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      11-23-2011, 05:14 PM   #1
jokergerm
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is 2 300hp engines in a boat the same hp as a 600hp engine

I have been arguing with a friend that 2, 300hp engines is the same HP as one 600hp engine
He thinks that 2, 300 HP engines would only be about 450hp
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      11-23-2011, 05:18 PM   #2
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      11-23-2011, 05:19 PM   #3
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That's how I feel
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      11-23-2011, 05:21 PM   #4
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Wow. You need new friends. I'd suggest looking in the engineering department at your local college.
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      11-23-2011, 05:27 PM   #5
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The math CANNOT be done exactly like that, but your friend is def stupid.

The output of 300 HP won't be the same as a 600HP, as different factors come into hand. but still, DEF not 450 HP. He is high as a kite.
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      11-23-2011, 05:27 PM   #6
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I dont know how else to explain it to him

He thinks that a boat with 20 5HP motors would not have the same pulling power as one 100 hp engine

it hurts my brain to think about
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      11-23-2011, 05:33 PM   #7
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Make him a teacher, profit like a Tr0ll






But ask him... would a 100kg scientist rolling, produce as much power as 2, 50kg scientists rolling over?
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      11-23-2011, 06:20 PM   #8
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He'll learn addition as soon as he's ready for kindergarten

He probably also thinks a pound of lead weighs more than a pound of feathers.
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      11-23-2011, 06:21 PM   #9
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Quote:
Originally Posted by immiketoo View Post
Wow. You need new friends. I'd suggest looking in the engineering department at your local college.
Or the math department of the local elementary school.
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      11-23-2011, 06:25 PM   #10
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Quote:
Originally Posted by abisson View Post

The output of 300 HP won't be the same as a 600HP, as different factors come into hand. but still, DEF not 450 HP. He is high as a kite.
The output of two identical 300 hp engines is 600hp unless you somehow have them geared to a common output shaft that isn't in line with the other two output shafts. Then you might have a little gearing loss. That isn't generally the case in boats- they usually have their own props.
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      11-23-2011, 06:36 PM   #11
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WHOA

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      11-23-2011, 06:49 PM   #12
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Quote:
Originally Posted by jokergerm View Post
I dont know how else to explain it to him

He thinks that a boat with 20 5HP motors would not have the same pulling power as one 100 hp engine

it hurts my brain to think about
He might be right on that one. 20 motors would create more drag and be heavier than the one single engine, so would not be able to pull as much.

Using the same logic, he would be also right if he said a single 100HP would go faster than 20 x 5HP motors mounted to one boat.
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      11-23-2011, 06:50 PM   #13
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Quote:
Originally Posted by carve View Post
The output of two identical 300 hp engines is 600hp unless you somehow have them geared to a common output shaft that isn't in line with the other two output shafts. Then you might have a little gearing loss. That isn't generally the case in boats- they usually have their own props.
exactly, this guy really needs smarter friends
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      11-23-2011, 06:59 PM   #14
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Quote:
Originally Posted by carve View Post
The output of two identical 300 hp engines is 600hp unless you somehow have them geared to a common output shaft that isn't in line with the other two output shafts. Then you might have a little gearing loss. That isn't generally the case in boats- they usually have their own props.
I agree with this. Being an outboard guy, all things being equal across the board, for instance (2) 150hp motors vs (1) 300hp motor(since they dont make 600hp outboard motors) here's my take:

2 engines = typically more weight, fuel & double the maintenance...basically more $$$. But looks cooler

1 engine = typically less weight, more fuel efficient, half the maintence...however if it breaks down, basically you're screwed
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      11-23-2011, 07:18 PM   #15
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Im getting really frusterated with my friend he is so sure that he is right. and that you cant just double the HP with 2 motors

Now He is trying to tell me that a truck with 2 300hp motors would be almost 50% less power that 1 600 HP motor
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      11-23-2011, 07:35 PM   #16
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Power to weight ratio might be different. Torque curve might be different. Drag might be different. Power output will be the same.
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      11-23-2011, 07:36 PM   #17
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Quote:
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Power to weight ratio might be different. Torque curve might be different. Drag might be different. Power output will be the same.
^^^ yes exactly
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      11-23-2011, 07:46 PM   #18
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Go stand next to your friend and do this
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      11-23-2011, 07:55 PM   #19
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So other than a little more weight and drag these two boats would go just about the same speed
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      11-23-2011, 08:07 PM   #20
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Sounds like a myth busters project...
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Thickness feels good to me and my hands aren't that big.
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      11-23-2011, 08:34 PM   #21
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Quote:
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So other than a little more weight and drag these two boats would go just about the same speed
No, that is an entirely different question, especially with boats.

These guys have a pretty cool product though they explain the drag and weight issues

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      11-23-2011, 08:40 PM   #22
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Quote:
Originally Posted by jokergerm View Post
Im getting really frusterated with my friend he is so sure that he is right. and that you cant just double the HP with 2 motors

Now He is trying to tell me that a truck with 2 300hp motors would be almost 50% less power that 1 600 HP motor
Explain a few things to him. First, torque stacks. If someone pushes something with 10ft lbs, and another person does the same, the effect is exactly the same as one person pushing @ 20 ft lbs.

Next Hp = torque x RPM / 5252.

So 2 identical engines will double the HP output at any given point.


Use a hybrid car as an example, they electric engines stack with the gas engines for much higher HP output.
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