Hi Will,
A few years ago I purchased a 12v, 55lb thrust minnkota transom mount trying motor for use with my m17 on a lake that didn't allow gas engines.
Like others, I found it powerful enough for only benign conditions. I grew to distrust its ability to power through heavier wind and waves. Nowadays I just use the sails as I feel more comfortable with sick and mooring approaches in force 5 or 6 under sail than I did with the troller. And if you can't trust it, what's the point?
I did once use it on mille lacs, a 130,000 acre shallow choppy lake, to get out of a marina and into the lake, and I guess it worked, but I also was going maybe 50° into the wind and raised the sails as soon as I could. Since then I've considered the power it provides too low for any serious duties.
If I were to repower with electric I'd look closely at a 24v, 100+ lb thrust model, but even that I fear just isn't made for aux work. For now I intend to use the old 6 horse Johnson on any water requiring auxiliary power. If I can only get it running again that is...
Dan Farrell
M17 #301
Wilson Frye <fryewe(a)mac.com> wrote:
>All,
>
>Will any M17 owner who has used a trolling motor as auxiliary propulsion for leaving and approaching the dock, and for short term auxiliary propulsion when winds are light, share what you may have learned from the experience?
>
>I have a 6hp Tohatsu SailPro. It drives the boat at hull speed in benign conditions with very little throttle (perhaps quarter throttle). it sips fuel. It has a 6 amp alternator that is advertised as capability for recharging batteries.
>
>Fact is, the alternator is inadequate for battery charging. We will be cruising with a 50 quart Dometic refrigerator this year, and as a result we’ll be taking a 1000EUi Honda generator and a Noco Genius 26000 (26 amp capability…@14VDC that’s 364W) along to charge the 200AH of deep cycle batteries to keep them near topped up from day to day.
>
>Today it occurred to me that if my 45 pound thrust 12V trolling motor will push the boat at a reasonable speed when needed, why not leave the Tohatsu at home?
>
>Here’s my thinking…
> - The outboard uses about a half gallon an hour at 6K RPM…about 5 knots under good conditions.
> - The generator’s 0.6 gallon tank will run the generator at full load for 7 hours.
> - Useful energy in the batteries is about 40 percent of capacity to avoid discharge below 50 percent…which is about 80AH.
> - The battery charger will provide up to 26A when bulk charging the battery if it is significantly discharged.
> - The trolling motor will draw 40A if run at position 5 (maximum speed), 32A at position 4, and about 24A on position 3.
> - The Dometic draws about 3A when running to maintain temperature, after cooled down, and it’s duty cycle is likely to be about 40-50 percent of the time while cruising in summer in the Gulf.
> - The Honda generator is quieter than the Tohatsu.
> - The outboard is a heavy load on the transom when not in use.
> - Solar panels are not mounted and are stored when underway.
> - On days when the wind is unreliable, on the trolling motor we can move about 20 miles (assume 3.5 knots) in 6 hours. If we run the generator long enough to bulk re-charge the batteries for their overnight use, about an hour, before getting underway, then the charger should be able to complete the absorption phase of charging during the six hours of re-positioning (is the assumption that the charger will provide 20A to the trolling motor while charging the battery a good one?)
>
>And the overall effect will be that I will use about a third of the fuel using the generator and charger and trolling motor in this fashion, rather than the Tohatsu. And be able to keep the batteries charged efficiently without running the generator for extended time at anchorage on days that we move to a new location (solar will be used if at anchor all day), and be able to leave that heavy outboard off the transom.
>
>Thanks for any comments on the feasibility of doing this…
>
>Will
