Wave propulsion for boat

[Paulco]

My wave power generator has worked out quite well so far (see “wave power” post)

But now I'm thinking if I can turn a generator I can also turn a propeller. That way the same unit can be used for power, propulsion or both.

This could significantly increase interest .  What do you all think?

I think I can offer it for sale for under a thousand dollars with both functions.

Anyone interested in a collaboration?

Paul

[Bruce S]

Normally these kind of requests are looked upon with a very skeptic eye from this group of people.
Here's my reasoning for saying this:
1) Only your second post
2) You've not told anything about this to on this forum
3) Another person posted TONS of information about what he did, including how he built it so others on this forum could freely try it out as well.
4) There's already a product on the retail market
5) Your asking about $$ which most people here are very keen on saving.
For now I will leave this post here, but,,, IF you don't get any takers do not be too surprised.
I'm honestly surprised no one has already asked you to show proof of concept.
 

[southline]

"My wave power generator has worked out quite well so far (see “wave power” post)"

Well.. How about some pics then?

Adam

[Paulco]

"4) There's already a product on the retail market"

What product is already on the market???

I'm not aware of this.

Thanks
Paul

[ChrisOlson]

I think I can offer it for sale for under a thousand dollars with both functions.

Anyone interested in a collaboration?

Probably not because it sounds kind of fishy.  But maybe post your project details with a whole bunch of pictures so we can all take a look at it.  I got a big yacht but it has sails that make it go.  It has a generator on it with a propeller that turns the generator and charges our batteries in the yacht.  Been used for years on sailing yachts - pretty much a proven way to generate electricity under sail - and it didn't cost no thousand bucks for that little hydro generator.

So I assume for a thousand bucks yours must be pretty awesome?

[Norm]

I can only envision a small electric outboard for use on a week end
after the wave generator has had all week to charge up a couple of batteries.
But easier is just a simple sail that has worked quite well for centuries .

  I see no advantage of wave power versus sail power.
Norm.

[ChrisOlson]

I don't see any advantage either because propelling a boat with a displacement hull is all about speed.  You can propel a displacement hull up to the hull speed where the length of the bow wave equals the LWL pretty efficiently with sails.  The amount of power it takes to exceed hull speed increases exponentially.  Most modern racing yachts can sail up to 2x hull speed and 3x wind speed on a reach with the right rig and a big roach main.  Cruising yachts are a little slower but still most can pretty easily sail at 1.2x hull speed.

The sails on our yacht develop the equivalent of many hundreds of propulsion horsepower because they work like an airplane wing and develop lift.  I do not see being able to do that by harnessing wave power, and especially being able to do it on points of sail.  As you say, Norm, sails have been used to propel boats since at least 300AD as recorded in the ancient Viking archives stored in Nuuk, Greenland.  And to this day, the record for a circumnavigation of the planet by a boat is held by a sailing yacht, and it beat the fastest mechanically propelled boat by about 15 days.

[birdhouse]

chris- i've heard about those hydro generators you tow behind a boat for charging batts.  i've always been curious about output at say 6-8-10 knots...  whats the diameter of the thing also.  do you have any data from yours?

adam

[ChrisOlson]

We have an Aquair 100 hydro turbine.  I'd say the screw on it is about 10" diameter.  At sea, sailing on a reach with the boat heeled, we typically tow our dinghy on the lee side of the stern and the Aquair on the windward side.  There is two different pitch props for it.  It's ideal tow speed is 7-8 kts and it surfaces at about 7 kts and limits its power output to 100 watts by "skipping" on the surface.  It can be towed up to 15 kts with the standard prop but it's hard on the tow line because of the skipping.  Our boat is very fast so we have a coarse pitch prop for it so it stays submerged at 15 kts and doesn't surface until 18 kts.

It pretty reliably produces around 2.2 kWh/day to the battery at sea.  And produces very little drag - I would say in the range of 15-20 lbs of pull on the tow line.