Technical Information

Many NZ players have called us about the erratic behaviour of their new narrow model bowl-explanation below on how and why.

Introduction...most important if you're buying bowls or had trouble with recent narrow sets playing erratically.
NOTE-in New Zealand our model Corsair has the same on-green bias as the WRB Test Bowl, any model seen to go narrower on the green does not have the Rules stated correct amount of bias. These narrow models carry a compliance stamp due to WB altering the method of bowl testing that allows manufacturers to market non-complying narrow biased models, yet still carry a WB sanctioned stamp. [ p.s. maufactuers are charged approx NZ $20,000 per year for the right to make bowls that carry the WB stamp ]

Many bowl models subtract or reduce bias as they run down the green, i.e. they go narrower than when tested on a table. And be aware there is effectively no "on-the-green minimum bias standard" in the Sport of Bowls as there was in the past and many models sold over past 20 yeras do not take legal green bias owing to the deliberate removal of Part B of the table test. World Bowls deleted the long standing IBB testing proceedure used by the manufacturers and wrote their own which essentially removed the part that shows what bias will be on the green.

The main characteristics seen on the green are: [see videos on the bowls page for further info.]
1. Often play quite well in morning but very poorly in the afternoon due to wind and many tracking marks left by other bowls. These marks are crossed at an acute angle and often pull the bowl off line.

2. Some deliveries turn into the head and others stay out straight. This is due to the percentage of bias-subtraction that is set into that model changing without warning due to very slight delivery changes or green type/conditions, causes the player to constantly make line alterations.
This design flaw cannot be overcome, and is most pronounced on the very narrow models made to defy the rules of minimum bias on the green. The sole shape has to be highly un-balanced to achieve test table pass making a Jekyll and Hyde situation. [ see the test table demo1 video shows balanced sole Professional and highly un-balanced sole Impact model under wobble test]

The "very narrow running" models marketed over recent years are not narrow biased on the test table under the current faulty test, they take as much or more bias as the Test Bowl, known in the trade as the Working Reference Bowl or WRB, and then subtract bias when played on a green, i.e. they take less bias than the Test Bowl on the green. Our greens testing has shown the WRB to take approx 1.75 mtrs of draw over a distance of 30 mtrs on 16.5 sec green, many recent models play narrower than this but are given legal status as World Bowls standardised testing to be only done on a table without the cant/wobble test and deleted any form of green-based testing or comparison.

The result is a double-standard for bias and has had a major impact on the game and bowl models are now sold that were illegal prior to this decsision. It is our considered opinion that any bowl played that does not take at least the bias of the Test Bowl/WRB does not comply with Rule 8.2.1/52.2.1 and is therefore illegal.

[ NB. A bowl tracks down the green based on the shape on the crown. At the top there are essentially 2 wheels of different sizes working against each other.
You could get the same effect on your car by changing the tires on 1 side to a smaller diameter than the other. The greater the difference, the more pull to one side if you took your hands off the steering wheel. ]

NZ suspended the 10 year test program in NZ 1983 after introduction of sand-type synthetic grass. The Board knew that many sets would fail at their next test after playing on sand and decided to hide that info from players to avoid political fallout. The Rules allow for member nation to opt out of 10 year testing, so they chose that option.

To fully assess events affecting this sport ,bowlers need to understand there was no Rule Book change to minimum bias, there was no change in the bias to the Test Bowl, just the the location of where testing must take place and how the test should be carried out. World Bowls deleted the former agreed testing regulations and wrote their own. It's now evident the relationship between bias seen on the test table and the green was not correctly understood by World Bowls. Manufacturers always knew the difference in bias displayed and allowed for the narrower bias seen on the green. The test table never did reproduce the bias seen on the green if the model was of the variable radius / bias-reduction type..see below, most models sold over past 70 years are this variety.

These very narrow running models are much harder to use and often play erratically due to the sole shape that's required to make the bowl draw wide enough on the test table and pass so-called legal bias test and then go much narrower on the green and not pass the legal bias of previous years greens testing. The main difference between the array of models seen in recent years is mostly the amount of bias that disappears as they run down the green, they all have virtually the same bias on the test table. Clearly then the narrower a bowl runs on the green the greater the in-balance in the sole shape explained below and the more unstable it will play, the result is usually a predominince of over-weighted run shots.

If you are new to the game of bowls there is a lot of info to catch up on. Bowls are not all the same, black or coloured and round, and there have been a lot of changes recently. Drakes Pride have recognized a problem that many players in NZ have found when purchasing bowls while travelling in Australia, after playing a few months back home at their club they're having consistency problems. The bowl suffers from inconsistent turn-in at the head, what went great in Aust doesn't in NZ. { A by-product of the inherent design flaw of bias reduction technology on very narrow running models }

Our greens are different and in some cases not high quality and are probably the fastest in the world. To make matters worse some clubs with normally very good green quality are experiencing problems over past years with noticeable deterioration. Some players who have joined the "go narrow"club have found their bowling is now hot and cold, and some have been told by administrators to purchase "narrow running bowls" to get into rep teams.

