 Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me. |
Forum Index : Other Stuff : power on a boat
| Author | Message | ||||
beaul Newbie  Joined: 28/12/2009 Location: AustraliaPosts: 4 |
Hi guys, I live on a 40 ft trimaran, which we intend to cruise throughout SE asia. I have my partner Christine on board so I need a few luxuries etc like fridge/freezer/water maker etc.(plenty of power needed) For power supply I have 600amp/hour Agm Batteries an Inverter and a 2kva Kipor generator with a 40 amp power supply. I have just ordered a 200 watt solar panel.(but the sun doesn't always shine) Wind generators on boats are not very useful. They only "work" in 15 knots of wind or more and most of the time on a yacht is spent in a protected anchorage.(no wind or light wind) Towed systems only work underway and slow the boat down. I have noticed that the tidal current when anchored is very consistant, 24 hours a day (actually 22 hours)and never stops plus it never exceeds 4 knots. I would like to make a generator to take advantage of this available power. I am aware that the generator will run slow but can be powerfull? if made to a decent design/size. I am thinking about a vawt type system hung over the stern of the boat, but it will probably need gearing and I intend to connect to a F/P modified generator.(above water) Boats when anchored face into the wind but move around a bit from side to side by the wind pressure on the sides of the hull (especially multhulls, which have no keel) Any suggestions/comments regards, Beau |
||||
KarlJ Guru  Joined: 19/05/2008 Location: AustraliaPosts: 1178 |
I like the idea, hadnt even considered tidal flow before only the potential height that results. I pictured a cone shaped device with the sides being at an angle , hence providing the rotation, will need a shaft through the middle and a couple of loops of sorts with flotation devices attached. Perhaps one of these shinbaru (s12) motors as on the windmill forum utilising the 6 to 1 ratio using some stainless cable. Spend some time sealing up the soalr panel with neutral cure silicon as otherwise the salty water will get in and stuff it, similarly paint all the aluminium pieces too as they will dissappear soon too. If it were my money i'd invest in some thin film panels as they are indestructable (unisolar)and more shade tolerant although 3 times the size as mono type panels. small windturbines for boats (in my humble opinion) are built for racing yachts as you suggest and just done have enough diameter, perhaps an AIR X with the larger blades available on ebay. Perhaps an F&P exercise bike for the missus, there is an easy 50W for an hour or two a day and will keep her and you fighting fit to boot! Luck favours the well prepared |
||||
Greenbelt Guru Joined: 11/01/2009 Location: United StatesPosts: 566 |
The link may give some Ideas but this is not made for salt water. hydro-turbines Time has proven that I am blind to the Obvious, some of the above may be True? |
||||
| Barry T Coles Senior Member  Joined: 30/07/2009 Location: AustraliaPosts: 109 |
Hi Beaul Good idea but has restrictions, it wont work effectivly in the open ocean unless you are in an area where you will get the large tides in excess of 5 metre that will make the water rush past/around your boat. If on the other hand you can moor up in a tidal creek you will then get a far greater flow on the incoming & outgoing tides. The basics of tidal power is; generate power while the water is rushing through a small opening in a large holding pond, store that water & when the tide is going out the power generation procees starts up again. Cheers Barry I need to learn from the mistakes of others. I dont have the time to make them all myself. |
||||
| beaul Newbie Joined: 28/12/2009 Location: AustraliaPosts: 4 |
I don't want to use it in the open ocean. 99% of cruising is spent anchored. Which is where you need the power for ice in the drinks at sundown. At least the tide is consistant day and night unlike wind or sunlight. I am aware of the low speed of the tidal current but I am hoping I can made that up my using a reasonably large Vawt type system placed in the water behind the boat and gearing up, to get the speed necessary to run the F/P generator.(200rpm?) I think the water wheel concept is too cumbersome. Another power source is the wave action, but again you do not always have waves which is why the tide action is more suitable for this application. Remember this setup doesn't have to put out a lot of power because it will be running reliabily 22hours a day every day. |
||||
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
I can see a serious flaw with your WAWT type water turbine idea when placed in the water behind the boat. VAWT vanes only make power during the downwind part of a revolution, they are a drag during the rest. In air this drag is overcome by the powering vane but in water, being about 800 times more dense than air, me thinks it will not turn at all - too much water to push out of the way. A waterwheel, turning on a horizontal axis, would turn all the time as long the axis is above the surface. But, since you placed an intersting idea into my head, I might borrow it for my next Kimberley cruise where we do anchor a lot up tidal creeks. I think I'll try it with the spare O/B propeller affixed to a flexible drive shaft of sorts. Klaus |
