Duffy Electric boats....?

Are there any Duffy Electric Boat people still on this forum? I own a Duffy 18 (1992) and I am in the process of restoring it. Thanks, Doug

Doug, there are indeed Duffy Electric people on this forum. Maybe you have some specific questions?

BTW, pictures are always appreciated. Good luck with the restore!

Thanks Rob! Great to know. I have a 1992 Duffy Electric 18 footer. It is mostly restored and I am in process of updating the entire motor assembly area, electronic controller, etc. and cutless bearing.

Here is the "before" image of the motor area. The motor is about 2 years old but everything else needs updating.

Doug, that's a beauty! Here's my 2010 Duffy M160, which I use on a 300 acre inland lake with no-wake restrictions in coastal South Carolina. It's a perfect boat for tooling around on this lake, especially during cocktail hour. It's also different than your typical pontoon boat, which I appreciate.




So, what are you planning to do for the controller, throttle (aka actuator), etc?

Again, that is a beautiful boat!

Thanks Rob,
I love your boat too! I was not familiar at all with that style of Duffy! It is great. Do they still make them? I think it would be an extremely popular design. As you say, perfect for cruising and enjoying some refreshments.
Thanks again for getting back to me. My plan is to have parts for my rebuild later this week and then to get going.

Doug, based on Duffy's website, it looks like they don't make the M-series any longer. They only show the models with a more "traditional" hull. Several of my neighbors have the more traditional Duffy style, and in my opinion, there are advantages and disadvantages to both styles. Previously, Duffy offered the M-series in two or three lengths, but apparently, they were not big sellers for Duffy.

Anyway, be sure to post some pictures and a description of what you are doing for the rebuild.

Have fun!

Thanks Rob, I will for sure post some pictures as I proceed with additional repairs. So far, I have done the following:

• New batteries and motor (installed by the previous owner in 2020
• New motor controller - I installed recently - the old one worked somewhat but was failing
• I am replacing the cutless bearing by the prop
• I am refurbing the motor area to include a new large sheave/pulley, new front bearing, and new dripless seal. I will also clean up the entire area.

Thanks, Doug

Terrific, Doug. It sounds like you've got a lot done already. What did you use for the controller? Did you have to program it, or did you get it pre-programmed from Duffy?

The reason I ask is that my boat uses a Zapi FS5050 controller, and I recently bought the hand-held programming device for Zapi controllers from a seller in China. I've used it to adjust some parameters and to calibrate the controller for a new actuator. I didn't want to deal with Duffy on this, if at all possible.

Best of luck, and please let us know how it goes.

Hi Rob,
It had an old Curtis 1204-413 controller in the boat when I purchased the boat. I guess very similar to what is used in a golf cart like the motor. It worked but the key switch for the boat did not turn it off and when the controller was cold it would not run the motor sometimes. After a Google search I found a company called Flight Systems Industrial Products (FSIP) who makes direct replacements for Curtis controllers. I had also contacted Curtis I seem to remember and they directed me to FSIP. The replacement is a new unit although they also will rebuild your old controller too. It was expensive at $577. However, it works flawlessly and was an easy drop in replacement. FSIP is at www.shop.fsip.biz I put in the Zapi FS5050 number on their site and they seem to handle it as well. They have a chat function on their website and might help you?
Thanks again and I will keep you posted. Doug

That sounds like it worked out well, Doug. That price is not out of line for these golf cart controllers, and it's worth it as a drop-in replacement. I'll keep their contact info, but I'm all set for now. I've owned this boat for two years, and after I got the controller programming unit, I discovered that sometime in the past, the controller had been wired incorrectly, so that the controller parameters for the forward speed worked when the boat was in reverse, and vice-versa. Things are working better now that I corrected that issue, but I still have a small problem with the throttle control (aka actuator) itself. I'm working on that now.

Good luck, and I can't wait to see what else you do to that beautiful boat!

Thanks for your help last summer with the motor bearings. This summer I need new batteries for our ElectraCraft LSR 18. It is a 48V system current using six 8V golf cart batteries.

I'm considering switching to four 12V batteries such as the attached from Costco. Can anyone comment on switching to 12V batteries? We use it on a small lake in Colorado so range is not an issue, my goals are lower cost replacement and ideally not needing to bring them into the garage in the winter.

