Maintenance Spring

 No, not spring maintenance, maintenance spring.

It started back in November when one day, when we boarded the boat, the primary bilge pump was running.  Huh.  After a long afternoon of troubleshooting, I was unable to find anything wrong, so I put everything back together.  Weeks later it happened again.  I finally concluded that it had to be the float switch, even tho it seemed to check out OK.  I installed a spare that I had on board, and that took care of that.

Next, we found that the refrigeration system was not running.  Thankfully there was nothing important in either the refrigerator or the freezer.  Eolian's refrigeration uses a belt-driven compressor, powered by a 1/2 hp 12V motor.  That motor had given up the ghost.

Now, in 1978, the motor had quit similarly.  At that time, Eolian was moored at the south end of Lake Union, right in downtown Seattle.  Back then, before the huge influx of cash from Amazon et. al. gentrified the whole area, I pulled the motor and walked it to a rebuild shop that was conveniently located near the marina.  Now however, I had a great difficulty in finding a rebuild shop.  I finally settled on a local automotive parts store who claimed to have a "relationship" with a major rebuilder down in Seattle somewhere.  I dropped off the motor.  Weeks later, having heard nothing, I called and was told that it would cost more than $700 because "...there were several small things inside that were no longer available and would have to be constructed from scratch by skilled machinists."  This not being my first rodeo, I recognized bulls**t when I heard it, and asked for the motor to be returned.  When I finally got it (another long delay), I tore it down and found a badly scored commutator and completely worn out brushes.  The bearings were pristine.  I also noted that no-one had actually disassembled the motor, despite the diagnosis I had been given.

So I ordered some brushes off of eBay for $6 and built a jig to turn the commutator, using an electric drill and a file.  I don't believe that the scoring was the result of wearing out the brushes.  Instead I think it was from that original rebuild way back when.  

Home made commutator turning jig

Before and after

After reassembly and re-installation in the boat, it worked great!  But...

While checking out the installation, I discovered that the Freon charge in the system was awfully low.  Getting that next maintenance item rectified was the subject of a prior post.  Been counting?  This made the third major maintenance item.

Finally, while topping off the water in the batteries, I discovered that the exhaust hose leading from the generator to its water-lift muffler had a big bubble on it and was leaking.  So, a trip to West Marine to get hose and a tube of silicone (has anyone noticed that the silicone manufacturers seem to have colluded to stop producing resealable packaging for silicone??!?). 

Installing the hose will happen this coming weekend, presuming that something else doesn't fail before then...

And to think that I was seeing this spring as an easy one...

Maintenance Spring

Frostline Marine Refrigeration

 

It seems that we are always ready to complain when a business fails to meet our expectations in some way.  But then we are silent when things go perfectly...  well this is one of those perfect cases.

Over the years (23?...) since Eolian's last refrigeration service, things worked well...  until the last year or so, when the refrigeration compressor would start, run for a few seconds, shut off, and lather rinse repeat.  Eventually tho, it would come on and run until it reached the setpoint.  I guessed that the refrigerant level had become so low that when the compressor kicked on, it would rapidly pull the suction side of the system down to the cutout pressure, and that this would continue until the entire system became warm enough to raise the refrigerant temperature to the point where its vapor pressure was above the cutout pressure.  So, after all those years, it was time for a recharge.

I tried to find someone in the Anacortes area, but no one was willing to take on additional work.

Looking further afield, I contacted Frostline Marine Refrigeration in Bellingham.

What a pleasant surprise!

Mclean was courteous and scheduled an appointment at our convenience.

When he arrived, he was prompt, fully equipped, familiar with marine refrigeration systems (quite different from domestic or industrial systems - not least because marine systems are so often crammed into almost inaccessible spaces), working on boats (protect varnish surfaces!), and most importantly, knowledgeable of refrigeration in general (I have two degrees in Chemical Engineering - trust me, I know).

He pumped the system down, removing the remaining R-409a (which was the replacement for the old R-12 back 23 years ago) and refilled the system with the newest and greatest R-12 replacement: R-417c.  And he was gone in 45 minutes.

If you have marine refrigeration needs, I cannot recommend Mclean and Frostline highly enough.

Frostline Marine Refrigeration

Turn, Turn, Turn

Back in 1998, when I was spending my first summer living aboard Eolian, the 12V electric motor which powers the refrigeration system failed.  Back then, 23 years ago, I pulled the motor and walked up into the South Lake Union area to a motor rebuild shop.  A day later, I had the rebuilt motor back in hand and reinstalled it.

Fast forward those 23 years, and the motor has again failed - the brushes have worn out.  But now we are berthed in Anacortes where there are no motor rebuild shops, and the South Lake Union area is now all expensive high-rise apartments and businesses.

So this time, I decided to do the work myself.   First, I found that the bearings are in great shape - it is only the brushes need replacing.   Well, that and the commutator needs to be cleaned up.

