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Re: Couldn't right my cat solo. Need advice [Re: Andinista] #256810
01/31/13 03:32 PM
01/31/13 03:32 PM
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Northfield Mn
Karl_Brogger Offline
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I've always understood it using hot, like almost boiling our boiling water, will freeze faster than cool water just because of evaporation making it cool more quickly.

I don't know, that was high school physics, and a quite a few empty bottles ago.

Does it really matter? Are we that bored?


I'm boatless.
-- Have You Seen This? --
Re: Couldn't right my cat solo. Need advice [Re: Karl_Brogger] #256816
01/31/13 04:39 PM
01/31/13 04:39 PM
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Posts: 5,590
Naples, FL
waterbug_wpb Offline
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if the water is evaporating, wouldn't there be less to cool?

Hasn't Jake already made a carbon-fiber resin infused test chamber for this experiment? Complete with wrap-around graphics?


Jay

Re: Couldn't right my cat solo. Need advice [Re: Andinista] #256822
01/31/13 05:24 PM
01/31/13 05:24 PM
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Northfield Mn
Karl_Brogger Offline
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When water turns from liquid to vapor, it cools. Same reason we sweat.


I'm boatless.
Re: Couldn't right my cat solo. Need advice [Re: Andinista] #256826
01/31/13 05:33 PM
01/31/13 05:33 PM
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Sebring, Florida.
Timbo Offline
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But...when you are cooler, you become more dense, thus weighing more, so you can right your cat, just as soon as you cool down enought to tip the CG past the CB, which is a BFD if you're not wearing your PFD, you could be DSQ'd.


Blade F16
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Re: Couldn't right my cat solo. Need advice [Re: Andinista] #256835
01/31/13 09:16 PM
01/31/13 09:16 PM
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SE MI / NE IN
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SE MI / NE IN
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Jeff R

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Re: Couldn't right my cat solo. Need advice [Re: Timbo] #256838
02/01/13 05:06 AM
02/01/13 05:06 AM
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Posts: 351
Santiago, Chile
Andinista Offline OP
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Originally Posted by Timbo
But...when you are cooler, you become more dense, thus weighing more, so you can right your cat, just as soon as you cool down enought to tip the CG past the CB, which is a BFD if you're not wearing your PFD, you could be DSQ'd.


And if the water is warm you recover your normal density and that explains why sometimes the cat tips over to the other side..

Re: Couldn't right my cat solo. Need advice [Re: Andinista] #256839
02/01/13 05:10 AM
02/01/13 05:10 AM
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Posts: 351
Santiago, Chile
Andinista Offline OP
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Wait a minute. When I'm cool I don't get more dense.. I get smaller!

Re: Couldn't right my cat solo. Need advice [Re: Karl_Brogger] #256840
02/01/13 07:56 AM
02/01/13 07:56 AM
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South Carolina
Jake Offline
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Originally Posted by Karl_Brogger
I've always understood it using hot, like almost boiling our boiling water, will freeze faster than cool water just because of evaporation making it cool more quickly.

I don't know, that was high school physics, and a quite a few empty bottles ago.

Does it really matter? Are we that bored?


try it.


and...yes.


Jake Kohl
Re: Couldn't right my cat solo. Need advice [Re: Karl_Brogger] #256843
02/01/13 08:33 AM
02/01/13 08:33 AM

M
MN3
Unregistered
MN3
Unregistered
M



noooo, we sweat because all the alcohols in our system has to escape, and you can only pee so much
Originally Posted by Karl_Brogger
When water turns from liquid to vapor, it cools. Same reason we sweat.

Re: Couldn't right my cat solo. Need advice [Re: Karl_Brogger] #256853
02/01/13 12:22 PM
02/01/13 12:22 PM
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South Carolina
Jake Offline
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Originally Posted by Karl_Brogger
When water turns from liquid to vapor, it cools. Same reason we sweat.


Yup, and at some point, it is the same temperature as the other water started at...so is it still cooling faster?


Jake Kohl
Re: Couldn't right my cat solo. Need advice [Re: Andinista] #256861
02/01/13 02:25 PM
02/01/13 02:25 PM
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Northfield Mn
Karl_Brogger Offline
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Couldn't tell ya, I'm just regurgitating what I was fed in high school. Neither would surprise me, water has many strange qualities unlike any other element.


I'm boatless.
Re: Couldn't right my cat solo. Need advice [Re: Andinista] #256869
02/01/13 08:00 PM
02/01/13 08:00 PM
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42.904444 N; 88.008586 W
Todd_Sails Offline
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The Specific Heat of Water


F-18 Infusion
#626- SOLD it!

