Every year at this time people try and shoot their longest distance with a compound and fall short. Just this weekend I was working with the Scottish juniors and discussing with them the ways they can get round this.
So what affects sight mark:
In order of biggest effects:
1) poundage (but the effect of an increase is as a percentage of starting poundage and the FITA limit, so a 3lbs increase has a greater effect for a 40lbs starting point than a 55lbs starting point and the limit is 60lbs).
2) Peep sight hight, (this is measured as the distance from the centre of the peep to the centre of the arrow at full draw, which takes into account axle to axle).
3) Arrow weight
4) nocking point. But we can discount this one as all compounds shoot best at zero to 1mm above square which gives the best sight marks
So it sounds complicated doesnt it:)?
lets set some simple rules to make it easier: bow speed can be used as a defining aspect of whether these long distances can be achieved and takes into account aspects 1 and 3 above. to make 90m the minimum bow speed is 260fps and to make 70m the minimum is 230fps. These minimum speeds can be used to quickly define if the distance can be made, if you are above these speeds and cant make the distances then you are anchoring abnormally high and therefore the peep sight hight is less than functional and you need to change anchor, minimum peep sight heights are 3.75 inches for gents and 3inches for ladies (measured as above NOT at rest).
So if you have a bow with less than the stated speed what can you do? Increase the poundage or reduce arrow weight (see other entry on this blog about how to select arrows).
If you can not alter these two factors what can you do?
1) move anchor point down and increase the peep hight. This can only functionally be done with a thumb release if you are anchoring higher than index finger on your jaw line. However you could use a wrist release and this will lower the anchor point.
2) shorten the nock loop which will alter the position of the string with respect to the eye, shortening the nock loop will require the peep to be raised giving an increase in sight mark.
These are the only factors that can be adjusted to functionally make distance, if these alterations do not let you make the distance then you may want to look at a faster bow.
