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.
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.
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.
The Wanderer dinghy – mine at least – has marine plywood cunningly concealed at the lowest point of the boat. The plywood runs from the front buoyancy tank, under the mast step, and to the centreboard case. Sitting at the lowest point of the boat, the wood is often sitting in water. My boat is now 40 years old and poking around in the front buoyancy the wood appeared a bit softer than I’d like. Well – the wood at the top could be pulled apart with my fingers.
In addition, my boat has a free-standing mast without shrouds. This is both a good and bad thing. The shrouds help to keep the mast upright, but they mostly try to pull the mast through the bottom of the boat. The wood is obviously designed to resist this downwards pull. However, the free-standing mast has huge sideways forces at the foot and if that foot isn’t really attached to anything strong then this would be a disaster – both for the boat and anyone sitting near the mast.
The oars supplied with the Wanderer (Custard) are 6′ long. Much too short for good rowing but easy to stow and thus fast to access. As described elsewhere fast access turns out to be the most important requirement for oars – for fendering off and close manoeuvering when things go wrong.
I have another set of oars supplied with the green boat (Owl). These are 6′ 6″ but I haven’t used them much:
They are too long for the low gunnels and high thwart of Owl – it is hard to get the blades out of the water.
The handle of one is damaged.
However they are a very good fit into Custard and the extra 6″ will help with rowing. So a bit of tidying up was in order.