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Yes, that will happen first, LED lights, new music system, new TV. 12v fridge is new but thermostat not working so I turn it off if I remember.

 

Then might go with the try it and see approach, i.e. add some solar and go sailing.

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I thought some might be interested in this. Here is a pic of my solar control panel the other morning. There are two 140w panels in series, producing the voltage on the left, and the associated amperage. The middle one is what is going into the batts. As you can see the MPPT controller is doing its stuff - reducing the volts to suit my batt, and uping the amps;

Solar.jpg

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Hi Farrari, This was a sunny day, but about 9am, The pic was posted to show the boost to charge that a MPPT controller can give.

 

My panels are flat on the bimini, (in fact one sloped slightly away from the sun, one slightly toward the sun at this time of day on the marina berth) The sun angle is not good at 9am this time of year. So far the setup has produced an average of 360w/hrs per day, which is not bad, but a bit lower than I had hoped. However it has rained and been cloudy a lot lately. I've not yet seen the max amp supply it can currently give (I've not been on the boat in the middle of a sunny day!). Perhaps it will be sunny around noon today, and I'll get a chance to have a look...

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Have to say I'm very impressed by the flexible solar panels. I had the perception that they were much less efficient than hard ones. I've put a 100W one from AA Solar aboard, and simply lashed it to the sail cover when anchored. It means I have nearly doubled my solar power, with a hard 110W aft. I often see my battery bank (300 Ahr) at 14.4V when the fridge cycles off. 

But there are cloudy days when I'm still happy to have the wind generator aboard. For serious cruising you need options.

 

Having just sailed to Fiji (on another Cat) I too am thinking of towed charging systems. At this time of the year the sun is out and effective for perhaps a third of the day, and modern auto pilots and nav systems need power all day and night.

 

How hard could it be to use a car alternator and regulator hooked up to a prop on a long solid trailing wand?

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Sure Tim, you can do that. LOTS of drag though - many alternators require several HP to provide good power output - so it's like running your 2HP outboard backwards while sailing!! There are boats around with fixed props that have alts off the driveshaft as well - just put in neutral, and let the prop turn it - BUT make sure your gearbox and stuffing box/shaft seal are ok with that.

 

Flexible panels are pretty good - and despite not being quite as good output as the solid ones of the same vintage, they often tolerate partial shading a LOT better - read the specs for whatever you are considering! :-)

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I have an outboard between my hulls that I retract to go sailing. Yes there is some drag if I leave it down, but not frightening amounts. I'll try and quantify it sometime.

 

Interestingly if the engine is in gear, it will easily turn it over, but flood it not start it.

 

Possibly the real problem with a towed charger is how little time as a percentage that a cruising boat is sailing for, relative to the rest of the time on anchor.

 

Have to say my wind generator has earned it's keep over the last couple of days; not much sun...

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I have an outboard between my hulls that I retract to go sailing. Yes there is some drag if I leave it down, but not frightening amounts. I'll try and quantify it sometime.

 

Interestingly if the engine is in gear, it will easily turn it over, but flood it not start it.

 

Possibly the real problem with a towed charger is how little time as a percentage that a cruising boat is sailing for, relative to the rest of the time on anchor.

 

Have to say my wind generator has earned it's keep over the last couple of days; not much sun...

Which makes me think that an outboard could be easily converted to give 6 to 10 amps when sailing. The alternator regulator and drive train are all there , just remove some of the drag inbetween. Easiest to use a 4 stroke with the oil in the sump to keep everything spinning, and because it is retractable you would only use it when needed and you were happy to have the slight extra drag. An old Yamaha 9.9 would be ideal and you could experiment with different props , the barge prop giving more revs /charge at slower speeds and a higher pitch prop less drag perhaps.   At anchor solar panels should do the job unless you are planning on running a big screen movie experience off batterys at night. Could also use just the leg and bracket mechanism of an outboard  and fit an alternator to the top of the shaft somehow inside the cover and using the space of the removed engine.  On a cruising boat at 6 knots I doubt you would notice a lot of difference caused by the extra drag of an outboard leg and prop.

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It would be fairly easy to test, next time you are sailing throw out a riggers canvas bucket or a similiar size drogue , at 6 knots I would say the pull on a rope may be 20 kg plus, but I don,t know if it would be enough to make to make a lot of difference to your speed as there is a lot of power to move your 40 ish ft boat at 6 + knots. I think it would be that easy, [ all you would need to do really is pull the sparkplugs out of a suitable outboard with an operating charging system and leave it in gear and connected to a battery] but thats more of a Wharram hippy style approach that does not suit everybodys sense of style or shiny boats. Of course not all boats can easily mount an outboard but for many cats, certainly most Wharrams, it would not be that hard and a constant 6 amps overnight on passage would keep a simple boats systems running,and batterys topped up, and I for one are happy to sail a little slower at night anyway.

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 At anchor solar panels should do the job unless you are planning on running a big screen movie experience off batterys at night. 

I resemble that comment. Whats wrong with spending 500W of naturally generated power this way? Haven't had that many complaints...

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Absolootley nothing. No point making and storing lots of power unless you can find a use for it, which gives me another idea , excess power could be diverted to a 12v element  in a small hotwater cylinder, to save lpg? 

 

I sometimes wonder if there is a fire danger from lots of solar panels pumping amps when the batterys are already full, I found one of my regulators melted once as it was overloaded and could not safely dissipate all the energy as heat. I tend to partially cover panels now if the boat is left and not using any power.

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Absolootley nothing. No point making and storing lots of power unless you can find a use for it, which gives me another idea , excess power could be diverted to a 12v element  in a small hotwater cylinder, to save lpg? 

 

I sometimes wonder if there is a fire danger from lots of solar panels pumping amps when the batterys are already full, I found one of my regulators melted once as it was overloaded and could not safely dissipate all the energy as heat. I tend to partially cover panels now if the boat is left and not using any power.

 

I have an isolator for exactly this reason because when the boat is in the marina shore power (not solar) is keeping things topped up.

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I'm looking hard at electric hot water systems even on my boat for the same reason. On a sunny day there is lots of power to use. And these days gas caliphonts have a high degree of installation difficulty with gas regulations. There are 5 and 10L ones available out of Aussie, I haven't seen any here in NZ.

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