Solar vs wind vs hydro

[sailorboy1]

If you already have solar the best bang for the buck after is having a Honda generator. I could use mine with my battery charger and make the OPs 100ah/day in 80 minutes using 1/4 gal of gas

[Na Mara]

The camping shower is indeed very basic, but then that is a bit of the fun when its sunny and warm and you are just getting salt off yourself.

How big is your hot water tank Noelex? I don't know how one could vary the amount of water heated in my system. I have a 40l tank so when I heat water I heat 40l whether I need all that or not (usually do as we are typically 4 aboard). It's a good idea though to have a thermostat on the tank to be able to adjust the temp of the water on the tank. Mine doesn't have one of those but that would certainly make the whole thing more efficient.

[noelex 77]

Originally Posted by Na Mara

How big is your hot water tank Noelex? I don't know how one could vary the amount of water heated in my system. I have a 40l tank so when I heat water I heat 40l whether I need all that or not (usually do as we are typically 4 aboard). It's a good idea though to have a thermostat on the tank to be able to adjust the temp of the water on the tank. Mine doesn't have one of those but that would certainly make the whole thing more efficient.

Unlike a calorifier where the whole quantity of water must be heated, we use a simple and more conventional (although insulated) water tank. We can add as much or as little water as required for the shower or showers. The idea is to only add and therefore heat up the water that you are actually going to use. The tank is empty at the finish of the shower or showers. There is no new cold water entering the tank and reducing the temperature of the shower water while showering as there is with a conventional calorifier.

Traditionally even yachts at anchor ran their engine every day or so to charge the batteries, but with the ready availability of solar panels and other forms of alternative energy this is no longer the case for most cruisers. Conventional calorifiers work well if you are using the engine frequently, but are poor if you are sitting at anchor for days at a time.

[Na Mara]

Huh. I hadn’t realized how inefficient my calorifier is until just now. I just learnt something very useful noelex. Thanks for that. How do you pump the hot water if you are emptying the tank when you use it? How do you do the heat exchange with the engine or don’t you? This is a totally new one on me, but switching to something like your system must be more or less mandatory when you go electric propulsion. Are there any standard marine solutions for this or did you cobble it together from domestic parts?

[Adelie]

Originally Posted by Na Mara

The camping shower is indeed very basic, but then that is a bit of the fun when its sunny and warm and you are just getting salt off yourself.

How big is your hot water tank Noelex? I don't know how one could vary the amount of water heated in my system. I have a 40l tank so when I heat water I heat 40l whether I need all that or not (usually do as we are typically 4 aboard). It's a good idea though to have a thermostat on the tank to be able to adjust the temp of the water on the tank. Mine doesn't have one of those but that would certainly make the whole thing more efficient.

Have you considered small on demand water heaters?

https://www.eemax.com/products/eemax-flowco/spex1812
https://www.chronomite.com/instant-f...AaAjNlEALw_wcB

[Pizzazz]

I still do not follow. First, you buy more solar than needed, then use the solar to heat a pre-measured tank of water (either directly or through supposedly efficient lithium battery inverter thingy), then you have to take the shower exactly at the right moment, otherwise the water gets cold, then in order to get the next shower you need to wait for the sun to recharge the battery. Have you guys really cruised? So what happens when you run out of water? You need to run a water maker, no?

There are many people who use their boats as day boats and dream of cruising while actually doing marina hopping. Others, like an old friend of mine would warm water in a kettle and use a spray bottle to wash himself with under two gallons of water. Yet, if we are talking about long-term cruising, not camping, in the northern sea, I believe the minimum should be:

- coffee machine
- ample fridge
- water heater
- cabin heater
- water maker

It is physically impossible (not to mention unappealing) to install renewables for this power requirement. So, you guys are telling me that you would stay at anchor for 2-3 weeks, without moving the boat, without going to shore, without making water and without running the engine? or you will be sailing for 3-4 days on end and would severely object to motor sail for 2-3 hours to replenish the batteries?

I think once you get to 35-40 ft or any size catamaran then you have plenty of space for sizeable solar. Bigger than that and you move to generator territory.

[noelex 77]

Originally Posted by Na Mara

How do you pump the hot water if you are emptying the tank when you use it?

The water is pumped out of the hot water tank with a short length of hose to a conventional marine water pump that is then connected to a push button shower rose. We only mix enough hot water for our required shower. This is not a fixed amount, as the desired length of shower is not always the same. For example after a sweaty trip ashore we will mix more hot water for a longer shower.

