Engines are in the boat, not on the swim platform cruisin down the highway. No wind chill.
24* for 24hrs is the general rule.
Get the NOAA_ weather data for the region and date time traveled.
What you are describing is the heat transfer rate due to CONVECTION. This is NOT wind chill, but one of the basic heat transfer modes (Conduction, convection, and radiation).
24 for 24 is a great rule of thumb.
Even in the Fall October/November when frost can build up on the lawn in the morning, you have not gone through a long enough period of to do this damage. Sun comes up, you're back in the 40's or more and everything is cool. (Get it? A little temp humor here folks.)
Take this from a guy in Maine. Something smells fishy here. If the warehouse was not heated, or didn't go inside right away or....whatever. We always are out at least on Halloween weekend as the last weekend in our boat.
Last edited by damdonzi; 05-18-2007 at 09:52 AM. Reason: type-o
I skipped over some of the thread.
Anything's possible, but it's highly unlikely that 30°F for 4-5 hours cracked a block. The wind might have brought the temp of the block down to 30° a little faster, increasing the risk, but wind would not make it colder than the ambient temperature.
Forget about antifreeze, if there's a possibility of short-term freezing temps, the best thing to do is just drain the blocks and exhaust manifolds. Just draining the motor is likely enough to prevent freezing for a whole winter, but not recommended. For a short term cold snap it's all you need to do.
Wind chill and heat index are just ways of measuring our body's response to environmental conditions. Heat is transferred 3 ways, convection, conduction, and radiation. Our bodies stay at a relatively constant temperature, and produce heat. we need to be in a slightly colder environment than our bodies temperature in order to maintain an appropriate body temperature. If heat escapes our body too fast, we feel cold, not fast enough, we feel warm. The rate at which heat enters or leaves our body is determined by conduction, convection, and radiation. You feel the warmth from a sunny day, that's radiation. You feel the cool breeze, that's convection. You touch the cold engine block (or the hot one) that's conduction. Wind is no colder than the surrounding air, it's just that more air is passing your body (or your boat, engine, etc.) It will increase the convection and the temperature will drop to the temperature of the air faster. But if you put something out in 30 degree weather, it won't get any colder than 30 degrees just because it's windy. If it's touching ground that's colder, it may lose additional heat through conduction, if it's sunny out, it may get warmer due to radiation. If it's windy out, it will get down to ambient (or up to ambient) significantly faster, though.
my 2cents worth.i have left my boat out in the cold[28degrees,or less] for 2 days w no cover.nothing never froze.i have worked in houses that had no heat for weeks,in frezzing weather w/hydro heat and cast iron radators and never frose.and some of these houses were reallll lose,rentals.
General rule up here in Canada is -5 for 12 hours ( celcius, which is about 23 F ), and you start to worry.
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