Using the TT35 as a solar-electric trawler

[rgano]

As Xsbank says, do yourself a favor and have a genset aboard, preferably an installed diesel, especially when you elect to "do the loop" or some other warm water boating. Oh, and that's the reason to retain the air conditioner for when anchored in warmish weax. Selling points. How about the loads for your navigation equipment, especially a radar? them figured into the plan?

 

[Scott Harris]

My plan was for two banks of traction batteries 60KWh apiece and a 30KWh bank for the house batteries. So 120KWh of traction and 30KWh of house. The house batteries would be connected to the solar panels but not the traction batteries.

In order to make this trip I need a range of 120 miles. Most legs are 60-70 miles with the longest leg being 97 miles. I need a 120 mile range for safety reasons. (An additional safety factor would be provided by transferring some of the energy from the house bank to the traction banks, or from sunlight if the clouds are cooperative.)

Mirage Manufacturing provided me with the performance estimates of 7 knots using 7000 watts. If this is accurate (and it is looking less likely the more I learn about boats and the more I learn from everyone's comments) I would have enough energy to make the trip.

I joined this forum to start learning the many things I do not know about boats. You have all been wonderful teachers and kind to share your knowledge with a "keyboard adventurer". I have learned many things, one of which is that this project will likely take more energy than originally calculated. But I still think it is doable and I am determined to do it.

The list of boats that I am now considering are:

1. TT35 (if I can get a trial and if 7 knots at 7kW is accurate)
2. Small FD trawlers like the Willard Nomad or C Dory
3. Small (less than 30') catamarans.

If you know of a boat that should be added to this list please let me know.

 

[OldDan1943]

A. figure out how many sq ft of solar panels you will need to charge the batteries at a rate greater than the motor/motors draw.
B. find a boat that can provide the required sq ft for the solar panel.
C. figure out the weight of the batteries
D. find a boat that safely carry that much weight
E. buy a small generator and promise to never never use it.

After you figure out the above, start hunting for boat to satisfy the above requirements.

 

[Scott Harris]

A. figure out how many sq ft of solar panels you will need to charge the batteries at a rate greater than the motor/motors draw.
B. find a boat that can provide the required sq ft for the solar panel.

This is good advice for places like Florida where the sun actually shines. In Alaska, along the inside passage, the solar insolation value is 2.0 during the sunny months.

So lets do the calculations.

Let's figure I need 9000 watts for 6 hours enabling me to cruise 36 miles each day. (notice that I am using 9000 watts for 6 knots, while still probably too optimistic it is much more realistic than the 7 knots on 7000 watts numbers I received from Mirage). So that is 54KWh of energy required just for propulsion each day.

54/2.0 = 27KW for the solar panels

27KW / 0.44KW per panel = 62 panels. (this is using the best Sunpower panels, figure 33% more for typical 350 watt panels)

62 Panels!. Yikes I'm going to need a bigger boat.

So you can't really travel the inside passage on solar alone. Especially since you could go several weeks without ever seeing the sun during the sunny months. The boat needs to get its energy from shore power and consider solar an added bonus.

 

[Nomad Willy]

Scott,
You can’t base your needs on the weather.
In some years SE Ak is sunny over 6 days a week. In 03 when we went to Juneau in our 25’ Albin it was in the 80’s in Ketchikan, Wrangell, Petersburg and Juneau. And on some years there’s less sun than that and almost constant rain.
But on average there’s better than half and half.
But your sunlight will definitely be limited.

But I thought you didn’t want anything to do w axillary power. That would change the direction of where you want go w the “go where no man has gone” objective (so to speak). A Honda generator would be better and w/o the solar panels. Axillary power in any event.

Re the most efficient boat you do need more consult. The SeaDory is not a FD boat. Not even SD. They are planing hulls and any bright spot in their efficiency would to be their light weight and narrow chine. And I don’t know what they weigh. And my Willard is only efficient at very slow speeds. Like 5.5 knots. A lower But I can’t imagine the dory carrying 1/2 the amount of batt you’re going to need. PC aft and a higher aspect ratio overall would/could double efficiency. But you’d be hard pressed to find a FD trawler w those features. I could design one and it could be built cheap (relatively) but most likely it wouldn’t be what you had in mind ...Aesthetically. A 26’ Allweather may work but it too may not carry 1/2 as much batt as the Willard.

A converted USN Motor Whaleboat (26’) would probably carry 1/2 (or less) the weight as a Willard but it may only need 1/4 as much power to drive making it twice as efficient. But I’m just wild guessing at the amounts.

 

[Scott Harris]

Eric,

You are right. I want to do it without aux power. Without liquid fuel. Without propane. That is the goal.

Scott

 

[Nomad Willy]

Got it.

