Electric Propulsion (migrated from Basecamp)  


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02/02/2018 3:20 am  

Nov 25, 2017 Notified 17 people
Siemens developed an electric engine that set a world record for the fastest takeoff and ascent in a two-seater airplane recently and has been refining the technology. DHX made an 80 hp electric motor that takes up less than one cubic foot of space. There are several open-source automotive electric motors that can be built for less than $1,000 and  others that cost more. Torqeedo is a commercial marine engine manufacturer that produces 40 hp and 80 hp electric outboards that retail for close to $24K. 

What kind of horsepower do we need to cruise at 15 mph? What would be the most efficient size/weight and power electric motor to use on Denali? 

Should we:

- Replace her twin, one-ton diesels (238 hp each) for twin Prius-style automotive engines (120 hp each)?

- Design “electric jet propulsion” and modify current electric jet engines? How many jets? 2-4? 6?

- Design propeller-based Propulsion? 4-8 high torque props? There are some advanced electric propeller-based engines - tiny but mighty. ...?

Use a combination? Is there a reason to use one over the other? Would certain conditions warrant one over the other?

We could build two electric engines that can power Denali and when she’s docked, they power 2 small cars/vehicles. The chassis for the electric cars could be part of Denali’s deck or flybridge  or...

Three Requirements:
{Modular} {3D Printable} {Multipurpose} 



Spruce Cox
I was already working on this. The original engines developed 225 hp each for a total of 450 hp driving Denali to speeds in excess of 18 mph. Straight unit conversion for 450 hp is 336 kW. Alternatively, it takes only 56 hp (42 kW) to go 9 mph. Somewhere between 9 and 18 mph is probably a good spot. I’m building that curve now.
Please ask our naval architect or maybe someone from a shipyard what our minimum speed is for ocean and river weather conditions (including crossing the Columbia River sandbar) and for navigation. I don’t know if there are legal requirements, general seaworthiness accepted practices, or operating experience and we might have to follow.
For your other questions, let me think for a bit. Got your 3 main requirements.

Great stuff here Spruce!  Thank you for the conversion - it does put things into perspective.  And if

Patrick J. Bray Patrick

is able to design an appendage to make Denali even more efficient, the energy requirements should go down a bit more. We can also think about integrating solar and wind power like solar sails and kite's to reduce energy requirements when there is sun light and/or wind.

I emailed Patrick about towing Denali and precautions.  I also found some info on the Lower Columbia Region Harbor Safety Committee but I didn't see anything about minimum speed, etc. And there is a PDF download on the Columbia River Pilots website under Guidelines > Vessel Movement Guidelines but I skimmed through and didn't come up with any info.  I will call the tug captain tomorrow.

Patrick J. Bray
Sorry I am travelling for one more day. I will be able to check back with you then

Best regards
Pat Bray

Here's what Patrick said in an email yesterday

The outflow of the river against an incoming tide will always make the waves steeper and the water rougher.  An outflowing tide will certainly help the passage.  Having additional pilot boats on hand is always a good idea to help with maneuvering.
Putting straps around the hull just to hold everything together may or may not be of benefit. I am just thinking that it may help to hold planks in place and keep the structure intact.  Check with the other people who have actually seen the boat and see if they feel it is worthwhile.  From my long distance vantage point it is strictly speculation.
I hope that helps.


Patrick J. Bray Patrick

- This weekend should produce some more information about her overall condition.   I'm learning about building an open-source ROV submersible with an HD camera to look at her hull in the near future.  I was also trying to find out about ways of measuring wood density under water but all I found was tomographic scanners for trees on land or ultrasonic density meters that seemed to be only for metal.  Does anyone know if there is something we can use to scan Denali's hull and measure density from inside or underwater?

Spruce Cox
I suggest tapping lightly with a hammer. This won’t give you density but will indicate areas of probable damage.

Spruce Cox
Hull inspection
 1) In my opinion, the reason to do a hull inspection now is to determine if there are any areas of damage that could affect getting her out of the water and onto stands. Density measurement data would be nice but I think it's more than we need right now. Besides, in-situ techniques seem to be, in my quick review, limited. For sick trees they measure depth of a pin. For specific types of wood they cut piece off and use an Archimedes volume test. We need a structural integrity test before we try to get her out of the water.
 2) I think doing a thorough "tap" test from the inside and from the outside a close visual inspection (with a local "tap" test if possible) using diver with or without camera or camera on a stick or maybe a mirror on a stick. We could get a few samples of 100-year-old wet wood and compare with new wood in our own Archimedes volume test.
 3) Just to note that item two (and maybe item one later) might be the stuff of technical papers. We could get a grad student to do it for us.

