August 2006 Editor: Tom Gillard
Please remember, in your thoughts and prayers, all our Troops around the
world and those on the way home.
Our Club Officers are:
Port Captain Secretary
Lucian Cayce Andy Myrick Harry Bloodsworth John Garibotte Theresa Higgins Debbi Merrill
Fall Regatta: Sept 23-24
Race PRO: Matt Crawford
Supper starts around 6:00pm
Meeting starts at 7:00pm at the HYC site.
• Theme for
August Meal is:
"Stolen Recipes at HYC"
Bring any recipe out of the HYC Cookbook(still on sale by Wendy) that is
NOT YOURS! This means that everyone can
participate. We will be talking about the Fall Regatta, Sunday Races, other
Racing Events and the food is always outstanding because you are the one's
who bring it, and everybody knows sailors are great cooks!
Everyone, please bring a dish and enjoy the friendship and fellowship out at the lake.
On behalf of the club I would like to thank everyone that help make this
a very successful event again this year. We had 17 participants.
Most of them hadn't ever been in a sailboat. We may have just witnessed
the next Dennis Conners starting their sailing excitement. Thanks again
Sunday Series: Don't forget to come out and race.
A schedule is on the web site. Click HERE
Contact David Ranstrom if you have questions.
As a reminder of what we take for granted. Here are some pictures from Kelli, Sally R.'s daughter. She is working in a hospital in Iraq.
Whenever different metals are placed in a conductive liquid you create a battery. If you connect these pieces of metal together, current will flow. The current will be removing metal from one of the metal pieces = "electrolysis". If this piece is the zinc in your flashlight battery that is good, but if one of the pieces is your propeller it is bad.
The zincs you use on a boat are called "Sacrificial Anodes". Zinc is used because it has a higher voltage in the water so the current will be more inclined to flow from it than from your propeller. To complete the electrical circuit, the zincs must be connected to the items they are intended to protect. Usually this is no problem because the zinc is bolted right to the shaft or underwater housing. Non metal boats will usually have a copper bonding wire inside that connects all the underwater metal items together so they all share the protection from zinc anodes. Since engines use the metal frame as the negative battery connection and the engine is connected to the prop shaft, the engine and the negative side of your 12 volt system are also part of this bonding connection. This bonding wire is usually connected somewhere to the rigging. This is not for electrolysis protection but for some protection from lightning strikes to conduct it into the water through the items connected together.
If other currents are allowed to get into this bonding circuit they can easily overpower the small voltage available from your zincs and defeat the protection you need. This is usually the most destructive form of electrolysis and you notice it because your zincs get eaten up very quickly trying to keep up. Under normal circumstances, zincs should last at least a year if they are working normally, and much longer if you don't have any problems. If they are being "sacrificed" in a shorter period you need to find where the external current is getting in.
The most common source of this external current is the shore power connection, especially the ground lead. Docks are notorious for bad wiring and often the ground lead is not connected to ground, is connected to the neutral, is being used for carrying current to a mis-wired boat, and all other sorts of problems. So the ground lead should never be directly connected to the ground bonding system we talked about earlier. The purpose of the shore power ground lead is to provide a return path for current if there is a short circuit or power leakage from an appliance or the wiring on the boat. You don't want it to connect all the underwater items on your boat to the underwater items on all the other boats and the dock because now your zinc is trying to protect everyone else too.
Unfortunately it is not always possible to keep the circuits separate due to interconnections such as shore power chargers. There are a number of ways to separate the shore power ground from the boat's underwater bonding system. The preferable and safest way is to use a galvanic isolator to introduce a 1.2 volt insulator in the circuit. This is enough to isolate most galvanic voltages but it will still conduct electrical faults and keep the boat safe in the event of a ground fault in the wiring or in an appliance. The galvanic isolator must be rated for the size of your shore power circuit.
If you can't afford an isolator, then the next best choice is to disconnect the two circuits so electrolysis currents can't flow. You will still have a solid ground connection on all the devices being operated on the AC power but this ground will not be connected to the boat underwater items or the 12 volt negative.
Keep in mind that this approach involves an increase in the danger level if there is an electrical fault. There is a possibility that if a short circuit develops somewhere between the AC supply and the 12 volt system, it will not trip the circuit breaker and leave things like the engine block and DC equipment alive. If you take this route it is important to make sure your rigging is NOT connected to the bonding circuit as this could theoretically put dangerous voltages on the rigging.
TESTING FOR CONNECTIONS BETWEEN THE SHORE POWER GROUND
AND BOAT GROUND
Disconnect (unplug) the shore power. Plug in and switch all shore power items on. (Make sure your inverter is off if you have one.) Use an ohmmeter to measure the resistance from each of the pins in your shore power inlet to the negative bonding system. All should be greater than 1 million ohms although readings as low as 100,000 ohms are not uncommon due to salt and moisture.
