Wind Generators conclusion
There is simply no sensible comparison that can be made between the Ampair Dolpin, designed to trickle charge a small battery, and the Air X designed to generate hundreds of watts: it's like comparing a moped with a 500cc motor bike, so it seems much more sensible to split these six machines into two groups. We've also added an extra category to our usual 'performance' and 'value' ratings. 'Functionality' sums up all the factors other that out-and-out performance which might persuade you to buy a scooter rather than a 500cc bike! In this particular context, it includes things like ease of installation, ruggedness of construction, size, weight, noise, and so on.

Trickle chargers
For most of the time, the smallest wind generators are likely to be producing less than an amp of current: enough to keep a small bilge pump running for a few minutes each day, and to put back, over the course of a week all the power that you might have used the previous weekend. They include the Ampair Dolphin, the Aero2gen, and the Rutland 503.

The Ampair Dolphin is an appealing design, but it normally doesn't produce enough power in normal conditions to justify itself. Of the other two, the Aero2gen does the job, at a realistic price, but is crude in appearance and aerodynamically inefficient. The Rutland 503 is cheaper, smaller, and lighter, but what really tips the balance in its favour is the ring around the blade tips, which makes it a much safer proposition on board a small boat and makes it the clear winner of our Budget Buy award.

Mid-range
The second group are those which develop a couple of amps in average conditions, to 'float' the load of your lights during a night passage, or to run a smallish fridge. The Rutland 913 and Aero4gen were clearly in this group.

The Ampair is robustly built, and designed to work and perform best in everyday conditions, but it's relatively very big and heavy for the power it produces, and is probably over-engineered for most users. The Aero4gen is another robust machine that could suffer from the same criticism compared with the lightweight and efficient Rutland 913.