Bullet-proof? Not hardly

 

Not even finger-proof

Well, now I have the answer.  

Remember way back, when I discussed Lexan vs. Plexiglass and postulated that polycarbonate (trade name: Lexan) would lose its properties when exposed to the sun over time? 

Well here is one of my polycarbonate storm windows, after 6 years exposure only in the winter, on the sunny side of Eolian in her slip.  I literally put my finger thru it when gently lifting it out of the slot today.  It is as fragile as a dry, dead leaf.  So much for 'bullet proof'!  And further, please look closely and note how the polycarbonate has crazed and browned up nicely where the port gasket did not protect it from the sun.

If you are changing/installing ports or hatches on your boat, specify acrylic (trade name: Plexiglass) instead of polycarbonate!  This is most important on hatches, where the possibility of someone standing on the hatch makes the choice of material a safety issue.

(One of the benefits of owning the same boat over a long time is the ability to do longitudinal studies like this.)

Bullet-proof? Not hardly

Public Service Announcement: Aerosol Cans and Heat

Some of you may have heard that we had a completely unprecedented heat wave here in the Pacific Northwest.  Seattle temps exceeded 110°F!

There are consequences from this kind of heat.

These are the remains of a Freon airhorn that we had kept in the cockpit, for decades.  It says right there on the can, "protect from temperatures above 120°F".  Well, sitting there in the fully enclosed cockpit, under the dodger windows, in the sun...

Yeah, it exploded.

And in doing so, some pretty significant damage occurred.  In a forensic reconstruction (by me...), when the pressure became too much, the bottom seam on the can came unwrapped.  The bottom disk (not that crumpled piece in the picture at the bottom of the canister - that's the diaphragm for the horn) stayed attached to the top edge just a tiny bit longer than the rest of the canister.  As a consequence, it flew upward, punched a hole in the dodger roof, and left the boat completely.

The canister, now propelled by a liquid/vapor explosion, rocketed forward with enough force to completely trash the 4 foot long teak 1x2 cleat to which the bottom of the dodger window is attached, breaking it into several pieces.  The top of the canister was severely dented in the process, and the plastic airhorn was completely destroyed.

The rocket exhaust from the exploding canister did more damage in the cockpit.

Thank heavens this was not a can of spray paint, or sunscreen, or even worse propane or butane.  At least the non-flammable Freon evaporated leaving no trace.

Those of you who are out in the southern climes probably already take precautions with aerosol cans.  But just in case, I hope that you will take this to heart.  Aside from the damage, someone could have been seriously hurt by this explosion.  And the way Murphy works with sailors, the canister would have exploded just as someone disturbed it by picking it up to put it in a shady place.

Public Service Announcement: Aerosol Cans and Heat

Water Heater Safety

Do you have a water heater on your boat?

Here’s a fact that you probably know, but which has direct bearing on the question:

Virtually everything gets bigger when heated

And of course this includes the water in your water heater.  Why is this an issue?  Well, because on a boat, the water heater is in a closed system.  There is nowhere for the expanding water to go because the check valves in your water pressure pump do not allow backflow to the water tank.

The pressure that expanding water can build is tremendous - two to four atmospheres per degree centigrade.  With a 100 degree temperature rise, this is easily enough to rupture the water heater tank if it is not released in some way.  In your onboard plumbing system, there are only three ways that pressure is relieved:

• The pressure relief valve on the water heater opens (never remove or defeat this!)
• The entire plumbing system swells/expands to accommodate the additional volume
• Something breaks
  

In a seemingly unrelated fact, most boats with pressurized water systems also have a "surge" tank (aka "pulse dampening" tank, etc) to smooth out the water pump running cycle.  The idea here is that this tank, with its enclosed air bladder, will fill with water when the pump runs, compressing the bladder.  When the pump reaches its shutoff pressure, the air bladder in the tank will force water out into the system when a valve is opened, eliminating the need for the pump to run, for awhile.

How this bears on water heater safety is this:  that surge tank also acts as an expansion tank.  As the water heater heats up its water, the expansion is accommodated by compressing the air bladder in the surge tank a little more.  Problem solved.

More and more municipalities are installing "backflow preventers" (aka check valves) on water lines entering houses, in an abundance of caution to prevent water that has been in household plumbing from re-entering the city’s supply.  This has made all water systems in these municipalities into closed systems, with nowhere for the expansion in the water heater to go.  Because of this, the market has ginned up, and there are now available a host of water heater expansion tanks.  Even the smallest of these (2 gallons) is more than adequate to serve as an expansion tank, flow smoother and rapid pump cycling preventer tank on any boat.  And they cost far, far less than the tiny pump cycle tanks sold at marine stores.  They should fit just about anywhere, with dimensions approximately 8" dia by 12" tall.

Installation is a snap:  Put a tee in your pump output water line, the closer to the pump the better.  And then hook up the side arm of the tee to the tank.  Some tank manufacturers give instruction about how the tank should be oriented for mounting, but I cannot see how this matters.  Perhaps someone out there will explain to me why this is important.

