Shelf Design
There has been quite a bit of discussion on The Leatherwall
recently about arrowshelf/sight window construction and modification.
I thought that this might be an appropriate time to look at this
subject in depth. The design of the shelf can greatly impact
arrowflight, due to the fact that when an arrow is released any
contact with the bow riser will create drag. Good shelf/sightwindow
design will help make a bow capable of shooting a wider range
of arrows and will be more forgiving of a less than perfect release.
There are 3 basic types of shelf designs; flat, radiused and
ridged. The diagrams below picture these 3 variations.
The radiused shelf is the most common on both longbows and recurves.
As illustrated in the picture, the radius reduces the amount
of arrow-to-bow contact.
The flat shelf is also relatively common, especially on some
older styled recurves. When a bow has this style of shelf it
is necessary to use an elevated rest to get the fletching clearance
necessary for good arrow flight. One trick that has been used
in this situation is to place a thin narrow strip of leather
under a rug rest and continue it up the sightwindow under the
strike plate. This will allow more clearance and therefore help
with flight.
The ridged shape, I believe, is the design that offers the best
clearance, since the arrow-to-bow contact is at its absolute
minimum.
Other characteristics of good shelf design are beveled edges
and narrow sloping shelves. Both of these factors limit unnecessary
contact. Figure 2 illustrates both of these features.