There is a column of data for a Catalina 30 on this table I made:
http://dan.pfeiffer.net/10m/edrive_collected_data.png
This is the footnote for that column:
[10] Catalina 30 “Zepher” boat speed data 8/31/18 - No sails up. Seas calm, ave of east and west runs, 12x5 2-blade prop
I forget where I found the data. Could have been a posting on this forum. I don't seem to have info on the motor type or any details on the installation. Zepher was basically hitting 5 knots at 5000 watts. I am making 5 kts at 3200 watts in my somewhat larger Pearson 10M (12500 lbs, 28.3 lwl, 18" prop) and I suspect the most significant difference is that I have a better optimized prop.
I have seen a couple other Catalina 30 electric conversions though I don't seem to have links (sorry). I would expect there are more since there are about 3 gagillian of the boats out there? Actually something like 6,000? There are 6 or 7 in my harbor. At least three that race in our club. One with a tired A4 considering electric.
I think the multi-pod idea is interesting and offers a couple advantages like boat maneuvering in harbor ("reverse starboard motors" said like Sean Connery in Red October...) and redundancy (though electric motors are pretty reliable?). But I think sailing with all those pods will be like dragging a couple milk crates behind you. Yes they are streamlined but you have four of them with props... And sailing performance is first for me. And it's a lot of added holes in the bottom which is a negative to me. Perhaps some mount on the ample stern of a Catalina 30 would make it easy to retract the pods? But it would be a lot of gear in the way of your prime dingy boarding zone and you will be wanting that in gorgeous Georgian Bay?
I think an inboard refit would be a better option. At $300 ea you're talking $1200 for the motors. And another 400 for controllers you mentioned you're at $1600 with no fabrication. That's getting into the price range of a 10kW Thunderstruck motor kit ($2000) and I think there will be a lot less to fabricate in the conversion than for the four pods.
Rule if thumb - 1kW/2tons? Quadruple that if you want any reserve power for a choppy entrance or head seas or to scoot out of the way of something in a hurry. Most of the installation I have seen seem under-powered to me. Not enough reserve power and only adequate in ideal motoring conditions. And when you are cruising at speed you are running at 90 to 100% capacity which is harder on all the components. Better to design for comfortable cruise at 60% I think. That's what I did anyway. Actually more like 45%.
I am on L. Erie just down the way from you. Georgian Bay is a goal of mine. With 1kW/2 ton I would maybe make 4 knots heading up the Detroit river which in effect is about 1 knot down the Detroit river. In other words a no-go. If I want to transit up to L Huron I need to sustain 6 knots in the river. That means 5000 watts all day long. And that means something like 50kWh battery or an aux generator because even with that 50kWh battery I'll be stuck at Sarina for two days waiting for it to recharge. It also means a motor that can run continuously at 5 to 6 kW. And that will depend on cooling. That's why I am water cooled.
As for regen, I can get 400-500 watts when I can sail at 6.5+ knots. Again, my prop is a very good match. I think that matters a lot. It's a feathering prop so no milk-crate drag under sail. It's good to have Regen but it's not a full charging solution for the way I use the boat.
See some of what I have done here (still adding material to this page):
http://dan.pfeiffer.net/10m/electric_drive.htm
Dan Pfeiffer
Thanks Kev and Ryan -
@kev - I'm not really looking for an outboard, since I don't need the steering an outboard offers or the speed an outboard is designed for. About the only part of an outboard I'm interested in is the waterproof motor on the bottom...which is why trolling motor bottom ends fit the bill perfectly. If I can get a waterproof brushed DC motor + prop for $300 and stick it on the bottom of the hull, I can provide a DC PWM controller. The rest of the problem is really just a matter of sufficient power. If you can find me a torqueedo bottom end for < $1000 I'm all ears :) The added redundancy of having multiple pods to provide enough power seems to be an added feature of the system (I think).
@Ryan - the through-hulls are a good point. You got me thinking - it may be less scary and more serviceable to run wires along the hull to the back of the boat, and bring them into the boat above the waterline. The motors would be mounted on threaded rods mounted to a base plate, which is in turn glassed onto the outside hull. That way we have 0 new holes in the hull.
One of the main selling points for me is the modularity and redundancy. If a pod stops working, I can keep a spare for $300. Simply dive down, unscrew the old pod, screw on the new pod and drive on. Also, if 1 pod goes down I can still use the remaining 3 until it's safe to stop and do the swap.
Likewise, a simple 60 amp PWM dc motor controller is less than $100. Also a cheap and simple swap out. Much better than carrying a spare $1000 sevcon. I understand sevcons are pretty bulletproof, but I've seen enough forum posts to know that they can and do fail from time to time.
4 individual throttles to the cockpit for the controllers would offer a lot of options for speed/manuverability, and you'd have 4 parallel dead-simple systems:
battery -> PWM controller -> throttle -> drive. That it - no belts, pulleys, mounts, couplers, contactors - it seems pretty simple if I'm not missing anything?
Certainly trying something new and different and the learning that happens in the process is one of the biggest motivators for this thought experiment :). I love boats, electricity and thinking outside the box - I'm eager to see what I can learn from this to apply to other projects I'd like to tinker with like SUP projects, repowering my blown dingy motor and who knows what else?
I haven't heard any deal breakers yet - - unless I'm still missing something.
I can probably stroke efficiency off the list of benefits above per Kev's comment. That's too bad, but not a deal breaker for me.
Can anyone offer any good arguments against any of the other benefits listed above? Or any other drawbacks I haven't thought of?
Thanks!
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