After a couple of coats of paint, the battery terminals and the marine-rated circuit breaker have been fitted. The battery sheets fit perfectly, with a millimeter of clearance on each side, and a few inches in the front for internal wiring. Just enough room is left in the back to install the tubing for a “someday” connection to the heating / cooling system (should that ever prove necessary.)
The 150A circuit breaker (MRCB) is a safety device that should overload and trip if ever there were to be a short-circuit in the wiring between the battery and the main buss bars. 150A is a generous amount of power, to be sure, but nowhere near what these batteries are capable of delivering in a short-circuit situation. Lithium-Ion batteries like these have a very high “C” rating, and wired in parallel could easily put out more than a thousand amps for short periods of time -- that’s more than enough juice to melt all kinds of metal or heat up wires enough to start fires. The breaker itself is waterproof, and can be opened (and reset) via the yellow switch in the center. This should make it easy to take the box “offline” for maintenance of the external wiring.
The breaker and battery terminals were installed with a small amount of SikaFlex-291, which was allowed to cure in order to form a gasket. When the screws are fully tightened the gasket around the fittings is compressed, making them water-tight. The box should be completely waterproof until fully-submerged, and my hope is that the EDPM lid-gasket would hold out for at least a little while in that (most unfortunate) event.
These blocks are cut to fit the hull, and will be permanently adhered in place. Seen here, a work in progress, the blocks are constructed from 3/4″ (18mm) Douglass Fir marine plywood that I had left over from another project and are laminated together with West System epoxy. For added strength, I chose to use 14mm dominos to secure two C-beams, each constructed from four more equal length sections of 3/4″ (18mm) ply. The C-beams and dominos were also set with epoxy. The feet of the battery box will be spaced to straddle these C-beams, and will serve to help lock-in the box to the mounting blocks.
After everything cures, the dominos will be cut flush and the mounting blocks will be sanded smooth of excess epoxy (drips and runs), then another coat or two of epoxy will be applied to get everything all nice and water-resistant. Once cured, it’ll be ready for final installation.
The mounting block will be adhered to the hull with SikaFlex 291 elastomeric marine adhesive, and everything will be given a couple of coats of Interlux BilgeKote (grey).
After a few weeks’ hiatus, I’m back on the case. I fabricated a lid, and spacers for the inside of the box to support each sheet of batteries. The spacers are 3″ tall, and the batteries have aluminum support tabs on them at 2″ and are 3″ high. I’ve epoxied in two, 2″ high permanent spacers in the bottom of the box to support the first sheet. Each pair of spacers is installed after dropping in a sheet, and the spacers are screwed to the side of the box from the inside. They come out easily enough if I need to remove sheets in the future, but should keep the batteries well secured otherwise.
The two “feet” you see in the picture above are spaced such that they will straddle the supports I’ve adhered to the boat’s hull, making it very difficult for the box to slide about.
I used Interlux Bilgekote (grey), to match pretty much everything else down in the bilge. I find that the paint, while a little expensive, holds up well and doesn’t seem to allow much in the way of flora and fauna to grow on it -- good news for keeping the bilge from becoming smelly.
The carcass of this battery box is constructed of 12mm (1/2″) marine plywood, and will measure about 760x335x385mm (30x13-3/16x15″) when completed. I’ve chosen to use West System epoxy and 5mm Festool Domino joints to hold it all together. Once finished, the outside of the box will receive a layer of woven fiberglass fabric and a coat of paint suitable for a life in the bilge. The goal is a box that is completely sealed, even water-tight when submerged, if possible.
The batteries that will live in these boxes are long (690mm/~27″) and low (75mm/3″), with aluminum mounting fins along the sides at about 50mm (2″) up from the bottom. The battery terminals are found on one end of the battery, so we need to leave about 50mm (2″) of room for internal wiring on one end of the box. The other end of the battery has ports for liquid cooling / heating -- life in a car is a much harsher thing than life as a house-bank battery in a sailboat and liquid heat management is a necessity -- and will require a bit of additional bracing to protect these ports from damage. Plumbing this should require minimal effort.
A 50mm strip of plywood for the bottom sheet to rest on has been run down each side of the box, and an additional block of plywood was added at the terminal end as a “stop” for the mounting fins to ensure that the sheets do not slide around within the box. As each sheet is installed, a 75mm (3") strip will be placed on top of the fins, for the next sheet to rest upon. This will leave a small amount of clearance between the sheets for air circulation.