(Quick lesson here for those not familiar with the internals of a DC electric motor.  The armature - the spinny part - has on one end a device called the commutator.  This is a series of pairs of copper bars, with the members of each pair on opposite sides of the armature.  Each pair member bar is the termination of one end of a coil of wire which, when powered, makes an electromagnet.  Things are arranged such that when the brushes contact the pair of bars and the magnet is powered up, it is just outside the field magnet and is strongly attracted to it.  But just as it gets there, the brushes break contact with that coil and make contact with the next one, via the next pair of bars on the commutator.  Thus the armature spins.)

Inspecting the commutator, it was obvious that it had seen arcing once the brushes had worn so short that they were not making good contact anymore.  But even more importantly, that motor repair shop which did the previous repair had done a very sloppy job of turning down the commutator.  First, they cut a trench that was just wide enough to accommodate the brushes, thus ensuring that if there was any play in the brush holder, the brushes would contact the edges of the trench and wear prematurely.  Second, they left a series of deep grooves in the commutator.  Now one might say, "Well, the brush will just wear to fit the contour of the commutator, grooves and all."  But again, if there is any play in the brush holder, then movement of the brush will defeat that reasoning, resulting in rapid brush wear.

So, OK - on to the repair.

I constructed a jig that would support the armature on its bearings, and connected an electric drill to the armature shaft.  This way, I could spin the armature while holding a file against the commutator, smoothing it out.  A lathe would have been much faster, but I don't have one.

 

It worked well, albeit slowly.  First I cut off the outboard wall on the commutator, making it all the same diameter.  (I couldn't do this at the inboard end, because this is where the wires are connected.)  Then I filed the rest of the surface smooth, and followed with 100, 220 and finally 440 grit sandpaper.

Before and After

I think it came out great!  (In the before picture I had already done some cleanup.)

I couldn't find brushes of the correct size, so I bought some that were too big and ground them down to fit.  This was an easy job, but messy since they are made out of graphite, which ends up going everywhere.

I checked the bearings (they are sealed bearings); they are in perfect condition.

The motor is now re-installed, and we have refrigeration once again.  And all that refrigeration downtime gave me a perfect opportunity to clean the interior of the refrigerator and freezer compartments - so bonus!

Turn, Turn, Turn

Room in the Reefer

Guilty.

I am guilty as charged.

Yes, there has been an unconscionable gap in posting to this blog - it's just that not everything in our lives is related to boating, and a bunch of that stuff came up recently.  OK, enough of the Mea Culpa.

Eolian's refrigerator compartment is huge for a boat.  But because it is so tall, much of the space in it either goes to waste, or we spend a long time sorting thru piles of things in there with the door open, looking for something.

Something had to be done.

I decided to make a shelf that would add 50% to the horizontal storage space in there, and put some of that vertical space to use.  Because I am a professional scrounge, I have a good collection of teak scraps discarded by others, gleaned from the dumpsters.  I brought some of this, and a collection of tools to the boat:

Some of the tools

Making a mess of the dock

In a project like this, it is important to make dimensional decisions that will fit with what you plan to store in the reefer.  To that end, I think I may have disturbed some folks at Safeway by walking around with a tape measure, measuring beer boxes, soft drink cartons and other things.  It was kind of surprising to see the variability in carton sizes, even for canned drinks.

The trick in building this shelf was that it needs to be removable, yet it needs to stay in place with a load of food on it when the boat is in a seaway.  I was most worried about the shelf tipping over toward the door when on a starboard tack.  Here's how I dealt with that:

• The left-hand support bracket has a foot that goes all the way to the door, about twice the length of the bracket.  With this extension, it would be very difficult indeed to tip the shelf on this side.
• On the right-hand (aft) side, I made the last of the shelf boards extend behind the holding plate, preventing any movement on that side.

Finally, to lock things together when it is in place, I made rabbits in the top edges of the support brackets to accept a rabbit on the cleats on either side of the shelf.  When the shelf is installed, it cannot move toward or away from the door because of these interlocking notches.

Three pieces, with clever interlocking

Yes, the shelf slats seem to be sort of unevenly spaced from side to side.  This is because the left-hand side of the reefer is deeper than the right-hand side due to hull taper.

Sadly, in my first attempt at making the side brackets, I failed to take into account that the rear wall of the reefer matches the hull contour.  So I had to redo the brackets.  In fact, every board was custom cut and fitted because of the hull contour and because the hull is tapering in as you go aft (to the right in the picture).

But in the end I got it.  And we've added 50% to our reefer storage.

Et voilà!

Seems like a pretty small thing for a day and a half's work.  But there was a lot of thinking and trial fitting.  And that beer box is no longer full...

Room in the Reefer

How much is it?

I just did a post which talked about establishing what the right amount of glycol in a holding plate solution was.  Well, OK, now that we know what we want to have in there, how do we determine what we actually have?  I suppose one possibility would be to simply empty the holding plate and refill it with a solution of known concentration, one that we just made up by careful measuring.  Yeah, that would work.

But what if we just want to add a little water or glycol to what we already have?  For that we would need to be able to measure the concentration in the solution. 

Hand-held refractometer

This is the tool for that:  It is a refractometer - it measures the refractive index of a liquid.

What is that?

