Hi,
You need to write a draft of a sponsorship request letter to send to companies. Tell them what you are doing, how it can benefit their company, and what you want from them, including whether you want to meet with them. If you have good results, tell them about those, and tell them about your plans for the future. Tell them how much exposure you will get for them. What form will your advertising for them take? Will there be TV coverage, and to what extent? Can you wear logos on your clothes? In the Olympics?
Anyway, write a draft and post it here. Then we can try to help you with comments.
I'm interested, because I'm also a triathlete, although not an Elite. In Ireland, do you do ocean swims? Sounds cold. In Ontario, it's all lake swimming.
Best wishes, Clive