Originally Posted by Na Mara

How do you do the heat exchange with the engine or don’t you?

This could be added, but we have not bothered. We do not do many engine hours and avoiding this complication keeps the engine cooling system simple.

If we do want to produce hot water from the engine (and this is rare) we do this electrically. Our large frame alternator supplies more power than our electic kettle consumes. With less than a 10 minute engine run time we have plenty of shower water for two people with no drain on the batteries.

Originally Posted by Na Mara

Are there any standard marine solutions for this or did you cobble it together from domestic parts?

It only requires standard boat parts. An on demand water pump, shower rose and water tank. It is better to add insulation to the tank, but even this is optional if you mix the water just before showering, as we do.

In use, add boiling water from a kettle heated by electricity, propane or diesel (around 1.5L per person is an OK shower) and then add cold water from your tank. The cold water enters the tank from the boats normal pressurised supply so this only means turning a tap. When the water is mixed to the perfect shower temperature the system is ready to use.

[Na Mara]

Originally Posted by Pizzazz

- coffee machine
- ample fridge
- water heater
- cabin heater
- water maker
.

Coffee maker - nice to have but not essential. We have two hot drinks a day from an electric kettle, to a cafetière, to Stanley thermos mugs. The kettle uses about 0,2kWh over the entire day.

Ample fridge- agreed but a well insulated top loading fridge uses about 0.5kWh on an average day.

Water heater - not essential. A kettle for dishwashing and hot water from the engine every third day or so for hot showers is sufficient. Cold showers on hot sunny days after a swim are a great substitute.

Cabin heater - agreed. At full tilt a forced air system uses a kWh a day.

Water maker - absolutely non-essential and actually quite a lot of trouble if you aren’t living aboard constantly. We carry 540l of fresh water in our tanks and maybe another 150l in bottles. Even with six aboard not watching water consumption the water lasts 2 weeks without cracking bottles. With our normal 2-3 on board and moderate rationing, the water we carry lasts months. The decks are also perfect for rain water collection, though we have never needed to do that as we have filled up with water at least every time we stock up on food.

Some would go even further than this and only run the fridge when motoring and use lpg for the kettle. Anyway, I comfortably cruise on 2kWh a day or less in consumption and that requires only 500W of solar to service. I am fitting 640W. That extra 0.5 kWh a day I might well use to heat water every third day or so for hot showers during the summer. Or if it’s cold and overcast during the edges of the season I might crank up the engine and shower for free. Either way, it is entirely possible to cruise comfortably on renewables alone even on a monohull during the summer. Winter in high latitudes is a different proposition.

[noelex 77]

I gather Pizzazz that you are not of fan of our shower or solar systems in general . As always it your boat, so it is your choice. To answer some of your specific concerns:

Originally Posted by Pizzazz

then you have to take the shower exactly at the right moment, otherwise the water gets cold, then in order to get the next shower you need to wait for the sun to recharge the battery.

We mix the water just before we take a shower. It only takes a few minutes to heat the water and mix in the cold. There is no need to wait for the sun. The power consumed is small and easily handled by the battery bank.

Originally Posted by Pizzazz

I believe the minimum should be:
- coffee machine
- ample fridge
- water heater
- cabin heater
- water maker

It is physically impossible (not to mention unappealing) to install renewables for this power requirement.

We have all the things on your list plus a few more such as a washing machine and freezer and it all runs from solar power (apart from the heater, which is diesel).

[fxykty]

Originally Posted by noelex 77

I gather Pizzazz that you are not of fan of our shower or solar systems in general . As always it your boat, so it is your choice. To answer some of your specific concerns:







We mix the water just before we take a shower. It only takes a few minutes to heat the water and mix in the cold. There is no need to wait for the sun. The power consumed is small and easily handled by the battery bank.







We have all the things on your list plus a few more such as a washing machine and freezer and it all runs from solar power (apart from the heater, which is diesel).

I’m intrigued by your showering solution. We have a standard 40L Isotherm water heater with 750W heating element and it takes about 90 minutes to raise the water from 20* C (ambient) to 55* C. Usually much less time as we keep it on all the time unless we have to conserve power due to power solar conditions and little motoring. We use hot water not just for showering but also washing dishes, baking, filling our still, and the washing machine.

