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Old 02-18-2019, 12:18 PM   #1
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Question Good small liveaboard candidates for conversion to solar/electric

I'm looking for suggestions for models that would be good candidates to convert to a solar/electric drive. Advances in battery and solar panel tech mean we are right about at the point where it could be viable.

What I would consider ideal would be a highly efficient hull design, a flat roof with large surface area for solar (extending hardtop over cockpit if needed), and enough room to live aboard frugally. I live aboard a 26' pocket trawler right now, so my expectations are sufficiently set!

Here's what I know of:

Great Harbor TT35
Polarizing design, which I actually love, and they have already started talking with Torqeedo about a solar/electric version. But they are working on hull #8 right now, and I haven't seen reports of ANY owners who are happy with the purchase experience.

33 Eco-Trawler
Definitely on the small side for attempting to live aboard. I haven't talked to them maybe they can easily enough make an extended cabin version? Not sure.

Solar Sal
This is essentially a solar/electric enthusiast who is having Devlin build a boat for them to put Torqeedo on. I've seen their boat personally at the boat show, so I presume they can deliver. They show a liveaboard version, but I may as well just talk directly to Devlin if I want to go this route.

Rosborough
The models available new right now are too small to live aboard, but they have made some larger models in the past that look right.

Beyond that, there are some specific individual boats that look possible, but most any I have found are ballasted full-displacement trawlers as opposed to the fast or eco trawlers above.

Sundowner Tug 30 Sedan

Maple Bay 27

Etc.

So, are there other good candidates I am missing? New or used? Thank you!!
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Old 02-18-2019, 02:54 PM   #2
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It would seem to me that a catamaran might be a good choice. Lots of area for solar panels.

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Old 02-18-2019, 03:29 PM   #3
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Prairie 29 would be an ideal candidate. Lots of live aboard room in a small length.
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Old 02-18-2019, 04:01 PM   #4
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How do you plan to use the boat.? There have been a number of sailboats where the owners have replaced the diesel engine with electric. In these instances, however, the electric engines are used for only short periods of time.

What is your budget for such a project? Are you looking at a new boat without a motor(s), or an older boat where you would take out the existing motor(s)?

Would you keep that boat in a slip, with electric? Or on the hook? This would, of course, impact on the amount of power you would have to generate.

I'm guessing that not only are you looking at surfaces for solar panels, but you also need to have an area for an adequate bank of batteries. A lot of sailboat also supplant their solar panels with wind generators, so that might be a possibility as well.

Ted's suggestion of a cat is a good one.

Good luck in your endeavor. I hope you keep us posted on this project.

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Old 02-18-2019, 04:14 PM   #5
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Agree on a cat. More room for solar panels and easily driven.

I remember reading about this guy. Not sure they made it around the loop. There have been others.

https://www.passagemaker.com/.amp/ch...red-canal-boat
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Old 02-18-2019, 04:28 PM   #6
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Update: As some of you likely know, the manufacturer made 2 of the 33 Eco-Trawler model and is no longer in production. So there is no possibility of an extended cabin version. Retrofitting wouldn't make sense. That one's out.
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Old 02-18-2019, 05:02 PM   #7
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Quote:
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How do you plan to use the boat.? There have been a number of sailboats ...
Jim
I live in Seattle on she ship canal inside the locks and would likely just cruise around the lakes and short jaunts into the Sound. I still work full time so I won't have weeks to dedicate to an extended trip. So I think an efficient hull plus modern batteries should give me a usable range.

I live at a marina now, and will continue to. There are very few people left living completely on the hook near Seattle. It's a completely vanishing lifestyle here as far as I'm aware.

Unless I'm missing something , catamarans and trimarans either require a double slip at a marina, or if they are small enough, then the interior is unusably small.
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Old 02-18-2019, 05:09 PM   #8
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Quote:
Originally Posted by JeremyZ View Post
I live in Seattle on she ship canal inside the locks and would likely just cruise around the lakes and short jaunts into the Sound. I still work full time so I won't have weeks to dedicate to an extended trip. So I think an efficient hull plus modern batteries should give me a usable range.