The technical part:
If 2 different models have the same bias on the test table but then 1 has only 60% of that table bias on the green, the narrower bowl has to negate or subtract the other 40% as it goes. Something has to be different in the engineering of the 2 sets. Herin lies the problem, in order to take a consistant 60% bias line and turn-in there has to be consistent bias read from the green onto the bowl to get the same 60% on every delivery. If a bowl changes to subtracting even more of its stated bias then it will take a narrower line and won't arrive at the jack as intended.

This usually makes the player adjust the line on the next delivery which switches back to normal and again has the bowl finishing on the other side of the head in the wrong place. Players are making line changes based on where the last bowl finished and in this example line direction was never the problem, it's green conditions or non-virtical delivery angle that's giving different bias percentage on different deliveries. Delivery angle, any wobble, green quality, grass type and especially windy weather conditions have a marked effect on this bias-subtraction bowl type. Although very poorly performing, we can make bowls that go almost straight on the green and it's reasonable to assume the game is easier to play with very narrow running bowls. Not true, they come with "strings attached" having their own set of difficulities due to the design flaw that cannot be overcome and generally play much better indoors.

Bowlers are discovering our new range of models, Striker,Corsair and Delta that have been engineered to have the flatter finish many players want these days but most importantly have consistent turn-in. There is little point in playing a set that only ocassionally lets you play at your best.

Points to remember:
A bowl is only "reading" the green and acting accordingly. Sometimes a wider draw set will go very narrow especially on a heavy or wet green and a narrower running model can sometimes have a lot more turn at the finish than it would on a hard and fast green. You may also experience a much wider draw on the forehand than normal and almost no draw on the backhand, usually caused by cross-wind and angles will change playing from the other direction. Various playing surfaces can have your bowls doing something different to normal when they are heavy.

Frequently Asked Questions

Q. Why has my play deteriorated recently?

A. The 2 main reasons for poor play are:
a] playing on sand-filled synthetics that sand your bowls as you play thereby altering the bias. As there is no current rule to test bowls many players take this to mean there is no need to test. NZ has the highest failure rate of bowls not complying with the rules, approx 60% we've checked in the past 9 years.

b] changing to a narrow running model that simply cannot work due to the inherent design flaw. They require perfect greens, no wind and very consistent delivery with no wobble, many players deliver from a greater height as they age or pay little attention to the way the bowl arrives onto the green. Older, wider drawing sets, and balanced sole type are much more forgiving than the recent models that have a high degree of un-balance on the sole to achieve the narrow path on the green but still have full legal bias on the table. Any model that goes more than about 10% narrower than 1.75 mtrs of draw on 17sec green is employing greater amounts of the un-balanced sole design and will not play consistently in this country. About 12 models sold here in the past 9 years fall into this category.

Q. Why are some bowl models much easier to play, why do some models go so narrow but play so erratically and are they really legal?

A. This is the most asked question/s and can be a bit confusing.
All bowls are currently considered legal as defined by the Rules if they have at least minimum legal bias as set down by World Bowls and group within 100mm on a test table. But due to the sole shape engineering many recent models take much less bias on the green than is present during table testing. These models subtract or negate bias as they run down the green, the Test Bowl [type A] does not do this and presents all its table bias on the green. World Bowls has not allowed for this in their test proceedure...a topic covered on the tech issues page

Basically there are 2 types of bowls, non sole-shape sensitive and sole-shape sensitive based on the shape of the crown which could be descibed as self-correcting or "balanced arc, or uniform shape sole"' and non self-correcting "un-balanced arc or variable geomertry sole shape" The uniform arc type including the WRB test Bowl does not subtract bias when played on a green and the variable geometry sole models do.

Sole shape and effect explained: [ simplified ]

Variable geometry bowl models will go narrower when wobbled and the sole shape or type is then displayed. Most of the old sets did this but had so much bias that they still went quite wide even with some bias-subtraction happening. If this happens it has a dual-sole or split-running sole i.e the arc of the sole that touches the green is made up of 2 different shapes joined together. We could call them A at the apex and B on either side. The A part at the apex tells the bowl to turn and the B part tells it to go straight. Neither win out so a compromise is made as to the actual bias path on the green and some bias subtraction happens.
On the test table only part A touches and shows all its bias. On the green both A & B touch and so the bias-subtraction part kicks in. The difference is in the size of the footprint contact between the table material and the green, like between your kitchen lino and carpet in the lounge.
The only way to see the final green result on a table is to wobble the bowl which averages out its sole shape, at present not allowed as part of the test and not needed during the years of greens testing.

The "variable geometry arc" type has the advantage of being made to take different tracks down the green and go narrower than stated bias, play the weighted knock-on shot a little better but can suffer in even quite normal weather conditions as many bowlers can attest to with models sold here over past few years that simply don't play well outdoors, i.e. you get varied results due to the sole geometry. You either play the odd brilliant game or just plain terrible, consistency is hard to come by. The biggest problem is the greens we have in many parts of New Zealand and sand filled synthetics that won't allow some bowl models to take consistent lines down the green and have consistent turn-in at the finish. The balanced sole bowl overcomes these problems but can't be made to take the very narrow line down the green that some players want or have been told to buy to get selected in top teams or rep play.

