Saturday, June 20, 2009

The Electric Powered Sailing Vessel Intrepid

Underway to Zamami jima
There are many electric powered boats afloat today. Among them is the sailing vessel, Intrepid. S/V Intrepid is a unique boat. This Bristol 32 sloop, built in 1967 was the third of about 300 Bristol 32s that were designed by Ted Hood and Dieter Empacher for Bristol Yachts in Rhode Island from the mid 1960s to the early 1980s. The Bristol 32 was designed as a modest production coastal cruiser, based on the old CCA racing rules design which featured exceptionally long overhangs, giving the boat a classic look. Bristol 32 number 3 was also the only Bristol 32 that was built with a fin keel, instead of a full keel or full keel and centerboard design, like the others.
S/V Intrepid was already unique but in 2009 Greg Martin decided to modernize this classic with a new auxiliary propulsion system. After removing the Yanmar 3GM30 diesel engine, the old engine was replaced with an Asmo Marine Thoosa 9000 electric propulsion system, powered by a 48 volt battery bank. The conversion project was done by the owner (an inexperienced amateur) in about 9 months, working part time and for the total expense of just over the resale value of the diesel engine.
Yanmar 3GM30 diesel engine 
The new electric auxiliary propulsion system uses a 9 kilowatt Lynch motor on a stainless steel mounting frame, which sits on the same motor mounts as the previous diesel engine. The propeller and shaft are also the same as with the previous diesel engine. The system consists of the motor, a motor controller box, a throttle control unit, a Xantrex Link 10 battery monitor and of course the batteries. The batteries that were chosen for this system were the best and cheapest that could be found in Japan at the time. They are lead-acid/ wet cell deep cycle forklift batteries. In Japan, the ratings for batteries are different than in the U.S. and elsewhere, but these Panasonic EB-160 batteries are the equivalent of 200 Amp-hr (C/20 rate) batteries that would be used for this application elsewhere.
Asmo Marine Thoosa 9000 with battery bank
Converting Intrepid to run on electric involved a major change in many aspects of the sailing experience. First, the removal of the diesel engine made the boat smell better. The USCG mandated oil placards were removed, since fuel and oil is no longer kept on board (except olive oil, for cooking) and the crew was now able to notice other smells, like mildew... which is easier to clean. The other big change was the change in the use of space on the boat. With the engine removed, the electric motor takes up much less space. The batteries now sit on the engine mount, which keeps the trim of the boat about the same but the battery box also makes a nice support for a teak ladder that was made in place of the engine compartment steps. In order to make room for the battery box, the old 1960s- style ice box had to be removed, which allowed for a small navigation station to be built in the corner. Also, in place of the fuel tank, an equal sized fresh water tank was installed, which doubled the fresh water capacity.

The removal of the engine and all of the associated systems actually made the boat a lot more simple. Now instead of an engine, with associated fuel, oil, coolant and 12 volt electrical systems, Intrepid just has one big 48 volt electrical system, with a simple 48 volt DC- 12 volt DC converter to power house loads.  The 12 volt distribution is handled with a simple panel and master breaker switch that isolates the house loads from the DC-DC converter. This takes the place of the battery selector and isolation switches in the conventional combustion engine system arrangement. Gone are the days of having to remember to isolate the starter battery or switch between different house batteries. When designing this system, it seemed that there was very little information and authoritative guidance available on how to reconfigure the overall electrical system when installing the electrical propulsion system. However, this amateur, jury- rigged design seems to be working perfectly so far. When the batteries aren't being used to run the motor, this giant house battery bank can also power any appliance you would ever want on a 32 ft boat. Once a new 48 volt inverter is added to the system, it will be interesting to see what other amazing improvements this new electrical system allows.
Intrepid crew

Since the electric conversion project was completed, s/v Intrepid has been back in service as an American Sailing Association (ASA) sail training vessel, taking sailing students on regular trips to the islands around Okinawa. Within limitations, the electric propulsion system has performed very well. The crew that embarks on these trips in open ocean conditions are always aware that s/v Intrepid is primarily a sailing vessel. The electric propulsion system has been totally reliable and works wonderfully for getting the boat in and out of the marina and maneuvering around the dock. The system can even drive the boat through occasional lulls in the wind on the open sea and can help generate apparent wind when there is no wind at all. With the system always on while sailing, if the crew accidentally tacks the electric motor is immediately available to help save the boat's momentum. One thing the electric motor system can not do however, is propel the boat great distances when the crew is too lazy to raise the sails. The crew of s/v Intrepid therefore, never fails to learn the importance of optimal sailing performance and always gains a full appreciation of the sailing abilities of a well designed sailing vessel.

