Solar vs wind vs hydro

[Joli]

I would add wind, it'll work most of the time for you 24/7. Passaging it's easier and less expensive to run the engine to charge batteries. Don't bother with hydro unless your sailing ALL THE TIME.
We sail 5,000~7,000 miles a year and just run the generator twice a day when passaging.

[Adelie]

I would get a wind turbine before a hydro-gen, most people spend 66-90% of their time at anchor with little or no water flow over the generator.

Beyond that I have a somewhat unusual opinion about windpower.
In general solar is the primary non-engine electrical source and it is generally concentrated in the aft half of the vessel. In order to minimize shading on the panels from the turbine and to minimize the risk to the sails I would get a vertical axis turbine and mount it abeam of the mast and above the heads of crew, possibly pulled up to the lowest spreaders. It would not be as efficient as a horizontal axis turbine, but I think the lower shading would offset that on average.

[Na Mara]

That’s an interesting perspective Adelie. Here is a VAWT you can actually buy.

https://www.leadingedgepower.com/documents/LE-v150-datasheet-April%202020.pdf

Power curve says you get nothing out of them until about 16knots with output topping out at 200W in storm conditions. They are pretty cheap and easy to mount up the mast. A pair mounted over the lower spreaders will produce 50+W in 20+ kn winds.

Advantages are cheap to install and no negative solar shading. Disadvantage is low and infrequent output.

I agree about the diesel stoves if you have somewhere to mount one and a suitable flue run. I would love one but struggle to see where one could go on my boat.

[Na Mara]

Actually looking at it again, if I junked the beer fridge (a little ancient and inefficient 42l cruise that I only run on shore power anyway) I could probably fit a refleks 66MV in the cupboard in the galley. The problem with that, aside from loosing some fridge space and deck vents coming up around where I work the mast, is that the output is only 1.7kW. The recommended output for forced air diesel heaters for my boat is 5kW. Wouldn’t a refleks like heater struggle on the typical 40fter during a Baltic winter?

[wholybee]

Originally Posted by Adelie

I would get a wind turbine before a hydro-gen, most people spend 66-90% of their time at anchor with little or no water flow over the generator.

Beyond that I have a somewhat unusual opinion about windpower.
In general solar is the primary non-engine electrical source and it is generally concentrated in the aft half of the vessel. In order to minimize shading on the panels from the turbine and to minimize the risk to the sails I would get a vertical axis turbine and mount it abeam of the mast and above the heads of crew, possibly pulled up to the lowest spreaders. It would not be as efficient as a horizontal axis turbine, but I think the lower shading would offset that on average.

I'm considering going the other way. Sailing downwind a wind turbine will be at a disadvantage do to the reduced apparent wind. But while sailing, I have more electronics to run, my autopilot, instruments, navigation laptop, etc. I can manage in an anchorage with solar alone. But sailing with everything else on I fall a bit short. I think a hydro generator will work better for that case.

I have seen boats with a convertible generator that flipped around for wind or hydro. I question if it did either well, but an interesting idea.

[valhalla360]

If you can fit solar, it's the easy winner. I would try everything I can to make solar work before considering the alternatives.

Wind is probably the next best as it can work while at anchor but as someone else mentioned, make sure it doesn't shade the solar. Downside is if you anchor in protected anchorages, you will often have little or no wind.

Hydro is really only a useful option if you spend a disproportionate number of days under sail (or regularly anchor in 4-5kt tidal currents). When anchored for 3-4 days, it produces nothing. If you are doing day sails, most times, you will be starting the engine to get out of and into harbor, so the alternator will give you boost on those days anyway.

Even better is to improve efficiency and reduce consumption. That's usually the cheapest and best solution.

[Adelie]

Originally Posted by Na Mara

That’s an interesting perspective Adelie. Here is a VAWT you can actually buy.



https://www.leadingedgepower.com/doc...ril%202020.pdf



Power curve says you get nothing out of them until about 16knots with output topping out at 200W in storm conditions. They are pretty cheap and easy to mount up the mast. A pair mounted over the lower spreaders will produce 50+W in 20+ kn winds.



Advantages are cheap to install and no negative solar shading. Disadvantage is low and infrequent output.



I agree about the diesel stoves if you have somewhere to mount one and a suitable flue run. I would love one but struggle to see where one could go on my boat.

I was thinking something like this:

https://www.tesup.us/product-page/at...ine-for-houses

[Na Mara]

The output stats on that VAWT are a bit too good to be believed but even if true it’s too big and heavy to mount on the mast of anything smaller than a super yacht. Stern mounted it will cause significant shading issues. That said, with the reported output who needs solar?

