Re: Rudder Stuffing Box Packing Material
One long piece spiraled around the shaft will most certainly NOT work. If Amel is not cutting it to length for you, it kind of defeats the purpose of buying from them!
It needs to be accurately cut to length--exactly one shaft diameter. I have cut mine straight, and that works. A bevel is fine if you can do it accurately. If you try to cut it yourself, it's a bad idea to cut it "a little long" and then trim it to exact length. If you try to cut a millimeter or two off at a time it's very hard to keep the end from crushing and fraying, and that makes a bad fit, and a bad fit means leaks.
A good article on the details of how to cut it with some things that make a good (or bad!) job: https://www.pumpsandsystems.com/what-are-key-steps-cutting-packing-optimum-performance
It's not rocket science, but it is technique sensitive. You can use the rudder shaft to size the rings, but it is awkward at best and hard to do a good job.
In my experience with this rudder shaft, and others, it takes some time for the packing to "settle in." For the first couple days of active steering underway you will have to keep a close eye on it and be ready to tighten it further if it starts to drip--no matter how tight you think you got it on the first go. After a few days of sailing it will likely be done, and will then be good for thousands of miles without further attention.