Hi John.
Thank you for posting your performance measurements. It's easy to see that the Torqeedo 4.0 delivers solid performance (in my experience, much better that trolling motors or "converted" outboards). But we can also compare your results to other converted Catalina 30s and similar boats.
James at Propulsion Marine published performance data about his converted Catalina 30, you can read about it at his "Electric Baot Design" website, look under the data tab:
http://electricboatdesign.com/
Here's a quick recap from his data:
663W = 3kts
1485W = 4kts
3200W = 5kts
6000W = 6kts
I've previously published performance data to this list from my conversion of my 1964 Cheoy Lee Berunda 30 ketch that displaces over 10,000 lbs. With a narrower beam than a Catalina 30, but a full keel and the prop in an aperture, I would predict similar performance from my boat. But apparently, I lucked out with my prop and gear ratio. Here's my numbers:
500W = 3kts
1000W = 3.9kts
1500W = 4.4kts
2500W = 5kts
4000W = 5.7kts
5150W = 5.9kts
You can read how I measured my performance in post # 17974 from March 28, 2011
http://groups.yahoo.com/group/electricboats/message/17974
You can see that every conversion is different, but you can also see that there are trends that can predict the future performance of a conversion much better than the computer models available around the web. Here's a couple of posts that discuss the accuracy of some computer model predictions.
http://groups.yahoo.com/group/electricboats/message/21902
http://groups.yahoo.com/group/electricboats/message/21905
So any time that a member here posts real world performance data, it is a huge help to others. Thank you again for your input.
Fair winds and smooth seas,
Eric
Marina del Rey, CA
--- In electricboats@yahoogroups.com, oak wrote:
>
> The following is just as a quick point of reference for anyone interested - this was not a scientific study, and I definitely do NOT have nearly enough data to be definitive.... (end disclaimer)
>
>
> Over the past several months, I've been fighting a fussy Atomic 4 gas engine on my 1981 Catalina 30.
>
> I sail on an inland lake, with moderate winds (5-20mph), some waves (no worse than the boat wake - nothing at all compared to bay or open water sailing), and no currents. I primarily NEED auxiliary power to get in and out of the marina, and would *like* to be able to cruise a couple of hours beyond that.
>
> Long story short, I ended up buying a Torqeedo 4.0 outboard electric motor, mounted on a outboard motor mount on the back of the Catalina 30. It's feed by 4 deep cycle "marine" batteries that I got at Academy - basically heavy duty lead acid batteries. Nothing special. I have a 3Amp ac charger to charge the 48V bank.
>
> Sunday, we finally had a chance to take the boat out and run a little with the outboard. Once we were away from the dock and out on the lake, I was running at about 1000W, and stable at about 3.0-3.2MPH, according to both the GPS built into the Torqeedo (nice), and confirmed by a hand-held GPS. This was INTO the wind and waves. Just to see what would happen, I increased the power / throttle till the Torqeedo was reading 2000W. This increased my speed to about 4 MPH (double the power, 25% increase in speed - that felt about right). By contrast, on the way home, we were running downwind (just electric motor, no sails, but a Catalina 30 still has a lot of freeboard to be influenced by the wind). Downwind, we still ran at about 1000W, but this time were going about 4MPH.
>
> As a separate point of reference, MOST of the motoring we did was actually using the gas engine. For the ~1.5 hours that we motored on the 30HP gas Atomic 4 engine, we burned about 1.5 gallons of gas (this is a VERY rough estimate - I wasn't watching the clock that close, and I don't have any kind of gauge on the gas tank). At very modest throttle, the gas engine drove the boat easily at 6 MPH.
>
> Observations:
>
> Since the gas engine can easily drive the boat to 6MPH, I know I'm nowhere near hull speed when the electric is at 3-4mph.
>
> The electric is rated to run up to 4KW. However, with the (cheap) batteries that I have currently, I can get 1-2 hours of run time at 1000W (at least from dock tests - need to confirm this on the water).
>
> 3MPH is fairly slow, but is definite progress. There have been summer days with light air that I've sailed much slower than that... :)
>
> I'm not sure I'm ready to REPLACE the gas engine with the outboard. But it is definitely nice to have both, so I know I've got a backup when it's time to go in and out of the marina. When out running around on the lake - if both gas and electric work, then I can exhaust one or the other (probably the gas for it's range and speed), and still be able to sail back to the marina, and use the alternate motor to get into the slip.
>
> John
>
| Reply via web post | Reply to sender | Reply to group | Start a New Topic | Messages in this topic (14) |
No comments:
Post a Comment