I wanted to get an idea of energy usage involved in towing Custard – a 14′ Wanderer sailing dinghy – so I could work out our range when towing the dinghy.
A Better Route Planner provides an easy way to work out how to get somewhere with charging stops along the way. You can also tweak your car’s energy usage. Their base figure is nominal usage at 65mph.
Custard’s trailer has higher drag that I would expect – in my Mazda 6 it looks like petrol consumption goes up by 25%. This doesn’t appear great for something that is fairly aerodynamic (boat shaped) and not particularly heavy (I guess around 340kg). When I used to tow a Jaguar 21 – 1100kg plus trailer – it seemed to double petrol consumption so for something much smaller 25% seems high.
Anyway, first guess was that the energy consumption in the Tesla would go up by 25 – 33%. The nominal energy consumption per mile is around 255Wh/mile at 65mph according to A Better Route Planner. This seems close to what we get on a normal local journey. So this would mean consumption of around 320 – 340 Wh/mile.
I took Custard to the lake for a shakedown at the end of last week. Everything went well, but getting her out of the water up the slipway was almost impossible on my own. Not pleasant. I managed in the end.
The hole through the foot of the mast was too tight for the stainless steel rod, so I ground the end of the rod as a quick and dirty reamer to make the hole the right size.
This worked well. However, on assembling the system in the boat a problem became apparent: when in the boat the rod wouldn’t go through as it wasn’t aligned perfectly. Boats are never straight and the mast wasn’t at right angles to my new mast step.
I solved this with three approaches:
Adjust the alignment of the metalwork with washers under one side;
Barrel the centre of the rod so the mast could move from side to side without jamming;
Put a big handle on the rod to help in applying force to get the rod in or out.
A big block cut from a fench post – possibly Larch. This provides somewhere for the screws to go and takes the vertical force into the old plywood hog (which I cut a section out of).
A top plate that is split into front and rear halves. Since the tabernacle is glued in, it isn’t possible to get the top plate in in one piece. The top plate transfers the side-to-side force into the new ribs.
A couple of fiddly little bits to block up the remaining hole in the front buoyancy tank.
Just because I don’t have enough projects on the go 😉 I’ve started making a bass ukulele. I call it a μ-bass.
The body is an old Port Wine box. Since this wasn’t glued I’ve run Titebond around all the joints so they don’t buzz. The neck is a old piece of mahogany that has been lying around for 20 years. I bought some bass guitar tuners on eBay – I’ll need to make the slots bigger. Soundboard will be birch plywood.
The idea is to reduce the towing drag, make the boat a bit more secure in transport and provide a cover when away from home. It is made from uncoated acrylic canvas. The colour was chosen on the basis that (a) it is cheerful and (b) it was half-price.
The towing drag is important as we are planning to get an electric car and towing can reduce the range by 50%. Custard has always felt particularly draggy on the trailer so hopefully this cover will reduce the drag somewhat.