Hi John,
Thanks for generating the data and posting it here. Your findings support the previous recommendations of a Torqeedo 2.0 as being fairly sufficient for a Catalina 22. At 2kW with the same Torqeedo prop, the boat should cruise somewhere aroundd 5.5kts. Of course, having the additional power of a Cruie 4.0 available for adverse conditions would be nice but there are additional costs involved as you noted.
As far as storage cost and weight, you're finding out why Lithium batteries are being used more often in recreaational boats, even for large house banks. They are lighter, smaller, deliver much more of their rated capacity under heavy loads, charge faster, have higher cycle life, etc. etc. The only downside is the cost, and realistically, they can be cheaper than lead based batteries if looking across many years, I know that I have a bad track record of killing lead batteries (FLA and AGM) though neglect. My Lithium pack has been neglected even more (I left it at 60% charge for more than 6 months) with no adverse affect. My 200 lb, 160Ah * 50V battery pack will drive my 5 ton ketch more than 20nm at just over 4kts. 500 lbs of FLA would have a range of around 17nm at the same speed.
Anyway, thanks for data collection. As you know, real world data is pretty scarce, and this helps us all.
Fair winds,
Eric
1964 Bermuda 30 ketch, 5.5kW Propulsion Marine drive, 8kWh Lithium batteries
Marina del Rey, CA
--- In electricboats@yahoogroups.com, oak <oak_box@...> wrote:
>
> This is VERY preliminary, and VERY approximate, and still somewhat oranges to grapefruit...
> But some might find the information interesting.
>
> I was able to get out yesterday and make a couple of brief experimental runs comparing a Torqeedo 4R, 48V system to a Minn-Kota Traxxis 80 24V trolling motor on a Catalina 22 (no sails, even the main sail and boom were not rigged - so this is the minimal wind resistance possible).
>
> I'm running on a reasonably protected inland lake. No current. The primary concern from waves is that from other boat wake (which can be significant on this lake). "HIGH WIND" for this lake would be whitecaps (18-20), and is probably considered "nominal" by many...
>
>
> The data I collected is on my web page at: https://sites.google.com/site/danrobertstx/home/sweet-pea/c22_electricpower
> I hope to collect more data, and eventually be able to plot a couple of power / speed curves.
>
> Bottom line:
>
> Torqeedo 4R (48V)
> ===============
> This motor has PLENTY of power for a Catalina 22. At full power (3300w), the motor easily pushed the boat at 6.5mph into a moderate wind. This is about as fast as a Catalina 22 is going to go. At moderate power (1500w), I could still achieve 5mph into a moderate wind.
>
> The Torqeedo is "rated" for a max consumption of 4000w. At full throttle, with the lead batteries I was using, I only got 3300w - but that was still PLENTY for my purposes.
>
> Minn-Kota Traxxis 80 (80# thrust trolling motor, 24V)
> =====================================
> While this motor could "push" the boat, and was definitely capable of getting me in and out of the marina for docking purposes, it maxed at at no more than 3.8mph, going downwind, in 10-15mph of wind - at full motor power (100%).
>
> Max speed into an estimated 10-12mph wind was 3.4mph at 100% power. 75% power speed was about 3.4mph into a moderate wind.
> It'll move, but it won't get you anywhere fast.
>
> I ran the Traxxis for about 45 minutes, at various speeds. When I was done, the control head was HOT. No signs of failure, but I was a little concerned that it might not stand up to several hours of motoring.
>
> The Traxxis has plenty of torque for a Catalina 22. It just seems to be lacking in speed. And this may be validation of the statements made previously that the trolling motor is designed to "troll", and is prop-pitch limited to slow speed.
>
> Note that I couldn't measure real power consumption on the Traxxis. The literature indicates that for the Traxxis 80, one could expect to consume about 60A at 24V for full power, but there is no power display, and I didn't have anything hooked up to provide that info.
>
> I'd be REALLY curious to put a Torqeedo prop on a Traxxis motor, and see what that would do!!
>
> Bottom line -
> The Traxxis would work fine as a inexpensive (~$550) "backup", but probably isn't sufficient for primary outboard use.
> The Torqeedo is more than sufficient for the Catalina 22 for primary backup use - but providing lots of 48V power is an EXPENSIVE, and very HEAVY proposition.
>
> John
>
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