Longest time/distance you've had to motor?

[mikereed100]

Originally Posted by Jim Cate

Just curious: on this route which is usually blessed along much of the way by reliable NW winds, how did this come to pass?

Jim

"Usually" is the operative word here. October, trying to slip down the coast between systems, time constraints. We felt a bit ripped off having to motor through "Gale Alley", but on the other hand, how often do you get to round Cape Mendocino sitting in a lounge chair on the foredeck?

[ArtM]

Originally Posted by bryguy67

It's understandable that there's a lot of confusion between the two systems but a quick internet search will provide some good basic explanations. Conventional systems serve people well and will continue to. But these hybrid systems have many advantages to those who are open minded and properly research them.

This is good to hear. This is more similar to a Prius-style hybrid system. This ought to be the combination that gives the greatest range of economy and performance from the smallest number of components..

[bfloyd4445]

Originally Posted by ArtM

This is good to hear. This is more similar to a Prius-style hybrid system. This ought to be the combination that gives the greatest range of economy and performance from the smallest number of components..

there are other better systems than prius like Fords in which you can run any combination you wish, electric only, D only, D& E together, In the prius they work together all the time which is not what you would want for a sailboat.
west marine sells one like Fords system I believe.

[whosescow]

Originally Posted by mbianka

Aargu:

For some boaters electric propulsion will never be ready. But, really one does not need have a motor at all to sail around the world. A motor is most useful coming into a marina or harbor situation. You don't need it out on the ocean what you do need is patience, planning and perseverance. Vendee Globe being the most recent example.
The longest I've motored so far has been 40 miles while using around 900 watts in a hybrid mode using less than a gallon and half of gas. I only did 40 miles because I had reached my destination. I could have kept going until my fuel ran out if I wanted. That 900 watts propels my 30 foot 8 ton boat along at 3 knots. My 900 watt limitation was the power supply/battery charger I was using.
It is hard to explain how different electric propulsion is to those who have not used it. Even how quiet it is. When I first converted I had many "what if" concerns about what could happen and what would I do if X happens. I've found over the past five years they were misplaced concerns as I gained experience with EP. Personally, I would never go back to diesel. Electric propulsion has proven more reliable and required much less maintenance than when I had the diesel on board. On most boats working on the diesel engine is not fun and plenty of boats have had engine problems while underway. Not to mention the diesel is usually in a cramped, dirty and hot location. An EP boat always has a clean bilge and lots of space around it. Most parts are located in convenient locations for access.
Plus there are also things you can do when you have electric propulsion that you can't do with a diesel. One of the things is making fuel (energy) when underway. You can do this with wind, solar and regeneration from a backwards turning prop that turns the motor into a battery charging generator. I do agree having a small generator does help keep things charged up and moving. In my case a Honda 2000 fills the bill nicely and is used for other functions on board like using power tools. For me the three legged approach to energy on board works very well and gives me options as opposed to relying only on diesel fuel for auxiliary propulsion.

Thank you so much for this post. The naysayers and holier than thou's have been getting me thinking about uninstalling the CF app.
Faith has been restored.

[Perfect Ride]

Hello Aargau,
Our longest that was not an urgent trek was from Bermuda to Azores in May 2015. We had a very large high that kept us in less than 5 knots wind for 6 days and ~800 miles. We slow motored our Cat on one engine at a time, Volvo D2-40, at 1800rpm and used about 80 gallons diesel. We have had many times we burnt more fuel to avoid/minimize storms or for medical urgency, but those were all less time & distance, just higher RPM or both engines.
Hope this helps with your decision.

[Thalas]

The new Tesla Roadster is sporting a 200kWh battery that is estimated at about 2,000lbs. Assuming an electric system with this battery was replacing diesel tanks (940L @ 1750lbs) the weight penalty isn't that bad. Does anyone have an idea of what kind of range an electric motor at 6knts would expect from that battery?

