Difference between revisions of "Rudder"

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The text already contains a lot of good technical detail, it mostly needed cleanup for readability, grammar, and consistency. I kept the tone technical and informal enough that it still reads like internal team documentation rather than something heavily polished.
= Propulsion System History and Overview =
 
[[File:Roer_2025.png|thumb|300px|2022 Rudder]]
---
 
# Propulsion System History and Overview


The main propulsion system is housed inside the rudder. The rudder is mounted at the rear of the boat, approximately 440 mm from the stern. Over the years several different versions of the propulsion system have been developed. A brief overview of the previous systems is given below.
The main propulsion system is housed inside the rudder. The rudder is mounted at the rear of the boat, approximately 440 mm from the stern. Over the years several different versions of the propulsion system have been developed. A brief overview of the previous systems is given below.


## 2022 – 2025: Underwater Mounted Inrunner
== 2022 – 2025: Underwater Mounted Inrunner ==


This system consisted of a carbon-fiber-wrapped 3D-printed rudder design. The rudder was mounted to the boat using a carbon fiber tube attached through a so-called “well”. The well itself was made using a slightly larger carbon fiber tube integrated into the hull structure.
This system consisted of a carbon-fiber-wrapped 3D-printed rudder design. The rudder was mounted to the boat using a carbon fiber tube attached through a so-called “well”. The well itself was made using a slightly larger carbon fiber tube integrated into the hull structure.
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Although the system performed well initially, it was ultimately scrapped due to continuous water ingress into the motor tube. The resulting corrosion of the gearbox and motor caused repeated failures and required frequent replacement of expensive components.
Although the system performed well initially, it was ultimately scrapped due to continuous water ingress into the motor tube. The resulting corrosion of the gearbox and motor caused repeated failures and required frequent replacement of expensive components.


---


## 2025: Mini Rudder V1
 
== 2025: Mini Rudder V1 ==


During the 2025 season a temporary drivetrain was constructed using a Flipsky 65111 waterproof inrunner motor. This system was designed as a backup solution for the heavily troubled main drivetrain and was used during the 2025 Amsterdam Solarboat Race.
During the 2025 season a temporary drivetrain was constructed using a Flipsky 65111 waterproof inrunner motor. This system was designed as a backup solution for the heavily troubled main drivetrain and was used during the 2025 Amsterdam Solarboat Race.
Line 29: Line 26:
The rudder featured a carbon-fiber-reinforced 3D-printed body and focused mainly on reliability and ease of deployment rather than outright performance.
The rudder featured a carbon-fiber-reinforced 3D-printed body and focused mainly on reliability and ease of deployment rather than outright performance.


---
[[File:Miniroer_v1.png|thumb|300px|Mini rudder V1]]


# Development of the New Propulsion Platform
= Development of the New Propulsion Platform =


Following the 2025 season, development started on a completely new propulsion platform. The main design goals of the new system were:
Following the 2025 season, development started on a completely new propulsion platform. The main design goals of the new system were:
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Construction started in late 2025 and was completed in early 2026, with the first on-water trials taking place in May 2026.
Construction started in late 2025 and was completed in early 2026, with the first on-water trials taking place in May 2026.


---
= Current Drive Systems =
 
# Current Drive Systems


At the time of writing two propulsion systems are in active use:
At the time of writing two propulsion systems are in active use:
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* Mini Rudder V2
* Mini Rudder V2


---
== New Main Propulsion Unit ==


# New Main Propulsion Unit
[[File:Roer_2026.png|thumb|300px|New main drive unit]]


The new main propulsion unit is powered by a Lehner Torqstar 3 7050/10 water-cooled outrunner motor. The motor drives a set of counter-rotating propellers mounted in pulling configuration.
The new main propulsion unit is powered by a Lehner Torqstar 3 7050/10 water-cooled outrunner motor. The motor drives a set of counter-rotating propellers mounted in pulling configuration.
Line 72: Line 67:
The transmission consists of an inner and outer shaft, each driving one propeller.
The transmission consists of an inner and outer shaft, each driving one propeller.


