Hynautic Engine Controls

Water based fluid in hydraulics? That seems odd. I ve never had to work on hynautic engine controls but I would have thought it uses the same hydraulic fluid used in their steering system

Hynautic controls are actually hydropneumatic, sort of.
In fact, they use air inside the reservoir to keep the circuit pressure constant regardless of liquid expansion with temperature.
Anyway, already in the cover, the manual leaves no doubt that they don't use oil!

Interesting. As I said I v used them but never had to fix them or even pull the manual! You learn something new everyday…

You were lucky if you never had to fiddle with them.
A boating mate of mine has them on his early 90s boat, and they still work pretty well, but he treats them with constant TLC.
To the point of having rebuilt some small bits that were not available anymore!
But they are very smooth and pleasant to use, I must say.

Hynautic support and parts is available. Just not on the top list of conversations or web pages.
Sea-Star corp found it was easier to purchase their small and medium boat engine and steering controls competition than compete.
They purchases up Hynautic and Capilano quickly.

And for a very long while all was good for them until the king of all marine products looked down to find another profitable company.
Dometic corp, the king of purchasing up competition and profitable companies bought Sea Star.

For the DIYr, it is hard to find Hynautic support, you just have to look deeper down the many layers of company names.

Part Number HA5455
West Marine, Amazon and others carry it.
https://www.westmarine.com/buy/seas...ngine-controls-1-gallon--14660948?recordNum=4

http://www.seastarsolutions.com/support-2/authorized-hydraulic-service-centers/
http://www.seastarsolutions.com/support-2/service-parts/service-parts-hynautic-helms/
http://www.seastarsolutions.com/sup...ion-manuals-mechanical-dual-action/#hydraulic
http://www.seastarsolutions.com/support-2/technical-support/hydraulic-steering/

On further notes;
A Hatteras I help support had some hynautic control issues last year. I went to start shopping for seal kits.

Not a lot left on the vendors shelves and the prices had over tripled within a couple of years of previous purchases.
I ordered seal kits for every Hynautic component on that Hatt. These spares are sleeping in better storage than Sleeping Beauty.

It was hard to pay $50 for a plastic bag with 4 different O rings but we did.
One day, I'll have to pull out my electronic micrometer and size these seals out.
Publish a O ring inventory per kit and just go purchase the needed 25 cent O rings when required.

Unless, somebody, somewhere has already done so???