Re-Powering a 1910 Yacht with Electric


Read more on the Vagabond Repower.

Read more on the Vagabond Repower.

Late in 2010 David Gillespie approached Huckins Yacht Corporation, an authorized Elco Dealer from Jacksonville Florida for assistance with re-powering his treasured restoration project “Vagabond”, a 1910 Yacht built by Consolidated Shipbuilding. This is when, Jon Hall, entered the picture being Huckins lead designer for nearly thirty years. After visiting the boat in her nearly restored condition still mounted atop the custom trailer where she had sat for 50 years. The challenge was to guess from an eye ball gut feeling and studying old pictures how she may have floated with her original machinery. Luckily David had “Vagabond” weighed at a truck scale before he started his retoration. After subtracting the trailor weight Huckins was off and researching re-power options.


Prior to David contacting Huckins, he did some in depth research on his own. The problem he discovered was there were so many options and everyone he contacted claimed their product or method was the ultimate. To say the least it was confusing. When David contacted Huckins they already had some experience with electric power and hybrid research as Huckins had been toying with the idea of designing and building an Electric yacht for some time. The use of electric drives in large ships is quite common as it is with locomotives, buses and now automobiles. The technology has been around since the late 1800’s.

Jon Hull guides you through a repower with his honest thoughts and insights.

REpowered with an Elco Electric Package“First, do we simply repower with a conventional diesel and be happy. The problem with that was the original motor was placed in the galley/salon smack in the center exposed with no sound or heat shield. Remember this was 1912 when reciprocating motors were a novelty in boats and it was “cool” to hand squirt your oil can to keep the valves lubricated as you chugged along and on occasion staining your white yachtsman attire. A further negative was the original 40 H.P. diesel weighed about 1800 lbs. A modern comparable diesel weighs but a fraction. Therefore we would have to add additional ballast to keep her in proper trim. A feat constrained by a lack of space to add weights as needed.

The second choice was to power with a diesel with an electric drive coupled to it and since it was smaller than the original, it could be tucked away easier. Since it relied upon batteries, these could be placed about for an acceptable balance. However, to date a suitable product did not have the electric portion powered enough to suit our 40’ yacht.

Following, we studied what others had done both commercially and hobbyist. Everyone had their own theory about which voltages were best, types of batteries etc. It was becoming increasingly clear the weak link to any electric system is the battery. I find it interesting to note that in 1897 an electric car was advertised for the amazing feat of attaining 40 miles on a single charge using “old fashioned” technology batteries. In 2012, 115 years later our modern autos advertise the same, 40 miles! But instead with hi tech lithium-ion units that cost several thousand dollars each. The other stumbling block we encountered was a suitable charger. The charger industry is woefully behind this new era and understandably so. The entire marine industry has been centered around 12 and 24 volts primarily.

Finally, we discovered Elco or should I say rediscovered Elco Motor Yachts. Huckins and Elco have a mutual background developing the P.T. Boats of WWII. I remembered in their early years they produced electric powered yachts so I contacted Peter Houghton and soon began conversing with their engineer, Joe Fleming, whose personal history also dates back to the P.T. Days. 

By consulting with the Elco experts it became quite clear as to our direction to proceed. As usual my lean toward going back to basics tilted. We would build from there to complete a reliable and user friendly system that meets David’s expectations. First, the Elco Motor is made in the U.S.A. Second they have a range of power units. We chose the EP-7000 rated at 35 H.P. DC. Third, they have a good track record, excellent communication skills and support.

Now that a motor has been selected, the next decision would be how to supply the power. Should we use a DC Genset or AC? A major factor for choice was physical size with relation to H.P. required. Also R.P.M. was a factor. High R.P.M. diesels seem to have inherently more maintenance and longevity problems than slow turners. A service network was also considered. DC generation could be simpler with a DC motor but also more costly. AC need to be converted to DC. However, it seemed sensible with our project to go AC. We chose a 6 KW Kohler 1800 RPM also USA made.

Next came a battery choice. We decided due partly with size, the choice to be the A614 Odyssey PC 1800 @214 A.H. each. These seem to be a tough battery for the money. As they can be drawn down quite a bit without damage as long as they are recharged immediately.

Now we have the major components, motor genset and batteries. However, at what voltage? The motor as MFG is rated for 108 VDC a rather odd number considering all is divisible by 12, a typical battery size. Therefore we would need 9 or more to produce an acceptable cruising range. Nine at 108 volts created two problems. First, our yacht is space challenged and the most logical place to locate them was exactly where the extra weight would be detrimental to her trim. Second, optimally an additional bank would have been preferred to minimize operating the generator. This dilemna led to my next challenge. 


Aforementioned were the severe lack of spaces to locate machinery, components and batteries considering this is a 40’ yacht. Due to the hull design there was minimal bilge space. The hull, typical of the era was shaped similar to a sailboat. The forward cabin soles were about 6” to 8” above the planking. The hull sides quite rounded rose quickly to close off all but a triangular void of minimal dimension under the settees and berths. That is why the original motor sat in the salon as a conversation piece, if one could speak above the noise and fumes. Just aft of the motor the rounded hull converged gracefully upward to form a pretty fantail. For a power boat the aft styling was beautiful but with the sharply ascending hull lines, much needed buoyancy was sacrificed. Adding to the mix the area aft of the motor was also the helm and lounge deck where all people congregated while underway. It could be interesting what the original architect had in mind for stability. To balance the yacht, 2 tanks for fuel and water were placed vertically in the fore peak usually reserved for anchoring and rode storage. A 4” x 3” x 30 ft railroad track steel rail shoe was affixed to the bottom of a shallow keel to lower the C.G.

