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August 1, 2000 Issue

August 15, 2000 Issue

August 1, 2000

Six Day Cruise Down the Chesapeake Bay (With 5hp!)

By Bill Zeitier & Herman Hopple

Here I am again in my converted 21', flat bottom, sharpie hull, ex-Bay Hen catboat, now my 5hp/4 cycle Honda PMT... " Poor Man's Trawler" Amenity. If you don't wish to read this report in its entirety, you might enjoy a chuckle with me over when I was cruising up the Severn River on Day 3 (May 15th) through the U.S. Naval Academy area near Annapolis, Maryland. A navy officer-student skipper of a gray Navy vessel, YP688, came up behind me to pass me on my port side. In accordance with proper nautical procedures (and probably with a naval officer-instructor looking over his shoulder) he gave me two very loud blasts of his ship's horn for permission to pass on my port side. Knowing most of the rules I grabbed my small red plastic lung-powered horn and gave him two lung-powered toots in return. Great fun!

Day 1: The ramp at the Triton Marina at Plum Point at the very head of navigation on the Elk River at the top of the Chesapeake Bay did not open until 0800. Because I wanted to cast off towards Annapolis, Maryland at 0600 the next morning, the nice folks at Triton allowed me to stay overnight at a little used ramp dock. NOAA weather radio sounded an alert for an extremely severe weather cell and front to pass directly over me that evening. I did not need the radio to tell me what was coming as the sky turned black as ink and all nature seemed to hold its breath. I doubled up my dock lines just as the rain started. I buttoned myself up in the cabin and hunkered down inside my cozy "womb".

After a few moments we were bombarded with golfball sized hail, fire hoses of rain and a continuous blitz of lightning and thunder. "It will surely pass in a few minutes," I said to myself. Wrong! After about an hour of this the rain let up a bit so I opened up and found about 6" of water in my cockpit. I quickly hand pumped it out when down came round two. By midnight I finally said, "the heck with it!" and fell asleep.

Day 2: At 0600 this morning I cast off and headed down the Elk River. It was a truly beautiful morning in all respects. A grand day for my five knot, 5hp cruise down to Swan Creek on the Eastern Shore of the Chesapeake Bay, my first night's anchorage. If one cruises just outside of the major big ship channel that leads to the Chesapeake and Delaware Canal it is quite safe as long as one keeps a good lookout. There is a two mile shoal that extends down southward from Swan Point where the water can be quite thin. Even with only 48" of draft I did kiss this shoal last year trying to shortcut across it and it scared the wits out of me.

This year I had decided to go around the shoal (vs. cut across it), but when I saw large keel sailboats shortcutting across I took a deep breath and followed them in over the shoal. No problem. I was getting quite fatigued as this entire area is also a minefield of crab pot floats and one really has to concentrate at the tiller ! (Note I have no major problem with crab pots as I love crab cakes!). However when I finally reached an upper section of Swan Creek I was very happy to drop anchor at about 1520 in company with a 50' power yacht and four large cruising sailboats, for which my PMT could have been a dinghy!

Day 3: At 0600 this morning I headed further south down the Bay cruising just off the Eastern Shore. My major target was the huge Chesapeake Bay Bridge now in view. I took a heading for the tall blue water tank at the Sandy Point State Park on the western side of the Bay and headed out across the five miles or so of open water to the western shore. This being a major shipping lane area for the port of Baltimore, the hour it took for me to cross went quickly as one is in constant and intense state of alertness for shipping. Most shipping stays in the lanes but smaller commercial vessels and pleasure craft can come from most any direction! As it was a weekday it was almost a solitary crossing, but it is always a relief to me to get to the other side. Down around Hackett Point we headed east past the remaining three tall naval radio towers built quite some time ago to communicate with submarines at sea. Then on to the entrance buoys of the Severn River at Annapolis. Passing through the US Naval Academy area, which is on both sides of the river, is quite interesting. One should be sure to know the rules of the road, nautical protocol, etc. as the officer-student skippers will be sure to do everything by the book and will expect you to respond properly. It was here that the US Navy requested little ol' me for permission to pass, which I granted!

About nine or ten miles up the beautiful Severn was my destination, my daughter's modest but nice house at HeraId Harbor. This area was so named long ago by the Washington, DC newspaper, The Washington Herald which owned the property at that time. Most homes along the actual shoreline are beautiful beyond imagination, especially Walter Cronkite's retirement "pad".

