Spirit of Acorn . com
Creating a small keel yacht designed for the soul, not the ego
Skyline of Melbourne, Victoria, Australia from Spirit of Acorn
Recent Modifications
While Spirit proved to be a delightful yacht to sail, I could see the need for some improvements. As built the cockpit drained through the outboard well,
and although the waterline passed diagonally through the well, water could surge into the cockpit in some circumstances. I tried adding a rubber skirt that the outboard pushed through when installed, but then I couldn't use the 180 degree rotate reverse. Also the permanent copper epoxy antifoul I had used was causing some problems. The sea critters in the marina, having avoided the antifoul at the start, now seemed to like it. The diver who periodically gave her a scrub found a strange jelly like creature adhering to the hull...
Spirit had been designed to take a small diesel saildrive, but I decided during building that I didn't really want a diesel in the yacht. I toyed with and electric motor through shaft drive at the time, but the shaft angle was more than I would like so I had dropped that idea and gone with the outboard. I had however acquired some of the bits required for electric drive: an ETEK motor, and SEVCON CONTROLLER. I had also noticed the falling prices on the optimal batteries for the task, LITHIUM IRON PHOSHATE (LiFePO4).
The decisions made, Spirit's mast was dropped, she was lifted out, placed in her trailer cradle, and taken back to the factory.
The cockpit sole was cut out, a new higher and more sloped curved sole fabricated and fitted along with a bridgedeck to give me an engine room for the new auxiliary. An old Volve saildrive was acquired, the gearbox removed, the leg rebuilt, then dropped through the hog and rigidly bonded in place (no vibration from an electric motor). A complex adaptor was machined by Zodiac Tooling of Braeside, Victoria. This contained an oil reservoir, and a short mating shaft with seals to adapt from the Volvo leg to the ETEK motor.
Two LiFePO4 packs were acquired, giving me 24 volts at 100Ah. My guess is this will give me between 2 and 4 hours running - we'll see. For safety all cells are monitored and networked such that a contactor can disable them if things go out of spec. The SEVCON CONTROLLER was programmed to run the lot, with it also able to disable things through another contactor. An intelligent charger was installed, able to recharge the batteries in 5 hours from the berth supply.
Kiwi Prop in New Zealand supplied one of their new composite folding props for the Volvo leg. This prop is light and the pitch can be adjusted, making it ideal for the application.
The trailer was modified with rails to allow the yacht to be lifted 50mm hydraulically and slid around 200mm to allow painting conventional antifoul over the copper epoxy. I also shaved about 32kg of the lower sections of the keel to trim the bow up a little and laminated a new tiller of pine with a mahogany contrasting strip.
Custom speed and direction controls were fabricated, and an electronic "fuel gauge" fitted.
I might be making these mods sound straighforward, but they were anything but. I'd built the cockpit sole so well that it took ages to remove it. There was a lack of information on electric conversions, and problems with programming the controller. I'd also had some problems with my rigid laid deck that need to be corrected, and some areas where UV was playing havoc with the vanishing.
Spirit was relaunched in October 2012, and relocated to the Anchorage Marina at Williamstown. While the electric installation proved quite workable, there was not a great deal of power. The issue was revisited in October 2013 while she was out of the water for annual antifoul. Some reprogramming of the SEVCON Controller has dramatically improved things. Heaps more power. The problem was a current limit I had programmed into the Controller, which seemed to interprete this as an indicator that my motor was wimpy (the ETEK is anything but), then limit the current further. Increasing my programmed current limit unlocked more of the motor's power. (For the technical a limit of 70amps was giving me a maximum of 40amps, a limit of 110amps is giving me over 70 amps. Just like driving a car you need the power to get moving, then drop the throttle back to conserve power. The ETEK can handle 300amps!) If you are contemplating going electric drop me a line, email me.
Follow this link to some photos.
While Spirit proved to be a delightful yacht to sail, I could see the need for some improvements. As built the cockpit drained through the outboard well,
and although the waterline passed diagonally through the well, water could surge into the cockpit in some circumstances. I tried adding a rubber skirt that the outboard pushed through when installed, but then I couldn't use the 180 degree rotate reverse. Also the permanent copper epoxy antifoul I had used was causing some problems. The sea critters in the marina, having avoided the antifoul at the start, now seemed to like it. The diver who periodically gave her a scrub found a strange jelly like creature adhering to the hull...
Spirit had been designed to take a small diesel saildrive, but I decided during building that I didn't really want a diesel in the yacht. I toyed with and electric motor through shaft drive at the time, but the shaft angle was more than I would like so I had dropped that idea and gone with the outboard. I had however acquired some of the bits required for electric drive: an ETEK motor, and SEVCON CONTROLLER. I had also noticed the falling prices on the optimal batteries for the task, LITHIUM IRON PHOSHATE (LiFePO4).
The decisions made, Spirit's mast was dropped, she was lifted out, placed in her trailer cradle, and taken back to the factory.
The cockpit sole was cut out, a new higher and more sloped curved sole fabricated and fitted along with a bridgedeck to give me an engine room for the new auxiliary. An old Volve saildrive was acquired, the gearbox removed, the leg rebuilt, then dropped through the hog and rigidly bonded in place (no vibration from an electric motor). A complex adaptor was machined by Zodiac Tooling of Braeside, Victoria. This contained an oil reservoir, and a short mating shaft with seals to adapt from the Volvo leg to the ETEK motor.
Two LiFePO4 packs were acquired, giving me 24 volts at 100Ah. My guess is this will give me between 2 and 4 hours running - we'll see. For safety all cells are monitored and networked such that a contactor can disable them if things go out of spec. The SEVCON CONTROLLER was programmed to run the lot, with it also able to disable things through another contactor. An intelligent charger was installed, able to recharge the batteries in 5 hours from the berth supply.
Kiwi Prop in New Zealand supplied one of their new composite folding props for the Volvo leg. This prop is light and the pitch can be adjusted, making it ideal for the application.
The trailer was modified with rails to allow the yacht to be lifted 50mm hydraulically and slid around 200mm to allow painting conventional antifoul over the copper epoxy. I also shaved about 32kg of the lower sections of the keel to trim the bow up a little and laminated a new tiller of pine with a mahogany contrasting strip.
Custom speed and direction controls were fabricated, and an electronic "fuel gauge" fitted.
I might be making these mods sound straighforward, but they were anything but. I'd built the cockpit sole so well that it took ages to remove it. There was a lack of information on electric conversions, and problems with programming the controller. I'd also had some problems with my rigid laid deck that need to be corrected, and some areas where UV was playing havoc with the vanishing.
Spirit was relaunched in October 2012, and relocated to the Anchorage Marina at Williamstown. While the electric installation proved quite workable, there was not a great deal of power. The issue was revisited in October 2013 while she was out of the water for annual antifoul. Some reprogramming of the SEVCON Controller has dramatically improved things. Heaps more power. The problem was a current limit I had programmed into the Controller, which seemed to interprete this as an indicator that my motor was wimpy (the ETEK is anything but), then limit the current further. Increasing my programmed current limit unlocked more of the motor's power. (For the technical a limit of 70amps was giving me a maximum of 40amps, a limit of 110amps is giving me over 70 amps. Just like driving a car you need the power to get moving, then drop the throttle back to conserve power. The ETEK can handle 300amps!) If you are contemplating going electric drop me a line, email me.
Follow this link to some photos.
Contents and Photos (c) 2010-2015 Paul Stuart - Contact to extract or link
