Adding Solar and a Water Maker to My Hunter 290

[analogscott]

I'm getting ready to venture out a bit in my Hunter 290. In addition to getting all the bits fixed up and doing lots of sea trials to break things, I'm adding Solar Panels and Also A Water System and I'd love to get some input on the design and for anyone to poke holes in what I'm trying to do.

As boat owners you all probably know that finding reliable people to work on your boat is at best a challenge, and always expensive. For my Solar panel mounts with some Canvas I got a quote around $4k, for a Marine Grade Water Maker, around $4.2k for a 12 volt system that's also portable.

As with most things on boats it usually turns out to be a "Do it yourself job". As my Auto-Pilot turned out to be, but that's another story. (Best thing I put in Boaty).

I said to myself, "self, that's a lot of money". So I'm going to build a Solar System, the supporting stainless steel framework and power a Water Maker that I am also going to build. I figure I'd share with you all and would love your input, flames, etc. as I build it. I'd love to hear about others that have put Solar on the smallish Hunter 290 and anyone that has experience with Water Makers or any suggestions around that and hooking into 12 volt systems. I've also posted the designs up as well for input from anyone that's interested and I'm happy to take any suggestions. I used AI to help with the design and I posted the Solar Panel Design and the Water Maker Design up on my site and I'd love to hear what people thing about the design. One thing I'm a little sketchy about is that it's a little over a hundred pounds and the 290 is a 2.2 on the capsize index. I've designed so I can pull the whole thing off and stow the panels.

I've got a newsletter, videos and other stuff going at skipperscott.substack.com and I'd be happy to share and answer any questions you have about how things are going.

Cheers,
Scott

 

[Don S/V ILLusion]

Where are you going that you need a water maker? increased tankage is a lot easier to maintain than a RO water maker.

 

[Stu Jackson]

The trick with watermakers is to get one that is large. This reduces overall energy consumption.

 

[dlochner]

Watermakers are major power hogs and take up a lot of space. How large a battery bank are you planning? And how are you going to charge that bank?

 

[analogscott]

Where are you going that you need a water maker? increased tankage is a lot easier to maintain than a RO water maker.

Going to sail down the cost w/ the Baja Ha-Ha. Being that my capsize index is 2.2 though, I think I'm going to hang a left at Ensenada. I also want to have a source of fresh water. Here is So Cal. We have one source of water, the Colorado River and it's having issues. It's rather build it and not need it, than need it an not have it. I wrote an article about it: Portable Solar Powered Water Maker from Sea Water, would love to hear your thoughts.

 

[analogscott]

The trick with watermakers is to get one that is large. This reduces overall energy consumption.

This design should pull 16 amps total. Would love any suggestions you have to make it more efficient. I went w/ a smaller motor to save a couple amps too. I also want it to be portable and the 290 doesn't have a lot of room.

 

[analogscott]

Watermakers are major power hogs and take up a lot of space. How large a battery bank are you planning? And how are you going to charge that bank?

I'm with ya on that. I think I've got something I can make portable and put in one of my cockpit lockers on Starboard. I've got 2 12v deep cycle AGM batteries and going to add a 3rd. Plus I'm putting in 400 watts of solar in 2 pannels on 2 controllers (shade resistent). I'll be posting up all the part numbers, vendors, etc. as I build it out on Talking to the Machine | Analog Scott | Substack

 

[jssailem]

I've got 2 12v deep cycle AGM batteries and going to add a 3rd.

Your boat was designed as a lightweight boat. You might want to consider LiFePO4 batteries. They are a 50% reduction in weight for an 75% increase in power density.

 

[Stu Jackson]

Scott, all of this information is meaningless, at least as it is presented. What needs to be done, and you may have done it, is an energy budget.
Storage: 3 XYZ batteries, each battery ABC amp hours, total amp hours, total usable amp hours
Loads: watermaker: XYZ amps, anticipated running time per day, per week, total amp hours used
Charging: solar watts anticipated daily and weekly power input in amp hours; alternator

Without this, all you're doing is listing "stuff", big deal.

Good luck, nice plans.