Cheap batteries will have to be taken in and out of the boat frequently, just to take them to the recycling dumpster.

Batteries, like many things in life, are "You get what you pay for". Good quality ones have thicker plates that last longer.

I don't know who wrote this about AGM Deep-cycles but I agree with them entirely.

https://www.solar-electric.com/learning-center/deep-cycle-battery-faq.html/#AGM, or Absorbed Glass Mat Batteries

Thanks Fishtigua, that was convincing. I've been thinking about this wrong and am now happy to pay 4x for a battery that lasts twice as long and doesn't need to come inside in the winter.

I'm hoping for some help with my electrical calculations. My motor sticker is below, it says 95 amps. Despite saying 72V, I believe this has always been a 48V system using six 8V batteries. The existing 8V batteries each say 145AH @ 5 HR, so the combined six battery system would be able to output 174 (145/5 * 6) amp-hours for 5 hours, correct?

I’m converting to four 12V batteries and want to have 2 hours of runtime (our lake is very small, one hour is the actual max). At 95 amps I need 180 amp-hours total, or 45 amp-hours from each 12V battery, correct?

This from West Marine:-

Battery capacity measurements are commonly expressed in Amp-hours (Ah) and Reserve Minutes. Amp-hours measure the total amount of energy that a battery can deliver for 20 hours at a constant rate of discharge before the voltage drops to 10.5 volts. This means that a 200Ah battery can run a 10A load for 20 hours. The reserve minute rating is the number of minutes that a battery can run a 25A load until dropping to 10.5V, just like with starting batteries. A Group 27 deep cycle battery with a rating of 180 reserve minutes will run a 25A load for three hours. House loads range from 5A to 25A or more. Amp hours is generally the more relevant measurement for house banks.

That 95A is the rating for the maximum amps drawn by your motor. What you really need to know is what your actual amperage draw is when running at your normal cruising speed. Keep in mind that flooded lead acid (FLA) batteries don't like to be drawn down below half of their capacity. Routinely drawing down below 50% will severely limit life of the batteries. Also, your Amp-hour rating of 145 Ah per battery doesn't multiply by the number of batteries when they are connected in series. 4 12V batteries connected in series will get you 48V, but still with only 145 Ah for the total battery bank.

Considering the 50% guideline, you really only have about 75 Ah to work with, so if your motor is actually drawing 50 amp at your cruising speed, you can expect the run the boat for about an hour and a half, and that's with new or nearly new batteries. Less with older batteries.

Are you sure your Electracraft isn't using the GC2 golf cart batteries, which are 6V batteries? In other words, 8 6V batteries to get you to 48V? IMHO, if you are sticking with FLA batteries, I'd stay with whatever your boat originally had. The GC2 batteries are well suited for these boats (I've got a Duffy), have a 200 Ah rating, and are relatively inexpensive.

Good luck with whatever you end up doing. Please let us know.

Thanks Rob. My boat (an ElectraCraft not a Duffy) came with my house and since I've owned it has always had six 8V batteries (T-875s). I appreciate you correcting my multiplying Amp-hours and I think I understand now.

I'd like to switch to AGM Deep Cycles for the many benefits in Fishtigua's link, especially the no maintenance and surviving a freeze.

Assuming I am going AGM, I'd appreciate any comments on the pros/cons of using four 12Vs vs six 8Vs as well as recommended brands.

Ted, volts are volts, so 4 12V are fine to produce 48V. The key is the right batteries with an appropriate Ah rating to meet your needs. The GC2 batteries used in Duffy boats have a 200-220 Ah rating, depending on brand, and that works fairly well for relatively short trips on inland lakes or calm rivers.

For what it's worth, I'm working on a project to upgrade to a 48V lithium ion battery for my Duffy for a variety of reasons. They cost a lot more, but have a much longer life span and deeper discharge cycle.

Good luck for whatever you end up doing!

I appreciate the previous help. I went with four 12V AGM batteries, the precise model is "Centennial CB12-85 12V 85Ah Group 24 Sealed Lead Acid AGM Battery"

Total cost was $1,035 from battsys.com (local pickup in Denver). My son and I installed them today and they are working fine, hopefully they last many years.