My best score over 9 holes is a 42, yet only 2 weeks ago I carded a 116 over 18 holes (best 18 hole score is 95 - shot the day before yesterday).

118 is not a bad score for your first round of 18. A lot of issues come into play that you normally never need to worry about over 9 holes, such as fatigue, dehydration and low blood sugar levels.

There is also a completely different mental strain because you need to concentrate for a lot longer, and the elements that can affect your mental game can be enhanced when you play double the amount of holes as you usually do.

Make sure you have plenty of water to drink or perhaps sportsdrinks like Gatorade. Fast carbs are needed too - bananas, chocolate bars or energy bars.

And you might want to work on some fitness elements.

Playing 18 holes is an entirely different game from playing 9, and need to be learned all over again.

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//Mox
2008 bag:
Mizuno MX-500 460cc 10.5* Fujikura Tour Platform 26.3 stiff. (about to be replaced by MP-600 10,5* UST Proforce V2 stiff)
Mizuno F-50 3w 15* Fujikura Tour Platform 26.3 stiff.
Wilson Deep Red 5w 18* Graphalloy Fatshaft stiff
Cleveland HALO 3i hybrid 22* graphite regular
Mizuno MP-60e forged 5i-PW True Temper Dynamic gold R300 steel
Mizuno MP Black OX raw haze 50/6 GW, 54/9 SW, 58/10 LW
Heavy Putter B3-M
Titleist NXT Extreme