I've got 2 12v deep cycle AGM batteries and going to add a 3rd. Plus I'm putting in 400 watts of solar in 2 pannels on 2 controllers

 

[Don S/V ILLusion]

Going to sail down the cost w/ the Baja Ha-Ha. Being that my capsize index is 2.2 though, I think I'm going to hang a left at Ensenada. I also want to have a source of fresh water. Here is So Cal. We have one source of water, the Colorado River and it's having issues. It's rather build it and not need it, than need it an not have it. I wrote an article about it: Portable Solar Powered Water Maker from Sea Water, would love to hear your thoughts.

You might want to get a handle on water quality through the area you intend to transit. It needs to be pristine in order to ensure you don’t spend more time doing RO maintenance than actually making water. Also, the hours consuming 15 amps can be considerable for sufficient operation time, not all of which a small solar array can maintain. And even if these issues aren’t showstoppers, you will still need to carry enough potable water in case the system doesnt meet the need.

We have a small RO system aboard but only as a last resort and have never had to rely on it even on extended cruises. While the “when all else fails” mentality is sound, it can be extended to the absurd on a small boat where storage space is limited.

 

[Stu Jackson]

This is from my earlier post you quoted in #6 about the size of the water maker. "The trick with watermakers is to get one that is large. This reduces overall energy consumption."

Your response makes no sense. While amperage, of course, is important, the FLOW rate is critical. What I meant was that small gallon per hour WMs running a longer period of time, actually use more power than a higher gallon per hour unit for a shorter time.

You can do the math, but most good water maker vendors cover this, not for marketing but for engineering.

This design should pull 16 amps total. Would love any suggestions you have to make it more efficient. I went w/ a smaller motor to save a couple amps too. I also want it to be portable and the 290 doesn't have a lot of room.

 

[CrispyCringle]

I see three problems: 1) A small boat and on any monohull the space limited for proper amount of solar. And by proper I mean actual off-grid independent. 3) It takes a lot of battery (and solar) to run a watermaker. Remember if a water maker HP pump pulls 10 amps A/C current thats about 1150 Watts. That means the battery running an inverter would be draining at about 88 Amps on the DC side. If you only have 2-300 Amp hrs of battery it wont last long. 3) water makers take up a lot of room. I doubt you have the space for a permanent installation.

You will definitely lose storage space to watermaker and batteries. Best option may be a portable water maker of the largest capacity you can make work and a Honda generator. But make sure its large enough to handle the start surge of the water maker pump.

In reality, I think your most practical option would be to definitely add solar, and if you dont have lithium batteries Id consider it. A way to passively recharge the batteries is always good. The charge profile of lithium is so much better than lead acid. And more capacity for the same size battery.

Get lots of jerry cans for water and figure out your water usage plan. Planned properly, you should be able to get water for that voyage. You need to be planning for at least 3 days between water stops, plus a reserve. You can get water in Turtle Bay. Im pretty sure you can get water in Santa Maria. And on the Ha-ha you can always mooch some from someone with a water maker.

 

[analogscott]

This is from my earlier post you quoted in #6 about the size of the water maker. "The trick with watermakers is to get one that is large. This reduces overall energy consumption."

Your response makes no sense. While amperage, of course, is important, the FLOW rate is critical. What I meant was that small gallon per hour WMs running a longer period of time, actually use more power than a higher gallon per hour unit for a shorter time.

You can do the math, but most good water maker vendors cover this, not for marketing but for engineering.

Appreciate your input on this. I was thinking large in physical size,I think you were thinking large in pump capacity. And you are right, there's a section (The power math is the real constraint). In the that it talks about amp hours in my details page on Fresh Water Aboard a Hunter 290 — Skipper Scott's, There's some math there, as my feed pump will be on demand, so it won't be on 100% of the time, which saved me a couple of amps. I'm also thinking about not wiring it through the house bank. Anyway you are 100% correct.

