Constant-tension winch: Anyone design an automatic mechanical one?

[pbmaise]

I guess I am just lazy. When the wind blows strong I want my winch to automatically sheet in and bring the sail to the center line. When the wind slacks, I want it to automatically play out.

Alternately this same type of device would be applied to a roller furler to roll up the sail and at the same time slacken the sheet so the sail can stow during a blow.

I have come up with a few ideas that solve the problem without resorting to strain guages, electric winches and a PID controller. With electronics the solution is rather simple.

Has anyone solved this problem before purely mechanically?

The root problem to overcome is the device has to sheet in when load increases.

I am sure other sailors have thought about this before and I lay you dollars to donuts someone has a patent on something.

[pbmaise]

Here is an example of an electric mechanical one.

Certainly some big rigs have employed these, however, again I am searching for purely mechanical ones.

https://www.palfinger.com/en/marine/...ension-winches

[denverd0n]

Originally Posted by pbmaise

The root problem to overcome is the device has to sheet in when load increases.

I would guess that the root problem is that it is not always the right thing to do, to sheet in every time the load increases. In fact, quite often, when the load on a sail increases, that's the time when you want to ease the sheets a bit. You would need to tie into heading, wind speed, desired course, rudder angle, the settings of all sails (not just one), and probably a dozen other parameters to really know when it is the right time to trim, or to ease, the sheets.

Oh yeah. Those constant-tension winches that you found? Those are used sometimes for towing, hauling nets, that sort of thing. I have never seen one used for controlling the sheets on any sailboat.

Not trying to rain on your parade, or anything. I just think this is a lot more complicated than you are imagining.

[Suijin]

Wind vane. Easier to just nudge the rudder than to change everything else lol.

[Uplander]

I did consider putting a spring system on to the main sheet traveller. If a gust hit the pressure on the traveller car would increase and the traveller ease automatically. When the gust passed it would return to its previous position.
Never got around to it.

[jmschmidt]

Saw a giant tourist cat in Australia once. Noticed what looked like strain gauges on the chain plates. I asked a crew member and he said the strain gauges talk to a computer which talks to the electric winces which keep a constant tension on the rig given wind conditions and other parameters.

[zstine]

i don't think constant tension would work too well and sheet angle has more to do with apparent wind angle... anyway, it has been done for mega yachts and is starting to get into mainstream. check harken Harken

[Uplander]

From jmschmidt's post it said that "the electric winches kept a constant tension on the rig given wind conditions and other parameters".
No doubt "going fast" would be a parameter and likely as not the computer would "learn" the best sheeting and other adjustments for the conditions. Pretty clever.

[Schooner Chandlery]

I like the idea of knowing (via strain gauges etc) how my rig is loaded up or unloading with different trim. That is actionable information that can make me a better sailor.

The idea that my boat does all of it automatically? Takes the fun right out of it for me. Of course, I'm also someone who has hanked on headsails by choice and who coastal cruised (just me and my husband) for over two years w/o using the autopilot just for the sport of doing things w/o assists... We each have our own way of going about doing things for sure.

Are you primarily a technophile and just love the idea of this, are you dealing with an especially large vessel and large forces of concern compared to the design of the boat's rigging, or what else is it that makes you want to have this particular trim tool aboard your boat? I can see interesting applications but they are not centered upon sailboat cruising.

[Uplander]

Greetings,
I think you mis-read my post. I said "pretty clever" not that I wanted it to be on my boat.
Appreciate that if you follow your logic too far you will have to do away with GPS's chart plotters, depth sounders and even your engine as well! Then we will be centred on sailboat cruising.
Good luck.

[Schooner Chandlery]

Originally Posted by Uplander

Greetings,
I think you mis-read my post. I said "pretty clever" not that I wanted it to be on my boat.
Appreciate that if you follow your logic too far you will have to do away with GPS's chart plotters, depth sounders and even your engine as well! Then we will be centred on sailboat cruising.
Good luck.

Ah...I wasn't responding to your post but that of the OP.

However, for coastal cruising, I do not rely upon GPS and only got a chart plotter when obtaining radar (which came with the plotter) for a hop from San Francisco to Alaska and wanted the extra bit of kit. Depth sounders are really a nice thing -- much better than a fellow with a lead line calling out soundings indeed. The engine? well, must admit it's only useful when coming and going from a tight low-wind spot like say a marina

The actual cruising? doesn't really require much more than the wind and sails and normal bits there, that's true.

Again--I do really love the idea of monitoring rig loading with strain gauges. Same as I love knowing a big tanker is headed my way (with AIS receiver) or a storm coming along (with radar) but don't expect the boat to automatically respond to any of those bits of information on it's own.