 

[OldDan1943]

I am near Hollywood FL, east coast, I guess you could call it south FL.
I have 2X130 watt solar panels.
My point is, the panels have contributed nothing to the batteries for the last two days. Soooo if I were relying on the panels to charge my batteries, without a generator, I'd be stuck in the eye of a coming tropical storm.
For now and maybe the next 5 years, you really should include a generator.
Battery chemistry and solar panels have come a long way in the past 10 years but they still a ways to go before solar and batteries reliable, less expensive and reliable.

No one has addressed the needed electric motors.....

 

[Nomad Willy]

Dan,
I’m not interested in solar panels or how they work. But I would think they would charge on a cloudy day .. just charge less. When I was into photography I was told that not unusually there is more light on a cloudy day that a cloudless sunny day. Diffused light I was told. Light reflected off clouds. Light coming from every direction not just from where the sun was. I don’t know exactly what a light meter measures or what it is that a solar panel converts from light to electrical energy but I was skeptical about this and observed the light meter readings and clearly what I heard or read was true. But like I say I don’t know anything about solar panels but I suspect that on cloudy days a significant amount of electrical power will be generated.

So if one ran out of power 3/4 of the way to a planned destination one would just anchor until the batts were sufficiently charged ... and then continue on.

Sometimes plans need to change and different action taken to “carry on”. There are those that plan their whole day w a string of waypoints and deviation from the plan is unthinkable. I buddy cruised w such a person. We both had Albin 25 boats but I had 34hp and he only 27. He felt as some people feel about religion that 6 knots was the speed an Albin 25 should go and waypoints was how to proceed.
We got along fine. He went in straight lines to and from his waypoints and I traveled as a snake does. I went alongside shores and over closer to a boat to get a better look at her but seldom in a straight line. At the end of the day my buddy and I arrived at the same place and usually at the same time.

So w an electric boat perhaps part of a cruising plan time set aside for charging batteries because of unforeseen eventualities.

 

[REO]

Electric trawler

Thank you for starting this discussion. There is so much interesting information here that I find myself re-reading it, just for fun.
I have made the Seattle to Juneau trip in a sailboat, and currently own an Albin 27 trailerable trawler that I would like to convert to diesel/ electric. Here is my 2 cents worth.
If you want to maximize efficiency, you need a light -full displacement boat. Trawlers can be full displacement, but they are seldom light weight. Remember that a planing hull boat and to a lesser extent a semi displacement boat is designed to lift the boat up to skim the surface at high speed. Unless you run at a brisk walk, a lot of energy is wasted lifting the boat to get it on a plane. Sailboats are almost always light - full displacement hulls. A possible solution could be to find a sailboat that fits your needs, remove the mast and build a solar mounting rack above most of the boat.
The wind and current conditions in the inside passage are challenging. Sometimes you will need to run against the tidal current to get through multiple rapids. For some unexplainable reason, when we made the trip, it seemed like the wind was always on our nose. On the brighter side we had lots of sun.
Your goal of making the trip without using a diesel generator is not achieved if you stop at marinas to charge up. The electricity at the dock is coming from a generator. Why not carry your own generator and give yourself the ability to anchor where you please. We made the trip to Juneau and loved the beauty and quiet of secluded anchorages. Only problem there is that you will be making some noise by running a generator.
I believe that it is currently impossible to make the Alaska trip on solar power alone, unless you build an ultra light with no amenities and get very lucky with the weather..
I got some good information from the folks at elco marine to convert my boat. My goal was to be able to run on electric while charging my batteries with my 6.5 kw generator. With that capability we could anchor without running the generator all night. They said I could achieve that if I ran at 5 knots- in dead calm conditions. Because of the high torque of an electric motor that speed would use a small amount of power.
I gave up because my plans are to do the Alaska trip trailer across country and cruise the Bahamas, and I feel that the wind, current and rough weather conditions are too challenging for an all electric boat, even with generator backup. I hope you can prove me wrong. I am sure advancements in the technology will make it possible -maybe soon.

 

[OldDan1943]

At the time of my previous message, 9:40am, my BlueSky indicated no input from the solar panels. Now, 2.2amp input. I would take a long time to charge the 9000 worth of batteries, per Scott.

 

[OldDan1943]

Dan,
So if one ran out of power 3/4 of the way to a planned destination one would just anchor until the batts were sufficiently charged ... and then continue on.

We have not considered the house-keeping requirements. In my case, a light, 12vt fridge and a TV, even if I eat cold sandwiches. Hmmmm, I do have my gas grill outside too. Let's assume no TV..... Gosh, back to camping again. LOL
I think I will stick with what I have. Diesel engine, diesel generator, A/C.

