What's the Difference?
The difference, besides cost, resides mainly in the quality, diameter and manufacturing of the aluminum tubing which is used in the spars. Quality is a function of the series number of the Aluminum thus, 7000 is higher in quality than 6000. As the quality goes up, so does the stiffness of the spar, so 7000 is also stiffer than 6000. Coincidentally enough, as the series number goes up, so does the cost. The diameter of the Aluminum tubing also affects both performance and cost. Larger diameter tubing is both stiffer and more expensive. All masts use the same diameter tubing, so the boom diameter is where it really counts. Most booms are either 40mm or 32mm, the 32mm being much cheaper and down right bendy. The manufacturing method also impacts cost and quality of the spar. A rolled and welded tube is much cheaper to produce than an extruded one. (extruded just means that it is formed in one continuous piece) Theoretically, an extruded spar is both stronger and stiffer. You can be fairly certain that an extruded Optimist spar is stronger but, don't count on it being noticeably stiffer.
What Should I be Looking For?
Choosing the right spars for your Optimist can be a confusing task but, here's some advise from our resident Optimist Coach. There are three major factors to consider when choosing a spar set, skill, weight and utility.
Skill is simple, it's pointless to spend $500 on racing spars for a child that can't sail to windward. On the other hand, if a sailor is a beginner and shows both promise and a commitment to improving their racing skills, then it's probably a good a idea to "cure the upgrade bug" and get a top notch racing spar early on, it will make a difference.
Weight is another important factor. Most Optimist sailors will achieve better performance from a stiffer spar set. Strong, stiff spars allow the sailor to trim the sail with out the spar distorting, giving the sailor ultimate control over the shape of their sail. The exception to the stiffness rules are very light sailors. (under 65 or 70 lbs.) Although a stiff mast is still very important, a bendy boom can be helpful to lighter sailors. Lighter sailors struggle to control the boat in heavy winds, a bendy boom can help depower the sail in two ways. First, the outboard end will bend in puffs, opening the leach and depowering the sail. Second, when sheeted hard, it will bend from the middle, pulling the belly from the draft of the sail and flattening it. Again, this depowers the sail.
Utility is simply a function of your intended use. Serious competition demands a good set of racing spars. The Optimist class has allowed varying levels of equipment so that each sailor may tailor their boat to a specific set of needs. The result is very inexpensive, long lasting spars for instructional purposes and more costly high tech racing spars for the serious racer. A learn to sail program has little use for racing spars. In fact, moving up to racing spars can be a serious detriment to instructional programs. Moving from club spars to racing spars requires accountability for all the blocks, plugs, pennants and pins that go with them. A club spar is self contained with no unattached pieces to lose.