If you have a water heater but no expansion tank/pump cycle tank, you should install one.  It could save your fresh water plumbing.

Water Heater Safety

Rigging Modern Anchors

If you have read this blog for any length of time, the name Drew Frye will be familiar to you.  If not, then I will tell you that Drew is an individual that takes nothing for granted.  For Drew, rules of thumb are fine, being derived from long experience handed down over the centuries, but  conclusions and rules derived from hard data are better. And Drew goes out and collects that data.

Bearing this in mind, know that Drew has written a book, based on hard data, about anchors and anchoring techniques.  Here is what he says about it:

"Working with a bricks and mortar publisher to get this in print has been a lengthy process for me, but well worth it. It encouraged me to dive far more deeply into the technical side than I might have for my own needs, and the result is the most technically detailed book on yacht anchoring written. And I don't feel I'm bragging unfairly. I simply did the work. [...] I spent years with a load cell, digging around in the mud. Hardly glamorous, but science is mostly about diligent work."

Rigging Modern Anchors

First print edition, 2018, by Seaworthy Press. About 156 pages.

I've been setting and trusting anchors with my life (climbing) and my boat (sailing) for 35 years. I've been testing and documenting anchor testing for 5 years, and I've spent the last two sifting, collating, and analyzing all that I have learned. The result, I believe, is a complete description of what is actually going on below the waves, not just descriptively or as oral history from an old salt, but with numerical back-up everywhere I could provided it. I hope it helps. I know I sleep better. From the back cover of the book:

“Rigging Modern Anchors” demystifies anchoring with today’s modern anchors. Through years of systematic testing, Drew Frye has produced a new benchmark of understanding based on empirical data instead of anecdotal wisdom, passed down from one sailor to the next without proof or deep understanding. In “Rigging Modern Anchors” we dig deeply into the how and why of anchoring, using hard numbers as our foundation.

Included are in-depth discussions of anchoring basics, loads, scope, and the effects of cyclical loading, soil consolidation and bottom characteristics on holding power. Special attention is given to problem bottoms such as very soft mud and rock. There are anchor-specific observations, discussions of tandem anchors and rigging methods, plus an extensive appendix containing test data, open source designs for bridle plates and anchor turners, strength and toughness for various chain types, anchor connector recommendations, anchor sizing guides and more.

Proper anchoring technique, rigging, and gear selection is vital to the safety of ship and crew. Instead of hoping your anchor and rigging scheme will hold, read “Rigging Modern Anchors” and be sure.

 

This book would fit nicely on any yacht's bookshelf, and would provide good reading evenings when the wind is howling outside...

---

Update!

If you have Amazon Prime or Kindle Unlimited, the book is available for free for a limited time!  Here's the link.

---

Rigging Modern Anchors

Runaway Starter

Starter motors are not designed for continuous service - they are not provided with any cooling capabilities.  This is because the design expectation is that they will see only intermittent service.  They are high-current, high-power devices however, especially the ones that are expected to crank diesel high-compression engines.  Now hold that thought...

A recent discussion on The Retirement Project bears review here.  It seems that when TJ went to start his engine, the engine start push button stuck, leaving the starter motor running continuously after the diesel had started.  Because of the lack of cooling, a runaway starter motor is a serious problem - aside from destroying the starter, a fire could result.

I recall an incident where a young woman pulled into a gas station where I was refueling my car, and proceeded to fuel hers.  Her starter motor was running, after she shut down her engine (presumably it had been running since she started her car...).  Running, but running poorly - the heat buildup had caused the armature to swell and it was dragging on the field poles, creating more demand for electricity and even more heat.  I opened her hood and found the battery lead to be red hot, smoking, with all the insulation burned off.  Remember, this was at a gas station, where this car (and mine!) were actively taking on fuel.  I shut off the fuel feeds to both cars and then used a tire iron to break the red-hot wire (easy - copper is soft when it is red hot).  The cause?  Welded contacts in the starter solenoid.

One time when driving (I was 17 at the time) my father's 1959 Oldsmobile, the same thing happened to me.  Again, the tool of choice was a tire iron, and I used it to try to pry the battery connection off of the battery.  And failed.  Instead, the post and part of the battery plates came out of the top of the battery, complete with plenty of sparks and acid.  In retrospect, it is lucky I didn't get to experience a hydrogen explosion.  Again:  the cause was welded starter solenoid contacts.

I guess it is not surprising that this happens - these contacts carry prodigious current - 75 - 100 amps in a car engine and more for a diesel, and are connected to a very inductive load.  When they are asked to open, the magnetic field in the starter collapses, boosting the voltage at the contacts, keeping the current flowing for an instant even tho the contacts are open: an arc occurs.  Most of the time, the contacts continue to open, extinguishing the arc.  But if the contacts are already damaged from arcing, the arc gets a head start because the contacts are already hot...

