Re: [electricboats] Pocket Trawler Electrification

Where you will find your configuration wanting is scenarios where you need to stern to move port or starboard to get away from or come towards something like a dock.  You can drive both pods full speed in opposite directions and all that will do is torque the boat, pointing the front of the boat into or away from the dock.  So the only thing you really have that might work in that scenario to get the stern to swing in is that bow thruster opposing that torque which would have the net effect of pushing the stern in.  Without that bow thruster, may as well throw a line to someone on the dock.

So yes, that bow thruster is an essential part of your plan.

 

From: electricboats@groups.io <electricboats@groups.io> On Behalf Of maaseidvaag via groups.io
Sent: Saturday, January 31, 2026 12:40 PM
To: electricboats@groups.io
Subject: Re: [electricboats] Pocket Trawler Electrification

 

Thanks all for all the feedback and insight.

 

The pods are completely independent of each other with their own controls, motor controller, etc., and can be run with differential thrust.  A failure of any component in one drive won't impact the other, so I should have get-home capabilities.  They will share three batteries that will typically run in parallel with each other but will be able to be isolated if needed.

 

As to low-speed maneuverability, I will have the differential thrust of the two pods and the front mounted Vetus bow thruster which I believe is rated at about 3000 watts.  It's the smallest they make.  Anything longer than a half second blip of the joystick sends the bow sideways in a hurry.

 

Currently, reverse rudder authority is basically zero, with a pronounced prop-walk of the stern to port.  With the new pods I'll should no longer have any prop-walk and can use either differential thrust or the bow thruster to get the boat pointing where I want it.

 

I don't think rudder authority going forward will be an issue either.  I've inserted a very rough image of the anticipated arrangement of the pods versus the existing prop indicated by the red lines.  I will fair the aft end of the full keel to both seal up the shaft log (that will remain embedded in the keel) and smooth the water flow off the trailing edge of the keel.  I'll mount the pods as tight as I can to the centerline, which should put their wash down each side of the existing rudder.  Currently thinking about 4" of clearance between the prop tip and the keel, which is the same as the minimum distance from the top of the prop to the bottom of the hull.

 

As always, all ideas and advice are greatly appreciated.

 

Lars

 

For reference, the current prop in red is 17"x12", and the pod props are 12.5" x 8.3"

 

Actual picture of existing prop and rudder are the second image

 

Re: [electricboats] Pocket Trawler Electrification

Agree for large ships however these are 6kw not over 100kw. The boat is 10m or less not ten times thst.

I could see steering through differential thrust first off. Standard for catamarans. Spining the boat on its axis almost. At low speeds the rudders have low to no effect. If you want rudder effect from prop wash I assume the prop and rudder must be close to each other and indeed  that is what shown in ship design texts. Especially close with fishtail rudder types.

i am now starting to see the situation. Pods fixed underneath. No additional skeg to protect them and their props. Hmmm that sounds like a lot of care needs to happen to not hit one or more props. Even aluminium props get mangled blades.

I looked at pod drives but always had a method to lift them up. Indeed steer them. I sail shallow waters and my draft is 250mm which is a lot less than a pod.

Best regards

Lee Eldridge

0427874796

On 1 Feb 2026, at 21:52, Carsten via groups.io <Carstensemail=yahoo.com@groups.io> wrote:



Hi Lars,

Did you get the point, that fixed pod needs a separate rudder for each engine ?

I worked with big tankers for the Potomac River 24 years ago, in Hyundai Shipyard, Korea.

Dual engines, with 70 meters, hull 280 meters, fixed engines running both ways.

Rudders in the flow of the prop stream.

(Means two rudders).

Make your own design in a proper way.

Just an input...

Carsten

On Friday, 30 January 2026 at 22:25:47 CET, maaseidvaag via groups.io <maaseidvaag=yahoo.com@groups.io> wrote:

Hi Carsten & Paul,

 

Yes, fixed pods mounted so the props are in the same vertical plane as the current prop.  The side-mount controls just refer to the controls that came "free" with the purchase, as opposed to the top-mount dual control.  The dual control would be ideal I guess, but it does provide a single point of failure in a system that otherwise provides complete separation and redundancy.  The image below is near-enough to scale showing where the pods will hang on the hull.  My plan is to tuck them in as tight as reasonable against the full keel to 1) help protect them from striking anything, and 2) to keep the prop wash as close as possible to the single rudder that will remain.  I'm not worried about low-speed maneuverability as the boat does have a bow thruster.

 

Inside the hull above the pod mounting locations I will laminate in watertight bulkheads and covers to protect against flooding should I ever tear a pod clean off the hull.  Highly unlikely in the Great Lakes with a boat that draws 2.5', but easy enough to do and I'll be adding thickness on the inside of the hull where the pods mount, so a few more pieces while the epoxy is mixed won't be much trouble.

 

Lars

 

 

<mceclip0.png>

Re: [electricboats] Pocket Trawler Electrification

Hi Lars,

Did you get the point, that fixed pod needs a separate rudder for each engine ?

I worked with big tankers for the Potomac River 24 years ago, in Hyundai Shipyard, Korea.

Dual engines, with 70 meters, hull 280 meters, fixed engines running both ways.

