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Old 04-16-2013, 09:17 AM   #21
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This is all great stuff and what this thread is about, real numbers to compare to. I am interested in not just the good, but the bad and ugly as well.
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Old 04-16-2013, 10:12 AM   #22
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Bollocks.

Playing games with input power doesn't change the fact that boats are driven by output power measured at the propeller shaft. If your boat takes 15 HP to move through the water at 5 knots, it doesn't make one nanospeck of difference if that shaft is turned by an electric motor, a gas turbine, a squirrel in a cage, a steam turbine, or a diesel engine.

The metrics you guys use to develop interesting numbers for terrestrial vehicles simply don't apply to boats. A propeller doesn't act on the water like a tire on pavement or train wheel on a rail. The availability of high torque at low speed doesn't count for much in a fluid medium unless acceleration is your primary interest and I suspect few here are driving ship assist tugs, ferries, or drag boats.
This has been a major stumbling block to my understanding this from the very begining. HP is HP and boats are driving 'uphill' so to speak all the time. Part of the reason you dont find 5 speed transmissions in boats. I see where an electric motors inherent torque is an advantage but that still doesn't rule out the obvious, it's still HP doing the work. Minimum surface boats such as cats and tris have obvious advantages but the subject is converting my Owens, a mono.

I suppose calculating the hull speed and then finding the horsepower required to push it just below that speed are the next 2 things I need to do in order to get a better picture of reality.

I'm compelled to give you guys a bit of personal background to perhaps understand my facination with this subject better. I have been driving an electric vehicle daily for 3 years and really enjoy it. It has limitations as it only drives 25 MPH with 30 miles range but have found living within those limitations quite a bit easier than some might invision.
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Old 04-16-2013, 10:27 AM   #23
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The economic advantage of solar may or may not be there, depending on how you use your boat. IMO in most cases, it isn't ther yet - but its getting closer every year.

But really - who owns a trawler for economic advantage? All boats are an economic disadvantage unless you make your living from it.

What I love about projects like what Craig, Rueben and Bob are into, is that it pushes the boundaries. It's not just restoring old technology (nothing wrong with that), but it seeks to improve on a thousand+ years of boatbuilding design.
Successful or not, how can anyone knock that? As a bonus, it may leave a few gallons of diesel for future generations.

I congratulate you guys for your efforts!
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Old 04-16-2013, 10:44 AM   #24
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I was just thinking that a good candidate for conversion to electric propulsion would be a 30' Scout (Elco replica). She is a more aesthetically-pleasing platform with plenty of fore-deck and canopy for solar panels. I recall from her sea trials that she uses minimal fuel (ie. HP) at lower speeds.

Regarding the Owens - why not convince a good friend to tow you on a calm day with an adequate scale in line with the tow rope. Measure the pounds of resistance at a variety of speeds creating an empirical HP/Speed curve. A naval architect will be able to translate the pounds into HP for sizing the motor and battery. This should not be too difficult to execute with some planning.

One of the most attractive aspects of cruising an electric boat is the absence of noise and fumes. A well-equipped cruiser that spends significant time on the hook, will run a generator from time to time - sometimes daily - sometimes continually (for air conditioning). Not having to do this can increase the intangible pleasures of anchoring out - especially in crowded anchorages. Cruising yachts, by their very nature tend to be expensive - and choosing the best personal return for one's dollars is certainly an individual's choice. Many buyers of hybrid cars do so not to save money - but to use less gas. Rather than buy a Prius, one could buy an equally well-equipped Hyundai for significantly less and use the savings to buy gas for the length of ownership. But most Prius owners feel good about their return on investment.