My motor usage is almost exclusively harbor or a few hours waiting for wind. I'm wondering if a 200kWh battery could handle 99% of my needs. Add to that the idea of silent motor sailing to add a few knots for fun here and there and it seems intriguing. Of course, right now, it's not price feasible, but when there are multiple Gigafactories pumping out these batteries, it may be.

[44'cruisingcat]

200 kWh is 20 kW (about 30 hp) for 10 hours.

You'd get an awful lot more from 940 litres of diesel.

[Dockhead]

Originally Posted by 44'cruisingcat

200 kWh is 20 kW (about 30 hp) for 10 hours.

You'd get an awful lot more from 940 litres of diesel.

Nevertheless you could do a lot with 200kWh of batteries. That would give you 5 hours at 60hp -- pretty impressive. If you had a way to charge that and you are not doing long passages under motor, that could work pretty well on a roughly 12 to 15 ton vessel.

This amount today costs roughly $40,000 (LiIon or NCA as used in EV's, not LiFePo4) and weighs about 1200kg. By 2025, the cost is expected to fall by half: https://insideevs.com/lithium-batter...o-100-by-2025/.

I bet there will be some technological breakthrough with batteries, which will change everything.


I recently broke my own record for motoring -- 500 miles in one go with only a few hours of sailing, from Cowes to Scotland. It was not all pleasant slow motoring in dead calm either -- we had to motor against the wind in places too narrow to tack. I was glad to have 7,000 kW/h in the tank.

People who sail around bays in small boats find it easy to say "just wait for the wind to change". If you are trying to get somewhere, you don't always have that luxury. Where I sail, a "weather window" very often is just a short period of the least unfavorable of a few weeks of unfavorable wind. I once crossed the North Sea in a F8 because there was a week of F9 on either side of two days of F8. And a dead calm can be a great weather window when you are facing weeks of headwinds. For me, the ability to motor for long distances is a crucial capability -- YMMV, of course.

[StuM]

Originally Posted by Thalas

The new Tesla Roadster is sporting a 200kWh battery that is estimated at about 2,000lbs. Assuming an electric system with this battery was replacing diesel tanks (940L @ 1750lbs) the weight penalty isn't that bad. Does anyone have an idea of what kind of range an electric motor at 6knts would expect from that battery?

An electric motor at 6 knots will require the same HP at the prop as a diesel engine at 6 knots (HP is HP regardless of origin, despite the hype from various EP proponents).


With a 2000kWh battery bank, assume that 90% is usable ( from 5-95-% SOC, you don't want to overcharge of fully discharge lithium batteries), and that your propulsion system is 100% efficient. That means that you have 1800Wh or 240HP hours of propulsion available.



To maintain 6 knots in good conditions on one engine, I need about 15HP at the prop and that burns about 3.5 lph of diesel.


So diesel or electric, 1800kWh or 240 HP hours, is good for about 16 hours @ 6 knots or just under 100NM.



Key points:


That 100NM maximum range for your Roadster battery would use about 56 litres of fuel in a diesel engine. Your hypothetical "equivalent weight" 940 litre tank would give a range of about 1,600 NM under the same conditions.



The 100 NM figure above is for calm conditions. When beating into adverse conditions, that 100 NM ideal range could well be down to 30 -50 NM for the same energy usage.

[StuM]

Originally Posted by Dockhead

I recently broke my own record for motoring -- 500 miles in one go with only a few hours of sailing, from Cowes to Scotland. It was not all pleasant slow motoring in dead calm either -- we had to motor against the wind in places too narrow to tack. I was glad to have 7,000 kW/h in the tank.

7000 kWh ( no "/" ) is about 9400 HP hours. Rule of thumb for diesel consumption is 0.225 lph per HP. So I make that about 2000 litres of fuel. Yes?

[Dockhead]

Originally Posted by StuM

7000 kWh ( no "/" ) is about 9400 HP hours. Rule of thumb for diesel consumption is 0.225 lph per HP. So I make that about 2000 litres of fuel. Yes?

