Hydrogenerators

[Poey50]

It's far from a plug-and-play option, but for the sake of completeness when considering options, another method of generating power is to make better use of engine and fuel. A combination of LiFePO4 batteries, a high output alternator like a Balmar 6 series and external regulator can put 100ah back into a house battery in one hour.

 

[laika]

Weed can be an issue but I not only mounted it low, its also the long leg version so the prop is at least a couple of feet below the surface and sargassum.

I did wonder about long vs short leg: Is there any downside with the long version, e.g. significantly more difficult retrieval?

 

[lw395]

So, what happens if you plan your voyage around making 8A from your water turbine, but then you find you've got a freezer full of food and light winds after a couple of days? To support 8A, 24/7, you may need a lot of motoring hours? Do you carry enough fuel to live with that, or only set off when you have perfect weather windows? If you're carrying the fuel anyway, does the hydro justify its price?

 

[Koeketiene]

It's far from a plug-and-play option, but for the sake of completeness when considering options, another method of generating power is to make better use of engine and fuel. A combination of LiFePO4 batteries, a high output alternator like a Balmar 6 series and external regulator can put 100ah back into a house battery in one hour.

I do/did consider Lithium batteries. See: Lithium batteries - are they worth it?

I have also chatted to people who have them fitted and to boatyards who have fitted such a system.
The feedback I have gotten so far suggests that when it works it's great, but that the system can be delicate (and require reprogrammming) and it too is not entirely a trouble free plug-and-play option.

 

[Koeketiene]

So, what happens if you plan your voyage around making 8A from your water turbine, but then you find you've got a freezer full of food and light winds after a couple of days? To support 8A, 24/7, you may need a lot of motoring hours? Do you carry enough fuel to live with that, or only set off when you have perfect weather windows? If you're carrying the fuel anyway, does the hydro justify its price?

- Don't have a freezer - don't plan on getting one.
- Fuel tank is 100 ltr - room on deck to stow 4 x 20 ltr jerrycans of diesel.
- If I find myself becalmed or at anchor, I would deploy the removable solars (as mentioned in my OP). And when becalmed or at anchor, I would not need the AP thereby significantly reducing my power requirements.

If I were to try to equip the boat for every possible 'what if' scenario before I set off I would probably never leave my mooring.
And end up broke in the process.

 

[laika]

So, what happens if you plan your voyage around making 8A from your water turbine, but then you find you've got a freezer full of food and light winds after a couple of days? To support 8A, 24/7, you may need a lot of motoring hours? Do you carry enough fuel to live with that, or only set off when you have perfect weather windows? If you're carrying the fuel anyway, does the hydro justify its price?

Not being an owner but having thought about this because I'm a prospective owner...
The weather window isn't practical because you've got to plan for losing the thing altogether.
If I had a freezer I'd presumably not rely on it, ie it would contain the luxuries which could be dumped if necessary, falling back to dried/tinned food. In my actual case it would mean switching all the non-essentials off and hand steering whenever possible.
If you have a bunch of solar which is normally impractical to deploy at sea, presumably it may be more practical in light airs.

Your point about slow old boats and the return on investment with hydrogenerators is a very good one and one I have struggled with having a relatively slow, heavy monohull which really doesn't make best use of a hydrogenerator. However in my case it's more about convenience of the common case, independence and that eco-warrior smugness that comes with use of renewables.

I've been waiting for W&S to some out with a "new model" for years. They'll doubtless do it 3 months after I've ponied up the cash for the existing one.

 

[pcatterall]

Is the trailed Duogen a player or is this one already discussed under a different name.

 

[geem]

Not being an owner but having thought about this because I'm a prospective owner...
The weather window isn't practical because you've got to plan for losing the thing altogether.
If I had a freezer I'd presumably not rely on it, ie it would contain the luxuries which could be dumped if necessary, falling back to dried/tinned food. In my actual case it would mean switching all the non-essentials off and hand steering whenever possible.
If you have a bunch of solar which is normally impractical to deploy at sea, presumably it may be more practical in light airs.

Your point about slow old boats and the return on investment with hydrogenerators is a very good one and one I have struggled with having a relatively slow, heavy monohull which really doesn't make best use of a hydrogenerator. However in my case it's more about convenience of the common case, independence and that eco-warrior smugness that comes with use of renewables.