Since the bottom strips and terminal-side blocks are to be permanently installed inside the box, they’re pretty hard to clamp using regular clamps. I solved this problem by cutting some blocks of scrap plywood that are just a bit longer than the interior of the box is wide and wedging them in at an angle. These wedges are opposed by conventional clamps placed on the outside of the box. A couple of taps with a mallet ensures that the fit is snug.
I cleaned up the squeezed-out epoxy by brushing the excess along the bottom and sides -- these interior surfaces will eventually be coated with epoxy anyway, so no harm in getting a start on that.
We made a choice to remove one of our three water tanks and fill the newly vacant space with batteries. This decision was driven by a combination of factors.
Recently, it’s become possible to buy lightly used high-capacity battery “sheets” from wrecked electric cars -- we’ve had a Tesla Model S as a family car for the last two years, and have found the car (and it’s batteries) to be very reliable. Our car has lost only a few “miles” of capacity in the 50,000 that it’s been driven, so we chose to buy Tesla batteries for our boat.
One sheet works out to 5.3kWh, and the battery box above will hold four sheets -- 21kWh. As a bonus, these sheets are already wired for ~24v, the nominal voltage of our boat's house bank. In the space of the old tank, we can fit two such boxes: ~42kWh (or nearly 1700Ah @ 24v!)
Not long ago, we decided to install a water maker that will produce 150 gallon per day. With this water maker, producing a single gallon of water consumes about 17 watts of energy. So, a single battery box (4 battery sheets in total) could theoretically produce just under 1250 gallons of water, or about 25 times more water than the volume of the tank it replaces would hold. The two boxes/batteries/etc. will weigh about 250kg (~500lb) which is about the same as the old tank was, full of water. The added benefit is that batteries (hopefully) won't slosh around, and the power stored within them can also be used for other purposes.
With this new fitting, I can hook the generator up to the Groco U-Lube oil changing system. This will make changing the oil for the generator much simpler, since it will just be a matter of throwing a switch to pump all of the oil out of the pan and into a container for proper disposal. The system can be reversed to pump oil back into the sump, so no need to muck about with funnels and the possibility of spilling.
Thirty years ago, the generator came with a short length of hose hooked up to a similar banjo fitting, but in addition to being ancient, corroded and kind of worn out, it was crimped onto the hose. This made it a non-reusable part. A fitting like this (stainless steel, made for a turbocharger) will allow me to change the hose out for a new one if/when the need arises.
Westerbeke will sell a replacement hose, but it suffers the same length problem. It wasn’t obvious at first, but buried deep in the documentation was a reference to the size/thread of the bolt: 18mm with 1.5mm threads. Fits perfectly.
(I really need to hit this old thing with another round of degreaser and a brush to knock off the dead paint!)
So, the time has come to pick up a water maker for the boat. There are lots of options to choose from, and the wealth of information on the various products available on the Internet makes the decision process a little easier. Your situation is going to be different from ours, but maybe looking at our thought process will help you through your own decisions.
First consideration: Capacity.
Our boat was built with three water storage tanks, of roughly equal volume, totaling about 150 gallons (~560L). We aren’t terribly interested in living an austere style, and our three tanks tend to last us about a week. For two adults, that works out to about ten gallons per day, each. With a water maker and an expanding family, our consumption will probably go up, so I’m going to use 20 gallons a day per adult as an estimate (40gal/day total).
The number one failure of water makers seems to come from not using them enough. So, buying a unit that produces too much will result in longer stretches between uses, too little production capacity and we’ll hear it running all the time. To avoid the problems associated with underuse, we’ve decided that we’ll run it daily, or at most every couple of days. 4-6 hours of run-time per day to produce about 40 gallons seems like a reasonable target.
Water makers tend to be marketed by the number of gallons that they will produce in a day (24 hour period). Running a 150 gal/day unit for 6 hours would produce 37.5 gallons and running a 250 gal/day unit would produce 41.6 gallons. In order to hit our targets, we’d want to find a unit that has the capacity to produce 150-250 gallons per day.
Second consideration: How to power it.
These things all use power. Some use DC, some use AC and others are designed to be run directly from a power take-off on an engine. We have no desire to run our main engine or generator every day, so we’re going to drop engine-driven units from our consideration.