-- Here's that bit from the page. Do you think I should add more detail about the amp hours. At some point I also have to add in the Refrigerator, and I have a couple of Raspberry Pis plus monitors, then there's the instruments, radio,MFD's for navigation, autopilot, etc. I also want to add some additional 12v compute in there so I can have off the grid AI.
----------
The power math is the real constraint
Here's where the project actually gets decided, and it isn't money.
The high pressure pump pulls 15 amps. The feed pump is a demand pump, so it only runs a fraction of the time and averages well under one — call it 16 amps overall. Two hours of runtime gets you roughly 6 gallons and costs you about 32 amp-hours.
Now look at the other side of the ledger. A stock 290 house bank is likely a couple of Group 27s — call it 100 amp-hours you can actually use without abusing them. So one water session is a third of your usable bank, spent on six gallons.

What this means in practice
Run the watermaker while the Yanmar is charging — that 18-amp draw disappears into a 55-amp alternator without anyone noticing. Or run it in the middle of a sunny day once the solar is up. What you don't do is run it off the bank at anchor on a cloudy afternoon and then wonder why the fridge is struggling at midnight.
The corollary: resist the urge to size up. A bigger membrane means more amps you don't have. Three gallons an hour is correctly matched to this boat.
Which is a nice way of saying the watermaker isn't really a water project. It's a solar project with a plumbing attachment.

 

[analogscott]

I see three problems: 1) A small boat and on any monohull the space limited for proper amount of solar. And by proper I mean actual off-grid independent. 3) It takes a lot of battery (and solar) to run a watermaker. Remember if a water maker HP pump pulls 10 amps A/C current thats about 1150 Watts. That means the battery running an inverter would be draining at about 88 Amps on the DC side. If you only have 2-300 Amp hrs of battery it wont last long. 3) water makers take up a lot of room. I doubt you have the space for a permanent installation.

You will definitely lose storage space to watermaker and batteries. Best option may be a portable water maker of the largest capacity you can make work and a Honda generator. But make sure its large enough to handle the start surge of the water maker pump.

In reality, I think your most practical option would be to definitely add solar, and if you dont have lithium batteries Id consider it. A way to passively recharge the batteries is always good. The charge profile of lithium is so much better than lead acid. And more capacity for the same size battery.

Get lots of jerry cans for water and figure out your water usage plan. Planned properly, you should be able to get water for that voyage. You need to be planning for at least 3 days between water stops, plus a reserve. You can get water in Turtle Bay. Im pretty sure you can get water in Santa Maria. And on the Ha-ha you can always mooch some from someone with a water maker.

You are right on all 3 counts. That's why I am having paroxysms of geek joy engineering this. I'm avoiding the inverter for efficiency. And I'm using a 107ss pump motor and that with the feed pump will only draw 16amps. As pointed out by another poster, it's not really the point, it's amp hours, vs, the battery, etc. like you are also pointing out. And I understand about the Lithium but my house system is already lead acid, and mixing that with lithium and solar is more complexity. Some folks down at the end of the dock mixed the two and didn't do it right and set their boat on fire. Not saying it can't be done, if done right, it's just it's a small boat, room is precious, so I've got to leverage what I have. I'll add 3rd battery but the long story short is, I won't be running the water maker unless there is a) solar, b) generator or c) alternator power going, so it's more of a Solar project with Plumbing than a Water Maker

 

[CrispyCringle]

I dont know the particular water maker you are considering. If you are talking about an AC powered water maker, then the 16 Amp draw (thats what mine pulls as well) is not 32 Amp hrs from the battey. Watts= V x A. So when going from AC power draw to DC, the watts are true to both. Amps are not. So 16 amps at 115 volts is 1840 Watts. If your powering from the DC batteries you then have to take the Watts divided by the DC voltage to get the Amp draw on the DC side- Amps=W/V. Thats about 150 Amps. This does not include any inefficiencies with inverters, etc.

Also, dont plan on getting 100% output from your alternator. It would burn up at 100% for a few hours. Id use 50-75% for planning.

 

[analogscott]

You might want to get a handle on water quality through the area you intend to transit. It needs to be pristine in order to ensure you don’t spend more time doing RO maintenance than actually making water. Also, the hours consuming 15 amps can be considerable for sufficient operation time, not all of which a small solar array can maintain. And even if these issues aren’t showstoppers, you will still need to carry enough potable water in case the system doesnt meet the need.