 

[OldDan1943]

Thank you for starting this discussion. There is so much interesting information here that I find myself re-reading it, just for fun.
I have made the Seattle to Juneau trip in a sailboat, and currently own an Albin 27 trailerable trawler that I would like to convert to diesel/ electric. Here is my 2 cents worth.
If you want to maximize efficiency, you need a light -full displacement boat. Trawlers can be full displacement, but they are seldom light weight. Remember that a planing hull boat and to a lesser extent a semi displacement boat is designed to lift the boat up to skim the surface at high speed. Unless you run at a brisk walk, a lot of energy is wasted lifting the boat to get it on a plane. Sailboats are almost always light - full displacement hulls. A possible solution could be to find a sailboat that fits your needs, remove the mast and build a solar mounting rack above most of the boat.
The wind and current conditions in the inside passage are challenging. Sometimes you will need to run against the tidal current to get through multiple rapids. For some unexplainable reason, when we made the trip, it seemed like the wind was always on our nose. On the brighter side we had lots of sun.
Your goal of making the trip without using a diesel generator is not achieved if you stop at marinas to charge up. The electricity at the dock is coming from a generator. Why not carry your own generator and give yourself the ability to anchor where you please. We made the trip to Juneau and loved the beauty and quiet of secluded anchorages. Only problem there is that you will be making some noise by running a generator.
I believe that it is currently impossible to make the Alaska trip on solar power alone, unless you build an ultra light with no amenities and get very lucky with the weather..
I got some good information from the folks at elco marine to convert my boat. My goal was to be able to run on electric while charging my batteries with my 6.5 kw generator. With that capability we could anchor without running the generator all night. They said I could achieve that if I ran at 5 knots- in dead calm conditions. Because of the high torque of an electric motor that speed would use a small amount of power.
I gave up because my plans are to do the Alaska trip trailer across country and cruise the Bahamas, and I feel that the wind, current and rough weather conditions are too challenging for an all electric boat, even with generator backup. I hope you can prove me wrong. I am sure advancements in the technology will make it possible -maybe soon.

You have made a brave decision, diesel-electric. I applaud your decision.
Of course you will need a decent battery charger and lots of batteries. Keep us informed of your progress.
Now let's talk about your electric motor. What voltage, DC motor, variable voltage (throttle), how many HP? Water cooled, direct drive or via transmission?

 

[Nomad Willy]

So REO you’re saying burn a gallon an hour charging your batts instead of burning 3/4 gal per hour driving your boat?

 

[Benthic2]

What I've gathered is that you have chosen your boat based on roof area, and are approaching this with a very "open checkbook" mentality. What if you chose a hull based on what's under the waterline, and then created the space for the solar cells. If you purchased a 20 year old 30 foot sailboat, took off the mast and built a superstructure on it you would probably be more seaworthy, efficient, and have spent less than buying a brand new 35 footer. I think with a small mast you could have hinged cells that were vertical in port and then swung down when underway to extend outboard of your gunwales.

And....since we are sort of in a brainstorming phase here..........
What if your solar array was on a catamaran based structure you towed behind you. ( like a stripped down pontoon boat ) It would make docking more difficult but open up many possibilities. You could seperate the vessel and the solar array and maneuver the array with a small dingy in port.

 

[Benthic2]

In fact...something like this that needed a motor might be an ideal and inexpensive test bed as an intermediary phase before you drop a considerable amount on a new TT35. ( for protected waters only, of course )

 

[Nomad Willy]

Benthic2,
One dosn’t make a sailboat more seaworthy by taking the mast off.

But I agree many sailboats would have a more efficient hull than the TT ... basically a planing hull not having anywhere near the battery carrying capacity required.

And re the “toon” shown above can you imagine seeing it crossing Dixon Entrance?

 

[SteveK]

I see the tech is already available for sailboats. It does take less HP/fuel to propel a sailboat so that makes sense.
adapting the idea to a trawler is an ambitious project.

 

[Scott Harris]

Solar panels like direct light. That is why it is best to place them on a solar tracker or position at an angle that maximizes direct sunlight. Of course, this is not practical to do on a boat.

My wife and I are currently building a small retirement home. We increased the pitch of our roof to 9:12 in order to position the panels to be closer to normal with the sun. A pitch of 12:12 would be better still since I live at a latitude close to 45 degrees, but there were restrictions against that.

The wattage ratings of the panels are measured indoors (no clouds) with a solar simulation lamp pointed directly at the panel and a constant temperature of 70 degrees. Change any of these factors and the panel will not reach the rating on its label.

Clouds reduce the output of solar panels by reflecting some of the light back into space also by diffusing the rest. The attenuation can be as much as 90%.

 

[Scott Harris]

Your goal of making the trip without using a diesel generator is not achieved if you stop at marinas to charge up. The electricity at the dock is coming from a generator.

Old Dan,

You are absolutely right.

