Wednesday, January 18, 2017

Re: [Electric Boats] New to group, please evaluate my dual trolling motor setup

 

Hello John.  Thanks for the comments.   I will have a gas motor, which will get used in situations where close maneuvering is not needed, or for long days when motoring is necessary (may the forces of nature spare us too many of those days!).   The boat has very slender hulls so I should go slightly faster than an equivalent weight mono, but speed is not really the goal here.    Im looking for simple, easy to manage, and somewhat workable for some situations.  


Chris Curtis


---In electricboats@yahoogroups.com, <oak_box@...> wrote :

I would agree with Ken - two 35 pound motors on a 3500 pound boat that is 30 feet long seems to be a bit light.  You might be able to push it at 2-3mph in perfect conditions - but a cheap gas outboard would be your best backup bet (and a very good one) for dealing with adverse conditions.

Also, as he mentioned - your top end speed will be limited by the pitch of the trolling motor props.  They are inherently limited to no more than about 4mph, and my experiments were done with a Traxxis 80 pound 24V motor on a 2000 pound Catalina 22 sailboat.

Best of luck to you though!!!  Trolling motors are a cheap, EASY way to get you moving.  You may want to upgrade soon.  But it will get you on the water in a protected area.

Good luck!
John


From: "'Ken Cooke' ken.cooke@... [electricboats]" <electricboats@yahoogroups.com>
To: electricboats@yahoogroups.com
Sent: Tuesday, January 17, 2017 11:13 AM
Subject: Re: [Electric Boats] New to group, please evaluate my dual trolling motor setup

 
Hi, Chris,
 
I have a similar setup with two 55 pound thrust Minn Kota trolling motors with Kipawa after market props powered by separate solar panel arrays (450 watts) PWM Charge Controller feeding dual 220 AH 6 volt batteries wired in series for 12 volts pushing a 25' 3500 pound boat.
 
This gives me about three hours of cruising at about 3.5 – 4mph before I draw down the batteries to 50% charge.  My motors draw about 35 Amps at full speed.
 
If it is a sunny day, I can add about two additional hours of cruising for about a 20 mile range.
 
I might note that the top speed is set by the pitch of the prop and RMP's of the motors (about 5" and 1500 respectively)
 
If you are running while the sun is shining, the power from the panels will run across the batteries directly to the motors, so the motors will use all the power the panels produce.  The panels help keep your system voltage up.  You get better RMP's the higher the voltage.
 
I pause once an hour for about 10 minutes to allow the system to cool.
 
I might also note that the batteries have a C20 charge rating, meaning that they can only accept about 20 amps of charge before the voltages rise to the point the charge controller backs off from delivering solar panel output to the batteries.   But, you only get full charge from the panels a couple of hours a day.  (When the sun is at it's zenith or at right angles to the panels) so odds are you won't be exceeding this rating that often.
 
I can fully recharge my batteries in one day of sunshine.
 
I did have 30 pound thrust motors for one season.  It pushed the boat at a top speed of 2.8 –3.1 mph.  So fighting a 2mph current would pretty much suck the wind out of your day and range.  I would recommend having a gas outboard for supplemental power if you plan to travel anywhere a tidal shift or high winds would put you at a current disadvantage.
 
Thanks,
 
Ken Cooke
Kentucky River USA
 
 
 
Sent: Tuesday, January 17, 2017 11:04 AM
Subject: [Electric Boats] New to group, please evaluate my dual trolling motor setup
 
 
 
 
Hello to the group.   My name is Chris Curtis.  I'm building an obscure type of sailing muiltihull called a proa as a technology demonstration project.   Due to my Proas hull design there is a massive amount of available real estate to mount PV's.  Further the Proa has protuberances that will allow for drop down trolling motors on sleds.  This allows for electric power, steering and "spin" type of operations.
 
My current entry level plan is primarily dictated by my budget (2K).  I'll have each motor system have its own PV's (400w each), MPPT controller, and two T105's (220AH).  The motors will be standard saltwater 35lb thrust type.  Based on my painfully (likely wrong) rough calculations, in full sun I should get over 90 percent of current into the batteries (30A)  that the motor is pulling (about 35A).  What I'm looking for is the ability to run in full sun with very little battery assist.  On a sunny day I'd like to be able to take off in the ICW (or Abaco Sea) and go until the evening all on electrics without worrying about completely depleting the batteries.  If the project is successful, I'd like to add just a bit more and be able to run at full speed and still have enough power to charge the batteries.   For some perspective, the Proa is 30 feet long, has a 18 inch draft, all told is 20 feet wide and weigh's 3500LBS fully loaded in cruising mode.  The main hull is 32 inches wide at the waterline, 8 feet at the deck.  The small hull or outrigger is like a very large kayak. His (Proas are He's!) planned areas of use are the PNW and the Florida/Bahamas areas of the SE.  He is trailer-able at just over 2000lbs.
 
I created a folder called VolksProa Dual Electric Proa (or something like that).  If interested please take a look as its a hard boat to understand without a picture.  Please feel free to comment on my idea and plan.  I'm not expecting the world and I do have some experience living under PV (on a boat).  I'd prefer to go with a single system, higher voltage, better motors, etc but it does not fit with the design brief.  It must be a fairly low dollar affair.  Thanks for any time you give this.
 
Chris Curtis
 



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