Day 4: 1 cruised back down the Severn for a day out with my daughter and her friend for a picnic lunch at anchor in Spa Creek surrounded by millions of dollars worth of power and sailing yachts in the heart of the Annapolis area.

Day 5: At 0700 1 headed directly across the one mile wide Severn Round Bay to pick up my Marsh Hen sailor friend Herman Hopple, who was staying at his summer place on Dividing Creek on the Magothy River only a couple of land miles away but about twenty sea miles. Per the many e-mail plans we made to help pass the winter doldrums we met face to face for the first time at 0730, but I'll let Herm tell you about our great day out together as follows:

"Through the Internet Hensnest site (I own a Marsh Hen) I became acquainted with Bill over the winter and learned of his plan to cruise down the Bay and up the Severn to visit his daughter at Herald Harbor on Round Bay. Since my summer place on Dividing Creek on the Magothy is only a short distance by land (a mile or so) from where Bill was, I walked over with my gear and we cruised together down the Severn in Amenity for a one day, twenty mile circumnavigation of the Bi oad Neck Peninsula. We cruised back down the Severn, around and up under the Bay Bridge and into the Sandy Point State Park area for a picnic lunch ashore. From there it was up into the Magothy and westward to my place on Dividing Creek towards the western end of the Magothy where I moor my Marsh Hen sailboat. The day was again perfect and in less then an hour were at Annapolis.
After watching some naval cadets practice their ship handling, we took a side trip up Spa Creek soaking up the ambiance of that famous sailing area. On our way back we could not resist slipping into the Annapolis city Harbor (known as Ego Alley) and take a turn through this historic area.

By 1045 we had sailed out past Whitehall Bay, ducked under the Bay Bridge and into Mezick Pond ramp and docking area of Sandy Point State Park. We tied up at the public dock, stretched our legs and had a nice bag lunch ashore. It was especially interesting to see a fleet of very special open sailboats with special pivoting seats (and seatbelts) for the use of folks with serious physical disabilities.

Returning to the Bay, we found the temperature was in the low seventies, sun gleaming on the very calm water, just wonderful. We seemed to have the Bay all to ourselves. I couldn't recall a more pleasant time on the water. I remarked to Bill that this is the way everyone visualizes it when dreaming of boating on the Chesapeake.

We reached my place on Dividing Creek about 1500, made Amenity fast to my dockjust behind my Marsh Hen, had a few brews and headed into waterfront Annapolis by land for a delicious crabcake dinner. A wonderful day. The kind dreams are made of.

The next morning I saw Bill off at 0600 on his return trip back up the Bay to the upper Elk River. NOAA was reporting strong southerly breezes. I'll let Bill tell you the rest of the story."

Day 6: NOAA was calling for a southerly wind and scattered showers for this day to be followed by many days of a very slow moving low pressure stormy period with possible strong thunder storms the next day. I decided to head back up the Bay as fast as possible. I had planned a typical five knot, two day run home with an overnight at anchor on Fairlee Creek on the Eastern Shore. After casting off from Herm's dock on Dividing Creek on the Magothy River at 0600, it was one hour to the Bay itself. A bit of rain started and I put on my yellow rain gear and buttoned up the cabin. I quickly saw that I had a strong south wind (reported to be 25 knots), about I knot of fair current, and two foot waves on my stem. Mother Nature seemed to be pushing me back up the Bay in every way possible. Although it was gray and overcast I put up the bimini to get perhaps another favorable quarter of a knot of speed.

Since the following waves were moving a bit faster than I was, I surfed homewards on every other wave a good part of the time, sort of a giant surfboard with a cuddy cabin. It was quite an exciting ride. Although I felt little danger of broaching or pitch poling, I did have to mind the tiller. By noon I was abeam of my first night's planned anchorage at Fairlee Creek. I made a quick calculation and decided that at my current speed the prudent thing to do was to press onward homebound and beat the bad weather predicted for the next few days. I was later really glad I did.

I arrived at the Triton Marinia on the upper Elk River about a half an hour before they put the chain up at 1700 to close the ramp for the night, home a day early. I really do thank Mother Nature for helping me along as the weather was really ugly for nearly a week thereafter. Being at home, warm and snug vs anchored up in some cold, gray, rainy creek for four or five days is definitely the preferred locale for writing up a cruise report.

