Electric Drive on American Mariner 24
Slippery When Wet
Using "Amps" instead of Horsies since 2002, and not lookin' back June/2006
A few years back I was impressed when I saw a "dock maintainance barge" tooling around the cove in our Marina under the power of a little 12 volt trolling motor. It was small, old, but the persistance of the little thing moved the barge around quite well. I proceeded down to my boat, and embarked on the following procedure to go sailing.
Gentlemen, start your engines!
- Open the cockpit locker and remove 5 gallon gas can.
- Hook hose to 7.5 Merc. stored in the "UP" position.
- Pump the pressure bulb 5 or 6 times.
- Pin my head under the stern pulpit (for leverage) and lower the Merc. into the water.
- Extract my head from under the stern pulpit, and yank the pullstart rope on the motor.
- Yank a 2nd time...
- Yank a 3rd time...
- Yank a 4th time... Motor starts and dies...
- Yank a 5th and successful time...
- Adjust choke and gun the engine...
- Await a steady idle...
- 2 more pumps on pressure bulb for insurance against stalling...
- I'm ready to back out of my slip!
So, I started thinking about a quieter, easier, cleaner and quicker way to get in, out, and around the marina area where I usually use the outboard. A quick review of electric outboards wasn't in my interests because of the high price of a real, bonified electric outboard motor. They suffer from high price, many are "butt(Y)ugly", and some just look like an outboard with the engine removed and electric motor put in its place.
| The following link, however, is an exception. These guys have it together, and if I had the bucks, I'd go for this one. If your bothering to read this at all, you should follow the link for a look. Re-e-power.com. I saw them at the 2009 Strictly Sail boat show in Chicago. The industry has come a long way since I bought my Mororguide.. |
Thrust level was an important issue, so I found the most powerful transom mount trolling motor in a MotorGuide ET107V. Its capable of 107 lbs. of thrust, and offers far more efficient "reverse" power than my old Merc was capable of. I lost about 1 mph in forward max speed, but gain reverse power beyond my wildest dream. Backing out of the slip is quick, powerful, and silent; with the Merc, it was slow, underpowered, and turned heads because of the screaming engine.
Slippery When Wet...4600 lb's. displacement
| Max Forward with Electric motor | 4.7 mph |
| Max Forward with Merc 7.5 motor | 6 mph |
| Reverse Power | NO COMPARISON
..advantage electric.. |
A Few Details...update on 6/2006
I had to make a few changes. I had used a ChargeTek charger for the last 4 years. Good company, very responsive to my problems. The problem is, I had problems. The first generation was known to overcharge, so they replaced it free. Of course, it overcharged my batteries, boiling them dry. The second unit failed in the same manner, so did the third. They had no explanation, and offered a 4th unit for a $100 exchange. I felt it was time to move on to another brand, which brought me to the Dual Pro line of chargers.
I'm a layman, but I can tell you the logic behind the Dual Pro makes more sense to me. It charges the batteries, then shuts off the charging circuit. This allows the batteries to rest. If self discharge takes them below about 12.6, then the charger, which is monitoring the batteries full time, will kick back on and charge that battery back to full power, and then, shut off the charging mode again. I've never found my batteries below 12.6. IN CONTRAST, the Chargetek runs them up to around 13.5 volts, and holds them there full time. I feel this "logic" is behind the overcharging and eventural failure of the charger itself. The Dual Pro keeps things charged, but not peeked, and the charger is always "barely warm" as it monitors the battery status.
I have not yet performed a time test (4-30-2002), but will do so soon...Well, it's June of 2006 and I really haven't run that test yet. HOWEVER, I have motored around as much as any sailor does for, this is my 5th season, and I've never depleated the charge below 80% of full capacity. Like all sailors, I generally just motor out, set the sails and go. I don't need the motor again until I sail close to the marina, and motor back in. But on occasion, when the air is light, I'll motor sail at a slow rate of around 20 to 25 amps. This gives me just a little kick and keeps me moving. (Sure is quiet) I've done this for an hour or so, and gives the reason I've seen 20% depletion from time to time. Generally, I come back in with 95% or better still in the batteries.
NOTE: There is no neat formula or correlation between thrust and horsepower. However, I read a comparison that measured a 6 hp gas outboard produced just over 130 lbs of thrust, so that would class the 107 Motorguide in the realm of a 5 hp gas (give or take a little). Thats not a lot of power, but ample for my needs. I don't know how I'd fare towing in another boat, but I'll include towing in "tests to come".UPDATE: June/2006 I have towed twice. It works great. I was a little slower, but we motored in just fine.
 | Batteries now rest on cabin floor in the step-down keel. |
 | Batteries nest neatly in the step-down keel.
The cover offers a good place to sit or step.. |
 | Dual Pro 3 bank Charger |
Pro's and Con's...
I'm giving up some power in "forward", resulting in a slight loss of speed and probably towing power for another boat.
What I'm gaining is Quiet, instant power, and, finally, real power in reverse for stopping power when coming into the slip or approaching another craft. Since I always plug into shore power, I've always got a full "tank", and have no hassles with fuel, concerns of motor failure at a critical moment, no oil slicks, smoke, noise and motor starting antics.
I've never run my gas engine for more than 45 minutes, and almost never run it for more than 20 minutes, including going out and coming back in.
I can't imagine that the shortfalls of the electric over gas will give me any grief. Of course, I'm not selling the Merc. just yet.