GOOD  PRACTICE

All within reach and visible - properly locating electronic screens and controls.

Should I replace that bulb?  Signs that a lamp is nearing the end of it's life.  Also a few words on halogen lamps and what is appropriate for use in the engine room.

All about batteries

Appearance vs. Functionality

The Weep Hole

Dielectric grease

Cut Hands in Salt Water (ouch), What to Do?

Never Paint it Again: Using HDPE in the Marine Environment

Sieze Not - under reconstruction

The consequences of running a marine engine without oil is seizure, parts mechanically weld together. Not quite as bad as sinking, but right up there. Some non-electrical problems you discover working on boats are so serious that you are obligated to take action. This story is all about paying attention to details. You watch where you put your feet or you step through open hatches. Paying attention to the boat turns up pretty amazing issues. If you can do the job properly and it won't take too long, you fix it. If not, you let the owner know in writing he has a problem that needs attention. One way or another, you've done your duty.   I was doing a routine inverter install on a 32 foot sailboat. The inverter manufacturer recommends grounding the case of the inverter as a safety precaution. I took a look at the engine block, which is the mother of all grounds on a boat. The battery cable was connected to a fairly accessible bolt on the engine block, so I figured I'd put my inverter safety ground in the same place.

 !/weblog/images/19.jpg! Removing the bolt, I noticed something odd. The bolt threads were coated with crankcase oil. Looking closer, I noticed the washer under the head of the bolt was copper colored. The washer was also indented where the bolt head tightened against it. The bolt that was holding the battery cable to the engine block was was originally just sealing an unused engine oil pressure test port. With a little too much vibration working against the battery cable, the bolt could loosen up. It doesn't take too much imagination to envision a scenario where the engine pumps its lubricating oil into the bilge while the boat is cruising along.

 !/weblog/images/20.jpg! In this photo you can see the engine oil dipstick just above the center the picture. The oil pressure test point is just above and the left of the dipstick. The battery cable lug, with a telltale black oil stain on the inside, is between and below them. The rusty hole to the left of the battery cable lug at the left edge of the picture is an unused blind, tapped hole in the engine block. That's probably where the cable should have been terminated. When the boat was repowered from gas to diesel some years ago, whoever did it picked an unfortunate place to attach the battery cable to the engine block. Years have gone by and there hasn't been a problem. But they're very well could be a problem, particularly if I terminated one more cable under the same bolt. Probably nothing bad would happen. But I don't want to ever have to explain why I made a second ground connection at an engine oil pressure test point. So I've identified a good place were both cable should be connected. Over the years, however, the threads in the 10 mm hole have become coated with enough rust you have to look closely to even see that the hole was tapped. The rust has to come out if a new bolt is ever going to go in. Fortunately, this electrician carries a set of metric taps.

 !/weblog/images/21.jpg! This photo was taken during the process of chasing the original threads with a tap to clean them out. !/weblog/images/22.jpg! This shows the happy ending. Both the battery negative and the inverter grounding cable are securely fastened to the engine block with a new 10 mm bolt. The oil pressure test port plug is back in place. Strictly speaking, copper gasket washers shouldn't be reused because they work harden the first time they're put in and don't necessarily seal as well when they are reused. If this were the fuel system, I probably would have gone out and hunted down a new washer. But this washer still had some "squish" remaining when I tightened it down again, so I think it will do for the engine oil system. 

I'm not an absolute perfectionist.   I scraped the paint off the engine block where the cable lugs were going to seat. You should never rely on a bolt to carry the current. Stainless has relatively high resistance. I have seen bolts get hot from carrying starting current. With this small an engine, it's probably not going to happen. But I'm not in the business of guessing where the threshold might be where conduction through the bolt is not enough. So take another few minutes and scrape the paint off the block. If you have high and low current lugs on the same bolt, put the high current ones right against the block and leave the low current ones out by the bolt head. You will probably have to use a flat washer under the bolt head to keep from tearing the flimsy low current lugs. You could use a lockwasher too. With large lugs, I just let the bolt head dig into the copper lug a little and that keeps it from backing out. This is one example of the totally unexpected things that can arise in a seemingly unrelated job. And it's why I charge by the hour.

    Having written all this, I think there are limits to the duty to disclose or remedy shortcomings on a boat.  It's reasonable to conclude the owner knows about obvious non-technical issue. If it isn't part of the job I'm hired to do, I don't go out of my way to test stuff where there is no evidence that something has failed. I don't feel obligated to test every bilge pump if the bilge water is below the pump. If I look under the dash and see that the terminals are corroded, I have to assume the owner knows he has an old boat on the ocean.  If there are taped, barely supported connections visible inside the lazarette it's reasonable to assume the owner knows this too. If the spring clips on an open strip fuseholder have lost tension with age, I'll probably mention that or fix it, because unless you know inexpensive fuseholders for glass 1/4x1-1/4 fuses age poorly, you will not realize you have a problem. Boating is an inherently dangerous undertaking. There are no guard rails on docks, nor should there be. Originally published January 18, 2007


I've included a few photos for future entries.  Perhaps you can guess what the article will be about.

