[MHml] HP to Watts

[Glenn Brodie]

And on Maine Cat's Web Site tests with and OSSA install (power cat):
 
http://www.mecat.com/power/powerupdates.htm see
Maine Cat P-45 Update -  5/18/07

Round #1 - Sea Trials with OSSA Powerlite propulsion:

Conclusion was:
 
We recorded our fuel consumption numbers and found at 8 knots we
averaged 1.5 gallons per hour and at 9.1 knots we burned 3 gallons per
hour.  These are about the same speeds and fuel burns we get on our
Maine Cat 41 sailing cat on a new boat with a little less weight.  The
Maine Cat 41 is powered by twin 29 hp 3YM30 Yanmar diesels with
saildrives and two bladed folding propellers.  Very close to the
horsepower of the OSSA equipment we used on the P-45.
 
 
Regards,
 
Glenn
 
Indigo
 

________________________________

From: multihulls-bounces at steamradio.com
[mailto:multihulls-bounces at steamradio.com] On Behalf Of
PeterNice at aol.com
Sent: Saturday, December 15, 2007 9:56 PM
To: multihulls at steamradio.com
Subject: [MHml] HP to Watts


There is a very competent discusion about electric drives on the Lagoon
site.
 
http://www.cata-lagoon.com/420_specs_uk.php#
http://www.cata-lagoon.com/site_agents/pdf/L420_Hybrid_motorisation_GB_0
1-2007.pdf
 
I think they have been extremely honest in their appraisal and provide
some useful figures that we have been guessing at on the list. 
 
The propulsion battery bank weigh 840kgs and gives a 9 mile range at 80%
discharge 13.5 mile range at 60% discharge.
 
To regenerate 3 amps (assuming 72v) requires a boat speed of 9.5 knots
and causes a speed loss of 1 knot
 
The driven performance is directly related to the size of the generator
installed, the electric motors remaining the same.
 
Peter Nice
 
In a message dated 16/12/2007 12:00:39 Central Pacific Standard Time,
multihulls-request at steamradio.com writes:

	----- Original Message ----- 
	From: "Dan Frenette" <Dan.Frenette at Sun.COM>
	To: "Informed discussion of multihull issues" 
	<multihulls at steamradio.com>
	Sent: Friday, December 14, 2007 4:00 PM
	Subject: [MHml] HP to Watts
	
	
	>A simple formula of 1 hp required = 746 Watts looks simple 
	>but do we
	> really need that many watts to get the same effective 
	> power from an
	> electric motor vs an outboard?
	>
	> I know Johnson/Evenrude claim's they are measuring HP at 
	> the prop but
	> what does that mean in terms of what we would need from an 
	> eletric motor
	> to do the same thing?
	>
	> Should I be looking at units of thrust from the prop or 
	> ???  I don't
	> know if the thrust is commonly quoted??? An eletric motor 
	> has better
	> torque characteristics if I understand what's going on 
	> under water.
	>
	> Dan Frenette

 
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