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Core Sound 20: Hull #103


Alan Stewart

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Real men use internal oxidation reduction chemical reactions...

You know,  that's another advantage to rowing.  Ethanol based fuels are not nearly the problem as they are in Internal combustion engines....

Yes, you too can run your boat on cheap red wine....

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Ya know, I've been sailing the Bea Ann without a motor from the start.  Not so much a purist, as cheap.  I can think of several times I REALLY WISHED I had one: 1. when I'm dragging anchor, which I seem to do with some regularity.  (Anchoring instructions usually seem to include backing down on the rode under power to set it.  Doh!)  2. sailing Vineyard Sound against the current and suddenly having the wind die on me.  (On a recent trip we spent hours going backwards and spent most of the rest of the day getting back to where we'd started.)  3. when I need to get through Woods Hole against the current.  (I missed my tide once this summer, beached in the middle of the Hole until the current turned, and ended up crossing Buzzards Bay at night, finally arriving at the ramp after dawn.  Pretty miserable.)  I really enjoy planning a trip so all the ducks line up in my favor, but it can be really bad when one of the ducks wanders off.

ps: except for the rare day sail, I never leave the ramp without a nice red wine aboard.  Makes the wandering ducks more tolerable!

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EyeInHand posted a comment on http://cs20dawnpatrol.blogspot.com/2010/09/speed-sails-oars-motor.html   about the "third option"   --electric motors--   based on his own first-hand  (first-eye?)  experiences with an 82lb system.    

It raises the interesting question in my mind, "How heavy a propulsion system am I willing to tolerate if the pay-off is super-quiet auxiliary propulsion?"   What if it is out-of-sight so that I don't have to see it hanging on the transom? 

For adventure racing and day sailing we just carry the oars,  but for multi-day vacation cruising how much negative impact would a heavy system have?    If we capsize, which is more robust to a dunking: internal combustion system or electric system?  What happens to a battery submerged in salt water for 15 minutes ?

--Paul

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If you want to go really expensive: Torqeedos (expensive) solar charging system (http://www.torqeedo.com/us/hn/products/cigs-solar-charger-62-w.html) for their (really expensive) high efficiency e-motors. If you don't care the money it gives you a system which runs an electric motor directly by the solar panel, recharging the battery when the motor is not used with a total weight (motor, battery & solar panel) of 18kg (~36lbs). They say it's so efficient that the solar panel recharges the battery faster than the electric recharger. It only falls down if you have neither wind nor sun for two days in a row. If it only was half the price...

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   If we capsize, which is more robust to a dunking: internal combustion system or electric system?  What happens to a battery submerged in salt water for 15 minutes ?

--Paul

I have sent a query to Ed Sherman who wrote the "12vdc bible" he taught my ABYC marine electrician certification prep class to find out what effect would be had by relatively brief immersion of a battery in salt water.

Immersion of either an electric motor or an outboard would not be a good thing in salt water.

If the motor was not built for immersion and sealed, water would wick through wires and into electronics.

Even a gas outboard has a plethroa of electronics on board including computer brains in higher HP models.

While a gas outboard can be removed and thoroughly rinsed with fresh water and be brought back to running condition... ( all cavities need to be drained , rinsed drained again,  IE cylinders, crankcase, valve covers removed etc.  Long term it will still develop problems with the wiring and electrical parts.

If I owned an outboard immersed in salt water and had insurance coverage I would not accept the insurance company paying to service the engine for me  I would insist on replacement.

If I did not have insurance I would spend the time to service it and keep a  close eye on the wiring loom and electronics and replace at first sign of trouble.

In terms of capsize recovery reliability and likelihood to be able to get back home after a dunking, I think the lowly wood oars with a  strong back and weak mind clearly has an edge.

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Had  a few email exchanges with Ed.

He agrees that having oars as backup manual propulsion and a good anchor would be prudent  in event of capsize with either outboard or electric auxiliary.

A battery chosen for use on a Daysailor subject to capsize would be best if it employed SVR (sealed valve regulated) method rather than standard flooded cell with caps.

Battery acid and seawater when combined give off poisonous chlorine gas.

Salt water intrusion into the battery would mean end of battery.

If a battery with SVR system was immersed in salt water for brief periods likely salt waster would be kept out of battery.  But that is only part f the issue.  Immersed in salt water you will have a short across the terminals in the form of the salt water forming a conductor. 

Electrolysis will take place and should be rather vigorous given ampacity of battery and size of conductors exposed..    How much current flow would occur would be variable based on amount of attached conductors and surface area exposed as well as distances between conductors etc..  Total amount of amp hrs lost also would depend on length of time submerged.

While immersed the negative terminal would be eroding fairly quickly as well,  and amount of erosion would give a visual indicator of how much power might be left.  Severely eroded terminal would indicate battery would not be worth salvaging.

Whether the electric motor would be able to be used after immersion is also highly suspect.

Ability to start a gas outboard after immersion is also highly suspect.

Assuming operator does not excessively lose heat while submerged oars should work fine.

If substantial current is encounters,  choose different route / destination or use anchor to hold ground until tide changes..

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  My Honda 2hp 4 stroke has only a rudimentary hint of an electrical system (think lawnmower).  I've inverted and immersed it once, but not in salt water.  It will not start after that treatment, but my boat generally doesn't flip unless the wind is blowing too hard for oars to be of any help so oars are no better for me in a capsize than a dead motor.  Once drained, dried and re-filled it runs just fine, even years later.

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That of course presumes that the only way a motor will ever go swimming is due to a  capsize.

Motors and sailing itself induces a fair amount of vibration in a boat.  Clamps that hold motors to transoms have been known to loosen.  And brackets that hold outboards have been known to lose screws and nuts...

Even if there is plenty of wind in  body of water I have seen entering coves that are pretty much becalmed with a half mile or so to the ramp.  Nice to have some sort of auxiliary there as well.

If not oars a pair of short 4 foot canoe paddles can be stowed under cockpit seat via hatch and come in awfully handy for close quarters work.  I have both oars and canoe paddles for that reason.  Oars when I will be at them for a while,  canoe paddles for close in work.

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