Monday, June 15, 2009

Bristol 32 Electric Conversion Project

Bow heavy with engine removed
Since I've been sailing Intrepid and I started this blog, the biggest thing that has happened has been the project to convert the boat to run with an electric motor. This was a pretty big move that took some time to see through. When I acquired the boat, Intrepid came with a well functioning Yanmar 3GM30 diesel engine. The engine served us well for awhile but then one day there was an oil leak and the engine ran with low oil pressure long enough to cause some damage. The engine was taken out of the boat and after a long and inconvenient downtime period and at great expense, it was rebuilt and reinstalled in the boat. It was while the engine was out of the boat, that I first began to consider the alternatives and question the sense of having a diesel engine in a sailboat. When the newly rebuilt engine still gave me trouble, it was then that I made the commitment to make the switch. So one day I just hired a crane, pulled the engine out and went to work... Once the project was completed, enjoying the results and then hearing of world events such as the Gulf of Mexico oil spill, fully strengthened my resolve that converting to electric was absolutely the right move.



Before: Yanmar 3GM30 diesel engine

Converting s/v Intrepid into an electric boat, I have to say honestly, was a real pain in the #$^&. But in hindsight it was definitely worth it and it can be (and was) done by an inexperienced amateur. Working part time by myself, and making lots of mistakes, the project took me approximately 9 months to complete and cost roughly the resale value of a Yanmar 3GM30 diesel engine. Since the work was all consuming, I often forgot to take pictures and didn't take very good notes. What little I present here, is not meant to be instructive, but really just of interest especially to those who have sailed on Intrepid since and want to gain an appreciation for what all went into this green sailing wonder.

Since the marina charges a lot to be hauled out, I decided to do the entire project in the water at the normal slip. The engine was lifted out of the boat at the seawall and then we had to sail back into the slip. The winds were just right and we found that sailing around the dock is really no problem at all. What was interesting though was seeing the boat in the water with about 400 pounds taken out of the stern. S/V Intrepid would float front heavy, with her butt in the air, for the next several months.

Engine mess
One of the first things that had to be done was remove and de-tox the boat of all the diesel engine components and grime. All of the fuel, exhaust and cooling system components had to be removed of course. Removing the 25 gallon fuel tank opened up a large area under the cockpit. Also, the area where the conventional house and starter batteries used to be had to be removed. This opened up storage space in the cockpit lockers. Once all this area was cleaned and painted, a new 25 gallon water tank was able to fit in the same space where the fuel tank once sat. The area where the batteries used to sit on a shelf was cleaned and made into a dedicated dive gear storage space.

Removing and replacing the previous 12 volt DC system (batteries, cables, charger, monitor, etc.) was a big project. Of course re-doing the electrical system is really what this project was all about. As tedious as it was, it was actually very interesting at the same time to see how everything used to work (or really didn't!) and come up with a plan for how it really should work. I should've known my old system better, but the new system is so much simpler, actually. While re-doing the electrical system I was able to re-run the wiring the way it should be, neatly and was able to trace and inspect every wire. All of the supporting components, such as the new 48 volt battery charger, DC-DC converter, and eventually a 48 volt inverter and regulators for solar panels and wind generator are now all located in one convenient and protected area that is close to the motor controller and 12 volt distribution panel. All the electrical system components are now protected and easily accessible.

