Subject: [harryproa] Re: Windmill drive
From: Mike Crawford
Date: 4/10/2006, 9:17 AM

  I don't know anything about Rob's windmill cat, but since I coincidentally happened to be looking at another windmill cat last week, I thought I'd post the link:

  There's also a fellow working on powering a Hobie cat with a vertical turbine that will function identically at all angles of attack without having to pivot.  Provided it can be depowered in a gale, that could be interesting.

  I have to admit that I'm a fan of traditional sails, but there's definitely an argument that the foils in a windmill are much more efficient than single-layer sails. 

  If I did go with something that rotates, though, I'd probably go with electric motors.  From what I've read lately from Solomon and Fischer-Panda, there's more loss of power going through a traditional mechanical transmission than there is going from a generator to an electric prop.  This would be more pronounced in a windmill setup where the force has to go through a number of junctions before reaching the water.  Plus there's a host of other useful benefits, from having localized points of failure, to eliminating transmissive stresses, to being able to store the energy.

  There could be research to the contrary that argues for a mechanical linkage, but I'm not familiar enough with the topic to know of any.

       - Mike

colcampey wrote:
Someone on the electric boat group proposed the novel idea of
eliminating the electric motor between the wind generator and the
Do you think it's time to revisit your idea, now that you can use
carbon to keep the whole thing light and demountable (for gales). A
light carbon boat will also need a smaller windmill than your
original - or two even smaller windmills.
Use the windmill whatever the wind direction whenever there's enough
breeze and the kite downwind in light air.


Col C

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