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Old 30 October 2020, 06:27   #1
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Electric Auxiliary?

I'm thinking of buying a 55lb thrust electric auxiliary as backup motor. My thinking is it would be stored away and only mounted when needed, I'd probably have to extend the cable but connect it directly to the battery.

Are these credible? I'm only after displacement speed but how long/how far is realistic presuming the 110ah battery is fully charged before the main engine fails? Would it be able to overcome a 4 or 5 knot current?

Anyone else done this in preference to a small fixed petrol outboard?

Bonus: I could make a transom bracket and also use it on the kayak.
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Old 30 October 2020, 08:53   #2
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i had one wasn't impressed that was in the river sooner have a 2 hp two smoke OMO
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Old 30 October 2020, 08:59   #3
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>>>> Would it be able to overcome a 4 or 5 knot current?<<<<<
No. That's going to take more than 55lb static.
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Old 31 October 2020, 04:54   #4
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Via Google, 55lb thrust is about 2.5hp. Based on the 1hp per metre of length rule of thumb for auxillary outboards, I don't think it would be sufficient, particularly to achieve 5 or 6 knots.
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Old 31 October 2020, 05:35   #5
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You mention about being able to store it and then deploy it. In my experience you want an auxilliary on the transom ready to fire up. I've seen them attached to brackets in front of consoles, but I wonder if you have to use them in anger, then what?

I've got a Mariner 4hp on my Ribcraft 4.8m. I was looking for a Tohatsu 5hp, partly because they have narrow cowls for the main engine to turn. I think a 5hp can connect to main fuel supply too.

I think all these things will be electric in years to come, but right now my money is on technology that works.
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Old 31 October 2020, 07:49   #6
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Presumably one reason for a aux being needed would be loss of electrical power...

Most with petrol aux would have a can of clean fuel to at least let them limp to safety somewhere.

If the batter is flat. The main lump won't start. The radio won't work because the battery is flat. The best use for the electric aux will be on a rope as an anchor.
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Old 31 October 2020, 16:29   #7
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Quote:
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Presumably one reason for a aux being needed would be loss of electrical power...

Most with petrol aux would have a can of clean fuel to at least let them limp to safety somewhere.

If the batter is flat. The main lump won't start. The radio won't work because the battery is flat. The best use for the electric aux will be on a rope as an anchor.

I agree!....why add complexity a problem with a well proven remedy already.
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Old 31 October 2020, 19:42   #8
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Presumably one reason for a aux being needed would be loss of electrical power...

Most with petrol aux would have a can of clean fuel to at least let them limp to safety somewhere.

If the battery is flat. The main lump won't start. The radio won't work because the battery is flat. The best use for the electric aux will be on a rope as an anchor.
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I agree!....why add complexity a problem with a well proven remedy already.
Only have a handheld radio and if the loss of electrical power or main engine presumably the battery is fully charged and ready to go. Just attach the crocodile clips directly so you can't get much simpler.

However if the motor isn't up to it then it's a (pun) non-starter. Can't understand why the yachties have them if they are so crap.
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Old 01 November 2020, 03:41   #9
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If your battery was still ok you would be sitting there in the tide (assuming there was a tide) with your 55lb thrust motor spinning away getting no where until your battery went flat.

Small electric outboards are not much use if the water is flowing with any sort of power/speed
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Old 01 November 2020, 05:20   #10
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Can't understand why the yachties have them if they are so crap.

Iím guessing that theyíre useful for running the tender across to the harbour/pontoon/yacht club from the mooring. Saves having smelly cans of petrol aboard & the battery can be charged up from the yacht engine/solar/wind generator.
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Old 01 November 2020, 05:38   #11
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Only have a handheld radio and if the loss of electrical power or main engine presumably the battery is fully charged and ready to go. Just attach the crocodile clips directly so you can't get much simpler.

