Calculateing necesary effort on steering wheel at hydraulic operated rudder

[stipan_marinovi]

Greetings to everyone,

I have been trying to calculate steering effort on my hydraulic operated sailboat if I change my current cylnder.

Problem is that with my current specs I dont need to use any effort to stear the boat and there are too many turns on 70cm diameter steering wheel. And with sailboat it is necesary to have effort when sailing.

The cheepest way to do it is to change my hydraulic cylnder which is connected directly to rudder over tiller arm 18cm.

But with downsizeing cylnder I am increaseing effort on stearing wheel and I would like to know by how much and how.


I found couple of formulas and putted them down in excell sheet down below, for each rudder angle of attack, necesary tiller arm and different speed(since speed drops automaticly when you steer trough water).(In order to calculate aproximation +- 100/200 grams)

As you can see firstly I was calculateing force of drag for each angle of attack, and than transvering forces to hydraulic cylnder, and than moment on pump shaft.

Problem comes when I try to calculate drive power of pump in wats and put it Newton-meters per second...all goes wrong.At this point I am not sure what I am doing wrong.

For exhample I get I need to use 0,06kg/s for 3 seconds to achive feedback of ruder at the end of 3 seconds of 0,54kg... but 0.06+0.06+0.06=0.18kg

It has becomed highly complex,if anyone can help me I would be grateful.