Restore AC power quickly if your inverter bricks.  So that the inverter can automatically pick up supplying 120 VAC when shore power cuts out, shore power loops through the inverter.  The transfer relay is in the inverter in anything built in 20 years.  Inverters are pretty reliable.  When yours fails you will ................................

Appearance vs. Functionality

Occasionally I am called in to fix a problem with another person's work.  Usually the workmanship looks good but the circuit is hooked up wrong.  Sometimes the wiring is actually quite pretty, all 90 degree bends and tie wraps every few inches.  I call this "knowing what it should look like rather than understanding how it works."

begun 6/30/06.  in progress. . .

Transferred to new site 

Dielectric Grease under reconstruction Using an insulating grease on electrically mating parts seems to be a contradiction. The stuff insulates. So why do people recommend putting it between conductive surfaces and expect minimal resistance between the parts? I was suspicious for years. I would not use it. For a while I coated the outsides of battery connections after they were complete, but that was pretty messy. Dielectric grease tends to get tracked around when someone touches it. It's difficult to remove completely and nothing (repeat: nothing) will stick to a surface contaminated by a film of silicone dielectric grease.   My problem was thinking of the stuff in the same category as high-pressure grease. High-pressure grease has a high mechanical film strength to keep parts separated even when they're not moving. Dielectric grease has essentially no mechanical film strength. When pressing parts together, it readily flows out of the way, allowing metal to metal contact. (it can get trapped between two rough surfaces where it insulates. It essentially cuts down the contact surface area.) Usually a silicone compound, dielectric grease resists air, water, oil, acids and solvents. It seals a connection and prevents oxidation or corrosion.   By all means coat those battery terminals after brushing them bright. Then attach clamps and cables. The grease will flow out of the way and allow a good mechanical connection to be a good electrical connection. The tracking problem can be mitigated by using the compound sparingly.    Dielectric grease is appropriate for electrical connectors exposed to water. I never count on it to make things waterproof by itself. Being transparent, its too easy to miss a spot.  Having such little viscosity and film strength, it's too easy to brush off. Its better inside mating parts. The substance is particularly good for RF coax connectors. Silicone grease has the same dielectric properties as air, namely a dielectric constant of 1, so coax connectors can be filled with the stuff and it doesn't change their transmission properties. As long as water cannot get at the connecting surfaces, corrosion cannot occur. Again: corrosion CANNOT occur in the absence of water molecules, but that's another story. I wrote a few things about keeping battery terminals clean and dry before I figured out the wonder of dielectric grease.   Dielectric grease makes a wonderful sealant to use every time you thread a stainless fastener into aluminum. It keeps water out (no water, no dissimilar metal corrosion) and you will be able to unscrew the parts years later. added 5/30/06

Ventilation and the weep hole - under reconstruction

June 16, 2007. An article in this morning's LA Times motivated me to write something about the virtues of weep holes and ventilation. I discovered I'd already done that a year ago in the article below. So I'll just add this preface. It seems that the Great city of Tulsa buried a '57 Plymouth in a "bombproof" time capsule under the courthouse lawn 50 years ago as a publicity stunt. (Bombproof? It was the 50's.) When they recently dug it up, the car was up to its hubcaps in water and encrusted with rust. Oops.   

Water will penetrate any space. If you want to keep something dry, give the water a way to get out again. If you want to avoid condensation, ventilate. There are places where it rains a lot and the humidity is high. So what. You would think ventilating would let moisture in. Yes, but it lets it out again too. Think about it. The sidewalk always dries up after a rain. Lots of stuff on a boat doesn't need to be waterproof. The main electrical panel is often sheltered enough that you'd have to sink the boat to get it wet. I have a couple of rules about waterproofing. The first is that some things cannot or should not be waterproofed. It's a corollary to the law of scuppers. When water cannot be kept out, give it somewhere to leave again. I see a lot of electric heaters inside boats for the purpose of fighting humidity and condensation. Sometimes I see dehumidifiers too. What a waste of energy. Ventilation will do the job better than either heaters or dehumidifiers. You do NOT want to seal up a boat to fight humidity. Install a solar powered ventilation fan, as I have on my boat. If you have musty compartments, ventilate them. This includes the bilge and the sail lockers. Somehow this is counter intuitive and people resist the idea. Oh well. 