I live at a marina now, and will continue to. There are very few people left living completely on the hook near Seattle. It's a completely vanishing lifestyle here as far as I'm aware.

Unless I'm missing something , catamarans and trimarans either require a double slip at a marina, or if they are small enough, then the interior is unusably small.
See a lot of cats side tied on floating docks or T heads of docks.

Ted
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Old 02-18-2019, 07:18 PM   #9
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Are you going bigger? The reason I ask is your existing boat should be a reasonable conversion as it is a near total full displacement hull and should not need much power to drive it. Many, not that there are many, of them had the full cockpit cover which would add solar space.
Maybe a 30 Willard similar to Erics boat.
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Old 02-18-2019, 08:47 PM   #10
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If you could find a Camano without a fly bridge that might be a good candidate.
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Old 02-18-2019, 11:24 PM   #11
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I don’t want to rain on anyone’s parade, I just don’t think the technology is there yet. I have watched the UMA kids do the electric motor and batteries. They have been through 2 motors and 3 sets of batteries and 2 solar controllers. They are now using lithium batteries. Then every time they need to go 5 miles they strap the dingy to the side of the boat and motor using a 5hp dingy motor. I think they would have been money ahead to just rig a 10hp out board from the beginning. I get their situation, they sail 99% of the time and motor in and out of port only.

If you are trying to make some sort of technology statement more power to you. I wouldn’t spent much time on hull efficiency. I would spent my time on power efficiency. If you think there is some sort of financial advantage going solar, you are about to learn an expensive financial lesson.

Not saying you can’t do what you are trying. Just make sure you are doing it for the right reason.
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Old 02-19-2019, 01:40 AM   #12
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If you’re still working full time and you just have a need to puts around short distances, why not consider a house boat. A house boat has a lot of flat areas to mount solar collectors. A house boat is certainly more livable than a smaller monohull. Also, it would be a cheap way to experiment with propulsion systems that could be switched to a more tradition sea-going hull design in the future. Just my 2 cents.
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Old 02-19-2019, 05:38 AM   #13
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"Agree on a cat. More room for solar panels and easily driven."

Multihulls are more easily driven at speed.

Battery boats can not contemplate speed , so the extra wetted surface compared to a monohull of the same weight is a detriment.
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Old 02-19-2019, 06:45 AM   #14
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Quote:
Originally Posted by JeremyZ View Post
I'm looking for suggestions for models that would be good candidates to convert to a solar/electric drive. Advances in battery and solar panel tech mean we are right about at the point where it could be viable.

Can't contribute much, but three things you might review for additional ideas are:

1) Elco makes electric boats. (Might be another maker, too, but a name doesn't come to mind.) I think many of these are picnic boats or local harbor tour boats, but there may be something in their info that helps your thoughts.

2) A TF member had an older classic (Elco, I think) show-quality boat that had been built with diesel (I think) propulsion. She was converting it to electric, with help from (Elco, I think) and a local yard doing the actual work. I think her screen name was Star. You might rummage around for some of her posts, see if you can learn anything useful from that.

3) There are many threads on electric propulsion on cruisersforum.com; most of those are about sailboats, and the most common use case is just getting in and out of the slip, with maybe a little left over for weather issues. Still, there's maybe some useful discussion there about voltages, battery chemistry, charging systems, etc.

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Old 02-19-2019, 09:08 AM   #15
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Old (original) 34 Mainship model I with the extended flybridge deck.
Can be had very cheaply, esp with the original diesel which is most likely ready to be replaced anyway.
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Old 02-19-2019, 10:12 AM   #16
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I'd suggest coming up with some use scenarios, then running the numbers on what you will need for batteries, solar panels and/or dock power to recharge, and see how it will all work before you go too far.


Reality is that there has been very little change is solar panels over the years, other than a big drop in price about 10 years ago to sub $1/watt.


Battery technology has improved, but generally not in ways that will help you. Power density hasn't changed much since Lithium Ion batteries started being used in consumer electronics around 20 years ago. Costs have come down, and management technology has improved to make them viable in cars, which is probably what makes you think there have been big improvements.


