Lets talk about rats, and wire insulation

Discussion in 'Sailboats' started by pbmaise, Aug 30, 2012.

  1. pbmaise
    Joined: Jul 2010
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    pbmaise Senior Member

    I came across yet another boater with a tale of woe when rats found their way aboard and decided the electrical insulation wire was tasty! It happened on my boat too. The rat even decided to sample the plastic on a 370 amp hour battery. Thank goodness the nibble was at the top, however, the cell he broke into short circuited. I didn't see evidence of the nibble as it was the last battery jammed against the wall.

    In general I found that nice white insulation wire labeled "Marine Grade" should be honestly relabeled "Purina Rat Chow".

    I found one website listing rats as causing 7% of all home fires, and I suspect when it comes to boating the figure is higher. Or if it isn't a fire it certainly is a very expensive repair.

    So just a generic question this being a boater design forum:

    Once upon a time I owned a house that had a wiring system that was called knob and tube. The high degree of separation between wires meant zero chance of shorting and zero rat food. Anybody have thoughts along these lines?

    Wire is available tinned copper, and GFI circuit breakers would catch any water issues.

    If you never heard of knob and tube....here is a link.

    Failure of wire insulation is the number one cause of electrical fires and next to impossible with knob and tube, since it has no insulation to fail.

    This is kind of along the lines of getting rid of the boom. It is kind of hard to get killed by one when a boat doesn't have one.

    Oh, and so you don't think I'm a complete lunatic....I just saw a boat yesterday that had high tech rigging lines that eliminated turnbuckles by looping thin lines back and force to cinch rigging tight.

    Yet another old idea. That one has been around for centuries.

    And yes I know the U.S. Coast Guard would never approve something that was proven safer. Or would they?
    Last edited: Aug 30, 2012
  2. SamSam
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    SamSam Senior Member

    A neighbor in Wisconsin got stuck and left his pickup truck in the woods for the Winter, in the Spring he took me out and showed it to me. Every wire under the hood and the dash was completely bare of insulation, it was all just shiny bright copper and not one tiny strand of actual wire was chewed or broken. It was all where it should have been, nothing out of place, just no insulation whatsoever. He had to junk the truck.
  3. Submarine Tom

    Submarine Tom Previous Member

    Prevention can do wonders as can a healthy cat!
  4. Petros
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    Petros Senior Member

    There was some idiot idea that plastic insulation made from soy beans was more environmentally friendly. Soy based rubber and vinyl is also food for rodents, it is not environmentally friendly to have to junk perfectly good cars, boats, etc. after rodent infestation.

    My 28 year old Toyota has no issue with rodents eating insulation or rubber (we live on rural property), but the same year Honda cars have the soy insulation, and if left parked too long, or on the grass, you are in for major repairs. It is a bad idea. Consider if a major boat builder is forced to use "environmentally friendly" wiring and when out to sea random fires break out because of missing insulation, or major system failures at least.
  5. CDK
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    CDK retired engineer

    Two years ago starting my Kia Sorento resulted in a massive short circuit with several blown fuses. Rats had chewed on the main wiring harness under the hood in a corner behind the ABS unit where the cable enters a large grommet leading to the interior. They also cut a large hole in an air duct, digested the complete air filter and built a nest in the horizontal air conditioning fan.

    Replacing the cable was no option, in the manufacturing process the wiring harness is installed in a bare chassis as a fist step in the assembly line. I soldered 34 bypasses, isolated with shrink sleeve, sealed the corner with steel mesh and sprayed so much tar over the ugly knot that everything was immobilized.
    Then I built a small circuit with an ultrasonic transducer. It screams at 24 Kc. for approx. 50 seconds, then briefly switches to an audible frequency so I know it is operating. No rat has ever touched my car again.

    The car was under a car port roof, standing next to my wife's Ford that the rats ignored. Both my cat and the lazy tomcat never showed any interest in that part of our property, they didn't need to go there to chase rats because there were plenty around the house. I now have ultrasonic devices in our vehicles, the attic, the shed and my machine shop. Rats have disappeared, the cat now chases lizards.
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  6. waikikin
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    waikikin Senior Member

    Rats are a menace, last week I found a rat had been eating my plasticine, last year I found rodents had been nesting in a chewed hole into a box of balsa core........ not so bad the chewed hole but the pi$$ from them had ruined a fair bit. A rat died in our roof above one of my sons room, I had to pull off the tiles to get it out........... had to ralf over the edge of the roof a couple of times with that... the stink! Our Fox Terrier is pretty good at killing them but they are sneeky & learn to navigate along fence tops etc to stay out of her savage jaws. Jeff
  7. SamSam
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    SamSam Senior Member

    I opened the refrigerator one time and there was a mouse in there, having chewed through the rubber seal around the door. I usually try and think things through before acting, but this time I made a quick decision and grabbed the cat and threw it in there and closed the door. I wish I had thought it through, as the cat wanted nothing to do with being in a dark refrigerator. After some disruptive noise and yowling, I opened the door and the cat shot out of there while the mouse casually dropped off the bottom edge and went back under the 'fridge.
  8. rxcomposite
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    rxcomposite Senior Member

    Rat's teeth grow at a rate of 5" year so they have to gnaw at everything to keep their teeth from outgrowing themselves. I have rats at home because we live near a creek. I tried all options such as traps, glue, poison, repellants, but they keep coming back. Cats, and dentist is not an option.