All transparent substances slow the passage of light thru them somewhat - some more than others.  The refractive index is the ratio of the speed of light in a vacuum compared to the speed of light in the transparent substance.  So, if I tell you that the refractive index of a particular glass is 1.33, that means that, yes, light travels thru that glass only 3/4 as fast as in a vacuum.  You have witnessed refractive index differences when you, for example, mixed water and vodka, or dove in a place where fresh water and salt water are mixing (at Shilshole, for example).

But for our purposes, it is enough to know that the refractive index of a water/propylene glycol mixture changes in a predictable way with the concentration of glycol.  We don't even have to know the details of that change because the manufacturer has taken that into account in the preparation of the scale inside the instrument. 

All that remains is for us to obtain a drop or two of the solution and put it onto the prism covered by the clear plastic flap, and look thru the lens at the other end of the instrument, for a view like this:

Approximately 33% propylene glycol shown

But there is a catch (isn't there always?).  Before I sample the holding tank solution, I have to completely defrost the freezer.  If I don't, some unknown quantity of the water in the system will be frozen out, which would skew the results in the direction of increasing concentration.  So the refractometer stands ready for duty, waiting for a freezer defrost event.

Who knows when that will be?

How much is it?

How Much Is Enough?

The other day I got to wondering if I could improve Eolian's freezer - to make it colder, or to make the cold last longer, by fine-tuning the amount of propylene glycol in the holding plates.

But first, a word of explanation.  Eolian has two separate compartments for the refrigerator (one holding plate) and the freezer (two holding plates), but both are cooled by a single compressor.  The refrigerator has a thermostat in it, which closes a valve in the refrigerant line when the setpoint is reached.  The freezer on the other hand has no valve, and continues to chill - until the compressor shuts itself off.

So I decided to do put my education to work and do a little Chemical Engineering.

You may remember that in a previous post I discussed the phase diagram for the propylene glycol-water system earlier.  I suggest you go back and read that one now, because I will proceed presuming you have...

But this diagram unfortunately does not have any actual temperatures or concentrations delineated on it.  So I prepared an expanded version of the portion to the left of the eutectic point from some published data:

Portion of Propylene Glycol-Water Phase Diagram

But even this covers too much territory.  What we are interested in is just this portion:

The Part We Care About

As I mentioned in that previous post, I spoke at length with a Technautics sales rep at a Seattle boat show, and he recommended a 15% solution for freezer holding plates.  I don't know what the concentration in ours is (that is something I should rectify...), but let's assume that 15%.  Here it is plotted on the diagram:

 

The vertical pink line describes a 15% concentration.  Let's follow what happens as the temperature is dropped, moving down the pink line at the 15% concentration.  At first, the liquid just gets colder.  But at a temperature of 22°F we meet the line.  At this point, the first freezing occurs.  And what freezes out is ice - pure water ice.  Because of this, the amount of water remaining in the liquid phase is reduced, increasing the concentration of propylene glycol. 

Now let's look at the situation at 15% glycol cooled to 10°F... the intersection of the two pink lines.  By this point, we have frozen out a substantial amount of ice, removing water from the liquid phase.  In fact, the concentration of glycol in the liquid phase has followed the black curve down, and is now about 27% (the concentration of the total mixture has not changed - it is still 15%).  And the Lever Rule tells us that the total mixture is a slush of 12/27 = 44% ice and 15/27 = 56% glycol solution.

Now why did I draw the horizontal pink line at 10°F?  Because that is the lowest temperature our compressor can reach with our current refrigerant.    A low pressure switch cuts it off.  The only way to decrease this endpoint would be to change out the pressure switch (not recommended - the manufacturer decided that this is the lowest pressure at which the compressor should operate), or to change to a refrigerant that has a higher vapor pressure.  In fact, we have already done that; we replaced the original R-12 with R-409a, which indeed has a higher vapor pressure.  So 10°F is as cold as it can get in our freezer.

So that's one point settled:  The low temperature is 10°F.  Now how to maximize the time that the holding plates can maintain the cold?

 It is important to keep in mind that the holding plate is going to operate over a range of temperatures.  In our current case, once the compressor shuts off, the first bit of ice begins to melt, at a temperature of 10°F, diluting the glycol solution.  As more ice melts, the temperature rises, until finally when the last bit melts, the temperature of the mixture has reached 22°F.

To then summarize, with a 15% solution, the holding plates will operate over a temperature range of 10°F -> 22°F, and have a cooling capacity representing 44% of the total original solution.

We could increase the amount of glycol in the plates... say to 20%.  The plates would then operate over a temperature range of 10°F -> 18°F, and have a capacity representing only 26% of the total original solution (calculation left as an exercise for the reader).  So we would give up nearly half of our capacity to maintain temperature in exchange for a 4°F drop.  Doesn't seem like a fair trade.

OK, how about if we go the other way?  What happens if we decrease the glycol concentration?  Let's try 10%, the concentration that the Technautics rep recommended for refrigerator holding plates.  Now the holding plates operate over a range of 10°F -> 26°F, with a capacity representing 63% of the original solution.  Wow!  We increased our capacity by 50%!  But we have to tolerate an upper temperature of 26°F.  I think that is uncomfortably warm for a "freezer"...  many foods will not be solid at this temperature because their water content is saturated with eg. sugar - like ice cream.