In TJ's case above, the cause was not welded contacts in the starter solenoid, but rather a stuck starter button.  But in my experience, this is much rarer than welded contacts in the starter solenoid.  Regardless of the cause however, the remedy to a runaway starter is the same:  Disconnect the battery.

Easier said than done.

All cars, and almost all boats have a hard-wired connection between the battery and the starter.  In boats, the usual case is that that "Off-1-Both-2" battery switch is only carrying the house loads - the starter is hard-wired.

I believe that this is a pretty serious safety hazard.

Blue Seas M-Series Mini Selector Battery Switch

Those big battery switches can easily carry the starter current load.  Even the smallest ones have tremendous current carrying capabilities. Here's a mini Blue Seas one:

• Cranking Rating: 10 sec. 1,500 Amps
• Intermittent Rating: 5 min. 500 Amps
• Continuous Rating: 300 Amps

For comparison, cranking Eolian's starter (Perkins 4-236 diesel) draws 200 amps - I know this because everything on Eolian goes thru the shunt for our Link2000 monitor. And everything also goes thru the battery switch on the power panel. Including the starter.  I can't take credit for this - Downeast (Eolian's manufacturer) built her this way.

If the starter on your boat does not go thru a battery switch (or THE battery switch), I'd sure try to find a way to make it so...

Runaway Starter

AIS - Should you have it?

AIS - Automatic Identification System - is a system whereby ships (boats, yachts) broadcast information about their location, speed, course, and much more on marine VHF channel 87 and 88 as digital data.  (Tune your VHF there if you want to hear what digital data sounds like.)

There are two classes of AIS devices, Class A and Class B.  Class A devices are intended for commercial vessels, and transmit with more power and more frequently than the Class B devices, which are primarily intended for recreational craft.

For either class, there are two kinds of devices, transceivers (transmitter/receivers, also incorrectly called 'transponders' - a term meaning transmitter/responder, a device that provides data when interrogated by an incoming signal), and receivers.  As you might suppose, transceivers both broadcast their ship's data and also receive data from other transceivers.  The other type of device, the receiver, collects data but does not broadcast it.  In practical terms, vessels with transceivers can see each other, but tho vessels with receivers can see those with transceivers, they are invisible to other vessels.

In order to provide position, speed, heading, etc data, transceivers need GPS information.  Many have a built-in GPS receiver, a few can use an external GPS via NMEA sentences.  Receivers do not need access to a GPS.  Typically, both transmitters and receivers make the data they collect available via NMEA 0183 and/or NMEA 2000.  Some also provide the data via RS-232 or even USB.

How is the data made available to a human?  Typically, a chartplotter will be connected to the AIS device via a NMEA bus and will display detected ships as icons on the display in their correct position, usually with a speed/direction vector.  The chartplotter will also note Point of Closest Approach, and if that is within a settable danger radius, will sound an alarm.  Tho few computers (laptops, tablets) are equipped to receive NMEA signals, adapters are available.  And of course almost all computers have RS-232 and USB capabilities.  This means that if you are running a navigation application on your computer, and it is one which is capable of receiving and interpreting NMEA sentences, then your computer will display nearby ships just like a chartplotter.

But... there are web applications which show AIS ship data world-wide...  why would you buy an AIS unit yourself?  Why not just use one of these apps on your phone?

The problem with the web-based AIS apps is one of reliability and delay.  Imagine how many AIS receivers are needed to provide world-wide coverage.  Now imagine the internet network that is required to collect and process all this data.  It is a huge system.  And there are processing delays - significant delays.  And there are system and network failures.  Further, making use of the web app that results from all of this collection and processing requires that you are not in a cell phone dead spot (there are plenty of dead spots in the San Juan islands, for example).  All of this combines to mean that the web display will be at best a picture of the situation from some time back.  I used a web app on my iPhone before we got our AIS receiver.  There were times when the display showed a Washington State ferry more than five miles away, when in fact that ferry was right next to us.  Kind of funny in bright sunlight, but not so funny in dense fog.  If you have your own AIS receiver, you won't be depending on someone else's system with all of its inherent delays and dependability issues, or your local ability to connect to the Internet.  Complexity is the Enemy of Reliability.

Coming also is the use of synthetic AToN (Aids To Navigation - buoys, etc.).  For this, a VHF station on shore broadcasts AIS data as if it were an AToN at a particular spot.  There is at least one of tow in Puget Sound, and you can expect more, particularly for situations where a buoy has gone missing or has drifted out of place.  The synthetic AToN will show up on your chartplotter, even if you can't see it with your own eyes.

The case of the out-of-place bouy is an interesting one...  suppose that a buoy has drifted 100 yeards into shallow water.  Would you believe your eyes, or would you believe the display on the chartplotter?

If you never are out and about in less than good visibility, then you won't need RADAR or AIS.  But if you find that you need to navigate at night or in poor visibility, then you should have both RADAR and, at the least, an AIS receiver on board.

Are they expensive?  Receivers are much less expensive than transceivers.  As a personal example, I traded an old iPhone for a used AIS receiver.  Watch eBay and craigslist - many boats that originally had just a receiver are now upgrading to a transceiver.

