Duffy Electric boats....?

Thanks for that! Here is the barely helpful response from Duffy after I sent them the same photos:


Thank you for the photo's.

Unfortunately all of the parts your are inquiring about have been discontinued since 1998. In this situation we recommend upgrading to the Duffy Infaspeed Controller System (part # SMI-215-ASSY) for $2,400.00 plus shipping. The assembly includes the controller, the actuator and all of the necessary cables, there is a 7 business day lead time from the date of order for these parts.


Regarding your existing parts I was not able to find the original parts numbers only the vendor information. The Black controller was made by Curtis Instruments, there should be a metal label on the unit with a part number or serial number that could aid in your search. The actuator/barrel switch was made by EPC (Electric Power Controls) they are located in Long Beach, CA.


If you would like to place an order or would like additional technical assistance please contact our Newport Beach Parts & Service Office (949)650-4633 and request to speak with a technician.


Thank you for choosing Duffy Electric Boats!

I am going to remove the "switch" assembly to see if I can get any useful ID from it.

Isn't there an electric boat guy at Campbells place in Batchelors Point?

I recall there is or was another electric boat guy in Oxford, maybe the same person but I think there was a Duffy dealer at Batchelors Point a couple of years ago. There should be some local help available.

If nothing else, PM me and I will give put you in touch with electric propulsion guru at the MEBA school who should be able to help.

JIMG, I would not say Duffy's email was useless, I think it's quite helpful. Start calling those companies (Curtis and EPC) that manufactured the parts and they should either have something on the shelf, be able to rebuild the part, or be able to point you in a better direction to retrofit something. They should also be able to tell you how to test the parts.

You have to understand that at best you're dealing with parts not made in almost 20 years.

I agree...Duffy gave you some names and places to start ! Good Luck.

OK, I guess I was expecting more. I have now tested the EPC switch and found that the rheostat part is working with v
I have also found a manual for the Curtis controller (online) and wiring diagrams. I am convinced that I have a wiring error. What I am experiencing is full throttle no matter where the handle is, forward and reverse as if the rheostat were bypassed. Any thoughts?

My boat is fixed!! The secret is that the voltage in and out of the potentiometer is 36 and not the 12 Duffy's diagram shows. Don't have to do those crazy markups!

Well done !!

I need to replace the belt on my 1990 20' Duffy. Boat is on a lift. Do I simply slide the shaft aft after "unbolting" the thrust bearing? How is the thrust bearing likely to have been mounted? Backing plate? Nuts on the bolts? Access? TIA

You could also leave the thrust bearing alone and take the shaft out of it. HOWEVER, you might want to just leave the shaft in the thrust bearing if that is a sound connection and just remove the trust bearing. If its like mine there are only two nuts and the whole assembley should slide back just enough to get the belt off and the new one on.

Thanks for that! Here is what I see:



I can see from my photos that the pulleys are slightly out of line too. The bulkhead on which the thrust bearing is VERY solid in spite of the appearance in the pic. So, just the 2 bolts and then care to support the shaft and slip the belt off?

Hi all. Just took ownership of a 1983 Duffy 18 (pop top?). I trailered it from VA to LA after spending the whole vacation building a custom trailer to haul it with. The boat is in excellent shape and runs well. I've installed a new shaft bearing and belts, replaced the shaft seal with fresh Palmeto wax rope. My 2007 Interstate 36V battery bank discharged 130AH on a several hour cruise in the Achafalaya basin to what appeared to be 30-40% SOC. That old brushed motor makes a **** ton of heat though, 100F air in, 140F air out. The brushes are in great shape but the motor is very noisy. I have the ancient two-speed 18V/36V selector switch. I am exploring motor replacements to improve efficiency and reduce noise. BTW I am completely new to boat ownership but am a decent mechanic and excellent electronics technician. Glad to see other Duffy owners here. How many do we have?

Might be just me ? I have a 1999.

This is very interesting. So my 1983 controls just switch between 18V (3s2p) and 36 (6s1p) volts for low and high respectively. You have reversing contacts in your switch plus a pot to control speed at your motor.

I am still here and my Duffy is running perfectly after replacing the belt. Welcome aboard!

I have replaced the rope seal, the inboard propeller shaft bearing, new belts and careful re-assembly of my sheaves to minimize wobble. I've added an inexpensive watt-hour meter and a precision voltage indicator on each of the batteries. I have LED bulbs coming for the nav lights, cabin and stern light (100W of light!).

My planned upgrades are:
Upgrade the traction system to 48VDC with two more batteries. 12V converter and 12V battery.
Switch to a modern brushless motor and speed controller, or a 48V trolling motor.
Build a larger pop-top roof that has flexible solar panels on it.
Refurbish weathered teak wood.
Overhaul console with some modern electronics.
Make all of this stuff look really good and get to some boat shows.

I am considering two options right now for re-powering Duffy to get it quieter and more efficient.
Golden Motor's 48V 3kW or 5kW BLDC with a controller and boat throttle stick, $1k to $1.3k
Caroute's 48V 2.5kW BLDC trolling motor (180lbs thrust) and installing it as a pod in place of my rudder.
Exploring a couple of other propulsion options but they are all quadruple the price.