CCA Installation
Stagefright Installation by Suspect Culture in conjunction with Stage Hire Scotland and RSAMD Technical and Production Arts students Calum Willoughby, Kirsty Campbell and Louise Marr.
The Project
We were asked to be involved with Suspect Cultures Stagefright Instillation at The Centre for Contemporary Arts (CCA) in Glasgow. This installation involved an element of suspending between 20 - 30 Silver Birch trees (sourced from a sustainable forest) above the Cafe/Bar in the CCA. The cafe has no structure above it but is an open space climbing 2 levels to a glass roof. The cafe is in fact located between the two buildings that have been linked to make the CCA.
We were restricted as to the infrastructure we could build because we could not damage or mark the buildings in any way. Any structure had to be completely self supporting in that respect.
It was decided that Stagehire Scotland would be responsible for building a "Grid" structure spanning the two balconies and we would be responsible for suspending the trees.
Our Solutions
Number 1 - Calum Willoughby
What it is
Use Petzl Rigging Plates [£2.50] and coach screws [£2.79 for 10 {M10 x 90mm}]
Drill a pilot hole into the trunk on either side of the base. Screw one plate on either side and attach steels with a half ton shackle. Higher up the tree put another two plates on the remaining two sides. Shorter drifts will be needed on these points.
By securing to four different points then we are allowing ourselves separate safety points as well as securing them in position.
POA for rig
Use a Chain Hoist to lift the tree at the end of the cafe with the bar. Choke a round sling around the trunk and let the Chain Hoist take the weight whilst the 4 lines are attached to the grid. Finally the tree is slid out to its required position using guide ropes. The steels can be attached to the Stagehire Scotland grid using wire rope grips on either side of the shackle.
Costing
One Tree
4 Petzl Coeur Hanging Plates [£2.50 each Outside.co.uk]
4 M10 x 90mm Coach screws [26p each [Box of 10 £2.66 Flints Supply and Hire]
8 1/2ton Bow Shackles [£2.89 each Flints Supply and Hire]
22 Trees
88 Petzl Coeur Hanging Plates Total £220
88 M10 x 90mm Coach Screws Total £23.94
176 1/2ton Bow Shackles Total £508.64
TOTAL = £752.58 +VAT
Number 2- Kirsty Campbell
What it is
I propose to drill through each tree trunk in two separate places, the position of which would depend on it's size and weight. Large Eyebolts would then be put through the holes and an eye-nut put on the end. This would provide us with 4 hanging points per tree. To ensure that the tree remained vertical we would have to make sure that the position of the hanging points did not make it top heavy and cause it to tip.A drift would then be shackled to each eye and then shackled to the grid system. These could then be lx-taped to to the grid to stop them from slipping along the steels.
POA for rig
Ideally I would like to use Stagehire Scotland's method of installing the truss sections to gain access to their grid in order to hang the trees. However if this was not possible we could try and find a point capable of housing either a chain block or hemp rope so that we could haul the trees up to the desired height. We could then attach the trees to the grid system from the second floor balcony. If we attached a piece of hemp rope to the trunk we could then use it to pull the trees across to the correct position on the grid.
Costing
- Item- Eye bolts (Available from Flints.)
- Type- Drop forged collared long shank eye bolts.
- Size- M12, 178mm thread
- Price- £9.84 (each)
- Notes- These are expensive although they are safe to use with non-vertical loads
- Item- Wire rope
- Type- 7core soft flexible steel rope
- Size- 5mm
- Price- £1.79 (per meter) £139.00 (per 100 meters)
- Item- Shackles
- Type- Blue pin bow shackles
- Size- 0.5t
- Price- £1.84(each)
- Item- Nyloc Nuts
- Type- Steel nylon insert nuts
- Size- M12
- Price- £6.90
Total costing for 22 trees
- Eye bolts(44) £432.96
- Shackles(88) £161.96
- Nyloc nuts (100) £6.90
- 44 X 5m 3mm 7 X 19 Blackwire rope drifts with eye thimble terminations £220.00
Total cost-£821.78 + VAT
Number 3 - Louise Marr
What it is
- A very simple system of drilling a hole through the trunk of each tree then running PVC covered steel rope through the hole and up the trunk of the tree secured as far up as possible by grummets. Each tree would have two sets of lines running at right angles to each other.