'Long Live the Legend of Chris Kyle'
Re: Couldn't right my cat solo. Need advice [Re: Todd_Sails] #256871
02/01/13 08:15 PM
02/01/13 08:15 PM
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Basic thermo.... Q = m Cp dT

Translation... Jake is right.

sm


Last edited by srm; 02/01/13 09:21 PM.
Re: Couldn't right my cat solo. Need advice [Re: srm] #256888
02/03/13 01:52 AM
02/03/13 01:52 AM
Joined: May 2006
Posts: 1,383
Kingston SE South Australia
JeffS Offline
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Not sure how many times it needs to be repeated, but apparently at least one more time... the angle of the line(s) has no bearing on whether or not the boat is righted. Over the hull, under the hull, using a righting pole, holding with your hands, holding with your harness, or holding with your teeth, it makes no difference. All that matters is the horizontal distance of your center of gravity from the fulcrum (which is the center of bouyancy of the lower hull). How you get your CG into position only effects the reactionary forces on your body (your comfort level), it does not effect the righting moment applied to the boat.

It is just like the teeter-totter we played on in elementary school- the rig is at one end, you're at the other end, and the hull is in the middle. Weight times horizontal distance.

sm [/quote]

If you had a proper diagram in front of you it would be obvious that your weight is 18 inches or more further out when you use over the hull and pull with your hands from above your head, which is a handy increase in leverege, in all of Scarecrows diagrams there is no righting moment at all because all of the people pictured are laying in the water.


Jeff Southall
Current boats
Nacra 5.8 1703 Animal Scanning Services
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Re: Couldn't right my cat solo. Need advice [Re: Andinista] #256890
02/03/13 07:47 AM
02/03/13 07:47 AM
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pgp Offline
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Nothing is ever quite as simple as it seems.

http://en.wikipedia.org/wiki/Angular_acceleration
http://en.wikipedia.org/wiki/Angular_velocity

I'll leave you to do the math.

I am certain, absolutely, the best solution is one which is proven and reliable.

Attached Files
angular velocity.PNG (14 downloads)
Last edited by pgp; 02/03/13 07:53 AM.

Pete Pollard
Blade 702

'When you have a lot of things to do, it's best to get your nap out of the way first.

Re: Couldn't right my cat solo. Need advice [Re: Andinista] #256891
02/03/13 08:11 AM
02/03/13 08:11 AM
Joined: Aug 2003
Posts: 351
Santiago, Chile
Andinista Offline OP
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So what?
O is the hull, P is the butt. No line on the math

Re: Couldn't right my cat solo. Need advice [Re: Andinista] #256892
02/03/13 08:17 AM
02/03/13 08:17 AM
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pgp Offline
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Originally Posted by Andinista
So what?
O is the hull, P is the butt. No line on the math


Return to start. For me and many others bringing a line over the hull is a simple and effective solution.

I just resist being told what works in practice doesn't really work and I should be using a different system.


Pete Pollard
Blade 702

'When you have a lot of things to do, it's best to get your nap out of the way first.

Re: Couldn't right my cat solo. Need advice [Re: Andinista] #256897
02/03/13 10:11 AM
02/03/13 10:11 AM
Joined: Aug 2003
Posts: 351
Santiago, Chile
Andinista Offline OP
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If you are holding the rope with your hands there's no doubt it's better, beacause it requires less force to hold your weight. That's it. It doesn't mean it will provide more lever arm, it will just be easier for the same effect. The effect is only dependant on how far out is your weight.
Now this discussion is poitnless anyway.. Bring the line wherever you want, it's not that you are compromising anything else.
BUT.
For setting up a righting pole it is worth to realise this mathematical and empirical fact (it doesn't matter whether the line is above or below the hulls in terms of lever arm). Why? Just because it's way easier to set the lines below the hulls. Making efforts to do otherwise is pointless.

Re: Couldn't right my cat solo. Need advice [Re: Andinista] #256898
02/03/13 10:21 AM
02/03/13 10:21 AM
Joined: Aug 2003
Posts: 351
Santiago, Chile
Andinista Offline OP
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This case for instance:
http://www.hobiecat.com/forums/viewtopic.php?f=13&t=44504&hilit=righting&start=15
Instead of passing the line around the above hull he could just shackle it to the beams.
Like mine here:
http://www.youtube.com/watch?v=DKuSSZ7JxBA
It has worked three times already, by the way.. two for testing and one for real

Re: Couldn't right my cat solo. Need advice [Re: Andinista] #256900
02/03/13 10:33 AM
02/03/13 10:33 AM
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pgp Offline
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You've sold yourself on the need for an apparatus, fine. Find the right one, learn how to use and you'll have no problem.

In the mean time you make several assumptions that I'm not going to argue over.

Most of us throw a rope over the hull and do just fine.


Pete Pollard
Blade 702

'When you have a lot of things to do, it's best to get your nap out of the way first.

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