However if the motor isn't up to it then it's a (pun) non-starter. Can't understand why the yachties have them if they are so crap.
There are quite a few sub 3m tenders that come with a 2.5 hp outboard and as PD says they are just meant for going ashore / getting back to the boat. In this use, the electric equivalents are probably quite a good option - lighter, quieter and less messy than a petrol outboard. There is a price premium for this but I can certainly see the attraction
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Old 01 November 2020, 08:46   #12
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Electric outboard( trolling motors) seem to bring out some strong opinions, particularly against! I used a 55lb unit as my backup on my last boat. ( now have small sib, so no longer used).
Mine would push my 15ft cuddly cabin boat (approx 500kg) quitehappily in tidal waters, at about 3/3.5 knots . It was accepted that in a strong tide, it may well struggle, but I thought a small petrol would also. I canít remember its range, but at steady pace, would run 1.5 hours or so on 100ah battery, which I thought was good enough to get to shore, or even back to base, depending on distance and conditions. It is clean, requires almost nil maintenance, is easy to stow, deploy, and use, and is almost silent, making its use in areas of wildlife areas a revelation.
In the end, itís a personal choice, based on where you go boating, potential risk, and running/ maintenance costs.
With a good anchor, and handheld radio, I think it was a viable option in the appropriate environment.
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Old 02 November 2020, 11:46   #13
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Be aware that a lot of these elec motors are for fresh water use only
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Old 02 November 2020, 14:15   #14
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Good point Jeff. mine is salt water compatible, with anode, but you do need to check. Also, some come with battery state meter, which allows you to monitor available range. Some makes come with different shaft lengths too.
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Old 02 November 2020, 14:50   #15
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I've got a Torqeedo 1103 - it's designed to push heavy'ish boats along slowly. I didn't get much opportunity to try it out this summer, but on a calm lake it pushes the boat along at 4/5 knots. I found it difficult to steer using the elec outboard, so I'll try using the main engine as a rudder next time. I'm not convinced it has enough power to get home, maybe off the rocks...

I also need a transom aux engine mount to make it easier to use.
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Old 02 November 2020, 16:26   #16
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I've got a Torqeedo 1103 - it's designed to push heavy'ish boats along slowly. I didn't get much opportunity to try it out this summer, but on a calm lake it pushes the boat along at 4/5 knots. I found it difficult to steer using the elec outboard, so I'll try using the main engine as a rudder next time. I'm not convinced it has enough power to get home, maybe off the rocks...

I also need a transom aux engine mount to make it easier to use.
My aux is held in the "ahead" position with a stiff stainless spring onto the "A" frame and I steer with the main engine (trimmed well out). It does have a friction screw but I'm yet to find one of those that actually stops the engine turning. Can still move it for close in maneuvers if need be but ideal for shallow water where you don't want to risk an expensive prop...
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Old 24 November 2020, 03:45   #17
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I've got a Torqeedo 1103 - it's designed to push heavy'ish boats along slowly. I didn't get much opportunity to try it out this summer, but on a calm lake it pushes the boat along at 4/5 knots. I found it difficult to steer using the elec outboard, so I'll try using the main engine as a rudder next time. I'm not convinced it has enough power to get home, maybe off the rocks...

I also need a transom aux engine mount to make it easier to use.

I have a 25 foot alum Rhib with a 200 Etec. I enjoy heading out to investigate but often wonder what having the engine fail would look like. I considered a Torqeedo 1003 but don't know if It would actually push the boat. At 35 LBS it would be fast to hang off the transom, (if I kept the battery charged )

I wonder how large your boat is .. do you think a Torqeedo would move a 2 ton boat ?
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Old 24 November 2020, 06:21   #18
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I have a 25 foot alum Rhib with a 200 Etec. I enjoy heading out to investigate but often wonder what having the engine fail would look like. I considered a Torqeedo 1003 but don't know if It would actually push the boat. At 35 LBS it would be fast to hang off the transom, (if I kept the battery charged )

I wonder how large your boat is .. do you think a Torqeedo would move a 2 ton boat ?
Hi Rick,
The 1103 is rated to push a boat upto 1.5T (mine is a little less than this) and I operate in an area with small tidal flow (c 2M) and I have pretty low expectations about what progress I'll make when using it.

My view is that the 1103 is not not adequate to push a 2T boat.
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Old 23 January 2021, 21:56   #19
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Would appreciate opinions on the 3hp/8kg aux motor below:

55lb/2.5hp electric motors are about 12kg so this is about the same price, lighter and more powerful. Nice simple 2 stroke.

Edit: I found a cheaper 5hp/12kg version.
It's a garden strimmer lol. Disposable at this price. Not bothered about the noise for emergency use.
Also a 4 stroke 4hp/13kg:
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Old 24 January 2021, 13:30   #20
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Quote:
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Would appreciate opinions on the 3hp/8kg aux motor below:

55lb/2.5hp electric motors are about 12kg so this is about the same price, lighter and more powerful. Nice simple 2 stroke.

Edit: I found a cheaper 5hp/12kg version.
It's a garden strimmer lol. Disposable at this price. Not bothered about the noise for emergency use.
Also a 4 stroke 4hp/13kg:
I wouldnt give any of those engines house room (or boat room) I'd rather a 20 year old yam merc tohatsu etc 2-3.5hp lightweight
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