Electric propulsion

[Bob Bois]

This has been discussed on several other forums. We are interested in electric propulsion for our Tiki 46 and have been in touch with several builders who have installed e-pods, etc. However, does anyone currently using electric motors for propulsion have a report on the practicality of the current products?
There's been alot of discussion regarding the weight of the batteries as a limiting factor, the best (and worst) power regeneration methods, the best (and worst) products currently available.
I don't want to summarize it all here, but I would like to open the discussion and see if there is any further interest within this really knowledgeable community in brainstorming how this might (or might not) be worthwhile (and cost-efficient). I'd be interested in any aspect of electric propulsion anyone might want to discuss, from recharging batteries to the best placement of electric motors and the pros and cons of the overall concept. I received an email from some builders who are using e-pods with their Pahi 63 and say they are really pleased with it. Ther

[Bob Bois]

Thanks for all the information. That is an answer worth chewing on for quite some time. You're right about getting it all down on paper and looking at the numbers in the cold light of reality. I have little desire to let my propulsion system take up a quarter or more of my payload capacity.
Inboard diesels in each hull is an attractive option as far as maintenance, manouverability and reliability; however, then we're back to having fixed hardware below the water line and we really want to get the units up and out of the water when under sail.
What do you think of Bjorn's suggestion: take, say, a 15 horse outboard that is deployed via the designed engine box and on the opposite side one e-pod 3000 unit, deployed similarly. Split the difference? I don't know: you're still lugging a 600 pound battery bank around (but no generator).

[Bob Bois]

Maybe I should re-think this: I have two strapping sons who will be in their early teens by the time construction of the boat is completed. I should switch to building a Tiki 30 and use the savings for raw meat and protein shakes for the boys and just install a yuloh....

[Jeff Kittle]

Our system is not fully tested. We have 2 E3000 epods on our boat. I wanted to put them on engine boxes but winter was coming and I placed their supports vertically though the backbone between the keel and the skeg. It was solid, quicker, closer to the batteries than the engine boxes, and more solid than connecting to the side of the hull. I felt this would be more streamline but also feared that it might block waterflow crossways when turning(extending the keel effect). We had built our deckpod and cockpit almost 12 ft wide so our engine boxes would have been wider and given us more torque to turn the boat if we used engine boxes, but maybe later we will take advantage of this . We had a 50 hp johnson outboard on another boat and I (Mr Cheapo) put this on a single engine box in the center before we ever put the boat in the water. I did not want to rely on the electric engines alone. The electrics worked well for docking as we went down the Mississippi last year. but we could not sail and had no generator. We charged them when we could dock with electricity.
I cannot tell you a lot about their performance at sea. We just finished sewing our sails and most of our rigging this spring. We sailed and motored from Mobile to Apilachicola and back,
but we only used the electrics for docking. I am workng about 1000 miles away from the boat right now;so she sits still. What I can tell you is they ruin the silence of sailing. It sounds like there is a gale blowing because it echos in the hulls even if they are spinning free. It sounds louder in the cockpit than in the berths. So being able to take them out of the water on engine boxes would give better sailing performance and would be much more quiet. With rough waves our 50 hp motor does pop up near the surface of the water causing slight "cavitation" effect so I would be careful about mounting engines wells/boxes farther aft if not putting the engines deeper in the water. I would even consider putting them farther forward.

[Jeff Kittle]

I thoght that last photo was of the outboard motor but I will post another. And we bought the generator from re-e-power before we left michigan but I have not put it together yet. It is still in pieces on the boat. Apparently it usually comes assembled but he had changed components and I have to put it together.

[Budget Boater]

Bob Bois said:

What do you think of Bjorn's suggestion: take, say, a 15 horse outboard that is deployed via the designed engine box and on the opposite side one e-pod 3000 unit, deployed similarly. Split the difference? I don't know: you're still lugging a 600 pound battery bank around (but no generator).

I like to have redundancy without having complexity. For me, the outboard on one side and epod on the other seems to be asking for trouble. Each will have different thrust ratios, controls, and longevity.

Having your epods on individual raising foils (think fin keel shape with the epod at the bottom) is the answer. If you are like me, you will also have a RIB inflatable dingy with a 15 hp + outboard that could be used to drive the boat in a pinch. The way to do this is to make a modified version of the outboard ramp JW specifies for the boat with your dingy outboard in mind. This allows you the redundancy without the complication.