## Bearings
=== Bearings ===


The drivetrain uses the following bearings:
The drivetrain uses the following bearings:
Line 82: Line 77:
* 2× 638/8 (8×16×6 mm) for the remaining driveshaft support points
* 2× 638/8 (8×16×6 mm) for the remaining driveshaft support points


## Seals
=== Seals ===


Three shaft seals are used throughout the drivetrain:
Three shaft seals are used throughout the drivetrain:
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* 1× NBR R 20×28×7 between the housing and outer propeller shaft
* 1× NBR R 20×28×7 between the housing and outer propeller shaft
* 2× NBR R 8×16×7 between:
* 2× NBR R 8×16×7 between:
** the inner and outer propeller shafts
** the housing and the upper main driveshaft


  * the inner and outer propeller shafts
=== Keys ===
  * the housing and the upper main driveshaft
 
## Keys


The following keys are used throughout the transmission:
The following keys are used throughout the transmission:
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At the time of writing the transmission is lubricated using 40–60 mL of Kroon Oil ATF A gearbox oil.
At the time of writing the transmission is lubricated using 40–60 mL of Kroon Oil ATF A gearbox oil.


## Transmission Specifications
=== Transmission Specifications ===


* Maximum motor power: 10 kW
* Maximum motor power: 10 kW
Line 114: Line 108:
* Maximum gearbox torque: 18 Nm
* Maximum gearbox torque: 18 Nm


---
== Hydrofoil Trim System ==
 
# Hydrofoil Trim System


The hydrofoil trim system uses a custom aluminium hinge assembly actuated through a carbon fiber pushrod.
The hydrofoil trim system uses a custom aluminium hinge assembly actuated through a carbon fiber pushrod.
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The system allows hydrofoil adjustment over a range of approximately 12 degrees.
The system allows hydrofoil adjustment over a range of approximately 12 degrees.


## Hydrofoil System Bearings and Seals
=== Hydrofoil System Bearings and Seals ===


* 1× NBR shaft seal 6×16×4 mm
* 1× NBR shaft seal 6×16×4 mm
* 4× 6701 bearings (12×18×4 mm)
* 4× 6701 bearings (12×18×4 mm)


---
# Mini Rudder V2
The second-generation mini rudder consists of an aluminium structural skeleton with a 3D-printed hydrodynamic outer shell.
The system is powered by a Flipsky DC6374 140KV 3600W waterproof outrunner motor and uses a custom aluminium propeller.


Because future plans include water cooling for additional electrical systems, the Mini Rudder V2 also includes a cooling water inlet similar to the main propulsion unit.
---
# Rudder Mounting System
Both rudders are mounted to the steering tube in a similar manner.
The steering tube features M6 mounting holes at the bottom, allowing the propulsion units to be mounted from underneath the boat. The steering tube also contains an integrated cooling water pass-through, making it possible to connect the cooling circuit without installing additional hoses through the hull.


The Mini Rudder can be installed without modification to the steering tube. Only the power cables need to be routed through the tube, allowing quick replacement of propulsion units and ensuring continued operation in case of drivetrain issues.
== Rudder-controller ==
''Full documentation: [[Rudder controller]] — board function, connector pinouts, CAN messages, servo behaviour and firmware updates.''


The new rudder design needs a controller of its own to run the integrated cooling system and the back-foil trim. That controller is now a purpose-built board, the '''[[Rudder controller]]''' (Altium project <code>AKD-Rudder_Controller</code>): a 4-layer STM32L471 design that hangs off the [[CAN-bus]] and drives the trim stepper, the cooling pump and the cooling instrumentation. It replaces the 3D-printer tool boards that were used for prototyping up to late 2025.


=== Rudder-controller ===
It takes commands and reports everything over the [[CAN-bus]] — there are no local controls.
To accommodate the new rudder design and its features, a controller is needed. With this controller we want to enable a multiple of functionalities that will help with the integrate cooling system and the control of the back-foil.