Spruce Cox
Electric propulsion
 1) So we don't get confused, we should separate discussions of primary power (guaranteed to get us home) and secondary or experimental power (test out high-tech ideas before we commit to build). You're probably already thinking about this. For primary power we need a system that's developed and in production. We could use Prius or Tesla donated electric propulsion systems with batteries, but we would have to design a new motor output to propeller shaft adapter.
 2) For primary power we could use modern day car or boat motors using proven fuel technology at first then experiment with greener fuel as we go. If we go this way, I think  we should keep the inboard motor configuration that Denali has now, unless something else comes up that would give us the reliability we need for primary power.

3) For experimental power we could use any or all of the systems Rick identified above, testing each one up to a certain size or power level, and if one or two ideas keep showing promise, we or another company could build prototypes, test more, complete development, start production.

4) If any experimental system gets far enough along with reliability, cost, etc., we the Z-NEV company can choose to adopt it as primary power and replace the old primary systems. The only point here is that we Z-NEV will be making decisions about electric or other power for two systems upfront that have completely different requirements.

Great ideas Spruce.  I like the idea of separating into primary and secondary or experimental vs guaranteed.   There are a couple things I want to clarify first though.  Since this project is meant to focus more on the journey of learning rather than the goal of producing a vessel that meets net-zero specs, we can always afford to fail at anything we try to accomplish as long as we learn from it and keep going.  I don't want to rely too much on using entire systems or applications that have already been developed unless we have to modify them so much to adapt them for Z-NEV that they are a completely different version.  I like the idea of using Tesla and Prius technology since they are open source and I would like to look at "marinzing" those EV engines.  I think we should really look at the open source electric vehicle technology that thousands of people are using and contributing to.  And we should be following a company called Local Motors  who is commercializing 3D printed, autonomous electric vehicles.

I've been looking at what it means to truly be net-zero or zero-net (no difference).  In the world of green building, they have the "Living Building Challenge" which has a Red List of materials that are not allowed in their certified buildings.  Much like the USGBC and the LEED certifications.  I would like to explore this more to understand what it could mean for us to adopt the Red List or to create our own.  There are probably a lot of toxic chemicals in those Tesla home batteries and in both engines mentioned above? 

We don't necessarily have to have an engine as our backup or even main propulsion system. Who says we cant just drift or use the energy from the wind and waves to get to where we need to go?  As long as there is food and shelter and we dont have a deadline, it really doesnt matter how long it takes to get anywhere.  Denali-Z-NEV will not be an ocean-going vessel.  She will be a near-coastal cruising vessel capable of cruising up to BC or down the coast to Baja in the summer time when waves are flat and storms can be avoided but she will break apart on the high seas because of her light construction - built for speed. 

If the ecological footprint, or wake in our case, to design and build a Z-NEV is more toxic than the total carbon footprint of just installing a bio-diesel or hybrid engine, then it feels like the idea looses its meaning to me and that isn't what I had in mind initially.  It will be quite a challenge, but if we have to think outside the box to come up with a different plan because long term sustainability is contradicted by short term singular benchmarks, I say we take the long road.  We can throw some paddles on board as a backup or learn how to ask whales and dolphins to tow us when the wind doesn't fill our rigid solar sails.  I don't think we should look for easy ways, I think we should look for the best ways with our legacy in mind (earth/humanities legacy-survival). 

I recognize that this can change everything because energy storage is a huge part of the equation - the production of electric vehicle batteries has been a soapbox subject for environmentalist for a long time. But so what.  If we have to make excuses to adopt a technology that compromises our values then we should probably question our intentions and think deeply about why.  The only way we are going to solve all of the challenges that Z-NEV imposes is to ask for help and to open up the box we try to fit reality and our perception of it into.  I started asking for help about four months ago and look at us now.  We're doing this Z-Team. 

With all of this in mind, I want to look at ways to store energy that is sustainable before and after the energy is stored, and think about the use of materials on board.  I also want to start really considering Biomimetics to inform everything we design (requirement #4?).  Everything we need has already been developed by nature.  Propulsion, water filtration, navigation, you name it. Can we use a tail that moves like a whale or snake to push us through the water and fins to cut the drag?  Can we design hydraulic propulsion based on the same physics principles that plants use to pull water up through their root system?  Can we combine multiple systems to power one or two propulsion systems?  Can we put some bicycle pedal stations in the engine room and let people pedal-power the emergency backup system or turn Z-NEV into a pedal boat?  This Japanese sailor crossed the Pacific averaging 1.5 mph using a wave energy system he invented.  That was in 2008... what can be learned from this?