No, you are taking into account the efficiency of the diesel engine. I didn't say 7000kW/h of PROPULSION, I said energy. Of course it's not an apples to apples comparison. I have 700 liters.

Incidentally, neither electric motors nor battery storage are 100% efficient, either, although obviously they are much more efficient than IC.

[StuM]

Originally Posted by Dockhead

No, you are taking into account the efficiency of the diesel engine. I didn't say 7000kW/h of PROPULSION, I said energy. Of course it's not an apples to apples comparison. I have 700 liters.
.

Ah, I thought that sounded a bit high. So effectively, you've got about 2300 kWh or 3100 HP hours at the prop. Or about 12 of those Roadster batteries (which would be about 24 tonnes and almost 1/2 a million dollars based on your figures above )

[BigBeakie]

The figures for a 45 foot cat of cruising displacement 14ton with efficient hull design, i.e. more performance based, ( Outremer, TAG, Grainger, Stanton, Schionning, etc.) is for 6 knots in calm water it will take about 6kW to 6.5kW from the propulsion battery bank, using Oceanvolt SD15 motors.

For a 200kWh bank that's about 33 hours of motoring, or just under 200 nm.

But IMO, this is the wrong solution for a cruising cat, especially a coastal cruising cat. Basing long distance motoring for EP on overly large battery banks puts you in a vulnerable position on the recharging side of the equation. You must be able to put that energy back in a reasonable period of time, in case you need it again, soon, for adverse conditions. Even with a 15kW DC genset like we have, that would still take about 13 hours of recharge time. Who wants to run a genset for that long to get such a huge bank back to full charge? What happens if the weather makes an exposed anchorage dangerous in the meantime?

What we think is a better strategy is to have enough Lithium for about an hour of full power, a DC genset that gives you adequate boatspeed under adverse conditions, and a good investment in solar for becalmed conditions.

For example we will be in the tropics alot, and it can be windless for days at a time. With our Oceanvolt 15kW Servoprop motors and our 4.5kW solar array fully deployed, we will motor at about 4.5 to 5 knots on the output of the solar alone, and be able to then dip into the Lithium propulsion bank as the solar drops off late in the day for another silent 5 hours battery based motoring. If we still need to keep going, then the genset comes on and recharges our bank fully in 2 hours as we continue motoring at 5 knots. That cycle continues until about 10am next morning when the solar kicks in again.

When the wind returns then it's gravy time as the Servoprops regenerate at a significant rate ( 3kW at 8 knots boat speed !! PER MOTOR &#128512 and the DC genset is retired from the energy equation until the next becalming or some adverse condition arises that requires motoring such as current in restricted manouvering area, when it will be longer than an hour of motoring etc.

It is silly to harp on about energy density of diesel compared to battery when it is obvious you are not going to try to go long distances on battery alone. For EP, battery is perfect for maximum power for about an hour, or for manouvering the boat with instant torque. Then let the solar fill your tank again.

Guys, it's really not such a hard concept to grasp.


Sent from my iPad using Cruisers Sailing Forum

[44'cruisingcat]

An efficient 45 foot catamaran that weighs 14 tonnes?

I doubt if it's a Tag, Grainger, certainly not a Schionning - their 45 footers weigh closer to half that.

[a64pilot]

Originally Posted by BigBeakie

Guys, it's really not such a hard concept to grasp.


Sent from my iPad using Cruisers Sailing Forum

It’s not, just I think your numbers are optimistic, and when you start stacking optimism on top of optimism, that is how you talk yourself into things that just won’t happen.
I see it in aircraft all the time, we call them paper airplanes, cause the theories work on paper, too bad we don’t fly paper airplanes, or sail paper boats.
However I wish you luck with it, I hope you pull it off, others have tried and failed, maybe you will be the one to pull it off.
First one that does is going to get a LOT of attention