The design should therefore have the following requirements:
{| class="wikitable"
{| class="wikitable"
|+Requirements for the rudder-controller
|+ Rudder-controller functions as built
!Feature
!Feature
!Description
!Description
Line 166: Line 142:
|-
|-
|Power
|Power
|Power will be coming from the [[CAN-bus]]
|24 V from the [[CAN-bus]] cable, with an on-board step-down module for the logic rail.
It is important that the inrush of the connected motors must not decrease the [[CAN-bus]] voltage.
A design requirement was that the inrush of the connected motors must not drag the [[CAN-bus]] voltage down; this is handled by 150 µF bulk capacitors local to each motor driver rather than by current limiting.
|4-pins connector that hosts the [[CAN-bus]] and Power
|Two 5-pin connectors carrying [[CAN-bus]], 24 V and the safety line
|-
|-
|Communication
|Communication
|The board will use the [[CAN-bus]] to communicate and retrieve commands
|CAN 2.0A at 1 Mbit/s, 11-bit identifiers. Firmware can be updated over the bus without a debug probe.
|4-pins connector that hosts the [[CAN-bus]] and Power
|Shares the two 5-pin [[CAN-bus]] connectors; wired in parallel so the board sits in a daisy chain
|-
|-
|Back-foil control
|Back-foil control
|A TMC2209 or comparable is needed that supports [https://www.analog.com/en/lp/001/building-better-stepper-motor-system.html StallGuard™]
|A TMC2209 stepper driver, using [https://www.analog.com/en/lp/001/building-better-stepper-motor-system.html StallGuard™] to find the mechanical end stop during homing. Position is open-loop step counting against that stop.
|Available on the platform connected to the back-foil motor
|On board
|-
|-
|Back-foil motor
|Back-foil motor
|The [https://www.omc-stepperonline.com/nema-11-stepper-l-31mm-w-rear-shaft-gear-ratio-14-1-planetary-gearbox-11hs12-0674d-pg14 Nema 11 Stepper motor] fits the rudder design to control the back-foil.
|The [https://www.omc-stepperonline.com/nema-11-stepper-l-31mm-w-rear-shaft-gear-ratio-14-1-planetary-gearbox-11hs12-0674d-pg14 Nema 11 stepper motor] (11HS12-0674D-PG14, 13.73:1 gearbox) drives the back-foil. Commanded as a 1000–2000 setpoint over the full travel, roughly 12 degrees of foil movement.
|4-pins connector for power and control
|Four coil pins on the shared 10-pin connector
{| class="wikitable mw-collapsible mw-collapsed"
{| class="wikitable mw-collapsible mw-collapsed"
|+Connection information
|+Connection information
Line 199: Line 175:
|}
|}
|-
|-
|Water pump  
|Water pump
|The available waterpump: [https://nl.aliexpress.com/i/32870145384.html ZC-A210](24 V version)
|The [https://nl.aliexpress.com/i/32870145384.html ZC-A210] (24 V version), driven through an H-bridge with a firmware-set current limit of 1.0 A. It runs only while the [[Battery|battery]] reports that it is discharging.
|2-pins connector  
|Two pins on the shared 10-pin connector
{| class="wikitable mw-collapsible mw-collapsed"
{| class="wikitable mw-collapsible mw-collapsed"
|+Connection information
|+Connection information
Line 215: Line 191:
|-
|-
|Flowmeter
|Flowmeter
|We have 2 flowmeters for inlet and outlet: [https://nl.aliexpress.com/item/1005006813605315.html?gatewayAdapt=glo2nld#nav-specification DWS-MH-02]
|Two [https://nl.aliexpress.com/item/1005006813605315.html?gatewayAdapt=glo2nld#nav-specification DWS-MH-02] flowmeters, inlet and outlet. Each gives a pulse output, counted in hardware, and an NTC. The TDS pair is not connected on the board. Only the inlet meter is read by the current firmware — the outlet meter's NTC shares a microcontroller pin with the motor NTC.
|6-pins connector  
|Inlet on four pins of the shared 10-pin connector; outlet on its own 5-pin connector
{| class="wikitable mw-collapsible mw-collapsed"
{| class="wikitable mw-collapsible mw-collapsed"
|+Connection information
|+Connection information
Line 222: Line 198:
!Function
!Function
|-
|-
| style="background: #ED1D0E;color:white;" | Red  
| style="background: #ED1D0E;color:white;" | Red
|5-24v
|5-24v
|-
|-
Line 238: Line 214:
|}
|}
|-
|-
|Platform
|Steering angle
|Right now(10-11-2025) the [https://www.duet3d.com/duet3toolboard1lc Duet 3 1LC] is available to use for prototyping.
