We were awoken in the night by a noise roughly akin to someone revving up a 125cc trail bike with no baffle in the tail pipe. It was a very windy night, forecast at 35 mph but gusting maybe 50. When it got light I realised that my wind turbine was whizzing round at insane speeds, and barking like a dog. It kept us awake, but I was terrified it might also disturb my neighbours, who up to now have been super-understanding through the entire lifeboat restoration process.
In theory the turbine (an Air-X Marine 400W) has a microprocessor-controlled internal braking system which uses torque to slow the blades almost to a standstill whenever it detects high winds. This is to prevent it from vibrating itself to pieces in a gale. And it’s rated to withstand winds up to 110 mph which is higher than has ever been recorded on the Suffolk coast. But it appears the braking system gave out for some reason. I made a frantic call to V3, the gents that installed it for me, but all I got was their voicemail—not too surprising at 7.30am on a weekend. My next call was to Theo Bird, the local large scale offshore windpower specialist who had introduced me to V3. Theo had some ideas, and so he nobly drove over to my place.
Theo pointed out that the barking sound was actually the tips of the turbine blades going supersonic in the gusts! That’s pretty cool. We tried putting a load on the system by turning on a blow heater, thereby lowering the battery charge to the point where the turbine would short out. Then we went the other way and topped up the batteries to maximum charge using 240v, which is also supposed to kick in the braking system. Nothing made any difference, and the noise inside the boat was deafening. We noticed that the LED on the base of the unit was not lighting up either, which made us suspect there’s some kind of a failure in the wiring between the turbine itself and the wheelhouse electrical system.
Our next move was to climb up on the deck and lower the mast to physically stop the blades from whirring around. This was no mean feat. I’ve set up a rigging system which under normal circumstances makes it easy for me to lower and raise the mast on my own. Today it proved exceedingly hard, even with two of us, because of the pressure on the mast and turbine from the 50 mph Easterly. But once we got the mast down close to horizontal, the blades slowed down enough so we were able to stop them altogether, and tie them with rope.
Once V3 get in touch we’ll figure out what the problem is. Could it be something as simple as a blown fuse? I’m not familiar enough with the system yet to draw any conclusions. It’s overcast so the solar panels won’t be much help. It’ll be interesting to see today how long I can work in the boat for on a single battery charge. Hopefully I won’t run out in the middle of an inspired vocal take. Theo said philosophically “welcome to the world of renewable energy!”
So there is such a thing as too much windpower. Who knew?