: making 'rope' from soft drink bottles

Image copyright Advocate Egerov

From Russia, via Youtube, comes this technique for converting a PET soft drink bottle into a strong 'tape' that can be used for lashings. Адвокат Егоров (Advocate Egerov) has two videos that explain how to build the Bottlecutter2.0 device to strip the bottles, and demonstrates how to use the strips to make lashings. Because PET shrinks when heated, he uses a hot air gun to 'frap' the lashings and tighten up the structures.
Image copyright Advocate Egerov
The first video (available with subtitles English subtitles) includes some basic lashings and instructions on making the machine to strip the bottle:

 While the second one goes through some detailed techniques and a rather elaborate willow branch chair:

Thanks to Clarke over at ScoutmasterCG for sharing this on one of his live chats- I recommend heading over there on a Tuesday or Wednesday morning (US time/afternoon European time)