So, AC or DC? Well, on our boat they’re basically the same thing. We have pretty big batteries and a couple of large inverters, so AC power is really just DC power with a little bit more overhead. Our inverters are 90+% efficient, but we’ll just round that down to 90% to work with. In order to compare apples-to-apples, we’ll convert all of the power consumption numbers for AC units to DC and add ~10% (for losses in the inverter.)
The added losses from the inverter will probably skew our decision toward a DC unit, but we’ll definitely consider AC units.
Third consideration: Power consumption.
Many of these units vary in the way that they present their specs pretty wildly, even amongst products from the same vendor. In order to make decent comparisons, we’re going to need to come up with a metric that we can convert all of them to. We’ve decided to use watts per gallon. This should make it a little easier to see which units use power efficiently. To calculate this we determine the amps required, nominal voltage and gallons produced in a day. Volts times Amps * 24 hours in a day yields the rough number of Watts per day, and since most units are specified in gallons per day, dividing this number by the gallons per day figure will give us the watts per gallon.
For example: The 200-DML-1 from EchoTec is a DC unit that produces 200 gallons per day, while consuming 9.5 amps at 25 volts. 9.5a * 24v * 24h = ~5500 watts per day. Divide that by 200, and we get about 27 watts per gallon.
Fourth consideration: Cost.
None of these units are cheap. We’re expecting to pay somewhere in the $4k-8k range. We’re pretty handy, and we plan on installing whatever unit we do choose ourselves to mitigate some additional cost. Having someone else install a unit for us could easily add another $1-2k to the price tag.
The construction is pretty simple: A piece of 6mm marine plywood, covered with vinyl that is secured with an adhesive and a bunch of copper staples. Spacers are also made of 6mm plywood, but are attached with slightly longer copper staples. Between panels, varnished mahogany strips are inserted. Pretty easy stuff.
Many of the old panels are warped and well, old. Over the years, small leaks from the deck have caused water damage to some of them. Other panels had large and ugly lighting that caused them to sag under the weight.
The goal is to eventually replace them all, while making some improvements to their design that will result in longer life, better insulation properties and will make way for new, low-power lighting fixtures. I've also used Monel staples, which can't rust and are sturdier than the copper.
The new lighting fixtures are low-power LED fixtures from the Ventura line, made by Imtra. They run on anything between 10 and 30 volts and are dimmable, with the option to have a second color (red) for night lighting. Pretty cool. A whole string of these lights uses less power than one of the old fixtures.
Bench cookies are pretty much the coolest thing since sliced bread.
These little plastic pucks have a pad of soft rubber on both sides, to keep them from slipping around on a work surface. By placing them strategically underneath your work piece, you can use your tracksaw to cut without damaging the the work surface. If you accidentally cut into one (as I have!) there’s no metal in them to damage your saw (or you!)
These are especially handy when the work must be on the ground, like for breaking down large sheets (I have small work tables) or on the dock. Just remember to properly set the depth on your tools!
A new AC power distribution panel, almost complete.
A while ago, I started installing a CZone system in the boat, which brings all kinds of advantages to the DC electrical system. Having seen the cool things that could be done with that, I wanted to do something similar for the AC side of the boat’s wiring.
To that end, I sourced some industrial circuit breakers that could be electrically switched, an Arduino-based CAN-bus interface, and then set to work on building a power panel that could be controlled by other things on the boat’s network. There’s a fair amount of software that’ll need to be written to get it talking to everything else, but software is kinda my thing. It’ll be a fun winter project.
The goal is to produce a distribution panel that has both electrically-switched and manual circuit breakers in series, with the idea being that they both have to be enabled for the circuit to be hot. Under normal circumstances, the manual breaker would be left on, and the electrically controlled one could be left to turn the circuit on and off (via control signals from the network). During maintenance, the manual breaker can be switched off... guaranteeing that no power will flow through the circuit.
What’s missing from the picture is a master breaker (80A), a power meter, and some additional wiring.
It's a Westerbeke 8.0 BTD, rated for 8kW. That works out to about 66 amps at 120v, single-phase. The engine is a 3-cylinder Mitsubishi K3D and is apparently used in lots of small tractors and construction equipment. Parts seem to be readily available, reasonably inexpensive, with completely rebuilt units available under for $3k. It runs at a stately 1800rpm, putting out a low frequency rumble that isn't exactly quiet, but isn't unpleasant either. The spec sheet says it weighs about 450 pounds!