Conclusions

• Technautics has it right.  The 15% concentration provides a good balance between capacity and temperature range.
• And I need to assess the glycol concentration in our freezer holding plates.

* Someone is almost certain to suggest that the glycol concentration be raised to 30%, or even more, to get a lower freezing point.  That would certainly accomplish that, but because of the limitations of the compressor and refrigerant, we would never reach that freezing point.  In fact, the holding plates would have zero capacity the way it was assessed above - they would contain nothing but liquid at the compressor cutoff, and would begin warming immediately.  The magic of the holding plate is the ice - melting a gram of ice at 32°F to a gram of water at 32°F absorbs 80 times more heat than raising the temperature of that same gram of water from 32°F to 33°F. 

How Much Is Enough?

Rusty Hinges

You may remember that one of the early projects we did on Eolian was to rebuild the refrigerator, from the hull out.  As a part of that project, I discarded the original door and replaced it with one that I got at the old Doc Freeman's for $10 because the decor panel was damaged.  I replaced that panel with a sheet of black Plexiglas (thanks Clear Cut Plastics), and remounted it on the original hardware.

Perhaps that was a mistake - reusing the old hinges.  But at that time I did not know the marine supply business in Seattle nearly as well as I do now.  The reason that this was an issue is that the old hinges were very rusty.  I cleaned them up as best as I could, but they were always ugly, even to this day.

Ewww...

The ugliness finally got to me, and I sought out new hinges. Well, it turns out that I almost waited too long.  Tho the refrigerator is a complete custom built-in, the door (and hinges) were from a Norcold unit.  I thought that all I would have to do is order new hinges from Norcold.

BZZZZT! 

Not a chance.  That door and those hinges have been out of production for a long long time, and nobody had any left in stock - not even Fisheries.

But, as it turns out, one of the businesses in Ballard sells Norcold:  Sure Marine.  Sure Marine is one of those great places, a little off the beaten path, at the very, very end of 28th street in Ballard.  No, they had no hinges in stock, but Graham found a set of used ones in near-perfect condition in the back somewhere.  Woo HOO!

(Almost) new and shiny!

One of the last remaining vestiges of Malolo is now gone.

Rusty Hinges

Renewal = removal?

Looking back, sometimes it seems that our time on Eolian has been dominated by deinstalling things and hauling them off the boat, some large, some small, and some almost trivial.  Here's what I remember so far, over the 15 years that we have now been responsible for her care:

• I think the first think to go back in 1997 was a rusty  suspended metal three-basket set.  It was ugly beyond belief.
• Remove a whole host of corroded brass doodads that celebrated dolphins. 
• Remove another host of straw fabrications, presumably procured in Mexico and attached to various places with generous quantities of silicone
• Removed an ancient battery charger, and eventually the batteries that it ruined.
• Removed (and refurbished) the insulation of the refrigerator
• Removed and plugged the refrigerator opening that had been cut into the countertop, apparently by a drunken logger with a chainsaw that needed sharpening
• Removed (and replaced) the refrigerator door
• Removed (and replaced) the original stove/oven.  This was at least 20% by weight congealed grease
• Removed a 110V crash pump - a large 110V centrifugal pump.  In a situation that needed it, it was likely that the time spent getting it to prime would have allowed the water to rise up and drown the generator.  
• Removed (and replaced) 3 bronze head thru-hulls and associated leaking bronze tapered plug valves
• Removed (and replaced) the original bilge pump, installed when there was nothing else in the hull, apparently.  Spelunking skills were required.
• Removed a corroded and non-functional antenna tuner
• Removed an unbelievable quantity of "mystery wire" - wires that went nowhere and caused no end of difficulty in troubleshooting electrical problems.  At today's copper prices, I wish that I had saved it for recycling - I'd be rich.
• Removed (and replaced) the old bowsprit
• Removed (and replaced) the old inner forestay pad eye
• Removed  (and replaced) the old Benmar autopilot
• Removed the leaking fuel daytank
• Removed (and replaced) the refrigerator cooling water circulating pump
• Removed (and replaced) the holding tank
• Removed (and replaced) the bilge pump controls
• Removed (and replaced) the forward electrical distribution panel
• Removed two non-functional diesel filters
• Removed (and replaced) the stern lite
• Removed (and replaced) the masthead lite
• Removed (and replaced) the old microwave
• Removed (and replaced) the water heater
• Removed (and replaced) the corroded section at the foot of the mainmast
• Removed (and replaced) all the running rigging
• Removed (and replaced) the old cockpit canvas/bimini/dodger/side curtains
• Removed (and replaced) the old Groco heads
• Removed (and replaced) all the head plumbing
• Removed (and replaced) the exhaust elbow
• Removed (and replaced) the exhaust manifold
• Removed (and replaced) the alternator
• Removed (and replaced) all the original instrumentation (except windspeed/direction)
• Removed (and replaced) the original inverter
• Removed (and replaced) all the interior cushions and upholstery
• Removed (and rebuilt) all the cockpit cushions
• Removed (and replaced) the large fixed cabin windows
• Removed (and replaced) four of the eight opening ports
• Removed the original 110V space heaters
• Removed (and replaced) the original TV
• Removed (and replaced) the original VHF
• Removed the LORAN set (replaced with GPS)
• Removed the remains of the original airconditioning equipment
• Removed a non-functional oil change pump
• Removed (and replaced) the mizzenboom gooseneck fitting
• Removed all the original wood-grain formica
• Removed (and replaced) all the engine rubber hosing
• Removed (and replaced) the original fuel level senders
• Removed (and replaced) the original fresh water pressure pump
• Removed (and replaced) the original anchor wash-down pump