Any re-enterable enclosure exposed to the elements is going to get water in it. I don't care what kind of gasket or how much sealant you use. Be it a navigation light, a radome or an instrument cluster, your only hope is to include a weep hole so the water can get back out again. Enclosed spaces breathe as ambient temperature changes shift the pressure of the air inside. If you wonder how water got inside your gauges and condensed in droplets on the inside of the glass, now you know. It seeped in as water vapor mixed with air through what could be microscopic openings. Very few displays are hermetically sealed. If you have a problem with moisture condensation there are two solutions. The first is counter intuitive. Drill holes in the gauge case (in back of the panel, obviously) to allow air to circulate and moisture to escape. Moisture wants to get out of the gauge just like puddles always seem to dry up. This assumes the interior of the boat is at least minimally ventilated so that water isn't condensing on surfaces inside and making everything rusty. VDO relies on it's illumination lamps to keep the gauge faces dry. The other way is to heat the gauge a little. Wire the illumination lamps to run at a lower voltage continuously and apply full voltage only when you really want to see them at night. Keeping the inside of the gauge just a few degrees warmer than the ambient will drive water out the same way it got in. You can also glue resistors to the outside of the gauge case as a heat source, but the pilot lamps will do. The only disadvantage of this approach it it uses a very small amount of power continuously. If your batteries don't get charged every so often, they could slowly run down. Don't worry about the lamps. Run a little below their rated voltage, incandescent lamps will last essentially forever. 

The other thing that people sometimes try to waterproof is a hollow sailboat mast. This is mostly a problem where the mast steps on the cabin top and water in the mast can drip down out of the ceiling. If the mast steps on the keel, the water will run into the bilge and you will never notice it. There are lots of little places water can get inside the mast, particularly if you have halyards running inside. A cabin-stepped mast leaks because wires for the navigation lights and VHF antenna enter the mast through a hole in the bottom. It's possible to construct a mast where most of the water runs out somewhere else, but usually when a leak shows up people do things like squeezing a whole tube of RTV silicone sealant into the hole where the wires come through. This can be effective in stopping the leak, but it will cost you later. Eventually you want to add wind instruments or radar and some more wires have to get into the bottom of the mast. I can sometimes break the sealant up with a probe and pull enough out with a hook or even drill past it to open up a passage for new wire or to get old wire out. Or you can pay a boatyard to unstep the mast to get the sealant out. I haven't damaged any existing wires yet by poking around, but you can be sure I will need to drill a hole in the side of the mast near the base so I can thread the new wires through the mess. 

*Note July 4, 2008. This next paragraph just shows how much one can learn by working on your own boat. Who wants water in the tabernacle core?* What a bunch of crap I wrote ignorantly: "My suggestion to solve the "mast water leaking into the cabin" problem is to yield and admit the water is going to come in. Then fashion something on the cabin ceiling to collect the leakage and route it to the bilge through a small plastic tube. It could look like a decorative cap over the wires coming out of the mast and the tube could probably be routed along with the wires and you'd never notice it. I've never gotten to try this yet, but I'll post a picture and a report as soon as I do." 7/4/06 revised 6/16/07


    

 


Good to be Insured; Better not to Need It.

This story illustrates some of the silly things I did when I first started fixing boats.  Needless to say, I don't lug these around any longer.  The CO2 extinguisher fits nicely on my 28' Islander though.  Have you ever cleaned up after discharging a dry chemical extinguisher?  Dry chemical is inexpensive and effective, but it is also unbelievably messy if you use it.

I have heard it said that fire is the worst thing that can happen on a boat.   Not only does it burn to the waterline in minutes, it also leaves you nowhere to go but overboard.  Plus the boat is a total loss.

I take great care when working on live electrical circuits.  I believe in fusing all circuits at their source, just like the ABYC suggests.  This will prevent almost all electrical fires.  

But most older boat's primary circuits are not fused properly, and there are other little ways fire can break out, so the risk does not vanish completely.  Like many people who work on other people's property, I carry liability insurance.  Like most, I'd rather not use it.  

I spent ten years on a volunteer fire department in Colorado, the last several as Chief.  If I ever have a fire on a boat, I have enough experience to fight it.  With that in mind, I carry two fire extinguishers to every job along with my tools.  Its a lot to lug around, but having been a firefighter, I'm not going to just watch a boat burn for lack of the right tool.  The two extinguishers would let me fight a boat fire at two levels.

If the fire is small and contained, caught in the first fraction of a minute, I would probably reach for my 5 lb. CO2 extinguisher.  CO2 is good because it does not make a terrible mess like a dry powder extinguisher.  Dry powder is effective and inexpensive, but you don't want to clean up after.   CO2 is also good for fuel fires and inexpensive enough that you can easily practice with it.  It can be bad because it takes a bit of skill to use and it doesn't work well out in the wind.  

My second line of defense is a 13 lb. Halon extinguisher, which is pretty big as Halon extinguishers go.  Halon is almost unbelievably effective at eating fire.  You have to see it to believe it.  Halon is drawn into the fire and chemically combines with every wisp of flame, stopping it cold.  Halon is a heavy molecule compared to air or CO2.  It will settle in the hull, which helps prevent "flashbacks."  It also leaves no residue.  Halon will handle a boat fire better than anything short of one or two full-on 1-1/2" fire hoses.  Halon is the only last resort for fire you can carry.

Halon is quite expensive because it's also very effective at destroying the ozone layer, better than most fluorocarbons.  So it is considered very "environmentally unfriendly."  You don't really want to practice with it.  In fact, it would be illegal for me to practice with it.

So, is it socially responsible to buy and carry a Halon extinguisher? 

I believe the answer to that question depends largely on whether or not its your boat that might burn.

Electric Marine, August, 2002