This year I have constructed tunnels that can be picked up and moved in one go.
My frames are 6.5x2.5 metres, and around 1 metre at the highest point. There are five 150mm uprights on each long side of the base for the hoop pipe to sit over. These dimensions use up exactly three lengths of pipe, and require 14 tees.
You will notice 150mm of extra end pipe sticking out each end. These are the peg points to secure the structure to the ground.
Once the tunnel is in position, it is pegged down by four pieces of 500mm reo-bar that have been bent in a vice to make a giant tent peg. Make sure you place the peg firmly against the join of the tunnel base -- I pegged on the outside of the pegging points on my first tunnel, and was then gratified with the sight of a 6X2.5 metre piece of expensive garden equipment bowling majestically through the brassicas on the first strong winds of autumn...
In the photo you can see the baling twine that will be used to secure the end baton.
To secure the film to the base, I'm using the green Jumbo clips from veggiepatch.com. First I tried tucking the plastic inside the tunnel and clipping from the inside, but this creates problems with condensation pooling, as well as being difficult to get at, and I've found clipping on the outside far better (although less neat). Three clips to a bay, plus one to clip the middle of the end to the baton.....
To move the tunnel, untie the twine, move the furled baton and remove the pegs. With one person to each end, my wife and I move our tunnels without too much fuss.
3x6.5 metre, 25mm extra light galv. pipe $90
14x(25x25) thru butt tee $60
15metres 1.5 inch rural pipe $40
9 metres poly film $100
26 green clips (inc. delivery) $50
Delivery Nubco-Cygnet(Johnny Clifford) $10
I'm hoping the structures will last a good 10 years. Plastic may have to be replaced every 3-5 years, maybe longer if you are planning to use netting or shade cloth over summer (as I am).
I'm also going to cover one with wire to make a chook tractor. I'll let you know how it goes!
PS. Questions/ comments/ advice welcome...