Woo boy.  I'm pretty sure that there's more, but the list is depressing enough as it is.  And there are investments that don't show up properly in the list, like a new bow lite, or a new inverter/charger.  Many of the removals above constituted their own projects which are documented elsewhere on this blog (you can search either by keyword or by label, over there on the right).

It seems that our waterline should have moved down...

Renewal = removal?

*That* call

On Saturday, we got that call.  You know, the one that no boat owner ever wants to get.

Brent & Jill, our next door neighbors (bless you guys!) called us Saturday morning (we were away from the boat) and told us that our bilge pump was running every 20 minutes or so.

Yeah, THAT call.

I jumped in my TransAm and may have grazed some speed regulations getting to the marina.

Thankfully, what I found was not serious.  We were not in danger of sinking.  As Brent pointed out, the pump was no where near to running continuously, so the situation was stable.  But it was not pretty.

In order to describe what happened, I need to backtrack a little.  Remember when I told you that our refrigeration was seawater-cooled?  And that we had a small telltale stream running into the sink?  Now imagine that someone left the sink stopper in the sink, and that it managed to seal up the drain (something which we never seem to be able to get it to do).

Yeah, the sink filled up with seawater.  And because of our current state of trim, when the sink overflowed, the water ran outboard... and into the freezer.  Yes, we had a freezer nearly full of frozen seawater.  Not quite full of ice because of the near continuous stream of warm seawater which kept coming, but certainly full of seawater.  When the freezer overflowed, the water made its way behind the cabinetry attached to the hull, and then into the bilge, where the bilge pump took care of it.

There was no damage.  But do you have any idea how many pans of boiling water it takes to melt a block of ice that big?  No, I didn't either.

*That* call

Replacing ice with foam

Eolian's freezer is about 12" square, which doesn't sound like much, but it is 38" deep.  Lying on the counter top, I can just barely touch the bottom; Jane's arms are not so long as mine - she cannot.  Also, the two (!) holding plates do not reach all the way to the bottom - this means that if a not-yet-frozen item is dropped to the bottom, wedges under the holding plates and then freezes like that, it cannot be removed until the entire freezer is defrosted.

So.  The Previous Owner put two of those "blue ice" packs on the bottom, to keep things from going too deep.  And over time, a layer of ice also forms down there, entombing everything.   My idea was to fill this unused and unusable volume with extruded polystyrene foam instead of ice, thus improving the insulation of the bottom of the freezer dramatically.

Step 1: Defrost the freezer.

I removed as much of the freezer contents as I could get out (see "wedged under holding plate" above) and positioned a small fan over the opening to the freezer in the evening.  By morning, I was able to remove the remaining unidentifiable food items and expose the blue ice packs.  But they were still encased in about 2" of solid ice.

In a rush  to get this done before I had to go to work, I boiled some water in the tea kettle and poured it in there.   After letting it sit long enough to prevent getting burned, I swirled it about with my hand, spreading out the heat to melt the ice.  Two of these treatments melted all the ice and allowed removal of the blue ice packs.

Then I bailed out the freezer and mopped it dry with a sponge.

At that point, with an empty and clean freezer, I put the lid back on it and turned on the refrigeration system again to chill down the refrigerator, and went to work.

Step 2: Measure and cut foam.

There may not be any ice in there, but it is frosty, and it is *very* cold.  Stick a tape measure down and get a reading both ways - it comes back out icy cold.  Mark the pink foam (Scotty from Ghost said it looks like raspberry sherbert) and then cut it with a knife.  Well, not really cut it, but rather score it and then snap it on the score line.  Because of the presence of the two holding plates, it was clearly not possible to put a full-sized piece of foam into place.  So I cut each piece in half lengthwise (top to bottom in the photo) and put the two pieces in place, outside edges first, leaving the inside edges sticking up.  I got the sizes close enough that the halves snapped into place when the meeting center edges were pressed down.

Step 3: Install the foam

Drop the pieces in there and snap them into place... no real procedure here.  The final of the three layers (making 3" of additional insulation on the bottom of the freezer) had to be trimmed some to fit around the bottoms of the holding plates and their retainers.

This solves a problem and provides more insulation - a double win!

Replacing ice with foam

Telltale

Now here's a word which, standing alone, has negative connotations.  To me, it seems to evoke feelings vaguely similar to "tattletale".

But in the marine world, a telltale is a good thing.  It provides proof that a system is working.