A number of VHF radios now are available with built-in AIS receivers, seemingly a natural blending of capabilities.  However as a standalone AIS receiver their displays are so small as to be almost ludicrous, and they provide so little information that they do little more than raise the anxiety level on board.  But connected to a chartplotter, this is a viable solution.

How about the transceivers?  Well, I just checked eBay, and found a new one, with a built-in GPS for $400.  There are a lot more available in the $500 range.  You can also spend thousands for a completely self-contained unit that includes its own display capability.  I find these to be ill-conceived, since if you have a chartplotter aboard, you won't be using the display.  And if you're investing this kind of money, you almost certainly have a first class chartplotter on board.

As for us aboard Eolian, we have that AIS receiver I got in trade for the old iPhone, and it is hooked up to our chartplotter.  I will strongly consider getting a transceiver when the prices fall more, or when some start appearing on the used market at a lower price.  In the mean time, it is wonderful to be able to see a ferry approaching Thatcher pass from the inside when I am approaching from the outside with no sightline.

(A tip of the hat to Jason for prompting me to write this!)

AIS - Should you have it?

Kidde Fire Extinguisher Recall

If you are compliant with US Coast Guard regulations, you have a fire extinguisher aboard.  In fact, you probably have more than one...  And in your house there is probably one under the kitchen sink, in the garage, etc.  There is an excellent chance that all of these were manufactured by Kidde.

Not these...

Well, get ready for this:  Kidde has recalled more than 40,000,000 of its previously sold (since 1973) fire extinguishers.  It seems that some of the units had plastic handles or nozzles which were prone to fail at just the wrong time, meaning that depending on one of these units was worse than having none at all.

According to the Consumer Product Safety Commission (CPSC), “The fire extinguishers can become clogged or require excessive force to discharge and can fail to activate during a fire emergency. In addition, the nozzle can detach with enough force to pose an impact hazard.”

The BoatUS Foundation for Boating Safety and Clean water is urging recreational boat owners to check their boats for the recalled extinguishers and get a free metal-handled replacement by going to the CPSC recall website.

The recall affects both plastic-handle and push-button Pindicator Kidde fire extinguishers, including 134, ABC- or BC-rated models manufactured between January 1, 1973, and August 15, 2017.

The extinguishers are red, white or silver and were sold in the US and Canada through a wide range of retailers from Montgomery Ward to Amazon. The CPSC recall website shows how to easily identify the affected extinguishers.

In the recall, Kidde also acknowledged the free replacement push-button extinguisher being sent to personal watercraft owners is similar in size to the recalled model but may not fit in the same location as the old fire extinguisher.

“This may require a slightly different mounting orientation or location,” said BoatUS Foundation Assistant Director of Boating Safety Ted Sensenbrenner.”

CPSC says there have been approximately 391 reports of failed or limited activation or nozzle detachment, including one fatality; approximately 16 injuries, including smoke inhalation and minor burns; and approximately 91 reports of property damage.

Kidde may also be contacted toll-free at 855-271-0773 from 8:30 a.m. to 5 p.m. ET Monday through Friday, 9 a.m. to 3 p.m. ET Saturday and Sunday.

The company offers additional recall information online at www.kidde.com by selecting “Product Safety Recall.”

Kidde Fire Extinguisher Recall

Plea For Data: Salish Sea Bottom Hazards

Our recent experience in Friday Harbor tells me that our charts are not adequate.  There is at least one more wreck in Friday Harbor that is not on them, tho it is marked by a buoy.  But buoys break loose, and then the wrecks become marked only by local lore.

It strikes me that there is a lot of data on wrecks out there... existing as pencil scratchings on charts, notes in logs, etc.

It is time.  It is well past time, that this data be consolidated and made available to all.  Navionics has what they call "community edits" - crowd-sourced data, but not everyone uses Navionics.

So this is a plea:  A plea for all who read this post to dig thru their logs and charts and make all that accumulated wisdom and experience available to the entire boating community.

I will volunteer to maintain a public database of Salish Sea Bottom Hazards, until a better method for making this community data available to the entire community exists.

Here's how you can contribute and help your fellow boaters:

1. Dig thru those logs and review all those notes on your charts.  
2. For each wreck or other bottom hazard, note:
   
   • The location of the hazard - GPS/Lat-Long coordinates are most desirable, but if you don't have them then a verbal description
   • A description of the nature of the hazard, if known or available
   • The source of the data... Hard experience (!), NOAA, Navionics community edit, cruising guide, etc
   • If you wish to be associated with the entry and how (email, name, boat name, etc)
3. Send this information in an email to WindborneInPugetSound (at) gmail (dot) com

Please don't worry that you might be providing duplicate data - that's fine.  I will sort it out.

So dig thru those charts and logs!  Be an active part of our boating community - lets all help each other!

Looking forward to your emails.

