John,
I believe direct drive has worked out for you. I continue to struggle with the gear reduction despite the general consensus from those that have been involved with E.P. reduction is necessary for proper cooling which translates into efficiency. Maybe the type of motor folks are using requires this reduction in order to handle the tourque requred to spin a prop without overheating. Being in the mechanical industry I have witnessed direct drive motors being more efficient in power consumption than their horsepower equivalent turning a sheave with a belt. CFM of air movement was identical between both fans & the direct drive won hands down in power consumption.
Hydronic circultors are vfd driven today & can operate at pretty low rpm's without overheating. So, I'm still seeking how to build a better mousetrap...
Bob
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On Fri, 9/23/16, 66b6dcd5b59507e7d751ea81382ea1f6 <no_reply@yahoogroups.com> wrote:
Subject: Re: [Electric Boats] Re: Decibels
To: electricboats@yahoogroups.com
Date: Friday, September 23, 2016, 3:11 AM
Hi Bob,
Fair enough. One point though
it's not a question of 'feeling' it works at
24V, it simply does. As you know it's all down to the
power a person requires. If you don't require much and
have an efficient system there is also no issue of
'running too hot'. Of course, I run in a UK Maritime
climate so that helps. My cruise speed is at peak efficiency
for my voltage too and any loss there compared to 48V is
made up by not having reduction gearing. The final issue
folk need to consider (and remember I'm a sailing yacht
not motor boat) is simply how long you can run for and what
continuous use time you need at your max anticipated
continuous current. The most I've ever run continuously
is 3 hrs and max temp has been 55C at the controller. Motor
has a heat sink too so no issues for either with heat.
John R.
Posted by: bob jennings <sabre281@yahoo.com>
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