how is it applied

[burn em up chuck]

   how is the 5/8s rule applied to making longbow type bows? I know it's some type of ratio but thats as far as my knowledge goes on this subject.

                                                                             chuck

[WillS]

If you Google it there's lots of info out there on this.

I personally tend to ignore it when making ELBs though.  The "rule" is fairly straightforward - the width/depth ratio needs to be 8/5.  If your bow is 1" wide, the depth needs to be 5/8" (1" is 8/8)

Here's a quote from the GNAS (UK) regs.

At no point shall the depth of the bow, measured from back to belly, be less than 5/8 (five eighths) of the width of the bow at the same section.

 

Trouble is, getting that accurate along a stave (especially if you have knots or deflex/reflex areas) is quite tricky.  If your front profile looks like an ELB, and it's tillered properly, chances are it will apply anyway as far as I can tell.

[Squirrelslayer]

something tells me Del will contribute to this thread. but what Will said is good. SS

[DarkSoul]

The trick is to design the bow narrow enough, so you don't get below the 5/8 rule during tillering.  The midlimbs are most crucial; it's not difficult to get a 6/8 ration at the handle and a 7/8 ratio at the tips, but the midlimbs are the thinnest sections generally.

[burn em up chuck]

    thank you for the help. The general description was exactly what I was looking for. I have some narrow bow material to use and this gives me a place to start.

                                                                               chuck