IMO electric remains usable for entry and exit of harbor. Even with smaller batteries with greater storage capacity (maybe one day having enough capacity for a day of motoring - full day of no wind is common on the Salish Sea, in addition to the current against you half the time +) the issue for a cruiser remains recharge - unless you stop at a marina that has 120v and you stay long enough to fully charge you are stuck. Solar on a 15' and 17' boat will be limited by deck space so full recharge is counted in days. More ocean crossing sailors are converting to solar when their inboard diesel dies. These folks don't like to motor. These electric ocean crossers have solar but have simple low power draw electric systems as they cant run a generator/motor for four hours a day. So they use the electric motor getting out of harbor and have the crossing to recharge - multiple days or weeks of time. There are also a small number of day sailors that convert to solar - but they don't cruise, just go out of harbor, sail, come back in. There are a few high-end 20-30' daysailors (that big and they call them daysailors!) that are being manufactured with electric. I also believe that ComPac has made a couple of custom order sub-20' electric onboard catboats. I sold some Sage 17s with Torqeedos - in all cases boat was for daysailing and on a lake. :: Dave Scobie :: M6'8" #650 :: SV SWALLOW - sv-swallow.com :: former owner M17 #375 SWEET PEA - m17-375.com :: former owner M15 #288 SCRED - www.freewebs.com/m15-named-scred/ On Thu, Oct 15, 2020, 9:30 AM John Schinnerer via montgomery_boats < montgomery_boats@mailman.xmission.com> wrote:
The specs for that trolling motor say minimum draw 9 amps, max draw 20 amps.
So with your little 11 amp-hour battery, you'll get maybe an hour at minimum draw, and half an hour or less at max draw. Some basic electrical math:
11 AH divided by 9 A = 1.2 H.
Please don't head out on a 5 hour tour (or even a "3 hour tour" :-) without other means to get back if the wind dies...at medium draw (15A) you'll get about 40 minutes of runtime at best.
You can get a 50AH or 60AH or more lithium battery, and it will be much lighter than same capacity lead-acid, but it will also lighten your wallet by a whole lot more.
cheers, John
On 10/15/20 9:09 AM, casioqv@usermail.com wrote:
I've been playing with using a 12V trolling motor on my M15 along with a cheap "Golf Cart Voltage Converter" to use a 48v electric bike battery pack with the trolling motor. It seems to work very well so far, but doesn't have quite the thrust of a gas outboard... good enough for exiting the marina, but not for motoring into a chop. The weight and runtime is comparable to a Torqueedo but at a tiny fraction of the cost. I've never ran it empty, but I suspect I can motor for 5-6 hours on the battery at about 3 knots.
Here's what I have: -DPLANET 30A 360W 12v Golf Cart 48V 36V to 12V Converter ($35 on Amazon) -Watersnake T24 ASP Saltwater trolling motor - designed for Kayaks ($150 on Amazon) -2017 Rad City Battery Pack 48V, 11.6 Ah (557 Wh) (from my eBike, but $399 new)
Total weight of this setup is 14.1 lbs with 7.4lbs for the battery, and 6.7lbs for the motor (converter is small and negligible). This is comparable to the lightest gas outboard I think has ever been sold- the 1.5hp Cruise'N'Carry at 12lbs. I used to have a Cruise'N'Carry, and found it to be cheaply made and extremely loud, so not really viable.
A big 24v 80lb thrust trolling motor would probably push the M15 at near hull speed and into a chop, but would be much much heavier than a comparable gas outboard, and requires dual large heavy batteries.
Sincerely, Tyler '81 M15 #157 S/V Defiant
----- Original Message ----- From: "Rimantas Aukstuolis" <raukstuolis1@gmail.com> To: "For and about Montgomery Sailboats" < montgomery_boats@mailman.xmission.com> Sent: Thursday, October 15, 2020 8:18:41 AM Subject: Re: M_Boats: changing Honda 2/2.3 prop
What about those electric trolling motors? Hard to figure out thrust/power/torque comparisons. What little I know, comparing them to expensive Torquedo is that they use bulky 12 volt batteries vs lithium. Any thoughts? Rimas Aukstuolis