swaping Volvo Penta for electric drive

[AndyEss]

Originally Posted by boat_alexandra

If it's dangerous to loose your motor, it's better to choose electric by far more reliable.

The ocean not only is statistically safer than a road, you also have adequate propulsion from sails to continue which is already sufficient without any motor anyway. It is also sufficient to enter and leave harbors, and most cruising boats actually can tack into (for me 50ft) wide channels. With electric you can be confident tacking in narrow channel the same as my sculling oar prevents missing tacks from wind shift or collisions to other boats using the motor to hold place when other boats pass in channel then continuing tacking.

In this way the battery capacity actually needed is very small, about 100wh per ton already enough to motor a few miles which is more than enough.

Adequate propulsion from sails? If you hadn’t noticed, winds in many regions of the world are highly variable. You can have dead calm, while previously generated swells or currents still act on your hull.

Sculling? Most human history has been to develop other methods of energy harvesting other than use of human muscle, especially where significant levels of energy are required. Human bodies wear out from heavy to extreme exertion. Historically, disposable humans (slaves) or equally disposable draft animals were ubiquitous until Watt harnessed steam power.

From my observations, the large majority of cruisers are retired couples. I seriously doubt that sculling a boat large enough to comfortably house two adults of retirement age is a realistic option.

Even a young body wears at an accelerated rate when heavy or extreme exertion is demanded of it. Shoulder joints aren’t particularly robust as they are re-purposed quadriped joints adapted to a bipedal animal.

I don’t doubt at all that electric motors are far more reliable than ICE engines - just about all stationary industrial power applications use electric motors. Near universal application is prima facie proof that electric motors are superior to ICE engines in stationary applications. What is also nearly universally true are that these electric motors are connected to very large scale electrical grids, where the source of electricity is industrial scale hydropower, steam turbine (coal, gas, nuclear heat source) generation plants. Wind and solar generation is increasing every year.

Electric motors are great - batteries (and re-charging them) is a severe limitation for marine propulsion.

[Pete7]

Originally Posted by AndyEss

Adequate propulsion from sails? If you hadn’t noticed, winds in many regions of the world are highly variable. You can have dead calm, while previously generated swells or currents still act on your hull.
.

I think Arecuk is in Spain. If it's the Med coast then unlike the Caribbean with steady trade winds, the Med has either nothing or too much wind, frequently.

Others on here have jobs to be back to on a Monday morning. Perhaps in the future when I retire I can slowly sail about choosing when to go to sea.

An interesting science project for those who can live with the limitations and initial up front cost.

[Flamehand]

Originally Posted by arecuk

hey guys,

so I'm contemplating swapping 30yo volvo penta MD11C with saildrive for an electric drive, but can't spend too much money for the professional solution, and so DIY approach has to work for me somehow

I got 35ft, 12000lb sailboat, performance oriented for IRC racing

and so, I've found decent 10kW 48V bare electric engine, see attached pic and the link here:
https://www.thunderstruck-ev.com/sev...it-10.5kw.html

my biggest concern is the transmission ... I got saildrive, and now trying to figure out how to couple it with the electric unit



see the pic attached

I think either Option A or B would do best, but I'm not sure what would it take to do in DYI approach, any ideas?

and so, Option C seems to be more straightforward, but I guess I would lose some output due to multiple gears involved in various positions ... is that right?

in your opinion, what are the pros and cons between Option A and C, in terms of work needed and efectivnes of power transmission?

thanks a lot!

****************************************


I would recommend having a look at Sailing UMA on Youtube. They have gone through exactly that transition and would have a lot to share with you.

Regards,

Flamehand

[SieveSailor]

I did exactly what you are contemplating last year. I would be happy to share what I've learned. I have a boat almost exactly the same size, and I replaced an old Volvo Penta MD2B with the same TSM kit you are looking at. I've been very happy with it. It is quiet, no smell or vibration, and I can do 5kts all day for a couple bucks of electricity. You can look up some of my posts to see what kind of performance I've had and what I used for a battery etc. If you would like to give me a call, PM me your phone number. Also, not sure where you are located, but I'm in the Pacific Northwest so if you are nearby you could meet me after this virus thing is over and see how I did my conversion. Or I could share some pictures with you of what the final project looks like. There are a lot of little tricks and tips I could share if you run into obstacles. It was a lot of fun but an intense technical project, so be prepared to learn about electricity, batteries, and wiring. Happy converting!

[sparrowhawk1]

Here's a young couple that's lived with electric for a while and are upgrading. They're pretty cool I don't know why the clickbait. Before they replaced the motor they upgraded with Battle Born batteries.
https://youtu.be/GoD-j9Dy6xQ
I scrolled through too fast. I see flamehand beat me to it.

[AndyEss]

Originally Posted by SieveSailor

. I have a boat almost exactly the same size, and I replaced an old Volvo Penta MD2B with the same TSM kit you are looking at. I've been very happy with it. It is quiet, no smell or vibration, and I can do 5kts all day for a couple bucks of electricity...Happy converting!

Assuming that all day means daylight hours - let’s say 12 hrs.

Don’t know specific power curves, but say the 10kW electric motor has to run at 80% output (10 hp) to drive that 35 ft, 12,000 lbs hull at 5 knots. That gives a little over 2000 A*hrs as the useable battery capacity required. That’s a rather big bank of LFP batteries. If lead acid batteries were used, you would need 4000 A*hrs of battery capacity.

