Tensegrity Launch Trolley
Once I had this idea, I just knew I had to build one. A tensegrity launch trolley will turn some heads, and make my boat look lighter than it is.
In short, a tensegrity structure consists of a bunch of sticks, being held together by many strings/wires/ropes, such that the sticks a) do not touch each other, and b) are not subjected to bending. (I cheat a little with respect to the second requirement, since the wheel crossbeam must take some bending due to the placement of the wheels.)
Supplies
- The wheels are normal wheelbarrow wheels. Large diameter wheels will help keep the lower ends of the aluminium tubes off the ground.
- Thick-walled aluminium tubes, the kind used for boat awnings, were used for X:es near the wheels.
- Some stainless steel tube I picked up from a gutter, just happened to have the right diameter to serve as the wheel axes.
- The wheel crossbeam is a wooden stick, thicker than a broom handle.
- It was protected with liberal amounts of tar.
- The strings are 3 mm ultra-high-molecular-weight polyethylene rope. I did not need that for strength, but wanted it for low stretch and a skinny look. (3 mm instead of, say, 2mm, made it much easier to tie the knots.)
- Near the end of the aluminium tubes I installed short, 5 mm diameter, stainless steel studs.
- Some webbing was used instead of rope in some places, in order to spoil the boat.
- They were held in place with some polyurethane sealant-glue-rubber.
Plan or Play
I guess it boils down to what kind of person you are. You could either design this ahead, or simply start building it. I did the former. The construction is highly modular, so mistakes will not cost a fortune.
Those of you who have a PDF-reader/viewer which supports embedded 3D documents, should be able to rotate and zoom the "picture" of my design in the supplied PDF-file. (Adobe used to have a Linux-version of their Acrobat Reader, but sadly enough, now they don't.)
The proportions is for a coastal rowing single, and you will have to tweak the proportions for other types of boats, other use cases.