On my old Tangaroa, the 20hp outboard was old and tired. I knew it was going to kick the bucket at some point, I just did not know when. I designed a separate drop down ramp to accept my 4hp dingy motor "just in case." Well, that just in case happened on the way across the the banks and gulfstream on our way back to Florida during a windless summer cruise. Since we used the custom bracket to "store" the dingy motor while underway, so it was an easy job to lower the dingy motor into the water. Yes, it pushed that big Tangaroa more than 100 miles. The only problem we encountered was when we tried to motor into Jupiter inlet on an outgoing tide. We could only make 1/4 knot against the current with the 4hp motor. I was not smart enough in my youth to just wait the tide out, but it provided a unique learning experience.

If you are adverse to weight in any way, an electric drive system is probably not for you.

That is my .63 (.02 adjusted for inflation)

[Bob Bois]

Thanks Budget....
I am definitely averse to weighing down our Tiki 46 with extensive (and expensive) battery banks. I am not a sailing purist; I'd like to have the time and skills to 'primarily' sail and do it most of the time. Some of my favorite memories on our Tiki 30 was shutting down that 8 horse Honda and just sailing quietly. However, there are going to be times when auxiliary propulsion is needed and if and when the boat is ready to splash into the water and the technology has still not reached an acceptable level in practicality or expense, then we'll mount two 15 hp outboards in the designed engine boxes and go our way until the time seems right to change to an auxiliary system that is quieter and cleaner. I have to say, I could deal with the 144 V risk a la Solomon Technologies, but I can't get past 1500 or so pounds of batteries and 3-6 days to recharge after 5 hours use. Those numbers are not currently thrilling me. But I remain optimistic that this technology is coming to maturity soon...I don't know what the breakthrough is going to be. I really don't have a 'green' fetish; I'd like to not leave a slick each time I fire up the auxiliary, but really what we want is a clean, quiet system that can be regenerated efficiently from wind and abundant sunshine.

[Jeff Kittle]

If you are going to have the diesel generator, you can get away with four batteries per side.

[Ann and Neville Clement]

It is impressive to see how much excellent and technical advice is available on this web site. I have sailed north and south mostly offshore but using the ICW as weather required too many times to count. When in the ICW one generally motors a third of the time, sails a third of the time, and motorsails a third of the time unless one has patience for waiting out weather conditions. My personality was totally at peace on my solo trans Atlantic when the old monohull ran out of wind for 3 days straight. Could have lit a candle in the cockpit. I simply put the sail covers on and broke out books and was contented with that because I was there to visit the ocean. Nev would have died if he had seen it. He is a go guy. So it is not only your own opinion, Bob, your crew will have a say too .

What about sound proofing issues? This seems to be an unexplored area. Our biggest noises are made when the engine vibrations cause a rattle in the engine boxes. Nev has put all kinds of things down there to stop those rattles with increasing success each year. We have no foam insullation under the boxes and they magnify the sound like a guitar does. It seems that both outboards and these new fangled electrics eventually get you into using fuel so sound is an important comparison issue. I would not want electric engines making noise when under sail and I guess that is how they recharge themselves. Blessed silence is so lovely under sail. I would hate to give that up. Our wind generator is noisy but effective and we live with it but it is a strain sometimes.

When Peace uses power for distance we generally use one engine unless there is a need for speed or against current or wind. With 2 engines and a clean bottom, our 9.9s give us 7 knots in no wind which is fast enough for us. One engine is good for 4 or 5 knots not at full throttle. 15 hp would approach excellence in my opinion.

Bob, how about twin yulos for the boys?

Ann and NEv

[Bob Bois]

Hi Ann and Nev,
If I don't take the opinions of the rest of the crew into account, I will hear about quickly - have no doubt.
Here's a question for everyone (especially Ann and Nev as they have the most extensive Tiki 46-specific live aboard experience (in the world, I would figure):
Can 15hp outboards be set up to recharge the batteries to run all electrics on board (with solar and wind assistance)?
The reason I ask is this: I would not want to sail into a nice quiet anchorage and have to fire up a deck-mounted diesel generator.
The thought of an electric drive that can be hoisted clear of the water that can be recharged with a small diesel gen to minimize the number of batteries required is appealing until I envision that gen running when all should be quiet. That said, I would rather carry diesel than gas and it's not like the outboards are quiet. So many considerations...it will end up as a compromise of course and I'm glad we have a few more years to think about it.

