posted 06-16-2011 09:20 PM ET (US)        

[UPDATE: 43.5-MPH was the highest speed I happened to see while glancing at the display, but the log on my display device says we hit 43.8-MPH as the highest speed.--jimh]

posted 06-17-2011 07:04 AM ET (US)            

ASIDE: my Evinrude engine has an atmospheric sensor or barometer included in the engine, and via the NMEA-2000 network connection the engine reports barometric pressure. I modified one of the information display pages on my multi-function Lowrance HDS series display to show the barometric pressure. Next time I am recording performance data I will make a note of the barometric pressure as reported by the Evinrude E-TEC.

Sea state was ideal for a speed run. The were no waves and just a little ripple on the surface.

Air temperature was probably about 60-degrees-F. On land it was warmer, but in the middle of the Lake with the water still this cold, the air is still chilly. Yes, mid-June at 45-degrees-North latitude.

posted 06-17-2011 10:44 AM ET (US)            

Barometric pressure, yes. Higher pressure, denser air, more power.

Also, the cold water will make the air temperature cooler as well. The air inducted into the motor is probably air that lies closer to the surface of the lake.

posted 06-17-2011 10:56 PM ET (US)            

quote:

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The water is more dense as the molecules hang closer together for warmth...

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quote:

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The water as it gets colder will continue to become more dense....

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posted 06-17-2011 11:47 PM ET (US)         

Just like one of those paddles with a ball a rubber band connected, the harder you paddle the farther apart they will get. The higher the temperature the farther part the atoms get in a substance get by bouncing off each other harder, but they are tied together by their chemical bonds or electromagnetic force like a rubber band.

Temperature is just motion. Heat is an abstract quantity of energy transferred causing temperature to change. Heat is like water it flows downhill from high to low temperature, unless you have an aptly named heat pump to move it uphill, such as a air conditioner or refrigerator.

Water has a special property like some molecules it forms crystals as the temperature goes low enough to phase into a solid. These hexagonal crystals push the molecules part slightly to fit together like puzzle pieces, this causes water to be most dense in liquid form at 39 degrees f then become slightly less dense as it turns to ice.

posted 06-18-2011 06:15 AM ET (US)            

I think boats will go faster in warm water with a high salinity content--lots of salt. Why? I don't know, but most water speed records were set on the Salton Sea in the desert in California. It's a couple times as salty as the ocean, and it [is] also below sea level. Records were attempted at sunrise when the air was moist which makes the air more dense (more oxygen.)

posted 06-19-2011 09:47 AM ET (US)            

My 2010 Evinrude E-TEC 225-HP V6 low-emission outboard has just been a delightful improvement to my classic Boston Whaler boat. It has:

--allowed me to cruise in the pristine fresh water paradise of the Great Lakes with the best, highest-rated, cleanest outboard engine on the market. No two-cycle smoke, no oil slicks, no air pollution;

--allowed me to reach new high speeds--faster than a speeding bullet;

--allowed me to reduce my fuel usage rate by a very significant amount, saving significant money on fuel;

--allowed me to enjoy much improved running characteristics from the engine, such as faster starting, smoother idle, less throttle adjustment, less engine speed hunting, and a much wider range of economical operation; and,

--allowed me to install and experiment with a modern engine data network that displays, computes, and logs all sorts of interesting information.

posted 06-19-2011 10:50 AM ET (US)            

Glad you had a good trip - bug-zapper and all. Makes boating fun again! (Well, it's always fun, but sometimes more fun than other times).

I had the same feeling when I went from a 1989 225 Johnson on my 1990 Revenge 22' - W.T. to the direct fuel injection 2003 225 Mercury Optimax. From a "hopeful" 2.0 nmpg when partially loaded with gear to over 3.0 nmpg when loaded with gear.

posted 06-21-2011 08:41 PM ET (US)            

quote:

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Records were attempted at sunrise when the air was moist which makes the air more dense (more oxygen.)

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Binks, you stepped in it again, brah. :) Moisture/humidity/water vapor makes the air less dense. It displaces oxygen. The runs were probably made early in the morning because the air is cooler, which is more dense with oxygen.

On an interesting note, when a vehicle, (even a boat), starts to go fast enough that air resistance becomes a factor, it is not a given that you want to be as low as possible to get the denser air. Turbine powered aircraft are an example. The turbine engines still make a lot of power at altitude, but the vessel itself needs the thin air, to really get cooking in terms of speed. Certain turbocharged cars can run a little faster in Denver than at sea level because they can make almost as much power, and the air drag is less... a little less.

posted 06-22-2011 10:21 AM ET (US)            

So, yes you need to leave room in the ice cube tray for expansion, but it will require less and less room as the temperature approches 32 degrees F and the molecules become MORE dense until it reaches 32 degress at which point it will start to expand or become LESS dense.

Carry on.

posted 06-22-2011 10:51 AM ET (US)            

Do I need to? How about fact checking it first?

From Wikipedia:

Density of water and iceDensity of liquid water Temp (°C) Density (kg/m3)[17][18]
+100 958.4
+80 971.8
+60 983.2
+40 992.2
+30 995.6502
+25 997.0479
+22 997.7735
+20 998.2071
+15 999.1026
+10 999.7026
+4 999.9720
0 999.8395
−10 998.117
−20 993.547
−30 983.854
The values below 0 °C refer to supercooled water.

