Eric , I believe also we need to remain well aware of not only the power that can be developed , but also how long that power can be sustained.
We all have different requirements , and I think I stated my case recently , in that I would like the best of both worlds , a hybrid.
That was confirmed to me today.
I agreed to help friends deliver a 26 ft motor sailer.
We left yesterday at 0930 , and found we had the wind on the nose , so started motorsailing.
And we kept at it , for the next 22 1/2 hours straight , battling against the wind , and rain.
The next 60 nm was going to be worse though , with the winds coming up to 40 knots plus , and then going in to the notorious , deadly Port Phllip rip .
That will take all of the new crews considerable experience , and every bit of grunt from the Nanni 50 hp diesel possible , after 35 hours + of hard slog.
A hybrid could do that , maybe even better , drawing on the electric motor through the very worst of it.
A pure electric , or solar powered boat ? , no , it couldn't happen.
It won't happen very often , but its an expectation I have is that the boat can keep on keeping on , in adverse conditions.
Thats my requirement.
Thats my requirement.
Regards Rob J.
From: Eric <ewdysar@yahoo.
To: electricboats@
Sent: Sat, 10 April, 2010 6:23:27 PM
Subject: [Electric Boats] Re: Pure or mostly solar powered boat?
1 hp = 746W according to every conversion table that I have found. So 1000W = 1.34hp. But that is a strictly energy conversion.
James could be stating that a general rule of thumb is 1hp ICE = 2.25hp electric. This does fall inside the range that I am familiar with, 2-3hp electric = 1 hp ICE.
The question here relates to the different efficiencies in ICE versus electric drives. So from real world experience, does anyone know what size electric motor will deliver the same power (not energy consumption) as a 200hp gas engine. My estimate was 66 to 100hp or 50 to 75kW electric drive to replace a 200hp gas engine.
Fair winds,
Eric
--- In electricboats@
>
> 1000w = 3hp so you need a 66kw motor.
>
>
> On Apr 9, 2010, at 12:10 PM, Joe Salzetti wrote:
>
> >
> > Have the same question but for a 200hp gas engine?
> > Also how many batteries would I need?
> >
> > Thank you!
> > Joe
> >
> > Sent from my iPhone
> >
> > On Apr 9, 2010, at 9:50 AM, "Eric" <ewdysar@...> wrote:
> >
> >>
> >> Dan,
> >>
> >> So what size electric motor would you suggest to replace a 100hp engine in a power boat? (assuming that the engine was appropriately sized)
> >>
> >> Eric
> >>
> >> --- In electricboats@
> >> >
> >> > It's not so much a matter of efficiency, since horsepower is measured at the output shaft and any inefficiencies are already taken into account. Rather, it is a matter of the power curves. An ICE's HP is rated at WOT where it produces max HP, but torque is usually starting to drop. Plus, an electric motor's HP is rated at the point were it can run all day without overheating. The fact is, electric motors can be run at higher rpms, and therefore higher HP, for a short period of time. You can use this limited service factor for conditions where you want more HP, such as maneuvering or emergencies.
> >> >
> >> >
> >> >
> >> > --- In electricboats@
> >> > >
> >> > > You are correct. People will usually figure that an electric drive will be 2 to 3 times as effficient as an ICE engine in converting energy into thrust, due to less energy lost as heat. Therefore, a 100hp gas or diesel engine can usually be replaced with a 35-50hp motor with similar performance results. Unfortunately, a 50hp motor will draw at least 38kW under full power, which translates to 380A at 100V. So these kinds of power ratings require even higher voltages to keep the amperages reasonable. That doesn't even begin to address the problems of energy storage...
> >> > >
> >> > > Fair winds.
> >> > > Eric
> >> > > Marina del Rey
> >> > >
> >> > > --- In electricboats@
> >> > > >
> >> > > > I thought that I read that a 100 hp motor would be the same as a 200 hp gas engine?
> >> > > >
> >> > > > Sent from my iPhone
> >> > > >
> >> > > > On Apr 7, 2010, at 9:44 PM, "peoria_diver" <daredster@> wrote:
> >> > > >
> >> > > >
> >> > > > Denny,
> >> > > >
> >> > > > Following sugestions from this group, I did a little online shopping today. Powerboat hulls just don't seem like good candidates to me. Even small trawlers have engines in the 100HP range. I switched back to sailboats and found a couple of centerboard boats at 28'. I am still a little concerned about the stability. I'll have to give it some thought.
> >> > > >
> >> > > > -Red
> >> > > >
> >> > >
> >> >
> >>
> >
> >
>
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