|A potentiometer on the steering column, calibrated on the vehicle and reported as a normalized left/centre/right position.
Other options are [https://www.amazon.nl/-/en/BIGTREETECH-EBB-36-communication-STM32G0B1CBT6/dp/B0B1JBH8R5?dib=eyJ2IjoiMSJ9.u31ykTjqWpKnziWf-HlcFHPpjlpjFLlMqEGFS3VpEFoPMYB-ntfAoEM9qNUGVXtrwW3rHJDEbeMY6RI2Lnt_Jtbu8Ol-uZWBKFFmNuOY6nmBhfIGwyNLOpUkqAEEaxYpMGk7qOkz7OW_7PpcIhFg62Eqz-3x8XMlKipaq8vMtd6wiodByGlve9HrpBM9C38kSyzMRwFGneHUDJH7guP-7ENePjKpuOrLC7x83iRWhyoga6SRJgVPjpXohVvbPL6_Za6mVcNkD2xQyB3WFCoZoBKtCA469K9urtnIuDb5imU.4tJLo0B2n2WNGx17gcoOJ0Y6ITTdpQukln7ZNMG0YR8&dib_tag=se&keywords=ebb36&qid=1762803999&sr=8-1&th=1 EBB 36] and [https://mellow.klipper.cn/en/docs/ProductDoc/ToolBoard/fly-sht36/sht36/ SHT36 with TMC2209]
|4-pin connector: 3.3 V, wiper, presence detect, GND
|Host listed connections above.
|-
|Board temperature
|An I²C sensor measuring the board's own temperature.
|
|}
|}
See [[Rudder controller]] for the exact pin numbering of each connector, the CAN message formats, and the outstanding issues.
== Mini Rudder V2 ==
The second-generation mini rudder consists of an aluminium structural skeleton with a 3D-printed hydrodynamic outer shell.
The system is powered by a Flipsky DC6374 140KV 3600W waterproof outrunner motor and uses a custom aluminium propeller.
Because future plans include water cooling for additional electrical systems, the Mini Rudder V2 also includes a cooling water inlet similar to the main propulsion unit.
[[File:Miniroer_v2.png|thumb|300px|Mini rudder V2]]
= Rudder Mounting System =
Both rudders are mounted to the steering tube in a similar manner.
The steering tube features M6 mounting holes at the bottom, allowing the propulsion units to be mounted from underneath the boat. The steering tube also contains an integrated cooling water pass-through, making it possible to connect the cooling circuit without installing additional hoses through the hull.
The Mini Rudder can be installed without modification to the steering tube. Only the power cables need to be routed through the tube, allowing quick replacement of propulsion units and ensuring continued operation in case of drivetrain issues.
```

Latest revision as of 12:23, 17 August 2026

Propulsion System History and Overview

2022 Rudder

The main propulsion system is housed inside the rudder. The rudder is mounted at the rear of the boat, approximately 440 mm from the stern. Over the years several different versions of the propulsion system have been developed. A brief overview of the previous systems is given below.

2022 – 2025: Underwater Mounted Inrunner

This system consisted of a carbon-fiber-wrapped 3D-printed rudder design. The rudder was mounted to the boat using a carbon fiber tube attached through a so-called “well”. The well itself was made using a slightly larger carbon fiber tube integrated into the hull structure.

The propulsion system used a Lehner 30100/12 three-phase inrunner motor combined with a Neugart PLE-6 series single-stage planetary gearbox. Over the years 4:1, 5:1, and 7:1 gearbox ratios were used. The complete drive assembly was mounted inside an aluminium housing, with the motor and gearbox thermally coupled to the housing using thermal paste for cooling.

The propeller was mounted in pulling configuration, meaning the driveshaft protruded through the front side of the housing. The inside of the motor tube was sealed from the surrounding water using a shaft seal, while the rear end of the tube was closed off using a custom threaded cap.

A magnetic encoder was mounted at the rear end of the motor. The motor tube itself was connected to the rudder using aluminium interface pieces and rubber O-rings. Power cables were routed through the rudder to the three-phase motor controller located in the rear compartment of the boat.

Two major versions of this drivetrain were developed, with V2 featuring improved structural reinforcement and mounting features.

Although the system performed well initially, it was ultimately scrapped due to continuous water ingress into the motor tube. The resulting corrosion of the gearbox and motor caused repeated failures and required frequent replacement of expensive components.