If the reading is low you need to find where the connection is and correct it. Unplug items one at a time until you find the culprit. MAKE SURE THAT THE SHORE POWER GROUND HAS NOT BEEN CONNECTED TO THE BOAT GROUNDING SYSTEM ANYWHERE. Unplug your battery charger and measure resistance from each of its power cord pins to the 12 volt outputs. All should be greater than 10 megohms. Check any other items that connect between the 120 volt system and the 12 volt system or engine frame, or anything grounded to the battery. Check amplified antennas which might be grounded to the rigging and be grounded by the coaxial cable to the TV or VCR.
If you have any other connections to shore (telephone, cable TV), do the same test on them - disconnect from the dock and measure from incoming connections to your boat ground system.
When you have removed all connections from your underwater metal items to the shore connections you are well on the way.
You can also disconnect the ground lead in the shore power connection of the boat you are checking. Measure the AC voltage, the DC voltage and the DC current between the ends of the ground circuit after disconnecting.
If the AC voltage is above one volt while the shore power breaker is on but disappears when the breaker is off, then there is AC leakage on the boat. You can usually track it down by turning off shore power items on the boat one at a time to find the culprit. Once isolated it should be repaired or replaced. If all appliances are off but it still comes and goes with the shore power breaker, then it is leakage in the AC wiring. Check the shore power connectors, all junction boxes, outlet boxes, light fittings, breaker panels etc., to look for dampness or corrosion.
If the DC voltage is below 1 volt, a galvanic isolator will provide the protection you need.
If the DC voltage is above 1 volt you have a serious problem that may not be solved with a galvanic isolator. First check that the DC source is not coming from the boat by disconnecting all 12 volt DC sources on the boat either at the battery positive terminals, or with a main switch, but check that the main switch is actually disconnecting everything. Sometimes there are curcuits like bilge pumps and alarms that are intended to remain on even when the main switch is off. If removing all sources eleimates the DC voltage, then reconnect and subsequently remove DC loads one at a time until you find the culprit. Once isolated it should be repaired or replaced.
If the DC voltage is still above 1 volt after disconnecting all on board DC batteries and chargers, then the DC must be coming from the dock ground. This is probably being introduced by faulty wiring in another boat connected to the common dock ground that is feeding down the ground line to all the other boats. The best way to isolate this problem is to wait until the other owners are away, or liveaboards have gone to work, and disconnect their shore power cords (after first turning off the dock breaker) one at a time until the voltage goes away. Please remember to replace them and restore power as you go. Having isolated the culprit, you have a public relations problem to convince the owner that he is not only risking damage to his own boat, but to all the other boats on the dock. Showing how disconnecting their shore power cord makes the DC voltage reading go away should convince them.
The DC current should be below 20 milliamps, +/- depending on the size and type of boat. Significantly higher readings indicate active galvanic action. Compare this reading to the current flowing with a galvanic isolator in the ground circuit to verify that it is providing protection.
There are other sources of electrolysis that you can't correct. The boats each side of you in the marina may be connected together through the dock ground lead and one may be eating up the zincs rapidly on the other. If your boat sits between them, this current may take a short cut by going in an item near one boat, and exiting via your zinc near the other. This will eat up your zinc too even though you are not connected to them. The best solution here us to use zinc fish while you are at the dock. They are large lumps of zinc, often cast in the shape of a fish, that are cheaper and easier to replace than the zincs on you shaft.
The "fish" come with a copper wire already attached which is also used to hang them in the water. They have an alligator clip on the end of the wire and this should be connected to the negative bonding circuit on your boat. If it is not conveniently available in the cockpit in the vicinity of the prop, you might consider installing a stainless bolt for clipping it to, with the head of the bolt inside the deck connected to the negative bonding system. Clipping it to the shrouds or railing will only work if somewhere on the boat the shrouds are connected to this boat negative bonding system.
Metal boats are more of a concern because if electrolysis eats a hole in your hull you can sink. Protection on metal boats depends on coating the hull with an epoxy insulator to minimize the amount of metal connecting to the water. Zincs are then placed all round to provide protection from places where the the coating has failed and for unpainted underwater items. There are electronic devices which use your 12 volt battery to inject current into the water just like the zincs do, to protect your metal boat. I personally have had some very bad experiences with these and highly recommend you throw them overboard. Although they can provide protection when they are working, the potential for disaster if they fail is not worth the saving in cost of a few zincs, which you have to install anyway in case the 12 volt supply is not available. Even when working correctly, I find the chlorine generated at the electrodes can eat up your underwater paint job.
Here is something that might happen during the Sunday series or during the regatta:
Two boats, Green and Red, on opposite tacks, are approaching a windward mark to be left to starboard. Green is on the starboard tack layline, Red is one boatlength to windward of the port tack layline. What should happen? Click HERE to see the illustration of this.
Knots are used by many people everyday, and sailors should have a basic knowledge of some of the most popular ones.
Animated Knots by Grog