Since this is a trawler forum and not a sailing one, I am curious why suggesting a sail boat as an alternate to an e-boat keeps being raised. Usually accompanied with comments such as how does a solar boat do at night? My suggestion is to reverse the situation - how does a sail boat do in a calm? Along the ICW? Going under bridges? Through crowded anchorages? Sail has its limitations just as electric propulsion just as diesel and gas. They're just different. Having lived aboard a sail boat, done some ocean passages and built over 300 of them, I feel I can speak with a modicum of experience.
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Old 04-16-2013, 11:43 AM   #25
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I was thinking the other day that a good candidate for electric propulsion would be a 30' Scout (Elco replica) - she is aesthetically pleasing while having plenty of fore-deck and canopy space for a PV array. From original sea trials I recall that she used minimal fuel at slow cruising speeds - about 6 knots.

Regarding the Owens - perhaps you could convince a friend to tow your Owens with a suitable scale mounted in-line with the tow rope (see attached photo). A naval architect could take the speed/pounds data and convert to speed/HP curve. Armed with this empirical data, you could then easily determine the amount of e-power and battery that would meet your needs.
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Old 04-16-2013, 11:59 AM   #26
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I agree the Scout would make a great candidate. Love those classic lines.

Towing with the scale or force gauge is something I'll try arranging.
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Old 04-16-2013, 12:06 PM   #27
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Bollocks.

Playing games with input power doesn't change the fact that boats are driven by output power measured at the propeller shaft. If your boat takes 15 HP to move through the water at 5 knots, it doesn't make one nanospeck of difference if that shaft is turned by an electric motor, a gas turbine, a squirrel in a cage, a steam turbine, or a diesel engine.

The metrics you guys use to develop interesting numbers for terrestrial vehicles simply don't apply to boats. A propeller doesn't act on the water like a tire on pavement or train wheel on a rail. The availability of high torque at low speed doesn't count for much in a fluid medium unless acceleration is your primary interest and I suspect few here are driving ship assist tugs, ferries, or drag boats.
Your right hp is hp regardless of what is producing it. The difference comes when trying to reach an rpm for a given hp. 9.9 hp outboards come in two configurations, standard and high thrust. High thrust just means the prop is pitched shallow to allow the gas engine under the load of a 7000 lb sailboat to reach its rpm range that produces those 9.9 hp, around 5500 rpm. It trades speed through the water with that lighter pitch because the gas engine does not produce enough torque at lower rpm. If you were to take static bollard pulls on a 4 hp electric vs a 9.9 hp gas, you would see through the pull that the electric would match (or exceed at very low rpm) what the gas engine was doing, so it is fair to say that a 4 hp electric has the same propulsive pull as a 9.9 gas, and that is what you as an operator depend on.

The same does apply to cars, trains, and boats. The diesel in a train at its rated rpm for hp does move the train, but could never get it started from a standstill because if it was direct coupled the diesel would stall under the load. The last ship I was on had the task of holding position over oil wells during all conditions and currents. This could never be done with the weak kneed torque of a diesel at low rpm. I had (7) Cat diesels, each rated at 4.6 Mw @ 900 rpm producing the electricity needed to power (6) 5000 hp electric thrusters. Through the entire rpm range the electric motors were doing a job the diesels with their torque curves couldn't.

For the few of you that have had the pleasure to do tight maneuvering in a current plagued marina know how precise you can handle your vessel with electric propulsion. No clunking in and out of gear, able to change prop speed quickly, and being able to choose as slow a prop rpm as you want, not dictated by the diesel's need to idle at 600 rpm. Reuben knows this feeling, I'm surprised he hasn't mentioned that in tight situations he has full linear control of his boat in a very precise manner. You have to try it to believe it.
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Old 04-16-2013, 01:21 PM   #28
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I had (7) Cat diesels, each rated at 4.6 Mw @ 900 rpm producing the electricity needed to power (6) 5000 hp electric thrusters. Through the entire rpm range the electric motors were doing a job the diesels with their torque curves couldn't.
I guess I should have added DP vessels to the list of those that normally operate at low speed and require frequent and rapid thrust changes to facilitate maneuverability.

The only time(s) electric propulsion has proven effective in what might be defined as "cruising" vessels is the very first installation which was chosen because there was no other way to power astern, during wartime when reduction gear production was limited to warship propulsion, a few coastwise product tankers because they commonly as much power to offload as they do to travel at sea speed, and cruise ships which spend the majority of their lives at zero speed with an enormous hotel load.

