Yes, trust your sails.
The question you have to ask yourself is whether you're running a motor boat with auxillary sails or a sailboat with auxillary motor. The answer to that question will be a big factor in sizing your electric propulsion. When I was young I use to pride myself on practially never using my auxillary motor. Not so much anymore. lol
Carter
From: Steve <sstuller@netzero.com>
To: electricboats@yahoogroups.com
Sent: Monday, April 15, 2013 2:14 AM
Subject: [Electric Boats] Re: does anyone have current real world performance figures please
To: electricboats@yahoogroups.com
Sent: Monday, April 15, 2013 2:14 AM
Subject: [Electric Boats] Re: does anyone have current real world performance figures please
An example of this dilemma of small and large electric motors can be seen in the older Torqeedo catalogs. The efficiency of the Torqeedo 801 is about 45% at 300 watts input while the larger Cruise 2.0 efficiency is 35% at 300 watts input. They are both 24 volt motors so the motor current is the same but relative to the motor ratings (~1 KW and 2 KW) the 801 is operating at a more efficient point on the its' amp input curve. If you let your sails serve as your second motor then you don't have to worry about adding the complexity of another electric drive. If you trust your sails you can get away with a smaller electric drive and gain the efficiency. Thanks. Steve S.
--- In electricboats@yahoogroups.com, "dan.randolph" <danlrandolph@...> wrote:
>
> Hi both Erics,
>
> Eric of Meander is correct in why I am thinking of this approach. I understand the extra loss WHEN both motors are engaged. BUT for the vast majority of our expected use (based on 18 months of cruising with ICE)will be at 3 knts or under, thus only using ONE motor. The idea is to maximize the efficiency of that system, with having a second motor to boost power for those rare times when we need it.
>
> From all the data I can find - admittedly a hard task to find good data as a lot of motor efficiency curves start at around 1kw, rather than the 1/3 to 3/4 kw I am focused on - it seems like most are less than 70% efficient at that power level, even the ones most employed on elec boats on this list. Having 80 - 90% motor efficiency (even if that is lab efficiency) would beat the loss of efficiency assumed by the use of the second motor (with second drive system) on those occasions when it would be used.
>
> OR, this is my thinking, and I am clearly open to the naysayers!!
>
> The redundancy may be a blessing or curse, depending on if it is redundant performance or maintenance!!
>
> Thanks all
>
> - Dan
>
>
------------------------------------
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/electricboats/
<*> Your email settings:
Individual Email | Traditional
<*> To change settings online go to:
http://groups.yahoo.com/group/electricboats/join
(Yahoo! ID required)
<*> To change settings via email:
electricboats-digest@yahoogroups.com
electricboats-fullfeatured@yahoogroups.com
<*> To unsubscribe from this group, send an email to:
electricboats-unsubscribe@yahoogroups.com
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
__._,_.___
| Reply via web post | Reply to sender | Reply to group | Start a New Topic | Messages in this topic (56) |
.
__,_._,___
No comments:
Post a Comment