Bob
s/v Eolian

(Selfishly, I am most interested in data from Blind Bay, Friday Harbor, Echo Bay, Reid Harbor and Parks Bay.  In Parks Bay especially I would like confirmation of reports that the charted pilings in the south end of the bay have been removed, as has been variously reported) 

Plea For Data: Salish Sea Bottom Hazards

Permanent moorage in Friday Harbor

The red arrow shows our location

We dropped anchor in Friday Harbor on Tuesday, pretty much in the normal place.  Well, one of the two or three normal places - anchorage is pretty limited there due to the number of (mostly unoccupied) mooring balls.

Not long after, after the tide had changed, we noticed periodic rumbling from the anchor chain.  This is unusual; we thought that the chain was being dragged across something on the bottom.  So we decided to move.  Well, not so fast, there Pilgrim...  with 125 feet of chain still out, the windlass stalled.  Attempting to free the boat by motoring in various directions was fruitless.

So here we sit, now permanently at anchor in Friday Harbor.  At the moment, our chain is straight up and down, so we are directly over the obstruction.  Our location is (mark this on your chartplotters): 48° 32.137' N, 123° 0.483'W

This makes the third wreck that I know of on the floor of Friday Harbor.  I know that one of them has a buoy marking it, and I know now that one does not.  The third one?  Not sure - maybe one of those unused mooring buoys marks it too.

All I know is that it is going to be very difficult to convince me to anchor in Friday Harbor again until the Port of Friday harbor reports these wrecks to the DNR and gets them removed. 

---

OK, here's the postmortem. 

When we anchored, I avoided the wreck marked on the chart, known locally as "the old fishing boat that had been permanently anchored there for years, and finally sank". But when our chain started 'grumbling' as the boat swung to the tides, I thought maybe the position marked on the chart was off. We tried to raise anchor, but stalled the windlass with 125' of chain still out. Thought for about a beer, and then contacted Jill and Brent who live aboard s/v Ambition at the marina for a diver reference; they recommended Kurt Schwalbe. He came out yesterday afternoon at slack water (currents in Friday Harbor can be very strong - trying to do work down there while fighting the current would be terrible). Kurt deserved the stellar reputation he has. He is friendly, professional, deliberate, and a problem solver. Before going into the water, he discussed his plan with us, in detail.

It turned out that this was NOT the fishing boat, but yet another wreck on the bottom of Friday Harbor - a 21' skiff. And our chain had not only sawed partly thru the fiberglass wreck, but had it wrapped up like a Christmas present. Kurt untangled everything, but was not able to pull the chain out from under the wreck, where one turn had wedged itself. So we put Eolian's Perkins 4-236 diesel to work. After 3 or 4 mighty tugs, we were FREE!!!

Kurt enjoying a well-deserved IPA after the dive

I have marked the position of this wreck on our Navionics charts as a community edit, so if you use Navionics, you already have its location. If you don't, here are its coordinates:
48° 32.137' N, 123° 0.483'W

Permanent moorage in Friday Harbor

Propane and propane accessories

20 lb propane cylinder

A recent post got me thinking about propane. On the TV show, Hank Hill worked for a company that sold propane and propane accessories - if you watched that show, you're hearing that phrase and my words in Hank Hill's voice.

Propane is one substance that is present on almost every boat - large or small, power or sail.  In its own way, it can be quite dangerous.  But modern technology, techniques and regulations have taken the edge off of the dangers, almost to the point where people think it is a benign substance that is sold in grocery stores.  Oh wait, it is sold in grocery stores.

I think everyone carrying propane onboard should have some basic knowledge about this substance.  First, because knowledge is power.  But also so that they are aware of the consequences of violating those regulations or short-cutting those techniques.  Now those of you who know me know that I am no fan of regulations.  But those controlling the storage and handling of propane are one of the things that make regulations worthwhile.  Also, those cruisers voyaging outside the range of those regulations will find a different world - one where common sense is more critically relied upon - and here knowledge is crucial.



So what is propane?  First, it is a member of that class of chemicals known as LPG, or Liquified Petroleum Gas.  It's composition is CH3-CH2-CH3.  It is a hydrocarbon - that is, it is made up solely of hydrogen and carbon.  It is the third in the series of straight-chain hydrocarbons, after CH4 (methane, AKA natural gas) and CH3-CH3 (ethane), and preceding CH3-CH2-CH2-CH3 (butane, which you are probably familiar with as the fuel in, ahem, butane lighters).

Why is propane such a ubiquitous fuel?  Because it is easily liquified.  And liquid fuels under pressure do not require pumps for their distribution from a storage tank - they deliver themselves.  Also, because it is a simple compound, propane burns quite cleanly, which is why fork trucks running inside factories are frequently propane-powered.