We have a small RO system aboard but only as a last resort and have never had to rely on it even on extended cruises. While the “when all else fails” mentality is sound, it can be extended to the absurd on a small boat where storage space is limited.

I think you're right on all counts. I know I'm in some ways trying to shave the corners of a square peg to fit into a round hole. In time we'll get a bigger boat, but we're working with what we got . I'll also be putting in 2 pre-filters before it get's to the membrane, a 30 that can be cleaned, then a 5 with lots of spares. I've also got to run about 12.5% efficiency or membrane will scale up in days or weeks instead of lasting a year or more, so that will draw more amps as well. I'm in the process of building out the table that will include all the other equipment I have like refrigerator, computers, etc. It is a last resort kind of thing, and I could just go with the hand pump model, but OMG, I'm old and stuff. Also I'll have to revise the price to get stainless steel is like $5,200. My budget is < $2k. So I'm kinda stuck w/ Hand pump or DIY in a portable Crate that will go in one of my cockpit lockers. I'm basically building this Watermaker: DC 12V. 600 W. 17 GPH Single Membrane | SeaWater Pro, for about 32k less. It will only do a little over a gallon an hour, but I pull less amps and get the same design, with less output. I'll be updating the pages, and some of my thinking about all of this is at https://skippersoctt.substack.com, and totally appreciate the input, you're amazing.

 

[analogscott]

I dont know the particular water maker you are considering. If you are talking about an AC powered water maker, then the 16 Amp draw (thats what mine pulls as well) is not 32 Amp hrs from the battey. Watts= V x A. So when going from AC power draw to DC, the watts are true to both. Amps are not. So 16 amps at 115 volts is 1840 Watts. If your powering from the DC batteries you then have to take the Watts divided by the DC voltage to get the Amp draw on the DC side- Amps=W/V. Thats about 150 Amps. This does not include any inefficiencies with inverters, etc.

Also, dont plan on getting 100% output from your alternator. It would burn up at 100% for a few hours. Id use 50-75% for planning.

Nope, DC. I've got the specs at Fresh Water Aboard a Hunter 290 — Skipper Scott's (or what I've got together so far). I still need to work on the table that includes all the devices and their draw vs. batteries, etc. I'm trying to avoid any inverters to AC, if possible. If I need AC, I also have a Honda 2200i generator that has 2 15 amp AC that I can plug into boat shore power that will also power the charger for the 12v system.

 

[analogscott]

Your boat was designed as a lightweight boat. You might want to consider LiFePO4 batteries. They are a 50% reduction in weight for an 75% increase in power density.

I'm with you and I thought about that, but mixing Solar and the exiting Lead/Acid w/ Lithium added more complexity than I wanted to deal with ATM. I have have to eventually go there, but I'd like to avoid it. I was reading about an article about how if your Lithium bank catches fire, you've got like 30 seconds to GTFO. Some people down the dock mixed the two improperly and set their boat on fire. Gonna get an extra Lead Acid, then maybe upgrade later, or get a bigger boat

 

[analogscott]

Watermakers are major power hogs and take up a lot of space. How large a battery bank are you planning? And how are you going to charge that bank?

I'm having tons of fun, trying to squeeze out the smallest amount of power and space out of a DIY water maker. I've got 2, soon to be 3 lead acid deep cycle AGM batteries and I will charge them w/ 2 200w solar panels, my Yanmar 18hp alternator and my Honda 2200i generator.

 

[Don S/V ILLusion]

App

What this means in practice
Run the watermaker while the Yanmar is charging — that 18-amp draw disappears into a 55-amp alternator without anyone noticing. .

Keep in mind that a stock 55 amp alternator produces only a small fraction of that capacity at slow RPM. More like 10 -12 amps with no engine load. . And reving the engine to produce a faster charge rate is not good for your engine. This becomes a serious flaw in your plan among the others people have mentioned. But it sounds like you have already decided to go forward despite the consensus so good luck!