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+--- Thread: Finding a suitable linear actuator (/showthread.php?tid=6943)
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Finding a suitable linear actuator - dave42w - 2026-05-29
Hi,
On the page https://pypilot.org/actuators/ this link isn't working for me.
"I really enjoy the following actuator on my boat. 3500N 300mm stroke 170mm/s speed 12V 24V DC Electric linear actuator"
I'm struggling to find a suitable linear actuator for my Rival 38 in the UK (happy to use AliExpress). Probably because I'm not really sure what I'm looking for. It seems difficult to find something with a speed as high as 170mm/s, especially with 3500N.
Any recommendations?
Thanks
Dave
RE: Finding a suitable linear actuator - PaddyB - 2026-05-29
(2026-05-29, 06:05 AM)dave42w Wrote: Hi,
On the page https://pypilot.org/actuators/ this link isn't working for me.
"I really enjoy the following actuator on my boat. 3500N 300mm stroke 170mm/s speed 12V 24V DC Electric linear actuator"
I'm struggling to find a suitable linear actuator for my Rival 38 in the UK (happy to use AliExpress). Probably because I'm not really sure what I'm looking for. It seems difficult to find something with a speed as high as 170mm/s, especially with 3500N.
Any recommendations?
Thanks
Dave
I use one of these on a heavy 33'
https://pcnautic.com/en/product/pcnautic-bare-tiller-drive
I know someone who ordered direct much cheaper but minimum order was 5 istr & didn't have electrical endstops or rudder feedback pot like the pcnautic one.
RE: Finding a suitable linear actuator - dave42w - 2026-05-29
(2026-05-29, 03:01 PM)Hi,Thanks. Very useful. That's quite a lot lower power and speed. How does it cope with different conditions and what's your boat approx displacement?Appreciate your help.Dave PaddyB Wrote:(2026-05-29, 06:05 AM)dave42w Wrote: Hi,
On the page https://pypilot.org/actuators/ this link isn't working for me.
"I really enjoy the following actuator on my boat. 3500N 300mm stroke 170mm/s speed 12V 24V DC Electric linear actuator"
I'm struggling to find a suitable linear actuator for my Rival 38 in the UK (happy to use AliExpress). Probably because I'm not really sure what I'm looking for. It seems difficult to find something with a speed as high as 170mm/s, especially with 3500N.
Any recommendations?
Thanks
Dave
I use one of these on a heavy 33'
https://pcnautic.com/en/product/pcnautic-bare-tiller-drive
I know someone who ordered direct much cheaper but minimum order was 5 istr & didn't have electrical endstops or rudder feedback pot like the pcnautic one.
RE: Finding a suitable linear actuator - Jean-Marc Douroux - 2026-05-29
Several of us have successfully tested a 300mm, 150mm/s linear actuator with an 85W motor. It's significantly faster than the one from PcNautic. This improves autopilot performance and also reduces power consumption. It's available individually from Kriohm, complete with a position sensor and reinforced sealing for the cable and rod guide, at a very competitive price. I'll post the full specifications and a 3D-printable motor protector on the navitop.fr website.
RE: Finding a suitable linear actuator - dave42w - 2026-05-29
(2026-05-29, 09:00 PM)Jean-Marc Douroux Wrote: Several of us have successfully tested a 300mm, 150mm/s linear actuator with an 85W motor. It's significantly faster than the one from PcNautic. This improves autopilot performance and also reduces power consumption. It's available individually from Kriohm, complete with a position sensor and reinforced sealing for the cable and rod guide, at a very competitive price. I'll post the full specifications and a 3D-printable motor protector on the navitop.fr website.
Thanks that would be great.
Dave
RE: Finding a suitable linear actuator - seandepagnier - 2026-05-30
Where is this Kriohm actuator?
I am currently looking at chinese options of the 150mm/s and faster variety. I used one on my own boat and the corrosion resistance was an issue.
Curious to know what you found and the cost.
Eventually I want to develop brushless ballscrew actuators without gears. Very quiet, fast and powerful with a low cost and completely ability to service as well as any size. This really could replace hydraulics even in large boats for a superior solution.
RE: Finding a suitable linear actuator - Jean-Marc Douroux - 2026-05-31
This actuator has an 85W motor, significantly more powerful than other actuators. The manufacturer states a 10% duty cycle at full load, but even with the 150mm/s, the motor doesn't strain on my 3.7t boat and operates within its maximum efficiency range because the power consumption is much lower than with my old Autohelm linear actuator, which reached 48mm/s. I've never seen the motor overheat. Despite its speed, this actuator is quieter than my old actuator. However, its weight is significantly higher. To prevent corrosion of the painted soft iron motor casing, I 3D printed a part that completely covers the motor. I sealed it with liquid sealant rubber.
It should be specified that you want a 1m long waterproof cable (stainless steel cable gland), reinforcing guide rails and rod seals.
The links for the 300mm, 150mm/s (150N) or 65mm/s (300N) linear actuator and the potentiometer are below.
https://fr.aliexpress.com/item/1005008895022633.html
https://fr.aliexpress.com/item/1005009263920297.html
I also created a 3D printed part to adapt the 8mm hole in the actuator rod end to the standard 6mm pins found on tiller arms.
RE: Finding a suitable linear actuator - dave42w - 2026-05-31
Hi,
Thanks for the link. My Rival 38 is around 8000kg displacement and 11.45m long.
So I'm not sure that this will be powerful enough.
Does anyone know how to check or have experience with a similar displacement?
Also we have a complex, solid rod 50 year old Whitlock steering system with 2 right angle gearboxes. While I want to attach the linear activator directly to the tiller (under the aft cabin bunk) I am concerned there might be more friction & more force needed than with other systems.
Dave
RE: Finding a suitable linear actuator - Jean-Marc Douroux - 2026-06-01
Hi,
A linear actuator with a clutch is then required.
A friend has set up a Raymarine T1 with a clutch as a backup, which he can quickly couple with a pin.
RE: Finding a suitable linear actuator - Jean-Marc Douroux - 2026-06-01
The link to download STL files for motor protection and 6mm pin adaptater
https://m32s2ibptsc.infomaniak.site/manuals-download-en