- The lines would then be terminated by wedge sockets and shackled to 4 points on the built “grid”.
VARIATION: Instead of running wire rope through the hole in the trunk you could cut a bigger hole in the tree insert a length of scaff; put barrel clamps on each side and shackle drifts onto these and up to 4 points on the grid. Then instead of a grummet you could use a ring plate at the top to act as a guide and stop the tree swinging. This would be dependant on being able to cut a 50mm diameter hole to fit the scaff through.
POA for rig
1) Drill holes in tree
2) Thread pre cut PVC covered steel rope through
3) Grummet the steel as far up as is practically possible
4) Terminate wire rope in wedge socket
5) Prep 4 rigging points on “grid”
6) Attach chain block to tree
7) Lift tree into air
8) Attach 4 lines to “grid”
9) Release lifting lines
- When rigging the chain block attach it to the grid by means of a round sling or similar so that once one tree is up you move the chain block to the next position and hall the next tree. This way takes slightly longer but each tree is lifted to its desired location avoiding the need to move them once up in the air.
- Because you are using lines to lift the tree into position there is little stress on the grummets so it is unlikely that they will have the forces on them that will cause them to pull out. They should also be put in with 2 machine screws and 2 wood screws as per manufacturers recommendations or bolted in.
Costing
- 5mm wire covered to 6mm; SWL 1380kg; 1m = £0.91; 100m = £81.00
- 5-6.5mm Wedge Socket - £8.82per socket
- 6mm Dogs (DIN 1142) £20.80 per 100
- Grummet - £1.00 each (£0.90 each when ordering 100)
Total Per Tree
Based on 8m tree and 2m gap between top of tree and grid:
- 19m + 15m = 34m Wire Rope - £30.94
- 4 x 5-6.5mm Wedgw Socket - £35.28
- 6mm Dogs (portion of 100) - £02.50
- 4 x Grummet - £04.00
Total - £72.72 (this becomes cheaper when buying elements in bulk)
Total for 22 Trees
Based on 5.25 drop from "grid" to first floor balcony (as given by Grant Williams)
- 352m Wire Rope - £288.50
- 88 Wedge Sockets - £776.16
- 264 6mm Dogs - £62.40
- 88 Grummet - £88.00
- 2 Boxes Machine Screws - £12.04
- 88 1T Bow Shackle - £308.88
Total for 22 Trees - £1535.98
Number 4 - Steve Macluskie
Method
Use commercially available climbing slings to make a prussic loop at the base of each tree. I chose this method due to the small diameter of the tree trunks and the worry that bolting through would split the trunks.
Attach a 5m 3mm 7X19 black wire rope to the prussic and up the length of the tree keeping it tight to the trunk. This will give a Safe Working Load of 68kg at a safety factor of 8:1 Data Here.
No tree weighs more than 30Kg.
About two thirds up each tree loop the wire rope back on itself in a timber hitch to keep the tree hanging vertical.
Attach the black wire rope drift to the tensioned wires using shackles.
The trees will be attached using Stage Hire Scotland's zip-up tower on Sunday 22nd March. A block and tackle will be temporarily rigged on the truss to safely lift and attach each tree.
A length of black sash will be attached to the base of each tree and run to each gantry. This will allow individual movement of each tree once the zip-up has gone
Kit
22 X 5m 3mm 7 X 19 Blackwire rope drifts with eye thimble terminations approx £110 +VAT
44 Small Crosby Screw Pin Bow Shackles £2.89 £127.16 +VAT
22 Short climbing slings £3.50 each £77
200m of Black Braided Polyester 8mm £200 +VAT
Block and Tackle set for raising and attaching trees Borrow
TOTAL = £514.16 +VAT