2025: Mini Rudder V1

During the 2025 season a temporary drivetrain was constructed using a Flipsky 65111 waterproof inrunner motor. This system was designed as a backup solution for the heavily troubled main drivetrain and was used during the 2025 Amsterdam Solarboat Race.

The rudder featured a carbon-fiber-reinforced 3D-printed body and focused mainly on reliability and ease of deployment rather than outright performance.

Mini rudder V1

Development of the New Propulsion Platform

Following the 2025 season, development started on a completely new propulsion platform. The main design goals of the new system were:

  • Move expensive and sensitive electronics away from direct water exposure
  • Improve the drivetrain mounting system for future development
  • Increase structural rigidity for future hydrofoil implementation
  • Add integrated features required for hydrofoil compatibility
  • Implement a counter-rotating propeller system for improved wake alignment and efficiency

This redesign required significant modifications to the rear of the boat, including:

  • Replacement of the drivetrain well
  • Replacement of the entire steering system
  • Replacement of the well support structure

Construction started in late 2025 and was completed in early 2026, with the first on-water trials taking place in May 2026.

Current Drive Systems

At the time of writing two propulsion systems are in active use:

  • New Main Propulsion Unit
  • Mini Rudder V2

New Main Propulsion Unit

New main drive unit

The new main propulsion unit is powered by a Lehner Torqstar 3 7050/10 water-cooled outrunner motor. The motor drives a set of counter-rotating propellers mounted in pulling configuration.

Power is transferred through an 8 mm steel shaft to an angled gearbox mounted at the bottom of the rudder. The rudder itself uses an aluminium clamshell construction housing the following systems:

  • Helical bevel gearbox using Graessner P054 2:1 gears
  • Hydrofoil trim system
  • Cooling water inlet system

The transmission consists of an inner and outer shaft, each driving one propeller.

Bearings

The drivetrain uses the following bearings:

  • 2× 63804 (20×32×10 mm) for the outer shaft
  • 1× 6002 (15×32×9 mm) for the inner shaft
  • 2× 688 (8×16×4 mm) for inner/outer shaft support
  • 1× 698 (8×19×6 mm) at the bottom of the main driveshaft
  • 2× 638/8 (8×16×6 mm) for the remaining driveshaft support points

Seals

Three shaft seals are used throughout the drivetrain:

  • 1× NBR R 20×28×7 between the housing and outer propeller shaft
  • 2× NBR R 8×16×7 between:
    • the inner and outer propeller shafts
    • the housing and the upper main driveshaft

Keys

The following keys are used throughout the transmission:

  • 2×2×10 mm keys at both ends of the driveshaft
  • 3×3×25 mm key for the front propeller
  • 6×6×30 mm key for the rear propeller
  • 4×4×10 mm keys for both drive gears

The motor shaft is connected to the main driveshaft using a KTR ROTEX 14 steel coupling.

The clamshell housings are machined from 7021 aluminium and bolted together using low-profile Torx screws according to ISO 14580-1 in various diameters and lengths.

At the time of writing the transmission is lubricated using 40–60 mL of Kroon Oil ATF A gearbox oil.

Transmission Specifications

  • Maximum motor power: 10 kW
  • Maximum motor speed: 7200 RPM
  • Maximum motor torque: 6 Nm
  • Maximum gearbox torque: 18 Nm

Hydrofoil Trim System

The hydrofoil trim system uses a custom aluminium hinge assembly actuated through a carbon fiber pushrod.

The hinge mechanism uses:

  • 8×12 mm stainless steel dowel pins
  • 4×8 mm stainless steel dowel pins

The pushrod is actuated using a brass threaded interface driven by a geared stepper motor (StepperOnline 11HS12-0674S-PG5). The rotational axis is redirected using a miniature universal joint.

The system allows hydrofoil adjustment over a range of approximately 12 degrees.

Hydrofoil System Bearings and Seals

  • 1× NBR shaft seal 6×16×4 mm
