Equipment Rationale (please note this applies to flight shooting only)
Much of what we know of the medieval warbow come from extrapolating information of the 137 yew bows recovered from the hulk of the Royal Navy Flagship, the Mary Rose. No other bow woods were woods were found. However, if another of Henry’s ships had suffered the same fate it would likely be different, if they survived the immersion. In a Navy inventory in 1514 the Trinity Sovereign carried two chests of yew and ‘witch hazel’ bows. The John the Baptist carried a staggering 151 bows of yew and 84 of witch hazel. A galley called The Rose had 55 yew bows and 40 of elm, probably wych elm. Thomas, Lord Howard wrote to his counsel in 1513 that...

It seems that Howard’s archers were of the same opinion as Ascham.
Warbow Wales recognises that self-yew bows are very effective and command a premium price yet white woods are just as deserving of their place in history, without hefty outlay. Indeed a 1542 statute forced bowyers to produce more whitewood bows.
"For one bow of yew shall make four of elm, wych, hazel, ash or other wood apt for the same."
This was to preserve precious yew for military use.
Although these woods are effective they are not at the same level of performance as their glamorous baccata cousins. Roger Ascham, in his seminal book on archery, Toxophilus (1545) has to say of other bow woods.

Esteemed bowyer Pip Bickerstaffe concurs with Ascham and states...
“Try making a (narrow) "D" section bow of Elm and as it fails miserably to meet your expectations and becomes just so much more firewood you will appreciate that it is the concept and not the design which lead to the English Artillery bows.”
White woods – White woods, such as wych elm were the medieval workhorses, with yew being the preserve of the gentry and military. During the zenith -The supply of yew suitable for heavy livery bows was scarce enough to warrant a statute in the reign of Henry VIII limiting its use to gentry and primarily military applications. During the medieval and Tudor period bowyers were obliged to produce four times as many white wood bows such as elm, wych hazel, holly, ash or pay on pain of a hefty fine. For an archer to use a heavy bow effectively years of prior training at the butts must have been undertaken with a livery yew weapon of commensurate power. Therefore, medieval bowyers must have been able to produce whitewood bows, from readily available indigenous wood, as heavy as yew bows. An interesting reference to two holly bows, presumably for military use, is made in an inventory of equipment at Chirk Castle in North Wales.
Welsh yew makes excellent bows. Warbow Wales’ Jeremy Spencer has made such a longbow, shot by Champion archer, Al Aston, that sent a wooden flight shaft 371 yards to claim a yet unrivalled FITA world record for a self longbow.

The quality of the best British yew is the rival of anything, indeed this is a fact that was well understood in medieval times. It is recorded that Nicolas Frost, Henry V's bowyer, was sent to collect British yew staves for the Agincourt campaign. Interestingly he was forbidden to take yew from ecclesiastical land by the ever pious Henry V. Clearly when native was good, it was the rival of imported yew. It is important to note that modern Italian yew warbows, like that sold by Barebow Archery, is from high altitude yew (not just any Italian yew) so like must be compared with like. Highly regarded bowyer, Chris Boyton, has stated that the best yew he has seen came from Britain. In 1436 Nicholas Hisham of York chartered four ships to sail to Prussia to procure yew staves such was the paucity in Britain. It seems that the voracious medieval appetite for yew staves outstripped the supply of native yew and supply from without was needed. Tax had to be paid in the form of bow staves on imported goods from without, such as wine. Contemporary instruction on their quality was even given, Butler’s Zurich letters to Ballinger state...

Pactical tests shown that if made appropriately white wood can perform effectively. Whitewoods are very tension strong but have comparatively less compression strength than yew. However, if made slightly wider and squarer, the belly (the weak link) has more working area and can cope with the strain. Making whitewood bows wider does not increase production time at all. Walk around a deciduous woodland and within ½ an hour a multitude of suitable whitewood staves can be identified. Recent experiments by talented Norwegian warbowyers have shown that very high draw-weight bows can be produced by replicating a yew bow section but even these are routinely heat-tempered with hotair guns and impregnated with resins for around eight hours to further toughen the wood in a process called malming. Whether this was a practise carried out by medieval and Tudor bowyers is open to debate. There is no real evidence apart from a cryptic reference by Ascham, again in Toxophilous.

However, it seems likely to be advise to store bow inside so the moisture content of the wood does not get too high.

Juxtapose the abundance of whitewood staves in most woods against finding a suitable yew stave. As any bowyer will tell you a fruitless day of searching is very likely! This highlights how precious yew was and how a design that maximised the number of staves per log, often of small diameter, made sense. Yew was precious and obtaining the maximum bows per log made sense. Yew wood possesses inherent properties to deal with a narrow rounded cross section design that white woods do not. Picture the different designs a bronze and steel sword necessitates yet both made of metal. Try to replicate the design of the medieval iron/steel two-handed sword in bronze and the reason a xiphos is so formed will become clear.