[Budget Boater]

Bob Bois said:

Hi Ann and Nev,
If I don't take the opinions of the rest of the crew into account, I will hear about quickly - have no doubt. Here's a question for everyone (especially Ann and Nev as they have the most extensive Tiki 46-specific live aboard experience (in the world, I would figure): Can 15hp outboards be set up to recharge the batteries to run all electrics on board (with solar and wind assistance)?
The reason I ask is this: I would not want to sail into a nice quiet anchorage and have to fire up a deck-mounted diesel generator.
The thought of an electric drive that can be hoisted clear of the water that can be recharged with a small diesel gen to minimize the number of batteries required is appealing until I envision that gen running when all should be quiet. That said, I would rather carry diesel than gas and it's not like the outboards are quiet. So many considerations...it will end up as a compromise of course and I'm glad we have a few more years to think about it.

Bob,

If your outboards are electric start, they will have a very small magneto charger built into them. This magneto is not designed to charge deep cycle batteries properly. Your house batteries (or propulsion batteries) will be a significant investment. Good batteries that are properly maintained should last 25+ years. AGM or cheaper lead acid batteries will last 5-7 years when properly maintained.

To properly maintain your batteries, you need smart charging. The magneto chargers in small outboard motors can damage deep cycle batteries and reduce their lifespan. If you want to properly charge your house batteries while at anchor, get a Honda EU1000i or EU2000i gas generator and a good quality 4 stage battery charger (Bulk, Absorption, Float, Equalize.) These generators are very quiet and allow you to have a normal conversation while sitting next to it. They also use the same fuel as your outboards. The Honda generator with a 4 stage battery charger will allow you charge your batteries without making a lot of noise in the event that your solar and/or wind systems are not doing the job.

I put my EU1000i in the aft hatch of my Tiki 30 behind the galley when not in use. I was able to not only top off the batteries while at anchor (I NEVER went to a dock for any reason), but also used the power to heat water in the Isotherm water heater. 30 minutes of run time did just about everything I needed and used about a pint of fuel. I would also sometimes run the Spectra watermaker when the generator was on, just as a boost in battery power. I had three 75 watt panels that did most of my charging work.

Here is a list of things we had and used on that Tiki 30 with only the three solar panels and the Honda generator for charging our single Rolls 4D battery:

• Made 8 gallons of water with the Spectra per day
• Ran the 1.4 cu ft refrigerator 24/7
• Heated 4 gallons of water
• Used the computer for 4 hours per day
• Operated our LED interior and cockpit lights for 5 hours per day
• Operated our 6 Caframo fans 24/7

The boat's electrical system was designed to revolve only around the capacity of the Solar array. We bought the generator simply as a back-up charging source and to operate the hot water heater. So when we fired it up to heat water, it also topped up the batteries through the 4 stage charger.

[Bob Bois]

Thanks. I'll definitely look into the quiet Honda gens. Now that I think of it, I was on Peace last autumn and at one point Nev fired up a generator while we were sailing (I think) and I could hardly hear it. Your explanation below definitely makes a strong case for dual 15 hp outboards with solar array, windmill, and a quiet gas powered gen repowering a more modest bank of deep cycle batteries. Also, widening the cockpit so as to gain more separation of the outboard boxes a la the Kittles would aid in manouverability. Thanks Shane, and to all who continue to contribute to this discussion. The advice of those with actual practical experience of these systems is invaluable.

[boatsmith]

Hi all, I looked around on the web a little and came up with these numbers. One gallon of gas = about 35 kwh. At 35% efficiency in an outboard this would be 12.25 kwh, at 12 volts that about 1020 amp hours at 50% discharge that's about 4 8d batteries at about 680 lbs. The larger Torqeedos run at 48 volts and 4000 watts, about 83 amps at 48 volts, 330 amps at 12 volts. That equates to about 3 hrs of running time per 4 8ds. A solar array putting out a daily average of 120 amp hours would need over a week to recharge the batteries.
Mind you I'm not an electrical engineer and feel free to point out any errors in my calcs here, but this is about what I understand the real situation with electric motors is.
Thanks Jeff for your real world input.
In the PHRF rating system you receive a 6 second a mile credit for a 1" shaft and a folding 2 blade propeller.
The drag imposed by two three bladed props with charging resistance must be ferocious.
There are lots of times when cruising that the ability to motor for extended periods will add considerablyto everyones enjoyment. Many of us are not sailing on unlimited time frames and sitting becalmed or sailing at 1mph for three days can take a large chunk out of a ten day cruise.
We are planiing to replace the 8 hp Yamaha in our tiki 30 with a 20 or 25 hp outboard. When we need/want to motor I would just as sonn go 10 mph as 5 1/2 mph. We live in a hurricane area and that considerably increases my freedom on where and when the boat goes.
Just some of my thoughts. David www.boatsmithfl.com