I am a solar enthusiast, not an anti-oil advocate. I have an electric car, a Chevy bolt, but I am connected to Rocky Mountain Power, which means that it is really a coal-powered car. I am ok with that for now. I also have a gas powered car which I never fail to take when the trip is longer than 250 miles.

So I am doing this not with any animosity towards diesel, or people who use diesel, but as a challenge.

I build my own LiFePO4 battery systems. I am currently building one for my new house which will double as one of the boat batteries. So the challenge for me is to build a battery systems that can propel a boat from Seattle to Juneau. I feel confident in building the three battery systems for this project, it is all the stuff I don't know about boating that worries me.

 

[Nomad Willy]

Soo,
Here’s a sailboat converted roughly and partially to a trawler.

The foredeck was cut horizontally, raised and re-attached. He made his own “saildrive” by cutting a hole on the aft bottom and “clamped” the powerhead to the lower unit. He may have given up on that because the vibration would probably be terrible. He probably used a sailboat rudder. The 2-stroke smoke is probably not pleasant either.

But it certainly worked. I saw a video of it underway from the cockpit.

 

[Scott Harris]

I just noticed that I have been promoted to veteran member on this forum. This despite the fact that I don't own a boat, know next to nothing about boats, and apparently have difficulty spotting a FD hull when I see one.

That's funny.

 

[Benthic2]

Benthic2,
And re the “toon” shown above can you imagine seeing it crossing Dixon Entrance?

I wasn't suggesting taking the 'toon to Alaska. I was saying for short money it would make a test bed to mount the solar array, batteries and motor to get real data on charge times, run times and so on.....but only in protected waters. I would think a motorless pontoon would be very inexpensive.

 

[OldDan1943]

I just noticed that I have been promoted to veteran member on this forum. This despite the fact that I don't own a boat, know next to nothing about boats, and apparently have difficulty spotting a FD hull when I see one.

That's funny.

You are smart enough to ask questions. If you ask enough questions you get promoted to guru like me

 

[twistedtree]

....currently own an Albin 27 trailerable trawler that I would like to convert to diesel/ electric...


...My goal was to be able to run on electric while charging my batteries with my 6.5 kw generator. With that capability we could anchor without running the generator all night. They said I could achieve that if I ran at 5 knots- in dead calm conditions. Because of the high torque of an electric motor that speed would use a small amount of power.

Based on the boatdiesel calculator, the Albin will require about 5kw to run 5kts. That leaves 1.5kw left for charging, and with efficiency losses, probably closer to 1kw. So depending on your planned battery bank size, you can figure how long it will take to recharge it. A bank like Scott has planned would take 120 hrs to charge, or 5 days.


Lots of torque or a little bit of torque doesn't change how much power is required to move any given speed. All it will change is the required gearing/prop pitch.


What's the goal of the hybrid? No matter how you slice it a hybrid boat is less fuel efficient, so you are burning more fuel in exchange for something else. What's the something else you are after?

 

[SteveK]

Soo,
Here’s a sailboat converted roughly and partially to a trawler.

The foredeck was cut horizontally, raised and re-attached. He made his own “saildrive” by cutting a hole on the aft bottom and “clamped” the powerhead to the lower unit. He may have given up on that because the vibration would probably be terrible. He probably used a sailboat rudder. The 2-stroke smoke is probably not pleasant either.

But it certainly worked. I saw a video of it underway from the cockpit.

I saw This Video

 

[BandB]

Mirage Manufacturing provided me with the performance estimates of 7 knots using 7000 watts. If this is accurate (and it is looking less likely the more I learn about boats and the more I learn from everyone's comments) I would have enough energy to make the trip.

And the odds of that information being accurate is somewhere between slim and none. You really need to use more reliable sources of information.

 

[Nomad Willy]

BandB,
Pardon me but how do you know that?
Why should his information be false?

 

[Nomad Willy]

I saw This Video

Would this power my boat .. power it like my diesel engine?

The home made conversion was only a project that didn’t result in any better mousetrap. But I like what he did to the boat. Just a conventional OB on a bracket would be fine and of course a LOT of finish work. I like it.
But being a sailboat I would like a mast and sail mostly as a stability system but as a get home too. Very few sailboats have acceptable stability w the sail rigging removed.

But thanks for the vid and I would go for it if it was better than my diesel engine. In the vid it looked like it was hydraulic drive. Is it?

 

[SteveK]

Would this power my boat .. power it like my diesel engine?

The home made conversion was only a project that didn’t result in any better mousetrap. But I like what he did to the boat. Just a conventional OB on a bracket would be fine and of course a LOT of finish work. I like it.

But thanks for the vid and I would go for it if it was better than my diesel engine. In the vid it looked like it was hydraulic drive. Is it?

I was just surfing. It says electric, could be electric hydraulic pump. IF I was interested in going electric I would go with a sailboat hull like this. Noticed there was no solar panels on the boat, hmmm?