Motor and battery mount under construction
Another big project- actually the biggest and hardest, was the placement of the batteries. Ideally, you want the heavy batteries to be low and center in the boat and away from the motor, especially if they are wet cell, like on Intrepid since they can give off explosive hydrogen gas. Of course on Intrepid, there is absolutely no other place practical to put the batteries, except on the old engine mount- right next to the motor! The best place would be above the keel, but Intrepid has a very shallow bilge and this would  require cutting up the cabin sole and taking up already cramped living space. Another option would be under the settees, but again, the space is cramped and the hull is thinner there and I don't think I'd want to add that much weight to the side of the hull like that. The area where the engine sat is the most reinforced area of the hull and is the only place I really felt comfortable placing 400 pounds of weight. The idea then was to build a box for the batteries that would adequately separate the batteries from the motor and prevent gasses from being ignited by sparks.
Motor and battery mount complete

Once the engine mounts were laid bare, they were cut to shape and support an FRP reinforced heavy duty plywood box that was made to fit the four EB-160 batteries that were to be used with the system. Transverse supports were glassed into the engine mounts to make a (tic-tac-toe shaped) matrix to support the weight over the mounts. They were very carefully measured so the weight would be evenly distributed over that area. My biggest fear was hauling out one day and seeing a huge crack in the hull from the weight being improperly supported. I think it's overkill now though, as I laid several more layers of glass, and in some places epoxy layup (epoxy over FRP, not the other way around, as I learned- thanks Don Casey, my best friend through this whole process!) to support the box in a sturdy matrix over the engine mounts. The box was then bolted to the matrix with stainless steel brackets, in case I ever want to remove it, I can.
Asmo Marine Thoosa 9000 installed

The motor by the way, the rails that come with the Asmo Marine Thoosa 9000 system were too long to fit on the old engine mounts the way I have the battery box mounted, so I had to have custom made motor rails for my system. Luckily there is a very good machine shop in Okinawa and they know me very well over there now. The custom made, shorter rails are actually thicker and probably stronger. The motor, with the custom rails fits just right behind the battery box.


Battery box
Finishing the battery box, first a cover had to be made that would protect the batteries, contain/ properly ventilate explosive gasses and also look nice. So I chose to make a teak cover that fit over the top half of the box and supports a storage box that acts as a step for the companionway. This also required that a ladder be made. In my humble opinion it looks alot better and is more functional than before. As for ventilation... this is a tough subject. There is a removable wall that completes the separation of the motor from the batteries (and cabin). Really, the batteries are part of the cabin and any gasses would ventilate mostly into the cabin. Originally, I had cut a big hole in the back of the top of the battery box to lead a duct hose, connected to a blower fan to ventilate out to the cockpit. But I haven't gotten around to finishing the blower fan and so far, in 2 years of operating the boat, it hasn't blown up yet. I really think that the natural ventilation through the top of the battery box is probably good enough, but it is still something that I'm cautiously watching.
Completed system

One last design issue, regarding the battery box placement was what it did to the surrounding cabin space. Originally there was a large icebox next to the diesel engine that had alot of thick insulation that was old and probably didn't do much. The usable space in the icebox was actually small so it was really a waste of space. I always thought it would be nice to have a proper sit down navigation desk so... in order to fit the battery box under the companionway, I had to knock out the old icebox, which very conveniently allowed for the placement of a sit down nav desk. It is very small and cramped, but good enough and the desk is big enough to navigate with and I made it open up to fit my laptop computer. Everything I ever wanted!


There's a lot more, I'm sure to say about the conversion and the design considerations. This is really just a summary of 9 months of work. In a future post I'd like to share some things about the design considerations for the propeller and shaft.  Of course more posts later about performance and... even better- all the fun we're having aboard s/v Intrepid now!

Monday, June 01, 2009

Introducing Project Intrepid Seas


Hello everyone and welcome back! I started this blog about my experiences sailing Intrepid in Okinawa, about 5 or so years ago. I didn't do much with it and then put it aside and forgot about it when I created a new Intrepid-Seas website that I maintained for awhile. Now I see that blogging is really a better way to maintain a web presence, so I am taking the old Intrepid-Seas site down and just maintaining the IntrepidSeas blog now. This Blogger account will act as the official site for "Project Intrepid Seas," while the WordPress based "ElectricSeas" will serve as a platform for the nonprofit organization of the same name. Electric Seas and Project Intrepid Seas are separate entities, with the former being a platform to serve the entire electric boating community, while the latter is my own personal account of my adventures sailing the electric powered sailboat Intrepid around Japan and eventually, beyond!