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Travel 1103 Torqeedo electric motor do I need the long shaft or is the short enough?


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Im going to be using this motor and batteries and solar panel charger for my travels on the  south west coast of Florida island

sailing shallow waters and electric when I want it. Down the south west coast of Florida exploring. Will be posting on my Youtube Channel. Getting things ready for this year after winter.

 

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I found this on the Torqeedo web site. Please don't ask me what it says.

 

To what depth must the propeller be immersed under water?

The immersion depth of a propeller has a major influence on the efficiency of the drive. Measurements performed by Torqeedo have revealed differences of up to 10 % in overall efficiency, of up to 20 % in range and of up to 5 % in top speed depending on the immersion depth of the propeller.

The reason for the significant influence of the immersion depth of the propeller can be found in the importance of the boat's wake for the propeller. Generally speaking, propellers can achieve optimum levels of efficiency when they make best use of the boat's wake. The best position for this varies from boat to boat. A propeller usually achieves very good levels of efficiency at extremely slight immersion depths (as close to the water's surface as possible but deep enough to avoid drawing air). The general rule of thumb is that the top of the propeller should be 3-5 cm below the bottom of the boat. Irrespective of this, we recommend determining an efficient depth of immersion through trial and error. The easiest way to do this is to determine the maximum speed for various depths of immersion using our GPS-based on-board computer.

 

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What boat? I worked super hard to do exactly what Captain Tim says above on my Coresound 20.3 and it was perfect for a bit, until the first time I went forward under power the prop came half out of the water.  If anyone needs a Suzuki 2.5 short shaft I still have it. Less than 20 minutes of use! Replaced it with a long shaft and all is well. 

 

In short, think it completely through! 

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Also believe hull rocker, trim underway, and expected sea conditions need to be considered to ensure prop is consistently under water.  That's why I like electric trolling motors with adjustable depth. Also read once that an outboard prop (gas) running too deep can put extra stress on the transom. Sounds like a fun adventure coming up musicmanx. Just thoughts, R  

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@musicmanx2— first of all, you can buy a lot of “expensive fuel” for what they charge for one of those Torqueedos.  But never mind that.

 

@Alan Stewart, (part owner of B and B ) put somebody’s Torq on the transom of his CS17 at the last Messabout.  It flew like the wind!  Hopefully, he’ll tell us here if it was long or short.

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The short shaft is about 24.5 inches (62.5 centimeters).  The long shaft is a bit over 29 inches (75 centimeters).

 

One thing to evaluate is whether you whip out the motor in gnarly conditions--I know I sometimes do, especially to windward.  In those instances of higher seas, your motor will be more prone to cavitate as the boat rocks.  Small boats don't have a lot of inertia, so there's a chance you get nearly stuck in the waves as the prop cavitates out and you lose momentum.  It's frustrating, and a little scary, to have the system failing (somewhat) just when you need it most.

 

I personally would take the hit on efficiency/range and go for the deeper prop if you are in between sizes.

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I have a 2.5 Suzuki on my Bay River Skiff.  It has a short shaft.  I had to notch the transom, to get it down far enough.  (I’d put an outboard bracket on my transom, if I had  it to do over.)  I did notice that if it is in neutral and idling, and I go forward to furl the main, the transom lifts out of the water enough to suck air into the cooling system.  This is an indication that the long shaft might be better. 


I think @Joe Anderson just bought a Torqueedo for his EC 22 last year.  Maybe he’ll chime in.  
 

I’ll have my Suzi with me, when I come to Sarasota in March.  Maybe we can play with it on yours, to get a feel for shaft length.

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I used a long shaft Honda air cooled 2HP motor on my CS17, and never had any issues with cavitation. Previously I had used a Minn Kota RT55 long shaft, which was great, but the 100AH battery that I used weighed over 30KG, and that was mounted in the aft locker, making the stern pretty much always sit in the water. I changed over to the Honda because of the weight, and the ability to top up the motor while out on the water...

Peter

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I’ve tried my Minnkota 35, with the battery mounted in the center of the boat in the bilge.  I wasn’t impressed with the performance.  I do know that the Torqueedo’s prop and thrust provide much more power and speed.  

 

For me, it’s a matter of economics.  My Suzuki 2.5 cost less than $1,000, and $5 worth of gasoline goes a very long way.  No chance of running out of fuel on a becalmed day (famous last words).  If I’m cruising with a Torqueedo, and need it recharged, I’d be forced to plug in somewhere.  If I add solar panels to the boat to eliminate that, how much gasoline could that have boughten with my solar panel money?  I know everybody’s going green, but I need to be practical.  And electricity is made from coal in the USA— not exactly green.  If this sounds like a rant, I apologize.  I’m mainly trying to provide another perspective to the Torqueedo trend.  I guess I need another cup of coffee.

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Hirilonde, I get all that and you don't need to apologize for presenting economic and energy facts.  What excites me most about an electric motor is the quiet!

 

Torqueedo is still expensive for something that is less power and runs the risk of leaving you stalled.  I wish there were more competitors, but the ones I've looked at seem to have zero to little distribution networks set up, and it's frankly confusing on how I would purchase one if I wanted to.  Hopefully some of these competitors can get better organized so there is price competition.

 

Of course, I could always row, but that's not quiet due to the muttering, panting, and complaining coming from the rower!

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I have a Suzuki long shaft 2.5 on Skeena for all the economic reasons presented. I also run a 50w solar panel that runs the ballast water pump, charges my phone and for nav and anchor lights.

 

But I run my house (heat and ac plus everything else), one of my cars on 13kw Solar. I am on track for an $80,000 dollar ROI over it's lifespan. The times they are a changing. I am hopeful to someday run my boat on solar charged by the sun. The quiet instant power of electric is hard to beat. My ICE car feels like the flintstone mobile (google it kids) when I drive it.  

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