Unfortunately, the atlas turbine is only recommended and waranteed for grid connected systems so not really viable on a boat.

[Na Mara]

Originally Posted by valhalla360

If you can fit solar, it's the easy winner. I would try everything I can to make solar work before considering the alternatives.

That is good advice outside of off season in high latitudes. Solar won’t cut it in those conditions. Wind will also struggle in the Baltic due to the Siberian highs that settle over the region bringing very cold and still air during the typical winter that can last for long periods. Similarly with the hydro generator, you can’t sail during those highs either.

Energy efficiency is part of the solution, I would argue off engine charging, preferably parasitic, is the other part of that solution but if you really can’t stand burning fossil fuel for power then the only viable options I can think of are really big batteries with shore power hook ups every few days or a fuel cell.

[bergius]

Originally Posted by Na Mara

but if you really can’t stand burning fossil fuel for power then the only viable options I can think of are really big batteries with shore power hook ups every few days or a fuel cell.

Yep, that’s the strategy we’re following now. Almost impossible to get enough out of renewables November-January.

Outside of the dark months, we generally get enough solar at anchor thanks to the deployable panels. Then the problem is more the runtime when we’re under way. That’s why I was looking at wind or hydro.

I’m adding some fixed solar based on this conversation. Here’s a quick estimate of what we could be seeing then (average Wh generated per day each month):



These numbers are based on NASA figures for average insolation in Berlin. They’d actually be a bit better in the summer for Sweden and Finland thanks to the longer daylight hours. 30 means we have enough to go that month completely without non-renewable charging (engine, shore power).

I didn’t include heating power consumption to that, so in reality the runtimes for the cold months are about half of what is shown - at least until we get one of those drip pot heaters.

[valhalla360]

Originally Posted by Na Mara

That is good advice outside of off season in high latitudes. Solar won’t cut it in those conditions. Wind will also struggle in the Baltic due to the Siberian highs that settle over the region bringing very cold and still air during the typical winter that can last for long periods. Similarly with the hydro generator, you can’t sail during those highs either.

Energy efficiency is part of the solution, I would argue off engine charging, preferably parasitic, is the other part of that solution but if you really can’t stand burning fossil fuel for power then the only viable options I can think of are really big batteries with shore power hook ups every few days or a fuel cell.

Off season, none of the options are particularly good. Best to keep the charging system simple and plan to either plug in at a dock or run the engine.

So off season doesn't really change the recommendation.

[bergius]

Originally Posted by valhalla360

Off season, none of the options are particularly good. Best to keep the charging system simple and plan to either plug in at a dock or run the engine.

So off season doesn't really change the recommendation.

Totally. The only question is how much can we push the edges of what's "in season". Most sailors in Sweden and Finland seem to sail only between (mid) June and (mid) August. That's when solar generates tons.

But since we sail (and stay some nights at anchor) around the year, the more months we can get by with renewables, the better.

[Pizzazz]

I am not sure if I keep repeating my view that it will make it more valid but renewables really will not help you extend your cruising season. Your aversion to using the engine to charge hinges on the misconception that you can only draw 50% of the alternator rated current which I have never heard before and there is no physical reason for it.

On my Hunter 31 in California, I replaced the 35A with an 80A alternator first (it was supplying around 60-65A), then with a 120A alternator (giving me around 80-85A). This is without any external regulators. These alternators cost $100 on Amazon and mine lasted for years. Not that difficult to replace if it fails.

Use the 5kW Chinese diesel heater to warm up the cabin (I had one and I was super pleased with it... it draws outside air, makes the boat cosy and dry), run the engine to heat water and charge the batteries. You need to make hot water to take showers, etc. anyway you look at it. You can't have hot water on solar or wind power. Since you have the BMS, get rid of the DC-DC converter and run the alternator direct. If it warms up after 30-40 minutes and the current drops, shut it down, run it again in the afternoon. After one season, feel free to invest in solar.

I can imagine your frustration coming to an anchor in the evening, your battery is down to 30%, you consume many amps for lighting, fridge, TV, may be a gaming console (500W) and then having to run the engine through that 30A DC-DC giving you 300-400W. But it does not have to be that way.

[Drunkonwatch]

Cool thread I have been thinking of passive power from a regenerative saber tooth style motor controller on a electric outboard. Similar to braking systems on modern cars. Anyone ever ponder something similar? It might not be much power but it’s on board.

[Na Mara]

I think there is an electric outboard company that already does motors with regen. I forget the name.

I agree that the best way to do electric power off season is a good alternator charging good batteries. The OP already has a really good battery setup, it’s a shame not to make the most of it with a good alternator.