Outboard motors typically direct a tiny part of their cooling water to a port where the discharge stream is made visible - so that you know that the cooling water system is functioning.  (The only outboard we have here on Eolian is the little 2 HP Evinrude on our dinghy, and it does not have such a port - it doesn't have a cooling water pump either, depending instead on ram-effect for cooling water propulsion.)

But on Eolian our main engine does have a (perhaps inadvertent) telltale - when the engine is operating, some of the discharged cooling water comes out the anti-siphon vent on the port side.  Inspecting the vent discharge is not more convenient than looking over the stern for water discharge in the exhaust, but I have heard that some boats direct the vent stream into a cockpit drain, thus providing easily seen proof of cooling water flow for the helmsman.  And occasionally wet feet.

Our refrigerator cooling water circuit has a (also perhaps inadvertent) telltale too.  With our new pump, it is not possible to hear the pump running (yea!), so this becomes particularly important.  Now, our galley saltwater foot pump draws its water from the line between the refrigerator cooling pump to the refrigerator.  Thus, when the pump runs, enough pressure is produced that a stream of water makes it thru the foot pump and shows up in the sink.  (Of course, this affects the logistics of washing dishes a little - you want to do the wash in this side of the sink, and the drain-for-dry in the other side.)  And the frequent flow means that the water in the foot pump and lines does not get stagnant and smelly - operating the foot pump always produces fresh, clean seawater.

So if you can, replace that negative connotation with a positive one.  Let the word "telltale" leave you with an impression of sitting in front of a fire with someone who is telling you a story - a story that ends saying, "all is well."

Telltale

Refrigerator magnets

No, not the kind that stick on your refrigerator, holding up the kids drawings or the grocery list.

I am talking here about magnetic drive pumps for the refrigerator.  Wait, what?

Let me back up a step.  Your household refrigerator discharges the heat it pulls from its interior into the surrounding air.  If you are old enough, you'll remember the "coils" on the back of the refrigerator, but now virtually all refrigerators have those coils concealed in the base.  Nevertheless, they are there, busy heating air with the heat removed from your food.

Here on Eolian, the refrigerator is water-cooled.  Other than the hassle of dealing with circulating seawater, this makes a lot of sense - the seawater is 48° right now, so it serves wonderfully to carry away the heat.  But there is still that circulating seawater thing.

Originally, Eolian had a very small Johnson brand conventional centrifugal pump for the refrigerator.  But not long after I moved aboard, that pump failed the way most such pumps fail:  the seal gave out and seawater dribbled along the shaft into the pump motor interior, destroying it.  That seal is the weak link in a pump.

There is an alternative, however:  the magnetic drive pump.  In these pumps, the rotor (the thing that impels the water into motion) has an embedded magnet, and is totally sealed off from the motor.  The motor drive shaft has a magnet on its end, and drives the impeller thru magnetic coupling alone.  There is *no* possibility of leakage at the seal - because there is no seal.

When that original pump failed, I sought high and low for a magnetic drive replacement pump, starting of course with Johnson.  The best I could do tho was a Sureflo baitwell pump.  It was oversized for the service, but it was indeed magnetic drive.  I bought it and installed it... and was disappointed because, tho it served well as a pump, it was terribly noisy.

So when I was visiting with my nephew Mark, who is National Sales Manager for SPX (the parent company for Johnson pumps), I brought this subject up.  Well, it turns out that Johnson does make a magnetic drive pump suitable for this service, but that their catalog incorrectly lists it as suitable only for freshwater or ethylene glycol service.  Mark told me that these pumps are used extensively for circulating brine - much tougher service than seawater.  He then arranged for Johnson to ship me a suitable pump for a beta test in my system.

After opening up the bilge space under the floorboards, I removed the old Sureflo pump.  As you can see, the Johnson pump is considerably more compact. 

Next, some plumbing changes were required, and tho I thought I had everything on hand to do the job, Reality checked in and I was short of the correct-sized hose clamps, despite my on-hand collection.  So a quick walk up to West Marine (thankfully close to the marina) and I was set.

The final installation - the pump is almost completely silent in operation - what a relief!  And because it is a magnetic drive pump, it should last as long as the motor.

Oh blessed silence!

Refrigerator magnets

Project: Rebuild the refrigerator

This is a project from September, 1999

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The refrigeration compartment on Eolian was in bad shape when we took possession of her:

• The door was bent, corroded, and didn't seal well.  
• The "decor" panel in the door was an unfinished piece of teak veneer, suitably filthy
• The interior was dirty
• The floor of the interior was cracked and broken - as if someone had dropped a bowling ball in there
• There was no drain
• Someone had cut an opening into the counter above the compartment in an attempt to make it a "top-loader".  The cut was clearly made by a near-sighted drunk with a sawzall.  The edges of the cut out piece were festooned with some stainless strapping to keep it from falling into the refrigerator when in place.  The strapping was sharp-edged and bent.
• The counter top thru which the hole had been cut was finished with the ubiquitous "wood-grain" Formica.
• The compressor ran frequently, for long periods.

Any one of these items would have been sufficient incentive to tackle the job, but as I was beginning the job of replacing the counter top Formica throughout the boat, this was the issue that provided the straw that broke the camel's back.

