# Question of Figuring How Many Watts



## dougchips (Apr 23, 2006)

I'm looking to buy an ice eater so I can keep my boat in the water at home this winter. I would like to know how many watts these two models are going to eat an hour so I can figure out my cost per month compared to hauling/launching in the spring.

# 3/4 H.P. energy efficient high quality motor with 36 pounds thrust
# 4.7 amps 115 volt one phase 60/50 cycle
http://cgi.ebay.com/ebaymotors/POWE...7851443QQptZBoatQ5fPartsQ5fAccessoriesQ5fGear

# 1/2 H.P. energy efficient high quality motor with 28 pounds thrust
# 5.0 amps 115 volt one phase 60/50 cycle
http://cgi.ebay.com/ebaymotors/POWE...9542906QQptZBoatQ5fPartsQ5fAccessoriesQ5fGear



Does .3 amps make much of a difference? 

Thanks for taking the time to answer my DIY question.


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## mahlere (Aug 6, 2006)

Amps * volts = va = watts


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## Magnettica (Dec 19, 2006)

4.7 amps X 115 volts = 540.5 watts
5.0 amps x 115 volts = 575 watts

_Does .3 amps make much of a difference?_

It'd be like leaving a 34.5 watt light bulb on all day. It adds up over time. I need to know how much your utility company charges per kilowatt hour then I can try to remember how to do the math to give you an accurate estimate of the cost.


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## dougchips (Apr 23, 2006)

Thanks, I can't find one of our electrical bills but if my memory is correct I think it's around 10 cents per kilowatt hour.

I'll end up running the unit on a timer, 30 minutes on, one hour off depending on the weather. <---no clue if this will work or not.


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## Magnettica (Dec 19, 2006)

So let's just say you choose the one that draws 5 amps at 120 volts. That's 575 watts per hour. The 30 minutes on, then off for one hour, is something I'll have to figure out. I am as far from a mathematician as they come. 

Suppose it's on 24 hours p/ day. 575 watts X 24 hours = 13,800 watts or 13.8 kw used per day. 13.8 kw x .10 = $1.38 per day. 

Does that sound right?


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## dougchips (Apr 23, 2006)

I ended up going with the 3/4 hp. At ten cents a watts at 50% usage it would run me around $20.52 a month. Since I would only need it for 3 months every year, I think I can handle $60--cheaper than taking the boat out of the water.


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## dougchips (Apr 23, 2006)

Magnettica said:


> So let's just say you choose the one that draws 5 amps at 120 volts. That's 575 watts per hour. The 30 minutes on, then off for one hour, is something I'll have to figure out. I am as far from a mathematician as they come.
> 
> Suppose it's on 24 hours p/ day. 575 watts X 24 hours = 13,800 watts or 13.8 kw used per day. 13.8 kw x .10 = $1.38 per day.
> 
> Does that sound right?


Funny timing, I had the thread open while I was doing my math and in the meantime you posted. I came up with the same $1.38 a day and then figured it at 50% usage. I'm sure I'll play around and see if I can cut it down to 30%, I can't imagine getting an inch an hour of ice.

Not sure if I posted a picture on CT of me taking it out last January in 2-4 inches of ice--not a fun job at all!


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## Magnettica (Dec 19, 2006)

dougchips said:


> I ended up going with the 3/4 hp. At ten cents a watts at 50% usage it would run me around $20.52 a month. Since I would only need it for 3 months every year, I think I can handle $60--cheaper than taking the boat out of the water.




Cool deal.


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## acrwc10 (Dec 10, 2006)

dougchips said:


> Funny timing, I had the thread open while I was doing my math and in the meantime you posted. I came up with the same $1.38 a day and then figured it at 50% usage. I'm sure I'll play around and see if I can cut it down to 30%, I can't imagine getting an inch an hour of ice.
> 
> Not sure if I posted a picture on CT of me taking it out last January in 2-4 inches of ice--not a fun job at all!


did you winterize the engine ? last thing you need is the water around the boat not frozen and the block cracked because of ice in the engine.


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## MALCO.New.York (Feb 27, 2008)

Magnettica said:


> So let's just say you choose the one that draws 5 amps at 120 volts. That's 575 watts per hour. The 30 minutes on, then off for one hour, is something I'll have to figure out. I am as far from a mathematician as they come.
> 
> Suppose it's on 24 hours p/ day. 575 watts X 24 hours = 13,800 watts or 13.8 kw used per day. 13.8 kw x .10 = $1.38 per day.
> 
> Does that sound right?



KWH is more in line with 19.5 Pence per hour.


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## MALCO.New.York (Feb 27, 2008)

acrwc10 said:


> did you winterize the engine ? last thing you need is the water around the boat not frozen and the block cracked because of ice in the engine.



Boat motors GENERALLY do NOT hold coolant in their system. It is an "OPEN SYSTEM" and drains upon the shutting down of the impeller. Drains enough to allow for the expansion of the H20.


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## K2 (Jul 8, 2005)

MALCO.New.York said:


> KWH is more in line with 19.5 Pence per hour.


 7 cents here if that is what you are talking about.


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## MALCO.New.York (Feb 27, 2008)

K2 said:


> 7 cents here if that is what you are talking about.



Have we forgotten "Delivery Charge" and "Line Usage"?????


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## K2 (Jul 8, 2005)

MALCO.New.York said:


> Have we forgotten "Delivery Charge" and "Line Usage"?????


Got it. Yeah access fees etc. can make it + or - but 7 cents is right about there including everything.... here. I've got some bills right in front of me. I've heard that some parts of the country pay over 15 cents so I guess I should just write some checks and quit complaining. :shutup:


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## acrwc10 (Dec 10, 2006)

MALCO.New.York said:


> Boat motors GENERALLY do NOT hold coolant in their system. It is an "OPEN SYSTEM" and drains upon the shutting down of the impeller. Drains enough to allow for the expansion of the H20.


 
Once again "not so young grass hopper" If it is an IO there will be a block full of water, and I have seen them crack from freezing. 
Even if the block is not full the water/ice will expand in all directions not just into an air void. Try filling a glass jar 1/2 full of water then put it in the freezer and see what happens.


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## Magnettica (Dec 19, 2006)

I never checked my rate before but mine is $0.05 p/ kwh.

PSE&G


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## K2 (Jul 8, 2005)

I think Malco's State of New York has the highest rates in the country for some reason.


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## acrwc10 (Dec 10, 2006)

K2 said:


> I think Malco's State of New York has the highest rates in the country for some reason.


Because they have a corner on the market. :laughing:


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## mdshunk (Mar 13, 2005)

When I see calculations doen that are generic to the whole country, guys tend to use 10 cents a kilowatt-hour as an average for everywhere. My bill comes in at 9 cents, everything included.


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## mrmike (Dec 9, 2008)

I live around many lakes & there are many docks that have the systems around them, but I never see any boats moored on them. Could be for reasons in other posts here. Anyhow, an air bubbler system would be alot more efficient, but a little more money to purchase. Depth of your water is a factor also. Either system works best by thermostatic control according to the temp outside...... Mike,


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