    The only time I got my revenge was when it hid in the fan belt of my car and was not able to get out before I started it.
  9. JosephT
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    JosephT Senior Member

    Rats are smart critters. For routing wire harnesses, flexible hoses and the like (both fun to chew for a rat) I would suggest incorporating wire routing tubes. Wires, for example, can be routed nicely inside rigid tubing (PVC, fiberglass, aluminum...whatever suits the purpose). Rats are less inclined to chew on harder, rigid materials. The routing tubes should be carefully fabricated so there are no interior sharp edges on the tubing that will chafe or cut your wires. I used to fabricate aluminum & lightweight stainless hydraulic & pneumatic tubes for various aircraft...they make fantastic routing tubes. Wires glide easily right in. For complex curves, a string tied to the end of your wire is the answer. Padded routing clamps fasten these tubes to bulkeads, interior hull, etc. Properly installed, your boat will be ready for the high seas and your wires will be safe and last year after year.

    To fabricate your own tubes, visit your local general aviation maintenance facility or just buy/borrow a tube bending kit. They work great. Below is your typical tube bending kit.


    In addition to what others have suggested, some other things to consider...

    -Open cabins are a culprit. Close the hatches!

    -Talk to the harbor/marina operators. If there's a rodent problem they should do their part by setting traps & keeping trash bins tidy.
  10. jonr
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    jonr Senior Member

    I agree. Someone needs to put more effort into putting a disagreeable taste into plastics. Until then, put significant effort into rat proofing.
  11. Petros
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    Petros Senior Member

    I am not sure "disagreeable taste" is the motivator, but rather nutritional value. Petroleum based plastic seem to not attract them, but soy based ones do. chemically they are similar, but one can be digested, the other not. Somehow they have to be made so there is no food value, if possible. I would hate to see toxic compounds used, but that might be an answer too.
  12. Petros
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    Petros Senior Member

    Some years ago Henry Ford became obsessed with soy based plastics. He had a vision to make whole cars out of soy beans, even had all of his business suits made from fabrics made of soy beans. His business managers finally talked him out of it and the idea was dropped.

    so leave a soy bean car in a field long enough and the rodents would have eaten the whole car!

    Little did he know the environmentalists are forcing the issue again after 75+ years. I hope they are not successful, I have had fires start in my old cars because of failed wiring insulation hidden within the harness covers. I would hate to add rodents as another hazard to anything that carries electric current.
  13. messabout
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    messabout Senior Member

    Miserable rodents, one winter, decided to nest in one of my most valuable jibs. The little demons not only soiled it scandoluosly but decided to chew several holes in the cherished sail, rendering it a hopeless rag. Who knew that rats had a taste for dacron?
    Last edited: Sep 1, 2012
  14. Frosty

    Frosty Previous Member

    Rats are small little things slightly bigger than a mouse but smaller than a moose.

    I don't like them very much because they have a horrible back side which distinguishes them from a moose/ mouse. However all species come complete with a leg on each corner.

    I drown them immediately.

    I have one that frequents my car and only eats the washer bottle cap and nothing else. If I can catch him / her I will send it to Rat heaven.

    I am told they don't like the smell of moth balls and will leave, although I have known this for some years I have never tried it.

    I always bang furiously on the bonnet of the car when I get it from the car park. Much to the amazement of other car park users they quickly realize what I am doing and nod approvingly. Usually I see one or 2 scampering from the engine compartment into a nearby drain sometimes with a baby in its mouth leaving all the other pink blind babies in the inner wing which crawl out onto the door jam.

    Mind you its better than the baby Pythons that sometimes get,--amazingly in exactly the same inner wing.

    Such is life when you park a car next to a mangrove swamp for 6 weeks.

  15. CDK
    Joined: Aug 2007
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    CDK retired engineer

    What is a disagreeable taste?
    There is an Italian rat poison with an added chemical that has the most bitter taste one can imagine, to avoid pets eating it. Rodents however cannot taste it because they do not possess a sensor for it.

    The poison is packed in small bags and the instructions tell you to place just one little bag in a corner where rats come. If the next day the bag has gone, place another one and keep doing so until the bag isn't touched anymore. That may take 4-5 days if there are a number of rodents.
    I kept replacing bags for more than 3 weeks, thinking there was a true invasion. Then a found a pile of these bags under a tree several yards away. Probably a single animal had decided that it was excellent food for the winter season and made himself a stash!

    Moth balls do not work, nor does peppermint or lemon grass. In my experience only powerful ultrasonic devices keep them away.
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