Now where to go for my next cruise in my PMT Amenity?

August 15, 2000

When Metals Corrode

By Ward Knockemus

In the April 1st issue of this valuable tome Robb White had a meandering and entertaining article (they usually are) in which he mentioned problems with persistent metal corrosion in an outboard engine that gets dipped in Florida Gulf salt water most of the time. Robb said the engine corrosion seemed to be faster on a boat that had stainless steel sheet attached to the hull.

This got me to thinking back to a couple of summers fifteen years ago when I did corrosion research for NASA at the Marshall Space Flight Center at Huntsville, Alabama. The research focus was to evaluate the ability of various greases to protect the steel of the solid rocket boosters after they parachuted into the ocean. In the labs there we could speed up the metal corrosion a hundred times or so to get a quick read on how well the greases worked.

Robb's problem of accelerated corrosion on the outboard fastened to a boat that had stainless steel (especially with the salt water environment) is not surprising and I want to give you a few principles to understand what goes on when metals corrode. Please forgive me if I sound like a chemistry teacher. Forty years of being one has given me some kind of brain damage that makes me too professorial at times.

Metal corrosion is an electrochemical process. Electrons are released by more active metal atoms and flow toward less active metal atoms. When the electrons get to the surface of the less active atoms, they usually react with water to form hydrogen gas which is released to the atmosphere. Of course, the presence of salt in water furnishes ions that provide an easy pathway for the electron flow. Distilled water with very few ions is a lousy conductor of electrons, but dirty and soapy water, and most solutions have plenty of ions to speed possible corrosion.

An important point is that salt water does not cause corrosion, but it sure does make it go faster. Washing and flushing metal surfaces after exposure to salt water is a good idea because it helps eliminate conducting surfaces.

Now comes the bad part. The metal atoms that lost electrons (and become ions) get kicked out of the metal atom lattice. When a few zillion are lost, a pit, hole, or void occurs on or in the metal surface and we call this corrosion.

If there were no areas to which these electrons could flow, there would be no corrosion. It is a cooperative arrangement between the more active metal atoms that lose electrons and the less active metal atoms often in another location that accept these electrons.

Robb's stainless steel served as a friendly host to the lost electrons and as strange as it seems, speeded up the corrosion in the outboard some distance away. Copper sheet or some similarly inert conducting surface would act the same way as the stainless steel completing the circuit for the electrons.

There is an electrical potential difference between the more active and less active metal surfaces and this voltage can be measured. It is usually 2-4 volts. This kind of corrosion can be called galvanic corrosion and sometimes is mistakenly referred to as electrolysis. For a chemist the electrolysis is the reaction of the electrons with the water molecules.

Even an object of one kind of metal can have areas of metal atoms more prone to lose electrons than somewhere else on the same piece of metal which permits corrosion of the more active metal area. An ordinary nail, for example, has zones more "stressed" than other places on the same nail. For some reason, the stressed sites tend to lose electrons and thus corrode.

Active metal sites are said to be "anodic" and those sites accepting electrons are described as "cathodic". When two different metals are in physical contact or connected by an electron conductor of some kind, one metal is always anodic and the other cathodic and galvanic corrosion eagerly occurs. Obviously, in Robb's boat the stainless steel served as the cathode and some part of the engine served as the anode and as usual, the anode metal disappears.

What about the role of atmospheric oxygen and is it needed for metal corrosion? How can corrosion occur under painted and protected metal surfaces? Can galvanic corrosion be prevented or at least slowed down? The role of oxygen in this fairly simple process called corrosion is surprising and I will now consider this along with some corrosion prevention strategies.

All you old Salts out there know that the contact of two different metals leads to the corrosion, sooner or later, of one of the two metals. Moisture and air speed up the process. Recently I noticed some pitting on an aluminum Hobie 16 mast where a stainless steel bracket was attached. This is inevitable though it may be slowed with a non-conducting spacer of some kind between the different metals. But remember water is always present in one form or another to complete the circuit allowing electrons to leave the more active metal (the anode) and go to less active metal(the cathode) which results in the destruction of the more active metal. Even a single piece of one kind of metal can have cathode sites and anode sites and corrode without the assistance of a less active metal in the vicinity as most of you have observed on a rusty nail. However, very pure iron with more internal homogeneity is less susceptible to corrosion.