The motor and genset weight totaling about 900 lbs, was less than half the original weight that came out. I performed no less than a dozen overlay sketches on the hull arrangement plan. With each sketch a new weight estimate was calculated to determine the balance effects both longitudinally and transverse trim.

Almost every scenario would mean encroaching upon living space and or altering the beautiful hand crafted joiner restoration David so meticulously preserved. 

We finally launched the yacht minus any of the three major components to get a feel for flotation. Following my most promising of weight distribution calculations we had about 10 of Huckins employees call out their body weights and then stand on the appropriate deck areas to simulate the actual installation. After a couple of tries I was satisfied we could begin installation.

It became glaringly apparent that I would not have the space to install 9 batteries in a practical bank allowing for minimal wiring. Mind you 4/0 cable does not bend easily. Now what! We needed 9 batteries to supply 108 volts this is where Elco and Joe Fleming came to the rescue.


Following several speed/performance studies along with Joe’s recollection of how easily these old yachts graced the waters he guesstimated a propeller size and determined the hull speed to be 7.5 to 8 knots.

Thus we could predict the rate of discharge for a given cruise speed and calculate the hours available to operate without the generator. As aforementioned the ninth battery was a problem to produce the 108 volts needed. We needed a trade off.

Knowing David’s projected use of Vagabond was mainly for luncheon or evening cocktail cruises on the beautiful lower usually calm St. Johns River. It appeared they could enjoy a good 5 hour amble in 5 knot silence. This is with 9 batteries. Adding to the 108 volt requirement problem was we could find no off the shelf 108 volt charger that had a satisfactory DC output. All the major players said they could custom produce one. However, it would be expensive as a one off unless several were ordered. 

We all traded thoughts as to real life usage. I noted if we could eliminate the ninth battery it would theoretically reduce David’s cruise time by only a little over an hour. This would still give ample time to relax and enjoy considering power off drifting or at anchor.

Joe with his background in electronics engineering and Peter concluded they could adjust the motor to only require a 96 volt supply! Thus my space dilemma was solved. Our guys began construction of a framework to house 8 batteries in a neat cluster centered around the motor area. This additional 1100 lbs rounded out the total 1800 lbs needed to replace the original machinery in nearly the exact hull location. The neat feature of the AGM Odyssey batteries is they can be mounted upright or on their sides.

Now all we needed to conquer was the charger problem, normally, most chargers can handle only 2, 3, or 4 batteries tops. Therefore we would require a minimum of two plus a third to service the house bank as the propulsion and house cannot be integrated. It has been our experience at Huckins, so called “smart chargers” especially in a marine environment sometimes are an electron or two short at best. To complicate their intelligence envision two or more attempting to supply the same bank in perfect unfaltering unison! Complicate the challenge further by adding the fact that the input algorithm required for optimum charge to the battery is different if the AC power comes from a genset or shore power due to the pulsating load on the motor. 

We found a charger company, Elcon that would customize their units as needed with no premiums for one-offs given my quest to “keep it simple” I preferred one charger only to supply all 8 batteries. Joe stepped up and worked with Elcon’s owner to build a charger to supply 96 volts equally and programmed to match the battery requirement whether being supplied from the genset or shore power. It can produce 45 amps at 220 volts and is marine tolerant. 

Finally, we elected to further the simple rule by monitoring the battery depletion rate to time left visually from a digital monitor. When the numbers require, simply start up the genset and continue the voyage. 

Following complete installation Huckins mechanic Eric doused the shaft bearings with WD-40 and flipped the switch all systems came up perfectly in a dry test. We are now ready for launch and river trials.


As Vagabond was slowly lowered into the slip below the travelift we all watched with wonder as she sank lower and lower into the nest of water. Did I guess right with weight replacement? The straps released their lifeline hold and Vagabond was on her own swaying to the slight current and breeze exactly where her newly painted boot stripe wanted her to be.

Joe was right, that type of hull is slippery. It doesn’t take but a light shove to send her off. We tied her to a dock and tested the genset part of the mix. Then we simply let the motor run in place to create energy use data. Remember this battery bank is our fuel tank. We needed to know where the full, half and empty marks are before sailing off to a point of no return unless David has a good set of long oars or a retainer with Sea Tow.

We chose a pleasant afternoon without too much breeze or current for the grand test. The results were exciting. The 18 X 10 wheel pushed Vagabond effortlessly and . . . with a lurch if you weren’t light fingered with the throttle. An electric motor is far different from a recip. First, the 35 H.P. rating is equal to a 70 H.P. diesel. Second, it has maximum torque at 1 RPM. Since there is no gear box, only changing direction of the motor rotation from clockwise to counterclockwise when docking is needed. It can be tricky at first because the only slow gentle maneuvers are directly related to your very light touch of the joy stick.

The motor top RPM is 2000. However, you can short boost it to 2500 in emergency. On a boat of this size and hull shape the 35 H.P. unit is more than David will ever use. The river cruise results we discovered were the following: We were going against an outgoing current so we did runs in each direction for an average.

At 400 RPM she ran about 2.5 knots. At 600 RPM we moved along a little over 4. At 1000 RPM it was a hair blowing 6.5 knots! At 1500 RPM we reached hull speed at 7.5 knots. Any faster and the bow tries to rise up while the stern settles concernedly. 

In conclusion at 4.5 knots David can expect about a 6 hour cruise adding to that time if he throttles back or cranks up the genset. At this writing we need more cruise time to build data coupling genset charge rate versus amperage draw to determine long range cruise potential.