I've been waiting for W&S to some out with a "new model" for years. They'll doubtless do it 3 months after I've ponied up the cash for the existing one.

If you are long distance cruising there is no difference between slow old boats and modern lightweight cruisers. We are in Horta listening to every boat clearing in over the VHF. The skippers get asked lots of questions including last port, days at sea and LOA. We see no difference in passage times at all. Apart from a super high performance cat times have been 16- 24 days typically. We did 17 days from Antigua (although we started from Grenada it took two days to sail past antigua) so our 40 year old boat was up there with the quickest. A Vancouver 28 did 21 days. A Moody 34 did 20 days. Lots of modern cruisers doing longer passage times but generally its all much of a muchness?

 

[Dave100456]

I did wonder about long vs short leg: Is there any downside with the long version, e.g. significantly more difficult retrieval?

Choosing the long leg option ensures the prop is lower in the water and thus has more water force on it giving better electrical generation. Deploying the long leg is harder as its a longer lever to lower into the flow of water. I use a length of dyneema via a 8:1 pulley system (similar to a windsurfer's sail tack downhaul). Retrieving is easy as it comes up horizontal due to the flow of water and then its a case of lifting vertical to store.
I should add that I have a transom step which makes the process easier.
I made the bracket initially out of wood with squash balls incorporated as I'd heard the units make a vibrating noise which I was keen to reduce. However the wood bracket was not strong enough and I went to 10mm aluminium plate that slides into two grooves so I can lift it out completely and store onboard. Its an aluminium boat.

 

[Poey50]

I do/did consider Lithium batteries. See: Lithium batteries - are they worth it?

I have also chatted to people who have them fitted and to boatyards who have fitted such a system.
The feedback I have gotten so far suggests that when it works it's great, but that the system can be delicate (and require reprogrammming) and it too is not entirely a trouble free plug-and-play option.

It's definitely not plug and play. Systems can be made robust but not simply or cheaply. If it's delicate or unreliable it shouldn't be on the boat.

 

[GHA]

Is the trailed Duogen a player or is this one already discussed under a different name.

Long distance cruisers with duogens seem to be usually very happy with them.

 

[lw395]

If you are long distance cruising there is no difference between slow old boats and modern lightweight cruisers. We are in Horta listening to every boat clearing in over the VHF. The skippers get asked lots of questions including last port, days at sea and LOA. We see no difference in passage times at all. Apart from a super high performance cat times have been 16- 24 days typically. We did 17 days from Antigua (although we started from Grenada it took two days to sail past antigua) so our 40 year old boat was up there with the quickest. A Vancouver 28 did 21 days. A Moody 34 did 20 days. Lots of modern cruisers doing longer passage times but generally its all much of a muchness?

It's not the average speed on the average passage, it's the probability of going too slowly for the gen to work well enough to meet your needs.

what is the probability of hitting a few days of only making a couple of knots in an Atlantic circuit? Somebody did look properly at the numbers a few years ago and it looked expensive then in many cases. Solar is even cheaper now.
It might be different if you are racing and the engine is not an option.

 

[pcatterall]

It's definitely not plug and play. Systems can be made robust but not simply or cheaply. If it's delicate or unreliable it shouldn't be on the boat.

Delicate and unreliable ? that's me banned from the boat then!

 

[duncan99210]

The Duogen is a bit of a curates egg. It’s does two things (wind and water) but neither of them as well as a decimated bit of kit. I’ve helped change bearing on a couple of Duogens because transiting from water to wind allowed water to become trapped in the bearings, which then seized.
I have an Aquair 100 which has a towed impeller for water and a wind turbine to convert it to wind. It’s great using water, making about an amp per knot with the impeller on a 30m long rope. It’s less impressive as a wind turbine, taking about 40 minutes to convert from one to the other and get it hoisted up into the wind. I only bother with the conversion when we are stuck somewhere waiting for a blow to pass through with expected winds of over 15 knots for more than a few hours. However, that‘s not much help to the OP as the Aquair is no long being produced.