First, I prepared for living a refrigerator-/freezer-less existence for an extended period by training myself to enjoy warm beer.

Next, I found a new Norcold refrigerator door suitable for the service at the old Doc Freeman's chandlry.  Because it had been damaged - the decor panel was dented - I got it for $10.  Then I got a suitable piece of black Plexiglas from Clear Cut plastics, and installed it in the door as the decor panel.

Now the fun starts.  In an orgy of destruction, I tore out the interior finish panels, and then the insulation...  back to the hull,  down to the floor, out to the walls, and up to the counter above.  I left the panel on which the holding plate was mounted alone, because I did not want to loose the refrigerant charge in the system.  The insulation I took out was foam-in-place polyurethane, and all of it (on the bottom at least) was saturated with water.  Clearly it had little, if any, value as insulation.  Urethane foam, broken floor and no drain all contributed to this problem.

Next I went to Home Depot and bought a 4x8 sheet of 2" blue polystyrene foam.  This stuff is closed cell, and will not absorb water.  And a can of spray foam (this is polyurethane foam).

Then I carefully cut and fitted sheets of the foam to the floor, walls and ceiling of the space, creating 2 full layers, for a total of 4".  I installed them with spray foam, and used the spray foam to fill the odd spaces where trimming was hard to get perfect.  Polystyrene is tricky because it will "melt" on contact with most solvents.  The polyurethane spray foam does not affect it however.

Next I got a 4x8 sheet of fiberglass-reinforced abs sheet designed for lining shower enclosures (I think this may be same stuff that s/v C'est la Vie used for their bimini roof, 11 years later  -Ed).  Carefully cutting pieces of this material, I glued it in place with 5200 (I didn't want to chance having expanding foam bulge the sheet).  I also carefully sealed the seams at the corners with 5200.  Outside corners around the door opening got finished with plastic moldings made for this purpose, and 5200.

And then I installed a drain, using a marelon thru hull.

Finally, I leveled the top surface where the savagely-cut lift-out had been using plywood, and with water putty for leveling.  With the new Formica installed, the repair was invisible.

As a finishing step, I cut and installed some of those snap-together soft plastic gridded cushion tiles to take the brunt and spread the load if another bowling ball should get dropped in there and to keep the food from sitting in any water that had not yet made it to the drain.

The end result is a *huge* improvement.  (That's not a mark on the door - it is the reflection of a fire extinguisher on the wall opposite).

Project: Rebuild the refrigerator

Why does a holding plate work?

"Any sufficiently advanced technology is indistinguishable from magic."

- Arthur C. Clarke, 1961 (Clarke's third law)

A holding plate is a magical device that keeps your refrigerator or freezer cold, even when the refrigerator compressor is not running. How does that work?

Here's the advanced technology behind the magic: The holding plate is a tank, filled with a water-propylene glycol mixture. The refrigeration system's evaporator coils (the source of the cold) are immersed in the liquid in the tank.

When the compressor is running, the coils get very cold, and begin to freeze water out of the glycol solution, eventually creating a kind of "slushy" inside the tank.

But wait... why doesn't the tank burst when the water freezes? The answer to that is the phase diagram for water/propylene glycol mixtures.

(Aside: why propylene glycol? Propylene glycol and ethylene glycol - which you probably know as automotive anti-freeze - are very closely related chemically. But, while ethylene glycol is a deadly poison, propylene glycol is a food additive. Both taste sweet, BTW.)

A sketch of the water/propylene glycol phase diagram is below:

The way to look at this diagram is like this.  The horizontal axis is delineated in % glycol, meaning that it runs from 100% water on the left, to 100% glycol on the right.  The vertical axis is temperature.
And there are two horizontal curves here:

• An upper one which has a dip in it.  This line marks the point, at any given composition, where freezing begins.  Above the line, everything is liquid; below it, a solid phase has begun to form.  (The lowest part of the dip is at a composition of 60% propylene glycol, called the eutectic point.)
• A flat one at -60° C.  Below this line, everything is solid.  Above it, there is some liquid present (except at the 60% glycol eutectic, where the upper and lower lines meet).

Now notice that at any composition away from 60%, the line, representing the melting/freezing point of the mixture, rises. Basically, this says that the best you can do in preventing freezing with propylene glycol and water is -60°C, at 60% glycol. This is a case where while some is good, but more is not better. (Not surprisingly, the water/ethylene glycol phase diagram is similar - putting too much antifreeze into your car won't help things...)

Next, notice that under the freezing point curve to the left of the 60% eutectic point, there is an area labeled "H₂O(s)+lq". This means that for compositions and temperatures that fit here, what is present is a mixture of solid H₂O (ice) and liquid. If you were to take a mixture of water and propylene glycol with less than 60% glycol and slowly lower the temperature (moving straight down on the chart), pure water ice crystals would form in the mixture. As water is removed from the solution by freezing, the concentration of glycol in the remaining liquid phase rises, and the subsequent temperature needed to freeze more water out of solution continues to fall... until the concentration of the remaining mixture is 60% glycol, at which time the remaining liquid all freezes solid at once.

