Electric Re-powering Expert

[Arby Bernt]

Hi to All,
I'm Arby Bernt. I'm an electromotive engineer and owner of Advanced Marine Electric Propulsion.
I'll be glad to offer advice on electric re-powering having installed over 20 systems in sailboats worldwide.
We replaced an A4 in our Ericson 27 with an Advanced Marine 5kw 48v system, and have loved every minute of it. We use a 200Ah AGM battery pack for power. The batteries can deliver full power for about two hours, or partial throttle all day long.
We've also re-powered three Catalina 30's currently in a day charter fleet at a local sailing school. The instructors love the direct drive system, as teaching docking no longer means trashing the transmission with panic shifts.
While I'll advocate our systems in private emails to those interested, I'll be glad to offer impartial advice on installation, battery and charging protocol, and questions from those wishing to fabricate their own e-drives from universal motors.

Be Well,
Arby

 

[Bill Roosa]

I'm wondering how many of the group would buy a sailboat with a 2 gal fuel tank? Two gal-->two hours of motor time.
Also how do I charge my batteries while at anchor for a week?

 

[captcoho]

I'm wondering how many of the group would buy a sailboat with a 2 gal fuel tank? Two gal-->two hours of motor time.
Also how do I charge my batteries while at anchor for a week?

Wind Turbine or Solar Array???

 

[Bill Roosa]

Unfortunately that nice snug anchorage has steep hills so the sun come up late and sets early and the wind does not tend to blow in those locations either.

Clearly either a day sailor solution or awaiting a breakthrough in fuel cell technology that converts diesel directly to electricity (and possibly potable water)

 

[Arby Bernt]

Electric re-powers have been proving successful for many years, provided the operator understands the dynamic of the power source. The general rule of thumb is 2kw per ton of displacement to have the power to reach hull speed. At 70% of hull speed, this figure drops to 500w per ton. Ease back a little, and the batteries will easily last all day.
We've got three Catalina 30's re-powered, each with four 8Ds, in a charter fleet. With thousands of hours logged, there's only been one instance of a boat running out of power. Compare that to several dozen diesel failures during the same operational period.
Electric power is ideal for day sailing, but not for long passages. Losses from the transfer from a generator to electric then back to rotation do not make small boats practical for pure electric power when used in long passage. The option of using power converters and a generator as a secondary power source does allow for extended motoring, but fuel consumption is worse doe to the transfer efficiency.
Electric power works well for the day sailor who still has half a tank of diesel after a season of sailing, but is not recommended for extended motoring days on end.

Arby

 

[Bill Roosa]

hey Arby
Don't get me wrong, electric is a clear solution for the day sailor as you mentioned. I'm just not one of those. Perhaps when fuel cell technology comes down in price it will have an expanded market.

Good luck

 

[sailaway78]

May work for some

This may be fine for some day sailors, but is just not suitable for most of us. I'm not knocking your systems, but stating facts. Hell, I have spent three or four hours, running full bore trying to get away from a front, when offshore. And, just wondering. Where in the hell do you put 4 8D's on a 30 footer.

 

[Arby Bernt]

Four 8D's fit nicely in a Catalina 30. Two under the port galley seating, and two under the starboard bench seat. Our Ericson 27 has eight 100Ah Northstar NSB100s, four across the back of the motor bay, two under the port bench, and two more under the starboard stern berth. A Rawson 30 with four NSB170s and four NSB100s, split into equal packs under seating on either side in the cabin. Four 8Ds fit nicely in Columbia 27, equaling the engine's original mass. All these boats love their electrics, though the Rawson 30 could use more capacity. It's a heavy boat, and would be better off with a hybrid...

 

[dj2210]

I'm very happy with our Electric C27 for lake day sailing. No winterizing, no oil changes, no fuel spills, leaks, or smells. Flick a switch and turn the knob. It replaced the inboard A4. An excellent choice for lake day sailing.

 

[Stu Jackson]

Arby, I find it confusing at best to even consider 8Ds. Besides the weight, most of them may not be true deep cycle batteries. Comments? Would not 6V golf carts fit the bill?

 

[TENACITY CS36T]

I'm very happy with our Electric C27 for lake day sailing. No winterizing, no oil changes, no fuel spills, leaks, or smells. Flick a switch and turn the knob. It replaced the inboard A4. An excellent choice for lake day sailing.

Same goes for my O'day 28, love the instant on, forward or reverse and next to zero transmission losses, full torque at any r.p.m. definitely not for all but can work nicely for many. I'm on Lake Ontario and its main uses are just in& out of harbour, sail mostly

 

[TENACITY CS36T]

Arby, I find it confusing at best to even consider 8Ds. Besides the weight, most of them may not be true deep cycle batteries. Comments? Would not 6V golf carts fit the bill?

Agree totally Stu, I use 8 x6v GC2 batteries, and find I'm never below 70 percent SOC. 4.6Kw motor, approx 7,350 - 8,000lbs of boat in use with crew gear etc.....

 

[Arby Bernt]

I like using AGM's because they can be positioned regardless of angle and don't fume acid during charging. I've used L16s in one install, but replaced the watering caps with re-combiners to cut down on maintenance. That boat, a Storfidra, also has a 3500w propane genny and 55 amp power converters in reserve.
You are correct in that flooded golf cart batteries are the most economical source when purchasing new, but there is another source of batteries rarely tapped. The FCC mandates a two year shelf life for standby power supply AGMs. These batteries are often 100Ah and larger, and can be purchased for a fraction of their new cost. I bought a load of Northstar NSB100s and NSB170s for $50 and $85 each respectively. Ask around, and chances are you'll find a friend of a friend with a garage full of most excellent batteries. Harbor Freight sells a great battery meter, part number 66892, which measures the internal resistance of the battery to determine its condition.

 

[atroon]

Agree totally Stu, I use 8 x6v GC2 batteries, and find I'm never below 70 percent SOC. 4.6Kw motor, approx 7,350 - 8,000lbs of boat in use with crew gear etc.....

Just purchased an O'Day 28 on Lake Michigan. Thinking much along the same lines as you, could you post photos of your setup? I haven't begun budgeting for the repower yet but within the next couple years, that's for certain...I'm still stuck with the SailDrive, and I am not a fan.

 

[Maine Sail]

Harbor Freight sells a great battery meter, part number 66892, which measures the internal resistance of the battery to determine its condition.

Please be careful taking those readings very seriously. Those are cheap attempts at a knock off of the Midtronics technology. They do not agree with either the Midtronics or Argus analyzers both of which are high quality units. I have also used them on TPPL AGM and LiFePO4 and they are absolutely incorrect in the internal resistance they "measure"... The Midtronics stuff is the industry gold standard but very expensive. My Midtronics analyzer cost me nearly 2k.....

The only thing the Cen-Tech is really good for is a measuring changes from a baseline when the batteries are new, other than that it is a pretty sloppy analyzer..