 

[geem]

The Duogen is a bit of a curates egg. It’s does two things (wind and water) but neither of them as well as a decimated bit of kit. I’ve helped change bearing on a couple of Duogens because transiting from water to wind allowed water to become trapped in the bearings, which then seized.
I have an Aquair 100 which has a towed impeller for water and a wind turbine to convert it to wind. It’s great using water, making about an amp per knot with the impeller on a 30m long rope. It’s less impressive as a wind turbine, taking about 40 minutes to convert from one to the other and get it hoisted up into the wind. I only bother with the conversion when we are stuck somewhere waiting for a blow to pass through with expected winds of over 15 knots for more than a few hours. However, that‘s not much help to the OP as the Aquair is no long being produced.

having owned a Duogen for 16 years and done four Atlantic crossings with it I can honestly say that its a pretty decent bit of kit. Ours is a mk1 and the later versions have noticeable improvements.
Changing from water to wind doesnt allow water to trap in the bearings. There is a weep hole at the base of the shaft that should allow water from the shaft to escape. If it doesnt then the double lipseal should keep water out. In 16 years I have changed bearings twice due to the lipseal wearing and allowing water in. You know when this has happened as it start to sound like a concrete mixer long before they seize.
In wind mode the performance is very good. Same blades as the D400 wind turbine and same alternator. Less output at low wind speeds due to extra friction of gears in air drive hub.
In water mode it runs our boat very well unless boat speed drops so low that we are inclined to start the engine.
It can be a pan in the bum with lots of weed about. We have a 4:1 rope block to lift it for weed clearing when under way as it can be really difficult to persuade it to leave the water.
Ours is now pretty worn out and we will make a decision when we get home whether to refurb it for the next trip or replace with a new model.
One advantage of it that I see is that at night the output of the Duogen in water mode keeps our batteries well topped up. We rarely drop below 25.4v (12.7v in 12v boats. Ours is 24v volt boat) and with good boat speed we are often above 26v all night so we dont need such a large battery bank to see us through the nighttime hours.
Sat here in Horta during a couple of days of wet and overcast weather, the Duogen in wind mode and our large solar array ensured that the batteries got to full charge by the end of the day. Cant complain

 

[Deleted member 36384]

The Duogen is a bit of a curates egg. It’s does two things (wind and water) but neither of them as well as a decimated bit of kit. ...........

Wow, that’s really, really bad if trashed kit works better ?

Seriously, interesting comment on the Aquair.

 

[geem]

It's not the average speed on the average passage, it's the probability of going too slowly for the gen to work well enough to meet your needs.

what is the probability of hitting a few days of only making a couple of knots in an Atlantic circuit? Somebody did look properly at the numbers a few years ago and it looked expensive then in many cases. Solar is even cheaper now.
It might be different if you are racing and the engine is not an option.

We turn the engine on of there is no wind. Even on an Atlantic crossing you would be unlucky to lose wind for more than a few days. We can engine for 8 days at 5kts with our fuel

 

[roaringgirl]

If you're thinking about long-distance cruising (you mentioned a potential Atlantic crossing) then you'd be better to consider how to reduce your consumption - we have 350W of solar and 540Ah of AGM battery. We discovered shortly after departing the Scilly Isles for A Coruña that our batteries were only holding a useable 50Ah of charge. We had to make a choice between switching off the fridge or the Raymarine autopilot. No problem, we stopped being lazy and deployed the Hydrovane. Hydrovane would come in a little cheaper than a Watt and Sea, AND you'll get a spare rudder too!

 

[GTom]

Hydrogenerators make sense on long passages (boat moving all the time) on fast boats. Looking at the output curves, you need a good 6kts log speed to reach a mere 100W! A racing trimaran or IMOCA 60 is where these things show their teeth. The 40' AWB cruising from bay to bay would only see meaningful output if you manage to anchor one in the Corryvreckan...

My bet is on solar, if you need more power, then more solar or a genset...

 

[lw395]

Hydrogenerators make sense on long passages (boat moving all the time) on fast boats. Looking at the output curves, you need a good 6kts log speed to reach a mere 100W! A racing trimaran or IMOCA 60 is where these things show their teeth. The 40' AWB cruising from bay to bay would only see meaningful output if you manage to anchor one in the Corryvreckan...

My bet is on solar, if you need more power, then more solar or a genset...

On a serious racing machine, one more £££ toy to buy is not a problem if you're properly funded.
And a hydrogenerator which puts out more power the faster you go is nicely matched to the demands of the autopilot, so there is less requirement for heavy batteries to store power for night time running.