(For completeness, to the right of the eutectic point, the unmarked area between the curves should say, "Glycol(s)+lq".  That is, for compositions greater than 60% glycol, what freezes out of the mixture is propylene glycol, not ice.  But still it is a slush.)

This shows why your holding plates don't burst. Until you get down to a temperature of -60°C, there will always be a slushy mixture of ice and water/glycol solution present.

So how much propylene glycol should you use?  I spoke at length with a Technautics engineer at a boat show about this.  He told me that Technautics uses 10% glycol in holding plates destined for refrigerators, and 15% in plates for freezers. So that's what I put in mine.

There.  Now you have the technology - magic is no longer required.

Why does a holding plate work?

Project: Refill the holding plate

A long time ago (Oct 1999) I rebuilt the refrigerator compartment from the hull out, removing and replacing all the foam insulation and installing a new liner (that'll have to be the subject of another post, sometime). During that process I did not rebuild the wall on which the holding plate was hung, since I did not want to lose the refrigerant charge from the system. Nevertheless, I bumped small brass fitting on the bottom of the holding plate, breaking it off. Nothing came out of the hole, so I assumed that it connected to an internal tube (presumably unused). I JB-Welded it back on and forgot about it.

Years later, Jane noticed that the refrigerator was running more than normal, and we both noted that the frost level on the holding plate now never reached more than about 3" high.

I confess that despite my Chemical Engineering background (or perhaps because of it...), holding plates seemed a little mysterious to me. Ours is a stainless steel tank about 12" x 20" x 4" in which the evaporator coils are submerged in a dilute glycol solution (propylene, not ethylene since this is an application where leaks could conceivably get on food. Ethylene glycol is a deadly poison, while propylene glycol is a food additive). The idea is that when the compressor runs, ice forms in the tank (in the form of slush, due to the glycol), thus storing the 'cold' for later release. It is kind of a formalized and self-contained "Blue Ice" system. This is a design which works well on a boat where the engine is run maybe once a day and it is desired to not use power when it is off. Anyway, I was reluctant to get involved with the holding plate.

Now I really had no choice. Presuming that the lowered frost level indicated the level of fluid in the tank, it was obviously leaking. Where? An examination of the tank showed that the little fitting on the bottom was once again loose - probably bumped again somehow. So I broke it off completely - way too easily. Nothing came out of the resulting 1/4" hole.

OK, next step - find the leak - all I'd have to do was put more fluid in the tank and see where it comes out. So how to do that? Taking a deep breath, I drilled a 3/8" hole in the far upper sidewall to gain entry for a hose for filling. Voila! As soon as the drill penetrated, the water (no longer any glycol - just water) gushed out the hole in the bottom! The hole really did communicate with the tank interior, but the water did not drain earlier because there was no way for air to enter the tank to take its place. Mystery solved.

Now... how to seal a 1/4" hole in an almost inaccessible location, and a new 3/8" hole that was easily accessible... against the possibility of some internal pressure (should it freeze solid), and proof against future bumping?

I remembered a device called an "expansion nut" that I had used in an automotive application. This is sort of a rubber analog of a pop rivet. When a screw is tightened into the brass insert at the bottom, it compresses the rubber between the upper flange and the brass insert, swelling it out. You slip it into the hole and tighten the screw - that's it. When finished, it is very low profile. The one in the 1/4" hole on the bottom is not visible, but the 3/8" one in the upper sidewall can be seen in the picture. The tank is now filled with a solution of 10% propylene glycol (aka "RV antifreeze") and the holding plate works beautifully.

Project: Refill the holding plate

Digging Into the Freezer

Eolian has a freezer. It is an excellent freezer, in that it really, umm, freezes things well.

It is not just a small compartment inside the evaporator plates for the refrigerator, suitable for holding 3 small boxes of frozen peas entombed in lump of frost. Instead, it is a completely separate compartment. But it is not the shape of your conventional household freezer. This is a boat - it was shoehorned into an available space. It is about 3 feet deep, and about 13" square on the inside, making it about 3.5 cubic feet - an incredibly huge freezer for a boat. It is equipped with two holding plates, which make the cold last all day long without additional refrigeration input. (But these take up some of that 3.5 cubic feet - believe me, it is worth it.)

Now measure your arms. Are they 3 feet long? Didn't think so. So, how would you retrieve that bag of frozen crab on the very bottom of the freezer?

Exactly.

Oh, and it is difficult to get the whole length of your arm to work for you, because the freezer is back in the corner of the galley counter space, pretty much where it is least accessible.

Finally, as a consequence of The Second Law of Accessibility, whatever it is that you want to retrieve from the freezer, is on the bottom.

Last summer when we were off the dock for two weeks, I made sure the freezer was full, since it works best at retaining temperature when it is full, by using up the slack space with a milk jug full of water. It easily wedged into the space between the holding plates at the lower back of the freezer, because milk jugs are very flexible. Problem solved!

Well not quite.

Now how do I get that jug out of there? Of course now that it is frozen, it will not come out of the space... I am going to have to defrost the whole system and melt that jug to be able to get it out. That will take a long time (days, in fact). A good plan, gone bad thru a botched execution.

Still, we absolutely love our freezer!

Digging Into the Freezer