I would second Phil's findings about exponential increases in power demand for linear increases in speed, even below the max "hull speed" of the boat. You can achieve higher than hull speeds for a little while, but not with an off the shelf trolling motor.
I have settled on 5 mph with the 17 foot canoe and about 4 mph with a 26 foot retrofitted sailboat.
Going down stream with the current is great fun, all day (0830 - 1700 on a sunny day at 37 degrees Lat) putter back upstream with the gas outboard (Yes, that is cheating).
RE: Mounting the Airplane Props: The 10X4 P LH Prop from APC comes with a slot for the trolling motor sheer pin. I use a 3/8" X 3/8" X 1" Nylon barrel spacer (white) from Home Depot to fill the gap between the shaft nut and the prop,
For other props that don't have the slot, I melt a slot in the hub by heating a sheer pin on a spindle with a blow torch then pressing it down to the desired depth. I tried some composite fiberglass props and ground the sheer pin slot with a Dremel tool, but the speed/efficiency performance of those props didn't improve on what the plastic !0X4 P-LH gave me.
Trick is to get everything centered and the slot of equal depth if you are grinding your own sheer pin slot and drilling out the shaft hole.
Trick is to get everything centered and the slot of equal depth if you are grinding your own sheer pin slot and drilling out the shaft hole.
Final note, these RC Airplane props don't fare so well in weedy waters. Part of the trolling motor stock prop design is to reduce weed tangles. These RC props will wind weeds like linguini.
Ken Cooke
Lexington, KY USA
On Fri, Jan 24, 2020 at 9:16 PM Phil Boyer via Groups.Io <philaboyer=yahoo.ca@groups.io> wrote:
Hi there, I don't think I have posted before so I thought I would post with my thoughts on solar electric boats which I have one of. It is a 18' wood strip based on an old design from the last century called a "Disappearing Propeller boat".My experience with my solar electric boat has been that solar electric powered boats make perfect sense if you want to go more on the slow side such as 6 m/hr (10km'hr). I have found the optimal speed for my boat is 5m/hr (8 km/hr) but my boat design is a displacement hull with a hull speed of about 6.8 m/hr (11 km/hr). As I start to increase the speed from slow to fast the current draw goes up exponentially. If I maintain my cruising speed of 5 m/hr I can travel all day if it is sunny. I have a Torqeedo 2.0 Cruise motor, 221 amp hr battery bank (lead acid golf cart batteries) and 860 watts of flexible solar panels on the canopy. I can travel for 8 hours, stop for the night and while I am stopped the batteries keep charging so in the morning I am at least in the 95% state of charge. If I have a cloudy day I simply reduce my speed and I will draw exponentially less power. I have used this management of battery power for some major trips, one of which I was out for 16 days and solely relied on solar power. I am now building a catamaran 18' long and the plan is to power it by a 20HP motor. I am thinking of an Elco which is just under 9KW. For this configuration I would be into a very large battery bank minimum 16 KW and I could put 1800 watts of solar power to assist. But the solar production for this arrangement would no longer do very much and to recharge the bank would take a couple of days at least. So my thinking is still cruise at a slow speed perhaps 7.5 to 8.5 m/hr (12 to 14 km/hr) but have the option to go fast when required. It all will come down to battery management.Here is a link to my channel where I have documented my trips.RegardsPhil
Hi there, my experience with my solar electric boat has been that solar electric powered boats make perfect sense if you want to go more on the slow side such as 6 m/hr (10km'hr). I have found the optimal speed for my boat is 5m/hr (8 km/hr) but my boat design is a displacement hull with a hull speed of about 6.8 m/hr (11 km/hr). As I start to increase the speed from slow to fast the current draw goes up exponentially. If I maintain my cruising speed of 5 m/hr I can travel all day if it is sunny. I have a Torqeedo 2.0 Cruise motor, 221 amp hr battery bank (lead acid golf cart batteries) and 860 watts of flexible solar panels on the canopy. I can travel for 8 hours, stop for the night and while I am stopped the batteries keep charging so in the morning I am at least in the 95% state of charge. If I have a cloudy day I simply reduce my speed and I will draw exponentially less power. I have used this management of battery power for some major trips, one of which I was out for 16 days and solely relied on solar power. I am now building a catamaran 18' long and the plan is to power it by a 20HP motor. I am thinking of an Elco which is just under 9KW. For this configuration I would be into a very large battery bank minimum 16 KW and I could put 1800 watts of solar power to assist. But the solar production for this arrangement would no longer do very much and to recharge the bank would take a couple of days at least. So my thinking is still cruise at a slow speed perhaps 7.5 to 8.5 m/hr (12 to 14 km/hr) but have the option to go fast when required. It all will come down to battery management.Here is a link to my channel where I have documented my trips.RegardsPhil
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