What is the lug width? If it is 22mm several people have used Sinn straps with much success. I have seen the Kemmner Octopus with a Sinn rubber, isn't that the same case as the Helson?
"It's such a fine line between stupid, and clever."
David St. Hubbins
Nothing wrong with that. I can't think of anything in 24mm that will work for you. Kobold makes a strap for the Arctic Diver but it is very expensive and more than likely won't fit.
"It's such a fine line between stupid, and clever."
David St. Hubbins
Not aware of anything at 24mm, however you might consider the Steinhart Triton rubber strap. It is a fitted strap with a deployment clasp. The ends are beefy so they fill the gap between the spring bar and case nicely. The Triton also has long lugs. http://www.steinhartwatches.de/en/Rubbe ... k,199.html
I just spoke to George at NFW, and ordered a Viperfish 24mm lug strap, and it comes with a curved rubber strap end. He said he wasn't sure if it would work, but pics on his site look like it might work.
This is a link to George's Blog, scroll down and look at Viperfish pics.