It appears this discussion provides readers with a glimpse behind the doors of the MEMMS.
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Old 04-16-2013, 01:46 PM   #29
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Rick,

The only real issue to cruising with electric propulsion is competing with the energy density of fossil fuel. Reuben has addressed that by having a daily trickle of energy being produced via solar and storing for night time propulsion. If a clunky, heavy cat like the C60 commercial ferry can cross the Atlantic on just 10 Kw of solar panels, does that not prove the concept viable? transatlantic21: The world's first crossing of the Atlantic on a solar boat

How about a purpose built, light weight cat that has 8000 nm on just 8 Kw of solar?
Boat - SolarWave

I could take Reuben's boat Sunshine with just 6 Kw of solar and circumnavigate. Granted it would take a bit longer to do so than in a fossil fueled boat, but at 27,000 nm the fossil fuel boat would burn through over 13,000 gallons of diesel.

The name of the game is hull(s) efficiency and light weight. My personal best is 32 w-hr per nm. With LiFePO4 that equates to 80 nm on 60 lb of batteries.
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Old 04-16-2013, 02:11 PM   #30
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The only real issue to cruising with electric propulsion is competing with the energy density of fossil fuel.
So who is competing? I am just saying that it is silly to imagine anyone can convert an existing "trawler" (or any other powerboat for that matter) into a solar powered or hybrid vessel and save money or energy, or increase propulsive efficiency and still maintain the utility and versatility of the original boat.

It may be great fun to debate the pros and cons of various bits of hardware but trying to justify it as a means to save fuel or money is more than just a stretch.

With enough cash and time, anyone can build, convert, or install pretty much anything available and given enough time and more money, go around the world a few times with it but leading people to think that is somehow more efficient or better than knocking around the San Juans or the Keys in a Lehman powered trawler is specious. If economy and efficiency are the real goals, build a raft. There is a current going your way somewhere ... eventually.
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Old 04-16-2013, 02:21 PM   #31
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I am just saying that it is silly to imagine anyone can convert an existing "trawler" (or any other powerboat for that matter) into a solar powered or hybrid vessel and save money or energy, or increase propulsive efficiency and still maintain the utility and versatility of the original boat.
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Old 04-16-2013, 02:45 PM   #32
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Ok just to be clear. No where in this thread did I state gas savings as the objective. If I want to save gas I'll sell the damn boat. I also stated in the OP that if a generator was needed to make a compromise system plausible that was fine too. I'm not some hippie trying to save the world here. There is no free lunch being sought after or desired.

Simply trying to see if existing, mostly off the shelf, parts can be used to make a more aesthetically pleasing electric powered pleasure boat. Retrofitting my existing boat is the paradigm I chose because its easily relatable.
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Old 04-16-2013, 03:08 PM   #33
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Simply trying to see if existing, mostly off the shelf, parts can be used to make a more aesthetically pleasing electric powered pleasure boat.
I think the esthetics component went away about 25 posts back.

"So we beat on, boats against the current, borne back ceaselessly into the past."

Most of the boats in Gatsby's era were powered by a single gasoline engine.
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Old 04-16-2013, 03:24 PM   #34
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Rick,