Drakes Pride models Professional [made since 1986] and Special [1992] have the "balanced sole type A" design and our new models Direct, Corsair and Delta now give players the choice of flatter finish bowls that have the consistent line and turn-in of these well known models as they are based on the balanced sole technology.

Q. Which model/track should I use?

A. Depends on the type and speed of the green and to some extent your skill level. In general the Ultra, Professional and Delta are slightly easier to use and more forgiving than narrower running bowl models which require good weight control, but play the weighted shot on fast greens better.
The Drakes Delta model takes a banana arc to the jack and is good for greens running 13-16 seconds.

The Corsair adds to this by holding a straighter line for a longer distance before even flatter entry to the jack, and is recommended for 16-19 sec greens.[our biggest selling model ]

The Striker SF is a slightly narrower version of the Corsair with longer finish and is our narrowest model without using too much vrg on the running sole shape. This model is the only VRG sole design that behaves like a balanced sole model, has a wide footprint for stability and we rate the Striker as the best competition model we have sold in nearly 50 years.

In general the trend in the last few years is towards narrower running models. Bowls that were considered narrow 15 years ago are now put in the too wide category. The dilemma for players who have plugged into the really narrow game of late is consistency. Quite simply it's just not possible to make bowls that go very narrow on a green, but still show full bias and pass on a test table, play consistently on most NZ greens. The new Drakes Pride models now give those players wanting the flatter entry to the head sets that have our robust tried and true playing characteristics. Our new engineering has resulted in the most consistent play of any bowls I've seen in NZ over the past 40 years.

Q. How do I know what type of bowl I have?

A. If you deliberately wobble the bowl and it takes virtually the same line as non-wobbled you have type A or balanced sole type. If it goes narrower than normal delivery it is type BAB including all the very narrow running models of the past 20 years

Q. How do I tell if my set is narrow or wide in comparison with the Test Bowl?

A. It's 41 years since sets were regularly tested so the comparison with the Test Bowl is a vague recollection for some and a total unknown for those entering the game since. Our greens testing has shown the Test Bowl to take approx 1.75 mtrs of draw over a distance of 30 mtrs on 16.5 sec green speed. [ If your set takes a narrower line than this, it is a model that would not be legal in the days of both greens and table testing.] This measurement is the distance from the centreline out to the place where the bowl went to its maximum curve before heading back to the centreline, not a reference to a marker peg on the far bank.

Q. Why do my bowls seem to go much wider than previously?

A. Many players don't check the measurement properly and often feel their set has suddenly changed. This is due to using the marker pegs on the bank at the end of the green to gauge their line and these pegs often are changed by the greenkeeper to get an extra rink for a big tournament. If the makers are usually 4mts apart but changed to 3.8m your "normal line" is now outside these and make you think your set has suddenly changed. Rink marker pegs can be 3.6 - 5.8 mtres apart, remember where you aim is not how wide your set goes. Get your bowl to finish at the jack, walk out after your bowl and drop a coin at its widest point and then measure or step out the distance to the centreline, this is how wide your bowl actually goes.

Q. Do I really need more than 1 set?

A. In a word, yes. If you like narrow running bowls you will need an easy-play set for inferior or windy greens. If the only set you have is a wider draw
set, competing against narrower models that play the weighted up-shot well is very difficult as the greens speeds up. It may play brilliantly on a 15-16 sec green but your options are restricted to only draw shots on a 19sec green. The new models are designed to give the same range of shot options as green speed get quicker.

Q. Which model goes best in wind?

A. All Drake models take consistent lines on windy greens, we've built our models to cope very well on NZ rather windy greens.

Q. Should I buy heavy or xtra-heavy weight?

A. Bowls are made from 3 grades/weights of material, medium, heavy & xtra-heavy which are descriptive terms only and do not signify a specific weight. As the various models differ slightly in shape, therefore differ slightly in displacement or weight. Modern slim-style bowls are often slightly lighter in weight than older broad shouldered bowls, adding more arguement towards extra heavy which is only available in black. DP coloured bowls are only available in heavy-weight.

Q. Is the weight of an Xtra-heavy size 3 the same as a heavy size 4?

A. No. As a general rule the 3XH bowl is approx 60% of the weight difference between a 3H and 4H.

Q. Why do my bowls track wider than my friends set?

A. While 2 identical sets will take the same bias on a test table, the player's delivery has a great effect on the actual path up the green.

Q. Why do my bowls pull up short as compared with another player's?

A. It is surprising how often we get this comment from bowlers, especially those who have down sized.
It is not possible to make a judgement unless you use both sets, and there is a re-learning process when changing your set, especially from an older wide drawing model. The weight, size and footprint on the ground all have a bearing.
While there may be a perception that your opponent has a set that gets upto the jack, your set will also if you give them slightly more weight.
Remember no set of bowls will jump out of your hand and go up the green on their own.