But your solution means we stop heating the 40L tank, which certainly saves power for poor solar days.Instead, you have a smaller 20L (?) tank near your indoor shower that you fill from a kettle (hot) as well as from your boat’s pressurised water (cold) for the temperature you want. So then is that tank pressurised, or do you use gravity to feed your shower rose? Or do you have a small water pump between that tank and the shower rose?

Not so convenient, but certainly works. We also have an exterior shower, so would need to duplicate the system there I suppose?

[Na Mara]

I have been wondering about using a small dedicated diesel heater for the water. It should only take about 0.2l a day of diesel to keep the tank toastie all the time when not connected to shore power or running the engine. If I’m using diesel for air heating anyway why not also for water? Burning fuels for heat is efficient and fuel quality isn’t an issue. When I repower to electric I could just have a small dedicated diesel tank for heating fuel and have the diesel heaters run off that. I could even cart biodiesel to the boat if I’m worried about the environment. 20l would be 200days of hot water, or maybe 10 days of space heating when it’s really cold.

Otherwise I would need over a 1kWh of solar to do what fxykty is talking about and whilst I can see how to do that while stationary in summer on my boat, it ain’t going to work otherwise.

[bergius]

Originally Posted by Na Mara

I have been wondering about using a small dedicated diesel heater for the water. It should only take about 0.2l a day of diesel to keep the tank toastie all the time when not connected to shore power or running the engine. If I’m using diesel for air heating anyway why not also for water?

I’ve been looking at this hot water system from Bobil. Seems like something that would work for us:

• Only 10l hot water tank so you’re not “paying” to heat more water than you’re able to use
• Heat exchanger to take energy from a forced air heater duct
• Can be heated from shore power when available
• Can be heated from 12V DC with settable voltage thresholds so it only happens on full batteries

However, for the moment the solution of heating water on the stove as needed works ok. Hot tap water would be a luxury.

[bergius]

Originally Posted by Na Mara

Water maker - absolutely non-essential and actually quite a lot of trouble if you aren’t living aboard constantly. We carry 540l of fresh water in our tanks and maybe another 150l in bottles. Even with six aboard not watching water consumption the water lasts 2 weeks without cracking bottles.

Agreed that this is not essential. But we’re still going to pick up a second hand PowerSurvivor 40E this weekend. Our boat is quite a bit smaller, so our water tanks carry only 200l.

Last summer was so dry that at least in Finland you couldn’t get water from any of the islands. It was a bummer to have to go to a mainland marina to fill the tanks every week or two.

This small capacity watermaker should handle our consumption pretty ok, at about 100Wh per day.

[hpeer]

When we want a hot shower we heat a kettle on the stove and mix in a 5 gallon bucket. Then we have a little 12vdc bilge pump connected to a shower head and a switch. Shower in cockpit.

Crude and simple but effective, efficient, cheap, almost zero maintenance. BUT we are in Caribbean.

We have a wet shower inside 1 head, no hot water. We just don’t use it. No desire to add hot water, yet.

We will take a shower shoreside when available. But not all of them have hot water either. So sometimes the bucket in the cockpit is more luxurious of the 2.

Surely not for everyone, but goes to show the range of possibilities. A lot of it is just where your head is at.

[noelex 77]

Originally Posted by fxykty

But your solution means we stop heating the 40L tank, which certainly saves power for poor solar days.Instead, you have a smaller 20L (?) tank near your indoor shower that you fill from a kettle (hot) as well as from your boat’s pressurised water (cold) for the temperature you want.

Yes, that is precisely the system. I have never measured the tank volume ( about 40L ?), but the tank is not normally filled. We just mix the required amount of water depending on the number of people wanting a shower at that time (We rarely have more than two people on board) and if we want a long or short shower. We use a digital thermometer to make sure the shower water is mixed to exactly the right temperature.

Originally Posted by fxykty

So then is that tank pressurised, or do you use gravity to feed your shower rose? Or do you have a small water pump between that tank and the shower rose?

We use a standard Jabsco on demand water pump to feed the warm tank water to a shower rose. The shower works normally. Push the button on the shower rose and warm water flows under pressure. There is a tap to adjust the desired flow rate, but there is no need to adjust any hot or cold tap settings, as the water has already been mixed to our preferred shower temperature. This temperature does not change as you are showering because no cold water is added to the tank while the shower is in use. This makes the shower very pleasant to use (no fiddling with taps to dial in the right temperature) and safer (no risk of scalding water from the shower rose).


The tank and the pump are all built into the shower cubicle so the hose run is kept very short, minimising heat loss in the piping while presenting a standard appearance.