You can convert a trawler and still have the best of both worlds. After time, a full return on investment. Take the PDQ 34 for example, with displacement around 15000 lbs and efficient hulls that reach 16 kt on a pair of 75 hp diesels. Cost of conversion is about $30K and you still retain 16 kt with the diesels, but now there is a pair of 7 Kw motors on the output shafts. With just 2.5 Kw of solar (so the entire boat isn't covered with solar panels) and 75 Kw-hr battery capacity, you could cruise a very typical Caribbean scenario, 100 nm passage followed by a week on the hook in some pristine anchorage, then another 100 nm passage. Do this type of full time cruising and the pay back would take about 3 years, after that your ahead of the game. No need for a heavy AC gen set as the electric propulsion motors are efficient DC generators, if needed and all AC loads would be handled by the inverter.
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Old 04-16-2013, 04:47 PM   #35
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I'm not some hippie trying to save the world here. There is no free lunch being sought after or desired.
Glad you cleared that up, Craig! You had me worried for awhile. ()
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Old 04-16-2013, 07:12 PM   #36
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I post here just to stay in this link... interesting!
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Old 04-16-2013, 09:16 PM   #37
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IMHO – The gist of this thread via Craig as OP... is... to see if the “power boating world” has a hope in hell of now manifesting a feasible propulsion package that can fairly well supplant the need to use quantities of fossil fuels, or, at very least to minimize fossil fuel use enough to reach the points of both good economic/affordability reasoning and also to help provide environmentally positive outcomes. Please correct me Craig if I read your intent for this thread incorrectly! That is my intent as can be told by next paragraphs...

With others outside this forum I have been working on similar project. Reality: 21st Century’s Q1 pleasure power boating industry in general is becoming economically high and dry (defunct)... it is “on the rocks” so to say. The need for current owners of existing self contained pleasure cruisers (range of: 26’ +/- to 50’ +/-) to have opportunity to install alternative power source that can still enable at least a little speed as well as some cruising range is now becoming a top priority due to fossil fuel costs and environmental reasons. Another side of this equation is to be able to mass manufacture drop-in cookie cutter hybrid power systems that are upgradable (as technology improves) and that can become purchase-affordable via economies-of-scale to be sized up or down in power ratios for working on various size and model boats. Another important point is the propulsion systems need to have decades long last ability for most of their components (at least the big ones) and the installation of these hybrid power systems also needs to actually increase the boat’s overall value in comparison to the diesel or gasoline engines being replaced.

These economic hurdles are not easy to jump over... especially when there currently seems no way to provide “New Hybrid Propulsion” sources that can reach the majority of boaters’ desired speeds and/or cruising range in the size and style of used boats that number into the millions internationally... not to mention new manufactured boats that still follow similar hull designs and weights.

All In All: It appears that unless a true breakthrough in value, affordability, use-economy and environmentally conscious cleanliness can be developed for pleasure cruiser power sources that the general boating industry will continue its downslide toward becoming a skeleton of its former industrial might.

Due to ongoing increase of fossil fuel prices: Across the U.S. yacht-harbors/boat-yards are too often in tough economic positions or closing, boat manufacturers are experiencing closures or hard economic times, boat abandonment and scrapping is becoming much elevated, and one time boaters are simply no longer willing (able) to continue with their previous love of participating in the boating community.

Question: Is there a way to create alternative power source that can save and even reinvigorate the pleasure cruising power boat communities???

Answer: Today unknown!
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Old 04-16-2013, 09:39 PM   #38
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Art,

I see long knife like hulls on a catamaran that is supporting 10~15 Kw of solar panels and substantial lithium energy storage. This would give ocean crossing capability and provide for all domestic energy needs. No need for propane, diesel, or gasoline for the dinghy. It is doable now, and Solar Wave is proof of concept.

Past attempts have merit for folks that don't want to go the sailboat route, and one that comes to mind is a trimaran called the Walker Wingsail, which I asked on the Cruiser's Forum if anyone remembers it. Remember the Walker Wingsail ? - Cruisers & Sailing Forums
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Old 04-16-2013, 09:39 PM   #39
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Always missed in these discussions are the end user coastal cruisers who are quite happy to spend the $2K to 10K per year in fuel - as Walt notes cheap as compared to the other costs. And definitely cheap when looking at buying and maintaining a non toy true trawler sized hybrid.

PS - Like many others, I do not want nor can I use a lightweight catamaran with LiX batteries and solar cells.
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Old 04-16-2013, 10:05 PM   #40
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Please correct me Craig if I read your intent for this thread incorrectly!
Nah Art. Just tryin' to see if I can run my old school boat on a new school battery

Rest of that's over this country boys head
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