The density of water is approximately one gram per cubic centimeter. More precisely, it is dependent on its temperature, but the relation is not linear and is not even monotonic (see right-hand table). When cooled from room temperature liquid water becomes increasingly dense, just like other substances. But at approximately 4 °C, pure water reaches its maximum density. As it is cooled further, it expands to become less dense. This unusual negative thermal expansion is attributed to strong, orientation-dependent, intermolecular interactions and is also observed in molten silica.[19]

The solid form of most substances is denser than the liquid phase; thus, a block of most solids will sink in the liquid. However, a block of ice floats in liquid water because ice is less dense. Upon freezing, the density of water decreases by about 9%.[20] The reason for this is the 'cooling' of intermolecular vibrations allowing the molecules to form steady hydrogen bonds with their neighbors and thereby gradually locking into positions reminiscent of the hexagonal packing achieved upon freezing to ice Ih. Whereas the hydrogen bonds are shorter in the crystal than in the liquid, this locking effect reduces the average coordination number of molecules as the liquid approaches nucleation. Other substances that expand on freezing are silicon, gallium, germanium, antimony, bismuth, plutonium and other compounds that form spacious crystal lattices with tetrahedral coordination.

Only ordinary hexagonal ice is less dense than the liquid. Under increasing pressure, ice undergoes a number of transitions to other allotropic forms with higher density than liquid water, such as high density amorphous ice (HDA) and very high density amorphous ice (VHDA).

Water also expands significantly as the temperature increases. Its density decreases by 4% from its highest value when approaching its boiling point.

The melting point of ice is 0 °C (32 °F, 273 K) at standard pressure, however, pure liquid water can be supercooled well below that temperature without freezing if the liquid is not mechanically disturbed. It can remain in a fluid state down to its homogeneous nucleation point of approximately 231 K (−42 °C).[21] The melting point of ordinary hexagonal ice falls slightly under moderately high pressures, but as ice transforms into its allotropes (see crystalline states of ice) above 209.9 MPa (2,072 atm), the melting point increases markedly with pressure, i.e., reaching 355 K (82 °C) at 2.216 GPa (21,870 atm) (triple point of Ice VII[22]).

A significant increase of pressure is required to lower the melting point of ordinary ice — the pressure exerted by an ice skater on the ice only reduces the melting point by approximately 0.09 °C (0.16 °F).[citation needed]

These properties of water have important consequences in its role in the ecosystem of Earth. Water at a temperature of 4 °C will always accumulate at the bottom of fresh water lakes, irrespective of the temperature in the atmosphere. Since water and ice are poor conductors of heat[23] (good insulators) it is unlikely that sufficiently deep lakes will freeze completely, unless stirred by strong currents that mix cooler and warmer water and accelerate the cooling. In warming weather, chunks of ice float, rather than sink to the bottom where they might melt extremely slowly. These phenomena thus may help to preserve aquatic life.

posted 06-22-2011 11:00 AM ET (US)            

quote:

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...as the temperature approches 32 degrees F and the molecules become MORE dense until it reaches 32 degress at which point it will start to expand or become LESS dense

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posted 06-22-2011 11:07 AM ET (US)            

However, Jim suggests that cold watre can have a profound effect on the speed of his boat but the reality is that while colder water is more dense, it is not a lot more dense.

The difference in density between 45 degree water and 75 degree water is *maybe* 1 percent.

posted 06-22-2011 11:25 AM ET (US)         

I am pretty sure that's what Len is saying, water is most dense at 39F then between 39F and 32F it freezes forming a crystal lattice that pushes the molecules apart slightly lowering density.

So water at 45F is near it densest point, salinity also affects water density, if salinity has an affect, so should temperature.

Other substances get less dense in solid form, silicon, gallium, germanium, antimony, bismuth, plutonium and other compounds that form spacious crystal lattices when solid.

posted 06-22-2011 11:30 AM ET (US)            

quote:

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These hexagonal crystals push the molecules part slightly to fit together like puzzle pieces, this causes water to be most dense in liquid form at 39 degrees f then become slightly less dense as it turns to ice.

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So if 75 degree F water has a certain density (specific density of 1?), does it become more dense at it gets colder, then at 39 degrees F it is most dense, then it expands and gets less dense than the 75 degree water? It only overflows the ice bin as it nears freezing.

Is that correct?

So Jim's 45 degree water should be more dense than my 75 degree water.

posted 06-22-2011 11:35 AM ET (US)            

If ice were not LESS dense than water, life as we know it would not exist; Earth would be frozen solid.

posted 06-22-2011 12:08 PM ET (US)         

Having a hard time finding a density chart for ice to compare to liquid water.

But Wikipedia says:

"Upon freezing, the density of water decreases by about 9%."

and:

"Water also expands significantly as the temperature increases. Its density decreases by 4% from its highest value when approaching its boiling point."

So it would seem the 75F to 39F is not as significant as I thought.

posted 06-22-2011 12:24 PM ET (US)            

quote:

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Yes, I couldn't agree more. Mostly because the speed of a Boston Whaler is very poor in solid ice.

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But not ON ice if you were to power a Classic 13' with a fan in airboat fashion;o)

posted 06-22-2011 08:30 PM ET (US)            

Denser water helps the propeller produce more thrust. It helps the hull develop more lift.

Denser air helps the engine. Although not intuitive, dry air is denser than humid air. Cold air is denser than warm air.

Water at 45-degrees; air at very moderate temperature, perhaps 55-degrees, and air with low humidity all help an engine, a propeller, and a boat reach higher speeds.