An example of greatly accelerated corrosion of one kind of metal is observed when the metal (such as aluminum, zinc, magnesium, iron, and many others) is dipped into hydrochloric or sulfuric acid. The metal dissolves as hydrogen gas bubbles off; hydrogen for man-carrying balloons hundreds of years ago and for observation balloons during the Civil War was prepared this way, the only problem of course was the great combustibility of the hydrogen as evidenced in the Hindenburg and Challenger disasters.

The much higher concentration of hydrogen atoms (actually hydrogen ions) in acid solutions is the reason for the faster corrosion of metals in acid partly because the positive hydrogen ions from the acid attract the negative electrons of the corroding metal.

How does atmospheric oxygen affect corrosion? Sometimes it slows it down as observed with the ubiquitous aluminum cans in the environment persisting for years and sometimes oxygen speeds up corrosion as in the case of iron and its countless alloys. Fortunately, (or unfortunately when roadside cans litter) the very active metal aluminum forms a thin, impermeable, protective coat of oxide and so protects the underlying metal from further corrosion. Magnesium behaves the same way. Stainless steel and Nichrome also form protective, impervious oxide coats in air.

But what about the rusting of iron? The corrosion of iron and many of its alloys to form hydrated iron oxide known as rust requires both water and oxygen. Iron will not rust in oil even if oxygen is present, nor if water is absent, or in very basic solutions above pH 9.

Here is how iron corrodes and rust forms. An iron object always has (as an example of nature's perversity) cathode sites and anode sites. As always the anode sites are eager to lose electrons that migrate to the cathode sites. At the cathode sites the electrons react with oxygen and hydrogen (from the water) to form more water. Water permits the electron migration, particularly salty water.

ne iron atom having lost two electrons now makes its way to the greater oxygen concentration at the cathode where it loses another electron, joins with oxygen atoms and water molecules and becomes hydrated iron oxide or rust (see the figure). The rust forms where the oxygen supply is greater, which may not be where the pitting or corrosion has occurred. I am sure you have noticed that while pitting occurs under a broken paint surface the actual rust is where the air (oxygen) is more accessible. A shovel stuck in moist dirt for a few weeks shows pitting under the dirt, but the rust has formed where oxygen is more available at the air-dirt interface.

Obviously we prime and paint iron surfaces to keep air and water away. But if the protective seal is broken by a scratch or scrape to expose bare metal, look out! The metal dissolves under the paint since it is there the metal is deprived of oxygen and becomes the anode, while the bare metal from the scratch (serving as the cathode) is where the rust appears. As the supporting surface under the paint dissolves, the corrosion steadily eats its way under the remaining protective coating until the whole area is a rusty mess. I saw this many times on car fenders and rocker panels during the several shivering years I lived in Iowa and Pennsylvania where salt used to melt road ice could do its damage in a single winter.

I observed many years ago an amazing example of a site-specific disappearance of iron in an instructional film. A tight rubber band was wrapped around a 4"xV iron panel 1/16" thick and the panel submerged in water into which was bubbled air. Over a period of several weeks, time lapse photography showed the rubber band eating its way through the iron panel just like a wide hack saw powered by an invisible source. Robb White has told me that even stainless steel with 3M 5200 sticking to it will corrode disastrously under the adhesive where no air is present.

The protective coating of zinc with galvanized iron works in a different way than paint. Zinc is a more active metal (chemically speaking) than iron. This means that whenever the zinc contacts the iron, the zinc is always becomes the anode. So the zinc dissolves not the iron. Even if the zinc coating is abraded through to the iron, the zinc is still the anode and dissolves being "sacrificed" in the protection of the iron.

This is called "cathodic protection" and the metal doing the protecting is known as the "sacrificial anode". Galvanized iron is protected from corrosion by the sacrificial anode surface, the zinc; the greater the surface area of the zinc, the better the protection. Often, buried iron pipes for their long term preservation are connected by conducting wire to buried magnesium blocks that serve as sacrificial anodes; the iron pipe does not corrode as long as some magnesium metal is present.

Finally, a word about the "tin" can. The thin tin coating on the iron can is unreactive to to foods in the can, while the more active iron would dissolve in acidic foods (tomatoes some fruits). Now, what would happen if the less active tin plate is scratched through to the iron'? The large area of the tin (the cathode) encourages corrosion of the iron and before long the can leaks, but the Tupperware people have known this for some time.

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