OK, those are the basics.  But propane is a substance delivered in a manner that is unusual for consumer goods - it is a liquid, but it is under pressure.  To better understand what this means, an analogy is in order.  Everyone is familiar with another simple substance: dihydrogen monoxide - water.  Under normal ambient conditions, water is a liquid.  If you were to put water into a propane tank, and then take that tank to a hypothetical planet Hypethos where the ambient temperature is 350°F, you'd have our analogous situation.  Water cannot not exist as a liquid on Hypethos, unless it is kept under pressure, just as propane cannot exist as a liquid on Earth unless it is kept under pressure.  Once our Hypothetical tank full of liquid water reached equilibrium with the surroundings, it would be under pressure - about 135 PSI in fact. If you opened the valve on the tank, water vapor (AKA steam) would fly out.

Propane does this too, but at the temperatures we are comfortable with here on Earth.  At 75°F, the pressure in a propane tank is about 150 PSI.  If you leave that tank out in the sun, and it gets warmed up to say 110°F, the pressure climbs over 250 PSI.

FACT #1

Pressure gauges are really completely useless in showing how much propane is left in the tank.  At a given temperature, the pressure in the tank will be the same regardless of the amount of propane in the tank, as long is there is one tiny drop of liquid propane still present.  Once the last of the liquid has evaporated, then the pressure gauge will tell you how much vapor is left.  But by that point, you don't have enough propane left to cook dinner.  Aside from those transparent fiberglass tanks where you can directly see the propane, the only reliable way to gauge the remaining propane is by weight.  If you don't have a scale, you can get an idea of the amount of liquid remaining by sloshing it about in the tank.


OK, so the pressure rises as the temperature rises.  Then you won't be surprised to find that the pressure falls as the temperature falls.  At about -35°F, the pressure in the propane tank drops below 15 PSI.  That is, if you opened the valve, nothing would come out (remember, ambient atmospheric pressure is 14.7 PSI).  But actually it is worse than that.  Propane accessories (stoves, BBQs, etc.) depend on the pressure in the propane tank to deliver propane gas to the accessory.  A regulator in the circuit ensures that, regardless of the pressure in the tank, the appliance will see a constant pressure, and therefore flow rate to the burner.  But regulators can only work by reducing the upstream pressure.  If the pressure in the tank is below the regulator set point, the regulator cannot make up for it.  Also, regulators are designed for a "reasonable" upstream pressure.  As the propane is cooled, the pressure departs more and more from "reasonable", and the flow rate drops...  Your stove flame gets smaller and your BBQ refuses to heat up.

Fact #2

What might make the propane this cold?  Well, if you sail in the high latitudes, you could see temperatures low enough to impede or stop propane flow.  But even folks in the tropics can have problems.  Why?  OK, you have liquid propane in the tank, topped with a layer of vapor.  As you withdraw the vapor, more liquid evaporates, replenishing the vapor.  Ah, but evaporation (call it boiling, if that helps you to imagine what is happening) takes heat.  Where does this heat come from?  From the propane itself - it cools.  Now as the propane cools, heat flows into it thru the tank walls from the surrounding air.  You've all seen this...  First there is condensation on the outside of the tank (serving, by the way, as a pretty reliable liquid propane level indicator).  As the cooling continues, the tank wall could drop below 32°F, and the condensation turns to ice or frost.  (Please note that the propane is still liquid inside the tank.  For it to freeze, its temperature would have to drop to -306°F.)  But the accumulation of frost on the outside of the tank only impedes heat flow, the propane cools, evaporation slows, the pressure falls, and the flow rate drops.  And your Cajun burner goes out, ruining your crab boil even tho there is still propane in the tank.

Fact #3

1. Liquids are virtually incompressible.
2. Things grow larger as they are heated.

These two facts combine to make a propane tank filled to the top (or nearly so) a dangerous bomb. If a full or very nearly full tank is warmed and the small vapor space above the liquid is compressed to extinction, the tank will surely rupture, because the expansion of the liquid as it is warmed is as inexorable as the expansion of water as it freezes. And this is the worst kind of rupture - because the propane is not just a gas under pressure - it is a liquid under pressure that will rapidly flash to a vapor when that pressure is released, flinging shrapnel for long distances at high speeds.

How to make this understandable?  Try this.  If a standard 20 lb propane tank were filled with compressed air at 150 PSI, in its roughly 1 cubic foot of volume it would contain 10 cubic feet of air that would want to rush out if the tank were ruptured. But if instead it contained liquid propane, that propane would instantaneously flash to something like 270 cubic feet of vapor at tank rupture.

This is on top of the obvious fuel-air explosion hazard. This is the reason that Overflow Protection Device valves were added to the regulations concerning handling liquid propane in consumer tanks back in 1988 - to ensure that there is always an adequate vapor space above the liquid to accommodate liquid expansion.  An OPD is supposed to shut off the filling of the tank when it is about 80 - 85% full.  (Note that the little 1 lb cylinders do not have OPDs because they are not intended to be refilled.  There are several "prepper" sites out there that advocate the refilling of these cylinders - don't do this!  Because of the lack of an OPD, you could be creating a bomb.)




OK - now you know:

• What propane is
• Why pressure gauges don't tell you how much propane you have left
• Why propane stops coming out even tho the tank is not empty
• Why you should have an OPD on your tank

Propane and propane accessories

Tis The Season

Every winter there are boat fires - fires which rapidly lead to marina fires except in the most fortunate circumstances.  And these fires are almost universally electrically caused.

