The canopy is to protect the passengers from the Australian sunshine. If the boat didn't have to travel on a trailer the canopy could simply stay in place on four legs. However, the boat is on a trailer and so the canopy has to be removable, collapsible or something for traveling down the road. My solution is an oval shaped canopy, same as the cockpit coaming, that can be lowered to form a "lid" over the cockpit for road travel. This will "cover the load" for legal trailer travel and keep the rain, leaves and dust out.
Note that the canopy has now become the lid! To work as a lid it has to be slightly larger than the cockpit coaming. Large enough to accommodate some sort of folding or hinged legs to support it in the up position. For aesthetic reasons it has to follow the sheer line of the hull. So, now it is oval and curved when viewed from the side.
I decided to laminate the rim of the lid from 3 layers of 5mm bendy ply; same as the cockpit coaming. Rather than making a mould to laminate around I used the boat by making a lot of formers that would clamp onto the cockpit coaming. This is what the formers looked like:
The notch fits over the edge of the coaming and the screw clamps the former in place. The L shaped piece at the bottom hooks around the bottom of the coaming to provide more support .
Here they are in place. I found that they didn't automatically stand vertically and needed individual fine tuning. This was done by inserting small packing pieces between the former and the coaming, tedious but it worked.
To hold the formers in place I wrapped a layer of 4mm MDF around them, and screwed it to the formers. This whole structure was surprisingly rigid.
Here the first layer of bendy ply is being fitted. The circumference of the lid is about 8 metres, the bendy ply is 2.4 metres so there are scarf joints where necessary.
Photo of the 2nd (and 3rd) layers of bendy ply going on. This was a very messy business and used a lot of epoxy! The combination of clamps and straps held the laminations together quite well.
After a trip around with the scraper and belt sander to remove the epoxy runs I marked the lines of the top and bottom edges of the lid following the curve of the deck. Now you can see why the laminations needed to be 250mm wide to give me a 100mm wide rim.
I cut along the top edge using a small hand held circular saw (about 70mm diameter blade which follows a shallow curve like this easily) and added some temporary bracing to keep the lid in shape. I don't think this bracing was necessary as the off cuts of laminated bendy ply were stiff enough to hold their shape.
Here the lid is lifted off the boat ready to be turned over and have the lower edge trimmed off.
With the lower edge trimmed the temporary supports were transferred from the top to the bottom and some permanent bracing added to the top edge. Glue blocks at the ends of all the bracing and halved joints along the centre. I put fillets of epoxy bog around all the joints .
Here is the result, about 3 metres long and 1.5 wide. I have thought a lot about what to cover the lid with, canvas or solid material? I've settled on 3mm ply because it won't sag and puddle when it is rained on and it will provide a better support for the solar panels I will eventually add to the boat.
Here's a prototype leg. Hinged at the top so it can swing fore and aft and also from side to side. At the bottom is a rigid fixing on the deck.
Unfortunately the round bases would not fit in the available space. I could have machined enough off the inside of the base but the result would have been ugly. Eventually I obtained some rectangular bases that solve this problem.
Where do the legs go when the lid is down? Here is one solution but the trick here is - how to clip the legs in the hinged up position when the lid is down? Difficult to get access under the lid to do this and the "clipping" needs to be firm enough to hold the legs so they don't come loose and bounce around inside the boat. Still working on this.
Here is the lid sitting on the boat.
And here it is raised up on some temporary legs as I work out how high is should be. This seems about right but 6 foot people will have to bend a little or wear hard hats.
At the moment I am waiting for the stainless steel to arrive from the supplier. It has been more than two weeks now - I think it is "unobtainium" not simple stainless!
There is a further impediment to progress on the lid and the launch generally: I have decided to build myself a sliding seat rowing skiff. I have been doing a lot of rowing in my Acorn 15 since late last year because I enjoy it and because it keeps me fit and builds up some to the strength I lost while "resting and taking it easy" for health reasons. You can read about my choice of skiff in the new blog.