For your application, cost per usable kwh is probably all that matters, and in that respect the cost has about doubled from AGMs to LFP, and about quadrupled from FLA to LFP. I wouldn't say that's an improvement.


Here's an example to consider. Your use goals are modest, which is good and makes it at least plausible that what you want to do could work.


Let's assume you are happy pushing your live-aboard boat with a 3hp motor. It's just a guess, but it will probably go 2-4 kts. Then let's say you are happy with a max cruise time of 4 hrs. That's a total range of 8 to 16 nm. That will take you from the lock to Lake Union, a lap around the lake, then back to the lock. Or from the lock out into Lake Washington for a peek, then back again.


3 hp for 4 hrs is 9kwh. LFP batteries cost at best $1 per wh, and more likely $1.5 to $2 by the time you are done. So that's $9,000 to $18,000 for LFP, or about $4500 for AGMs. Probably more for AGMs since you will be draining them at a 4hr rate rather than their nominal 20hr rate.


Now let's look at recharge. With a 30A shore connection you have a max of 3.6kw available. Let's say you can allocate 3kw to charging. That will recharge LFP batteries in about 3 hrs. Recharging AGMs (or FLA) will take about 5-6hrs.


With solar, you get about 5hrs of full power equivalence per day, assuming it's a sunny day. And let's say you can fit 1200 Watts of solar on your top, which by the way would be a huge accomplishment. I fit 700W on a 60' boat, and will get about 1400W on a 68' boat. That will take 1.5 days to recharge LFP, and probably 2-3 days to recharge AGMs.


But the solar charging assumes no house loads. If you are also plugged into shore, then the solar power is all supplementary. But if you are anchored out, you have house loads to cover. If you have an average house load of 200W, that's 4800wh per day, and only leaves 1200wh per day to replenish the propulsion power you drew out. Now it will take 7.5 days to recharge. When was the last time you had 7.5 days of full sun where you are?


People love the idea of a solar boat and really, really want it to work, so they believe, as humans are so capable of doing. But even with your use case which is about as well matched for electric propulsion as you could get, it's borderline at best. And worst case you could find your self with a boat that doesn't meet your needs, and is completely unmarketable.


Now I probably sound like a solar hater, but I'm quite the opposite. I have an off grid house that is all solar except for about 100hrs per year of generator time from Nov through Jan when the sun hides a lot. But the house doesn't have propulsion which is an order of magnitude more load.


My last boat had solar, and the one I'm building now will have it too. But on the boats it's really just a supplement to offset house loads, and indirectly reduce generator run time. There is a very slight chance on the 68 that I'll be power neutral while at anchor, assuming no laundry or other heavy loads. But that's optimistic.
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Old 02-19-2019, 11:02 AM   #17
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That was a great technical analysis of the case for solar on an electric powered boat. I am the one who usually posts the physics/math stuff and I know it is rarely understood. I can't think of a single quibble with your example.


Unless batteries get much better and/or solar panels get much more efficient I don't think it makes sense to try to power a boat with electricity from solar panels.


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Old 02-19-2019, 06:08 PM   #18
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All right. Twistedtree (and others in this thread) have the right idea. It is very possible to make a slim little lightweight launch with a full length solar hardtop shade and run it on a reasonably priced battery/solar setup. But if I were to add enough beam and windage to be livable, and weight and power draw of everything needed for even a minimal liveaboard setup, I'm already way past the limits of current technology.

Sorry, all. I know you have to deal with enthusiastic but naive threads like this all the time. Hopefully the technology catches up soon enough and we can start making this happen.
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Old 02-19-2019, 06:55 PM   #19
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Perhaps a motor sailer like this:

https://www.yachtworld.com/boats/197...dard%20listing

Fisher makes a 30, a 34 and a 37 motor sailer.
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Old 02-19-2019, 10:03 PM   #20
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On a smaller boat, you're going to have to have solar panels plastered all over like on this RV

https://www.greenmatters.com/news/20...HQvPu/solar-rv


You also have to allow for your environment. Your solar charge rate in Seattle is going to be a lot less than say LA.

A 3-hp motor might be nice on a calm day, but it might not be sufficient if there is any sort of breeze, current, or tide.
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