Also, I recommend following this Boat Design Forum - there are all kinds of great discussions dating back over a decade about everything from wooden boat building to zero energy devices.  We need a social media team leader to start scouring for info and start postings that attract people to Z-NEV projects. 

Spruce Cox
Following up from my 11/26 comment above, we were discussing electrical power requirements f get or main propulsion should we remove and replace the diesels. As excessive speed or power are not required for Denali's mission, perhaps a slower, more efficient, and less costly speed could be found that still meets requirements. I looked at several sites and one had a simple calculator that provided approximate speed versus power with caveats. The results are shown below. From this approximation there is no "most efficient" speed indicated, but this still can be used to compare different solutions relative to each other.

This comment was edited on 12/18. Incorrect data was used in the previous chart dated 12/12 as described in Rick's and Patrick's comments below. I was introduced to the proper data and used it in the updated chart. I also reviewed my analysis process by widening my search for more info and first-hand accounts of individual boatbuilders' and large companies' experiences.

The answers I found still show real-life predictions of boat speed based on today's large standard hull shapes could  be as close as 5% with that gap increasing to 10 or 15% as departures from standard designs are added. There was nothing even close to Denali's design for comparison, so I recommend at least a 20% fudge factor off the curves below.

 All this was incorporated into the updated analysis. The old chart was removed and replaced with the new chart shown below dated 12/18.

image.png 22.4 KB View full-size Download

Patrick J. Bray
Just looking over the graph below and wanted to make a few observations.

On the right is kW (kilowatts of power), on the left is hp (horse power). These are not equal.

100 kW = 134 hp

200 kW = 268 hp

300 kW = 402 hp

400 kW = 536 hp

500 kW = 670 hp

A quick search on the internet (I know risky) of similar vessels would indicate that Denali probably weighs in the neighborhood of 130,000 – 170,000 lbs. when half loaded with fuel, water, etc. An efficient hull, and I believe Denali is, would reach a maximum of 18 mph with 450 hp.

Best regards,

Patrick J. Bray

Naval Architect, Eng.L.

image001.png 79.3 KB View full-size Download

Great information, thank you

Spruce Cox Spruce

Patrick J. Bray Patrick

!  The estimate of 18mph with 450 HP matches her stats with her original Sterling engines and I believe I’ve read somewhere that 18 is her max with her twin 6-71’s.
It seems like something between 200-300 HP would be where we’d find the balance between efficiency and speed(?). 

It’s hard to read but it lists a max of 18.5 mph with 2 Sterling engines. View full-size Download

Another question: Walt James suggested, and we’re exploring the possibility of giving Denali’s hull an epoxy laminate coat (no glass, just resin). Any thoughts or experience with this? Would this also reduce friction by any noticeable measure? Or are there any treatments that we should consider? 

I produced an episode of Green Science Oregon on a lab at OSU that does research on treating wood with essential tree oils like juniper to preserve the wood.  That was 7 years ago and the technology has likely improved. I think they used a heat-treatment pressure chamber to pull the oil into the wood, which would probably not work on Denali. However, does this offer something to consider? Could we use a combo of epoxy and essential oils or would the chemical reaction break down or negate the process we’re after? Or is there an organic treatment that would offer similar benefits?

Spruce Cox
Wow! Looks like I pulled values for the three primary parameters I used in the website equation from three unrelated sources in this project. I sincerely apologize. Thank you both for catching this egregious error. I am updating the chart now. Here are the values I used the first time, and the ones I'm using for update.
 BEFORE:  450 hp (lesser of two values found, from Rick 11/25 comment vs flyer above),  15 mph (lesser of two values found, from same), 102,000 lbs (lesser of two values found, 53 GT from Rick 11/15 comment vs 51 GT from Rick 10/24 comment).
 AFTER: 450 hp, 18 mph, 150,000 lbs. OK?
 Patrick, you also had a question about how to read the graph. It's tricky with two vertical axes---it has to be treated as two separate graphs. To find power (hp) required for 10 mph, go across bottom to 10 mph, up to blue line, then left to blue axis for 200 hp. For power (kW), go across bottom to 10 mph, up to orange line, then right to orange axis for 150 kW.
 Rick, I don't know what any chemical process might due to the wood. However, if a hard, brittle surface is attached like glue to the wooden hull, the brittle surface will shatter as the wood structure underneath moves when underway.
 Guys, now I have a question. What is a double planked hull?

Spruce Cox
Updated analysis addressing all comments above was completed 12/18. Notes on the update and the updated chart itself are located way up this string where the original chart was. The original chart was removed and replaced with the updated chart dated today.


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