Your best bet is probably air freight. Expect to pay about $8 to $15 per kg. The way the calculate weight is actual weight vs. volumetric weight. What ever is higher is what gets charged as the actual weight.
Your first stop should be checking with the airline you are flying with. It's called "unaccompanied baggage". It essentially means you are sending your gear as air freight by dropping it off at the airport a few days before departure. The airline then tries to send the luggage on the same plane or around that time. In ideal situations you will be able to pick up your gear at the other end within a day of arrival. I haven't heard this working on overseas flights but it certainly has worked for people flying domestically within Australia.
Your second stop would be checking with a dedicated air freighter company. They are usually a bit cheaper than your first option.
Third option could be checking with the luggage storage facility at the airport. I know the guys at Terminal 1 in Singapore have international airfreight as a service option. It's cheaper than using Singapore airlines. Try Sydney or Melbourne airport baggage services to see if they have this option or might put you on to the right people.
Lastly, try various transport companies that specialize in helping out backpackers getting their excess luggage back to Europe (it's called Luggage Forwarding). You'll find flyers and adds in travellers mags at most major hostels and tourist locations in both Melbourne and Sydney.
Another option would be to see if you can cancel your ticket and actually choose an airline that takes windsurf gear without too much fuzz.
Did you know for example that if you fly via the US you are allowed 2 x 32 kgs of luggage vs. the measly 20kg in economy via Asia? Also, some airlines allow you to take a surf board bag instead of the second luggage item.
If you are traveling with windsurf gear you should always book your ticket with an airline that takes windsurf gear for little or no money... not the cheapest ticket you can get.
BTW, another option would be to only take a board and actually buy brand new sails/ masts and boom in Europe. Gun Sails for example will make you a pretty good deal if you buy say 3 sails plus mast plus boom plus extension and they usually offer free shipping.
Also take a look at these web sites:
www.globalsurfers.com/surfboard-airline-charge.cfmwww.flyingfees.com/www.surfline.com/surf-news/boardbag-fees-airline/18407?id=15425(there used to be a site which had a complete listing but I lost the link, maybe someone here can provide that)
They will list excess luggage policies of the different airlines. And what ever you do ALWAYS notify the airline in advance that you will be bringing a big surf board bag and get them to confirm the charges and get what ever they promise in writing.