Why do they happen so frequently in the winter?  Because (up here in the north, anyway), it is in the winter when the boat's electrical system is most taxed, keeping the boat warm.

It is the combination of high resistance connections and heavy current load which is the problem.  Ohm's Law, one of the most basic electrical principles says in one of its forms:

P=I²R

Where P is the power or heat generated in watts, R is the resistance in ohms and I is the current in amps passing thru that resistance.  What this means is that the heat generated at a bad connection is powerfully related to the current being passed thru that bad connection.

Here's a visualization.  Have you ever changed out a 100 watt light bulb that just burned out?  It was way, way too hot to touch, right?  Incandescent lights deliver about 97% of their output as heat and only 3% as light (thus the push behind CFLs and LEDs).  So now you have some idea of what 100 watts worth of heat is like - its a lot.  Now let's consider a 30 amp shore power connector that has gotten salt water on it and is a little corroded.  If that corrosion causes only 0.1 ohm of resistance in the connection, the amount of heat generated in the tiny volume where the two pieces of metal in the connector touch will be:  30 x 30 x 0.1 =  90 watts.

As bad as that is, it is not the end of the situation.  In the female side of the connection, the connection is made by a springy contact pair which wedges apart when the male end is inserted.  The heat takes the temper out of these spring contacts, making the poor connection even worse.  In fact, this can snowball, leading almost inevitably to this:

Uh oh...

Prevention is pretty simple.  First, just put your hand on the shore power connector while all those space heaters down below are running.  It should not be warm.  If you have any doubt about your ability to judge this, disconnect the connector and look at both the male and female ends.  If there is discoloration, you have a problem.  Both the cord and the connector on the boat should be replaced.  Why both?  Because regardless of whether the bad connection was where the wires are made up to the female connectors in the shore power cord, the connection between the female connectors in the cord and the male connector on the boat power inlet, or where the wires make up to the male pins on the boat power inlet, the whole shebang has gotten hot.  And that means that everything has been damaged.  If you replace just one side (say, the shore power cord), it is likely that the now-damaged shore power inlet on the boat will cause the new shore power cord to overheat.  So then you'd have to buy a second shore power cord as well as the inlet connector.  Save yourself some money, a second risk of fire, and do it right the first time.

By the way, the marina end of the power cord and the connector in the marina's power box are also candidates for failure - you should check that end too.

Tho the shore power connection seems to be a common failure point, every electrical connection in the boat's wiring is a candidate too.  There are too many of these for me to call them out individually.  But if any electrical connection down below gets hot or shows signs of having been hot, repairs are in order.  Bad connections make heat, and heat makes bad connections worse.

When doing a general inspection, check the connections that carry the most current first - and yes, this does indeed mean that the 12V connections are a bigger risk than the 110V connections.  Remember, the heat generated is as the square of the current, and the highest current connections on your boat are likely to be the 12V ones.

Tis The Season

Ferry weather

The winds in Puget Sound can be exasperatingly screwy.  A frequent forecast has winds in the north part out of the north and winds in the south part out of the south.

In the central part when this happens?   Often enough it is calm in the section between Shilshole and the north end of Bainbridge Island - after colliding, the air must blow straight up or something.

And like tidal swirls, the air does odd things as it flows around the Olympic mountains, the islands and the waterways in the Sound.

The NOAA forecasts (issued at 0000, 0300, 0600, 0900, 1200, 1500, 1800, 2100) contain observed wind speeds at various locations in the Salish Sea.  You would think that this would be enough information.  Frequently, it is not.

Quiet morning on Puget Sound

Now here is an apparently little-known fact:  A side benefit of our WA State Ferry System is that the ferries continuously record the actual wind speeds observed in their crossings of the Sound.  These are not predictions, or speeds observed at shore-based weather stations like those NOAA uses - they are the observed wind speeds and directions out on the water.

Oh yeah, and the shore station reports are shown too.  It can be kind of fun to compare the shore station information with the on-the-water readings to see what you miss by only listening to the NOAA observations.

Ferry weather

Not A bad decision... A SERIES of bad decisions

Bounty awash

Some of you may remember a short post I made a while back concerning the loss of the tall ship Bounty.

The question I asked in that post, "... why did the Captain of the Bounty put her off of the "Graveyard of the Atlantic" in a hurricane?" still remains.  But now it is at least partially answered.  Of course, since Captain Walbridge went down with the ship, we will never know the entire story.

I recently ran across this account of the Coast Guard inquiry into the sinking.  It reveals that the decision to go to sea in the face of the hurricane was not only a bad decision, but one of many bad decisions that led to the sinking.  Amazingly, it was not even the final bad decision.

I have a friend who is involved in the Tall Ship scene on the East Coast.  When the Bounty sank, I commiserated with him.  His surprising response was that she was a movie prop that was to be burned and sunk after the filming was over. He said that the one time he saw her, she was being kept afloat with her bilge pumps, and she had two of three of them running continuously.  Given the testimony at the inquest, I'd have to say that the loss may not have been a surprise to those in the know.

