Boats helm gone nuts - Ship keeps jumping 90*

[AoD_lexandro]

So I am trying to do my first crossing from Al'Ankh to the Emerald Isle. I am roughly just over half way and the ship has decided to go bonkers. The wind is coming from the east so I am running a tack southward, but the ship keeps swinging back 90 degrees ignoring the helm, causing it to "dance" back and forth for no reason.

The sails are set properly, I am tacking with the helm in hand. But its constantly rotating back upwind with zero inputs and doing so violently.

It literally feels like I have entered the twilight zone. Has this happened to anyone else and what is the cause?

*EDIT* Someone will likely ask about sheets and ship type so here is what I am sailing;

https://steamcommunity.com/sharedfiles/filedetails/?id=3418575331

[Spark Sunbright]

This is a bug that affects the Sanbuq from time to time. The developer is aware of it but can't seem to replicate or fix it.

As far as I know, it seems to only occur when the Sanbuq's mizzen has been removed. I've had it happen frequently with my Sanbuq using a forward-positioned main mast and no mizzen, as well as a centered main mast with no mizzen (similar to your set up).

Note that I could be entirely wrong about the lack of mizzen mast being the cause, but I've personally never had this bug on the default 2-mast Sanbuq. (Perhaps someone else can confirm or refute it.)

[EnkelTaip]

On Sanbuq, even with a second mast, there is a constant situation where the ship does not hold the set course, always deviating from it immediately after setting it by two points to the right or left, and it is necessary to reset the course several times taking this deviation into account, specifically setting a value greater or less than necessary, so that the result, adjusted for the programmed deviation, is what the player needs.
I did not understand what this depends on, since the situation arises spontaneously on the same courses and in the same conditions when the ship was on course normally.
Perhaps this is somehow connected with the wind direction model, when it starts to change too often, several times per hour, and the program does not have time to calculate the mechanics of the boat's behavior from constant wind changes.

[AoD_lexandro]

In this case I think I have solved the cause. The #2 mast is too far back for conventional sails and can only manage square variants. Anything else results in a "Dancing" helm in high seas.

By fitting the #1 mast option, its now placed much further forward. This now should counteract the twisting and dancing helm.