This particular one was probably installed sometime in the mid-80's, not long after the boat was built. I'm not sure if it was original equipment. It has about 2000 hours on it, which isn't all that much for this kind of diesel generator. They're pretty sturdy beasts.
This lovely will be receiving a fair amount of attention over the coming months:
General cleaning
Thorough degreasing
Repainted surroundings
New heat exchanger (and hoses)
New motor mounts
New water intake and exhaust hoses
Touch up paint
New wiring (to our inverters)
New oil-change lines
Upgraded sound insulation
As you can see from the photo, some work on this project has already been started. There's a lot of work left to do.
Minor adjustments to the floorboard, and a coat of paint on both sides. One more coat tomorrow and then I’ll drill, countersink and screw it down for good.
I used these nifty painter’s pyramids to hold the board off the dock after I’d painted the underside, so that I could get a coat on the top side of it as well.
There are six sets of hinges connecting the leaves of the table, three per side. Over the years the screws holding the hinges in have worked themselves loose. Someone had tried to repair this by jamming some sort of wood putty into some of the holes and reinserting the screws. Needless to say that this repair was less than ideal and has failed. Several screws could even be pulled out along with a “plug” of filler. Yuck.
A better way to do this, is to ream this junk out of the holes… I used a drill bit that was the same size as the shank of the old screws. I wrapped a bit of painter’s tape around the bit to mark the maximum depth and carefully re-drilled the holes.
Once the screw holes had been cleaned up, I mixed up some West System epoxy. I dipped a toothpick into the epoxy and worked a drop or two into each hole. By the time I had worked my way around the table, the epoxy had thickened somewhat. I waited a bit longer to allow the epoxy the thicken further… to about the consistency of peanut butter. I rolled each toothpick in the thickened epoxy and then I lightly pounded them into the screw holes, taking care to keep the toothpicks straight relative to the table.
While waiting for the epoxy to kick, I immersed the bronze hinges in a small plastic tub into which I had sprayed some PB-Blaster penetrating lubricant. I let the hinges sit for a bit, and then began to work them open and closed until the action was quite smooth. I did this carefully, without applying too much force, so as not to damage the hinge pins. Bronze is a soft metal and you can easily destroy an old hinge by working it too hard, too quickly.
After a few hours, the epoxied toothpicks had set up nicely. Trimming the toothpicks with needle-nose pliers and snapping them off with a twist let me know that the toothpicks had firmly adhered. I could then clean out the mortices with a small chisel and re-set the hinges. The new screws followed the shaft of the toothpick straight in, until fully sunk. Job done.
I used new silicon bronze screws (purchased from Green Boat Stuff) of the same shank size and length as the ones I had removed, but with a Frearson (very similar to Phillips) head instead of slotted. I really don’t like plain slotted screws - they’re hard to remove without damaging. When given the choice, I’ll almost always go with Robertson, Frearson or Phillips. There are lots of types to choose from!
Proheat X45 diesel-fired hydronic heater, mounted to the bulkhead.
A backing plate made from 12mm marine plywood was cut using the tracksaw, painted and screwed to the bulkhead, which itself is only 12mm. The backing plate is necessary both for added strength, as well as to accommodate the lid. I was careful to leave the backing plate about an inch shorter than the height of the enclosure in order to leave room for the lid, which is secured by hooking across the top. The lid has to be able to travel up about an inch before it will come off.
Mounting was easy. First, I removed the heater from the enclosure by removing four sturdy bolts from the bottom. Then, I drilled four holes through the back of the empty enclosure to allow for 5/16" stainless steel bolts. After that, it was pretty easy to use a couple of #10 screws to hold the enclosure to the bulkhead while I drilled through the backing plate and the bulkhead to make the bottom holes. Once I popped in a couple of bolts and secured them with washers (on both sides) and nuts, I could remove the #10 screws and finish drilling the second set of holes for bolts. With all of the bolts in, I reinstalled the heater into the enclosure.
Progress installing a new fan/heater from SureMarine in the saloon. The rough fit is looking pretty good. I just cut and fit the floor, but it still needs to come back out in order for paint.
I used ramboard to make the pattern. It’s nice in that it’s got enough stiffness to hold it’s shape, but you can still bend it when you need to. I then traced out the pattern onto some 12mm marine plywood. It was an easy job cutting it out with the tracksaw and jigsaw, right at the dock.