Hugh Soar, longbow historian and author, is arguably the world authority in his field. Of longbow sections he has this to say in his excellent publication – 'Coaching Long-bow'. “Historically, a number of cross-sections have been used. The more important are the elliptical, or ‘ogival’ and the square, or ‘rectangular tapered’. Each is of considerable antiquity and should not be rejected at Long-bow Society Meetings.”
Warbow Wales looks to his trustworthy guidance. It is interesting to note there are no known medieval or Tudor period specifications for warbows.

The square (or flatter curved) section is a good choice for tension strong/compression weak woods, like ash, as more belly area is available to share the stress. Ash and elm warbows readily suffer compression failures on the belly if too stressed or less than perfectly tillered. Wood from small staves, as many of the yew Mary Rose bows are, have a naturally crowned back which places it under more stress than a bow from a larger stave as most of the stretching is done by its highest point. Back failures are usually catastrophic, not idea in any situation, let alone during action. It makes sense, therefore to round the belly more to take more pressure off the back. It's better for a bow to take a little more set than explode. Yew cope with this ogival section as it is so elastic and , constructionally, it is easier to rough-out and tiller in this shape as the hand-tool cuts are only shaving in point-contact. The modern sub 5/8ths width to depth ‘D’ section is a Victorian concept that is more suited to a genteel York round on the vicarage lawn than a heavy whitewood warbow. Some of Mary Rose bow do not meet this criteria so it seems unlikely that less elastic wood longbows would have either. NB If you have the joy of making your own tackle and want to shoot in multiple organisations, check their website for their dimension/material criteria as most are different. Otherwise, make sure to inform your bowyer. It is best not to assume as this can lead to disappointment. 

All bow cultures produced designs that maximised performance within their working environment and the materials to hand. It seems unlikely Anglo-Welsh bowyers did not do the same for whitewood bows.
 
Therefore Warbow Wales has arrived at the following conclusions (for flight shooting only)...
1. Equipment

Bows
a) Only selfbows made from woods available to Welsh bowyers during the medieval and Tudor period are eligible for flight records
b) The arrow pass of the working handle section must be the widest and deepest part of the bow and the limbs taper from handle
c) Yew bows must have a section and length somewhere between the extremes of a Mary Rose bows, see link
d) Due to complete lack of evidence all bow sections are acceptable for other woods
e) Nocks - self, horn and antler nocks are acceptable. Side nocks are encouraged. For more information, see links below

Strings
a) Only strings and servings made from natural materials available to Welsh stringers during the medieval and Tudor period are eligible for flight records. Currently the string is the weak link in the archer/arrow/bow/string delivery system. Hemp and nettle fibres can grow long enough to allow for an unbroken strand in a bow string. However, good results have been obtained from Irish linen thread up to 130lbs. Warbow archer Simon Wenlock has successfully made strings his 130lb bow that have lasted for many shots and he has roved with such a string. Using modern Kevlar and Fast Flight synthetic strings has, somewhat, skewed the research as a vital link in the chain has been circumvented. A good indication of string diameter is the size on arrow nocks fon on-bour the Mary Rose and varied to some degree but none seem larger than 4mm.
An excellent article on medieval strings and their manufacture, by Erik Roth, can be found here

Arrows
a)The arrows to be shot for distance shall be the Mary Rose Livery x 2, Bearing Arrow x 2 per bow
Construction rationale and specifications available on the Livery Arrow page, see the link here
b) Only the arrows to be shot must be taken to the shooting line and have personal identification
c) If additional arrows are inadvertently shot the shortest arrow scores
d) All the shooting equipment must be made available for scrutiny at the shoot
e) Only arrows that have been scrutinised at that event are eligible to be shot, shoot organisers should put to one side arrow that fail to meet the specifications
NB
If an archer wants to take part in the flight shoot, arrows and bows meeting the above will gladly be made available to borrow

2. Shooting ground and measurement.
a) The distance is to be measured at right angles to a centre-line down the flight corridor
b) The flight corridor should be marked at a minimum of 50 yard intervals and ideally be largely flat and free from obstructions
c) A marked shooting line must be visible with the archer's feet behind it
d) The fight corridor should allows the current record + 50 yards of overshoot for whatever arrows are to be shot and have safe flank margins either side
e) Care should be taken to avoid shooting into unsighted ground or when public access areas are near, like footpaths for example
d) Distances will be taken with a laser rangefinder (+ or- 1% accuracy) and verified against pre-laid out pegs at 20 yard intervals

3. Technique
a) All shots must be off the fingers but not with a thumb ring

NB
The above ONLY applies to record flight shooting. The use of any types of longbow (laminated stave and bamboo backed) is acceptable for accuracy and other events