Rudders in the flow of the prop stream.

(Means two rudders).

Make your own design in a proper way.

Just an input...

Carsten

On Friday, 30 January 2026 at 22:25:47 CET, maaseidvaag via groups.io <maaseidvaag=yahoo.com@groups.io> wrote:

Hi Carsten & Paul,

 

Yes, fixed pods mounted so the props are in the same vertical plane as the current prop.  The side-mount controls just refer to the controls that came "free" with the purchase, as opposed to the top-mount dual control.  The dual control would be ideal I guess, but it does provide a single point of failure in a system that otherwise provides complete separation and redundancy.  The image below is near-enough to scale showing where the pods will hang on the hull.  My plan is to tuck them in as tight as reasonable against the full keel to 1) help protect them from striking anything, and 2) to keep the prop wash as close as possible to the single rudder that will remain.  I'm not worried about low-speed maneuverability as the boat does have a bow thruster.

 

Inside the hull above the pod mounting locations I will laminate in watertight bulkheads and covers to protect against flooding should I ever tear a pod clean off the hull.  Highly unlikely in the Great Lakes with a boat that draws 2.5', but easy enough to do and I'll be adding thickness on the inside of the hull where the pods mount, so a few more pieces while the epoxy is mixed won't be much trouble.

 

Lars

 

 

Re: [electricboats] Pocket Trawler Electrification

Again great feedback. 

Agree having rudder in prop wash is not beneficial for regular rudders (multiple references for this conclusion). However for fishtail type rudder used on really slow boats (barge and canal type boats), having prop wash adds a huge facility, reminiscent of bow thrusters.

In general it appears that props in "clean" water work better. Assume suitable depth and distance from hull.

I am now seeing 90 degree turns being possible in a sailing boat length. I have played with my rudder either going straight down and laying out aft. The latter provides huge steerage at low speeds - enough to highly stress the tiller when in reverse.

Best Regards

Lee@vombatus.com.au
0427874796

On 1 Feb 2026, at 7:27 am, maaseidvaag via groups.io <maaseidvaag=yahoo.com@groups.io> wrote:

Hi Matt - I did test steerage this last season with having the boat at cruising speed, going into neutral, and then applying vary degrees of turn on the wheel.  I didn't perceive any dramatic loss of control and could still do a complete 360 degree circle while coasting in neutral, probably in about 3 boat lengths by the (very slow) end of the circle.  With power on I can do the circle inside 2 boat lengths.

 

One hypothesis that will remain just a hypothesis is that straight ahead cruising might slightly benefit from not having the rudder directly in the prop wash.  Probably not an experiment that has been run, but maybe?  

 

Thanks for the feedback,

Lars

Re: [electricboats] Pocket Trawler Electrification

Thanks for the link.  I will configure them as outturning and call it good.

 

Tiny Boat Nation did confirm that I need to send my control and display back to be programmed for reverse rotation.  No charge other than shipping, and they have the LH prop in stock despite it being missing from the website.

 

Thanks - Lars

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Re: [electricboats] Pocket Trawler Electrification

Hi Matt - I did test steerage this last season with having the boat at cruising speed, going into neutral, and then applying vary degrees of turn on the wheel.  I didn't perceive any dramatic loss of control and could still do a complete 360 degree circle while coasting in neutral, probably in about 3 boat lengths by the (very slow) end of the circle.  With power on I can do the circle inside 2 boat lengths.

 

One hypothesis that will remain just a hypothesis is that straight ahead cruising might slightly benefit from not having the rudder directly in the prop wash.  Probably not an experiment that has been run, but maybe?  

 

Thanks for the feedback,

Lars

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Re: [electricboats] Pocket Trawler Electrification

Thanks all for all the feedback and insight.

 

The pods are completely independent of each other with their own controls, motor controller, etc., and can be run with differential thrust.  A failure of any component in one drive won't impact the other, so I should have get-home capabilities.  They will share three batteries that will typically run in parallel with each other but will be able to be isolated if needed.

 

As to low-speed maneuverability, I will have the differential thrust of the two pods and the front mounted Vetus bow thruster which I believe is rated at about 3000 watts.  It's the smallest they make.  Anything longer than a half second blip of the joystick sends the bow sideways in a hurry.

 

Currently, reverse rudder authority is basically zero, with a pronounced prop-walk of the stern to port.  With the new pods I'll should no longer have any prop-walk and can use either differential thrust or the bow thruster to get the boat pointing where I want it.

 

I don't think rudder authority going forward will be an issue either.  I've inserted a very rough image of the anticipated arrangement of the pods versus the existing prop indicated by the red lines.  I will fair the aft end of the full keel to both seal up the shaft log (that will remain embedded in the keel) and smooth the water flow off the trailing edge of the keel.  I'll mount the pods as tight as I can to the centerline, which should put their wash down each side of the existing rudder.  Currently thinking about 4" of clearance between the prop tip and the keel, which is the same as the minimum distance from the top of the prop to the bottom of the hull.

 

As always, all ideas and advice are greatly appreciated.

 

Lars

 

For reference, the current prop in red is 17"x12", and the pod props are 12.5" x 8.3"

 

Actual picture of existing prop and rudder are the second image