  • 4× 6701 bearings (12×18×4 mm)


Rudder-controller

Full documentation: Rudder controller — board function, connector pinouts, CAN messages, servo behaviour and firmware updates.

The new rudder design needs a controller of its own to run the integrated cooling system and the back-foil trim. That controller is now a purpose-built board, the Rudder controller (Altium project AKD-Rudder_Controller): a 4-layer STM32L471 design that hangs off the CAN-bus and drives the trim stepper, the cooling pump and the cooling instrumentation. It replaces the 3D-printer tool boards that were used for prototyping up to late 2025.

It takes commands and reports everything over the CAN-bus — there are no local controls.

Rudder-controller functions as built
Feature Description Electrical connections
Power 24 V from the CAN-bus cable, with an on-board step-down module for the logic rail.

A design requirement was that the inrush of the connected motors must not drag the CAN-bus voltage down; this is handled by 150 µF bulk capacitors local to each motor driver rather than by current limiting.

Two 5-pin connectors carrying CAN-bus, 24 V and the safety line
Communication CAN 2.0A at 1 Mbit/s, 11-bit identifiers. Firmware can be updated over the bus without a debug probe. Shares the two 5-pin CAN-bus connectors; wired in parallel so the board sits in a daisy chain
Back-foil control A TMC2209 stepper driver, using StallGuard™ to find the mechanical end stop during homing. Position is open-loop step counting against that stop. On board
Back-foil motor The Nema 11 stepper motor (11HS12-0674D-PG14, 13.73:1 gearbox) drives the back-foil. Commanded as a 1000–2000 setpoint over the full travel, roughly 12 degrees of foil movement. Four coil pins on the shared 10-pin connector
Connection information
Color Function
Red B+
Black A+
Blue B-
Green A-
Water pump The ZC-A210 (24 V version), driven through an H-bridge with a firmware-set current limit of 1.0 A. It runs only while the battery reports that it is discharging. Two pins on the shared 10-pin connector
Connection information
Color Function
Red 24v
Black GND
Flowmeter Two DWS-MH-02 flowmeters, inlet and outlet. Each gives a pulse output, counted in hardware, and an NTC. The TDS pair is not connected on the board. Only the inlet meter is read by the current firmware — the outlet meter's NTC shares a microcontroller pin with the motor NTC. Inlet on four pins of the shared 10-pin connector; outlet on its own 5-pin connector
Connection information
Color Function
Red 5-24v
Black GND
Green 50k Temp
Yellow Pulse out
Red and Blue TDS sensor
Steering angle A potentiometer on the steering column, calibrated on the vehicle and reported as a normalized left/centre/right position. 4-pin connector: 3.3 V, wiper, presence detect, GND
Board temperature An I²C sensor measuring the board's own temperature.

See Rudder controller for the exact pin numbering of each connector, the CAN message formats, and the outstanding issues.

Mini Rudder V2

The second-generation mini rudder consists of an aluminium structural skeleton with a 3D-printed hydrodynamic outer shell.

The system is powered by a Flipsky DC6374 140KV 3600W waterproof outrunner motor and uses a custom aluminium propeller.

Because future plans include water cooling for additional electrical systems, the Mini Rudder V2 also includes a cooling water inlet similar to the main propulsion unit.

Mini rudder V2

Rudder Mounting System

Both rudders are mounted to the steering tube in a similar manner.

The steering tube features M6 mounting holes at the bottom, allowing the propulsion units to be mounted from underneath the boat. The steering tube also contains an integrated cooling water pass-through, making it possible to connect the cooling circuit without installing additional hoses through the hull.

The Mini Rudder can be installed without modification to the steering tube. Only the power cables need to be routed through the tube, allowing quick replacement of propulsion units and ensuring continued operation in case of drivetrain issues. ```

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