||||
| beaul Newbie Joined: 28/12/2009 Location: AustraliaPosts: 4 |
I disagree with your comment about the vawt in water, it will work the same as used in wind. However I have this plan a design which will improve efficiency 
|
||||
| Barry T Coles Senior Member Joined: 30/07/2009 Location: AustraliaPosts: 109 |
Hi Beaul Your idea of using tidal flows is feasible if you can contain those flows; in your case having a trimaran puts you in a better position to do this than a single hull craft, you will be able to utilise the gap between the hulls as your containment, have a look at this link & check out the Parshall flume design this will give you the idea of what you will have to do to contain the flows. http://www.fao.org/docrep/t0848e/t0848e-09.htm I see from your profile that you are in Queensland and may already have reasonably bigger tides than down south, the best way to get a rough idea of how much water is going to flow between the hulls is to measure the time a weighted float takes to move from the bow to the stern, the float preferably needs to be below the water surface, if you do it on top of the water you are going to have to de-rate that time by 0.8 Cheers Barry I need to learn from the mistakes of others. I dont have the time to make them all myself. |
||||
Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Have you considered the generators that use the motion of the water to bob them up and down. I understand these have been used in some comercial offshore applications. I am guessing they are ring series of coils with rings of magnets that float up and down past the face of the coils. Then you are more than likely anchored in calm waters so this might not be a good option. Pete. Sometimes it just works |
||||
| Barry T Coles Senior Member Joined: 30/07/2009 Location: AustraliaPosts: 109 |
Hi Beaul Have you thought of using an old outboard with the motor removed & replaced by a F&P. The F&P could be housed inside the motor cowling attached to a footplate & direct coupled to the old drive shaft through the angle drive to the prop, you may have to up size the prop. Just a thought, sorry about the rough drawing. Cheers Barry 
I need to learn from the mistakes of others. I dont have the time to make them all myself. |
||||
| beaul Newbie Joined: 28/12/2009 Location: AustraliaPosts: 4 |
Thank you guys for all your comments. I have looked at the bobbing wave system Salter duck for example but again waves are not consistant in an anchorage. We try to anchor where there are no waves. I do like the old outboard motor concept. |
||||
| Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Thanks for enlightening me, I have yet to see a VAWT with movable vanes like your design. I simply assumed you planned to use a fixed vane design  .
I do hope you have lots of stowage space to keep all that equipment when your boat is on the move. Klaus |
||||
| Greenbelt Guru Joined: 11/01/2009 Location: United StatesPosts: 566 |
Beaul; Look at this. taken from one of my old scratch pads, very similar to the drawing you posted. may be useful. 
Time has proven that I am blind to the Obvious, some of the above may be True? |
||||
MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
beaul Hi. I like "off-the-wall" ideas and I have a dandy for you: If you want to trail a generator in the tidal flow behind your vessel while it's moored, I'd suggest something that floats and is not affected by the wind or by junk in the water (sea weed, floating stuff, etc.). Since your boat is a trimaran (?), it will likely offer limited wind shadow, so anything with large-surface-area-paddles or the like will be ineffective. If it were me doing this, I'd construct a floating cylinder that had several spiral fins originating at one end and spiraling down to the other end. Think of the old candy-cane-looking barber pole signs, you know those things that just twirl outside the barber's shop. It should look something like that, except instead of painted stripes, shallow (4"?) fins. As the tide rips past, this thing will float and spin at the water's surface. Any junk in the water would just sneak past it as it twirls. The tube could be anchored using a long-ish rod, which in turn could be attached to whatever drive mechanism you come up with to generate electricity. Heck, maybe you could just hook this up to a giant spring and an escapement. When the spinning float winds the thing tight enough, an escapement could let it go against gears and a generator. Depending on the load and the spring, the thing might put out quite a wallop for short spurts. Just some ideas. Good luck! Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
||||
 Print this page |
