Re: boat propulsion - miniature computer-controlled steam plant?

On 07/03/2024 00:51, Jim Wilkins wrote:

You machine each blade with two hole saw cuts like this into the rim of the disk:  ((
with a smaller radius on the back one so the blade has a crescent moon profile and sharp edges.

I tried that, but couldn't get it to work with a suitable geometry (for an impulse turbine) - I had problems with the back edge of the holesaw hitting the workpiece. If the saw was small diameter it would intersect the workpiece on both edges, and if the diameter was large enough that it didn't interfere the turbine blade was too straight.
Had visions of a flexible belt blade running over a curved surface, but that didn't work either. Though I am thinking of reviving the idea with a sanding belt for final polishing.
Nowadays I'd use a straight milling cutter on a CNC milling machine, or do a lost-PLA casting of a 3D print.
But my turbines are small, usually less than 50mm diameter. For a yacht you'd want something bigger.
But but ... does the electrical efficiency matter all that much for a yacht? If you are using CHP (combined heat and power) the otherwise lost heat can be counted as useful output, giving 95%+ overall efficiency.
Also, suppose you had 10% electrical efficiency from something burning oil or a similar taxed fuel. You could claim back the transportation tax on 90 % of your fuel, as you would be using most of the energy from it for non-transportation purposes.
Or possibly 97.5%, as you might be using the fuel solely for cooking or heating half the time, and using half the electricity on a microwave or summat.
(on boats fuel used for transportation is taxed at a much higher rate than fuel used for domestic heating or cooking. Or it used to be, it's decades since I lived aboard)
Peter Fairbrother