We had a go at making a composite shute this weekend.
The biggest breakthrough was finding a new mandrel material.
the mandrel requirements were:
- could be shaped into a tight radius without distortion of it's section.
Was circular in section could be removed from shute once cured
was cheap
Locally available.
After unsucessfully trying to heat bend some PVC plastic piping I went to B&Q for some inspiration. Having filled my basket with other usefully things like sandpaper, brushes and Araldite etc. I gave up on the mandrel hunt and went to the checkout.
Ureka!! i noticed that another customer had a length of foam pipe insulation. The type that is used to insulate copper plumbing pipes in lofts etc. I quickly found myself a piece and realised that it fitted all the above criteria, even better than the bicycle inner tube option.
At home i relised that I already had several lengths of the stuff.
Forming the shape was easy.
Parcel tape was used to tape the tapered ends down along the gunnel of the boat. this was to increase the radius of the gunnels and help retrival following a trawl. The hoop part was supported temporarilty by a few peices of wood while it was spiral wound with more tape. The tape held the shape and the supports were removed. Narrower Selotape was used to smooth some of the folds and cover some of the dips.
A layer of release wax and we were ready to get sticky.
The aim of the first hit was to fix the shape. Three layers of glass were applied in strips wrapped around the shape wrapped tightly in peal ply in a spiral fashion and left to cure.
After removing the cured shute from the boat and trimming off excess glass it was possible to push the foam up one end of the shute and pull from the other. Within 20 minutes the foam was out. it weighed 130 grammes at this point. I intend to added a layer of carbon and then more glass to add strength and wear resistance.