Read the account.  It is sobering.

Not A bad decision... A SERIES of bad decisions

Our G-Dock Heroine

Right across the dock from us, on s/v Ghost, we have a genuine credentialed heroine.

On Nov 20th, there was an electrical fire aboard Ghost; 10 year-old Ellie and Fathom the dog were the only ones aboard.  Ellie did the right things, in the right order to save the situation. 

And on January 18th she was awarded a special medal by the Seattle Fire Department for her courage. 

Way to go Ellie!

The Ballard News Tribune has the full story.

Our G-Dock Heroine

Headlights on your boat

What?  You don't have headlights on your boat?  No?  Why not?

White, bright

You should.  An LED headlight like this one is dirt cheap (I got it at the hardware store for a few bucks).  It serves to shine a lot of light on whatever you are working on - in the bilge, on the engine, or on deck.  When you turn your head, the light follows, since it is right there, on your head.  It's like you have a telepathic helper magically holding a flashlight, always just where you need it.

Red

And this one ("Energizer", by brand) also has a red LED for illumination while preserving your night vision.  Now really, you never know when this might become it's most important function.

Headlights on your boat

The Bounty is gone

Sunday nite, the tall ship Bounty sank in hurricane-whipped seas about 90 miles off Cape Hatteras.  Fourteen of the sixteen people aboard have been rescued.  Apparently 13 of the crew had made it to life rafts when the remaining 3 were washed off the deck.  One of those three made it to a life raft.  Reportedly all of the crew had donned survival suits with strobes, so there is still hope for the missing two crew members.  The search continues, but in the very difficult conditions created by hurricane Sandy.

Our prayers go out to the crew of Bounty and their families - especially to the families of the two missing crew.  But a nagging question remains...  with today's weather predictions and weather information, why did the Captain of the Bounty put her off of the "Graveyard of the Atlantic" in a hurricane?

Bounty appeared in several motion pictures, including the original "Mutiny on the Bounty" starring Marlon Brando.

The Bounty is gone

Got light?

You do have a flashlight aboard, don't you?  You should.

Aside from all the "regular" things you'd use a flashlight for when ashore, on a boat you'll also want to have one handy so that:

1. You can inspect the bilge
2. You can inspect your shaft log packing
3. You can inspect your thruhulls... all your thruhulls, especially if item #1 has suddenly become important...
4. You can signal other boats
5. You can bungee it to something astern to serve as an emergency stern lite (don't ask)

Now, how about a red flashlight, for all of those things above, when you don't want to ruin your nite vision?

Got light?

Breathing easier

It is probably a coincidence that the marina posted this notice at the head of our dock Tuesday, just a week after this blog posting.

And kudos and thanks go to Deborah and Marty of Three Sheets Northwest, for giving that original post prominence on their site, putting it just under the article about the two boats that recently burned in Edmonds.

Breathing easier

A little G Dock New Year's excitement

m/v Clupea

This morning when Steve cranked the starter on m/v Clupea, a gorgeous old wood boat, the starter solenoid exploded, starting a fire.

Steve was able to extinguish the fire before any real harm was done, and then he called the Fire Department to come check out everything with their IR gear to make sure that the fire was really out (I would not have thought of that).  Thank heavens that Clupea is a diesel boat.

A flash of genius

And thank heavens that Steve was able to get the fire out with what he had on board, since the Marina has recently implemented a policy of shutting down the fire hoses on the docks for the winter.   (Thankfully, most boat fires do not happen in the winter.  Oh, wait...)

The sign is cheaper

I suppose they have discovered that it is far cheaper to put up a notice than to properly maintain all those pesky freeze protection valves...

A little G Dock New Year's excitement

Safety Item: Orion issues recall for flares

Three Sheets Northwest notes this safety item - you need to check your flares. Note that the "signals" they speak of are the actual cartridges - not the gun that shoots them (although it too is orange in color).

Orion Safety Products has issued a recall for two models of its hand-launched aerial signals, citing problems with the devices failing to launch and/or ignite.

The recall applies to older Orion XLT and 12-gauge signals made with orange ABS plastic. XLTs are self-contained, hand-launched signals, while 12-gauge signals have a pistol-style launch and a plastic shell.

In 2008, Orion switched from orange ABS to red-colored, glass-filled polyethylene for its better strength, durability and resistance to moisture. The last XLTs that used orange ABS in the launch tube body expire this month, while the last 12-inch gauge shells using the orange ABS plastic expire in March 2012.

If you have an XLT signal with an orange launch tube that has an expiration date between November 2011 and December 2011, or an orange 12-gauge shell that has an expiration date between November 2011 and March 2012, you are eligible to receive a free, four-pack replacement at no cost.

For details on how to receive the replacement flares, check the original article at Three Sheets Northwest

Safety Item: Orion issues recall for flares