Choosing octave strings

[ChristoMephisto]

Is there a method for calculating what octave strings would match bass strings?
Have a Hagstrom H8 and the 'proper' strings they suggest are hard to find. Found one dealing in China, but that's a bit far to be ordering strings every time, hoping for something more local.
For the 8 string basses, Hagstrom suggests 40-55-70-95 and 15-25-40-55 for the octaves.
Right now I'm using Rotosound 66 which are 40-50-75-90 and some Dano baritone strings XL157. Just the middles ones 18-26-44-56. It's a 30.5" short scale so can get away with guitar strings.
Searched around and most gauge calculators are for guitar and not long enough in scale.

 

[mmbongo]

Welcome to Bass Strings Online - Your Custom Bass String Shop...

Jason can hopefully put a set together for you.

 

[ixlramp]

Supremely useful tension guide: http://www.daddario.com/upload/tension_chart_13934.pdf

The rough rule derived from physics is this: for equal tension octave up, half the gauge. But this is not so accurate when choosing a plain to match a wound.
More precisely use the tension chart to choose strings with a unit weight one quarter that of the lower strings (unit weight is independent of scale length so you can match a guitar string to a bass string this way).

 

[ChristoMephisto]

Thanks a bunch, took a bit to understand how to read the charts...
Took the bass strings i have, and calculated a quarter of the weight, and came really close to half of the gauge.
The .040 for the G string matched up with a 18 plain, or 20 wound, which is good cause i don't like unwound G's, even on guitars.
Guess when companies put together 8 string sets, they round off the gauges.

 

[ixlramp]

20 wound has a very thin core that may not take the tension at G, but Conklin Guitars & Basses Official Home Page sells wounds designed for F on a 34" scale so they might just work.

 

[JimmyM]

SIT has an 8 string set that would probably work for you.

 

[ChristoMephisto]

It's for a short scale bass, 30.5"