Join Date: Oct 2014
Location: Deale, MD
Thanked 2 Times in 2 Posts
Rep Power: 5
Khaleesea Evaluation and project costs
Here's my initial set of assumptions, copied from my first post on Khaleesea's conversion, and my comments:
~10kW motor @48V
I eventually settled on 12kw continuous @ 48v, water cooled.
~2 hours cruise speed @ ~5kts
I did a little better than this. At 40A, I can go ~5kts for about 3 hours.
Biggest, slowest 2-blade prop with the biggest pitch I can find - target RPM ~600 at cruise for maximum efficiency
In order to turn a prop at 600rpm and produce enough thrust to move the boat, I would have needed at least an 18" prop. While I could have fit one on Khaleesea, it would have required a longer prop shaft and the installation of additional support. In short, not worth it. I settled on a 3 blade 15/17 prop. While it doesn't accelerate the boat as well as the old two blade 15/12, it is remarkably efficient at cruising speed.
Hull speed under motor power alone for short sprints (current Yanmar cannot accomplish this feat, tops out at about 6.5kts WOT. hull speed is 7.2)
Until I install a water cooling system on the boat, I won't be pushing it to full throttle. Theoretically, I have enough power to go to hull speed.
Regeneration while under sail
This is still something of a question mark. I haven't had enough good sailing days to really test the regeneration.
Project completion ~ April 2019.
I blew by this one. I wasn't in the water until late June. Part of that was my fault, part of that was Thunderstruck's.
I'm open to suggestions as to motors, batteries, etc. I'm leaning towards a motenergy 1114 with a 5:1 gear reducer and used Volt batteries, since they're 9.5x9.5x10.5 and it will be easier to fit them in my available space than other lithium batteries.
I went with the Volt batteries, a 2:1 gear ratio, and a ME1115 water-cooled motor.
Total project costs:
Conversion kit: $2100
Screws, nuts, bolts, bits, turnbuckles, etc: $400
Plywood, resin, chop mat, etc: $300
Used Prop: $350
Cables, ends, etc: $150 (I recycled whenever possible. This would have been much higher had I not done so.)
Misc. Labor (prop install, coupler install): $750
Hours spent by me doing all other work: Lots
Gross Total: $5550
Money recouped from selling Yanmar 2gm20: $2500
Net Total: $3050
Satisfaction from completing project: High