At a charging rate of 200 A, it would take 10+ hrs to recharge. At a cost of $0.10/kW shore power and assuming 100% energy conversion, I come up with $8 to recharge.

[SieveSailor]

Originally Posted by AndyEss

Assuming that all day means daylight hours - let’s say 12 hrs.

Don’t know specific power curves, but say the 10kW electric motor has to run at 80% output (10 hp) to drive that 35 ft, 12,000 lbs hull at 5 knots. That gives a little over 2000 A*hrs as the useable battery capacity required. That’s a rather big bank of LFP batteries. If lead acid batteries were used, you would need 4000 A*hrs of battery capacity.

At a charging rate of 200 A, it would take 10+ hrs to recharge. At a cost of $0.10/kW shore power and assuming 100% energy conversion, I come up with $8 to recharge.

Close on some of that Andy. Takes me about 2kW of power to keep up 5kts. My length and tonnage are a little higher than his, but I probably make up for it somewhat with the narrow 9.5 ft beam. I have 13.5 kWh available in my 17kWh LiFePO4 battery. That gives me about 6 1/2 hours of run time which is "all day" to me. Electricity is $0.12 per kWh, which comes out to about $1.60 to recharge the top 80% my bank when I'm done. My charger puts it back at around 1.5 kw, which roughly translates to a little over 9 hours to charge at my slip. If I wanted to run 12 hours a day, I would need a second battery the same size (48 CALB 100AH in 3P16S). If I did that I would consider getting a 50A slip and use a second charger to charge both batteries simultaneously at 25A. I don't motor all day typically though and I carry a backup 3.5kW generator and have never had to use it yet, so it depends on the kind of sailing/motoring you do. I like to motor sail, so I am often using only a small amount of power and I come in at the end of the day and still have over half of my energy reserves. Being in the San Juan Islands means I deal with a lot of very light or undependable winds. One of the nice benefits of the electric motor is that I can quickly deliver a little power when needed to balance the helm or to keep my speed up through a low speed tack. I always say though that electric power isn't for everyone yet. But for those of us that don't need to motor for days on end, the benefits are totally worth it.

[AndyEss]

Glad to see that our numbers come out so close, except for my assumption of how much power it would take to drive the hull at 5knts.

I’ve had to side tow my rather heavier Hans Christian 38 when my starter went out and I couldn’t get the iron topsail running, with my dinghy and 5.5 hp outboard. At probably 60-80% full throttle, I doubt I was moving at more than 2+ knts. I wasn’t trying to be scientific, just wanting to get out of an anchorage that became exposed due to a windshift and get to a safer anchorage 3 or 4 miles away. I admit to have been more focused on trying to keep a young Brazilian hottie happy on being on a somewhat non-operational boat.

Again, I have no doubts whatsoever as to the vast superiority of electric motors over ICE, but even Elon Musk is only achieving incremental improvements in the energy storage problem. His work with Space-X is incredible.

[Tom and Maje]

You should watch the Sailing Uma videos on YouTube. They are two young architects with contractor experience. They removed a diesel engine and installed an electric engine. Their videos go into their thought processes.

Maje

[SieveSailor]

I strongly recommend something that allows you to change the gear ratio. Your BLDC motor will have high torque even at low rpm unlike a diesel so it's not easy to know what gear ratio is going to give you the most efficient transfer of power while keeping up motor RPMs which is important for a self cooling motor like the one you've chosen (which I also use). Using a gear reduction will allow you to experiment if needed to find the right ratio for you by swapping out the pulley for a different size. You should discuss with the guys at TSM.

[tp12]

Originally Posted by Tom and Maje

You should watch the Sailing Uma videos on YouTube. They are two young architects with contractor experience. They removed a diesel engine and installed an electric engine. Their videos go into their thought processes.

Maje

They're upgrading to an oceanvolt saildrive right now, too.

[tp12]

Originally Posted by arecuk

hi tp12, well Im not sure I understand your point ...

I apologise for not responding earlier. As boat_alexandra confirmed, the majority of people on this forum don't believe the technology can support going electric. Please note this is not my opinion and I'm pretty happy seeing more people going in that direction.


Good luck with it.

[asistephen]

Originally Posted by Johnniegee

Spend boat bucks to devalue your boat better to rerig and wire your boat and give the Volvo some love

Yeah I agree with this .

[asistephen]

RANGE range to me is really important and I think it should be for everyone. While people will say you have sails ,
in an emergency which can mean many things such as medical ,
you need to get into landfall quick,
you may have a number of other reasons not life threatening perhaps but still really important reasons to make way ,

I know a tank full of diesel on most cruisers will run for about 24 hours or more hours ,
and I’d be interested to know the range of most with extra jerrycans probably will be more .

If you could get that Range with electric then I’d Go for it . But I doubt you can get close. When you’re sails are of no use what’s your
range ? X you’re possible risk = possible outcomes

Risk assessment tells me you have to stay very close to land .

[tkeithlu]

I don't think I would pursue this project without including a genset adequate to power the saildrive when the batteries go flat. It's the same problem as all-electric cars as opposed to hybrids - they've got a limited range and a long slow recharge. I don't want to end up waiting on the side of the road for AAA to arrive with a battery, and I really don't want to be left sucking my thumb in an active seaway.