Most sports clubs are a member of a National Governing Body (NGB) e.g. FAI for soccer, GAA for gaelic games, IRFU for rugby. As far as I'm aware there are watersports NGBs - Irish Sports Council website will list contact details.
NGBs generally take out Public Liability and member to member insurance for their affilitated clubs (cost is usually included in membership fees). This type of insurance would cover you in the event of a club official being sued.
My advice:
If you are a member of the NGB - contact them and get confirmation of what insurance is in place for your sport. If the NGB does not have insurance covering individual clubs, it at the very least will have arrangements in place with an insurance company that member clubs can become part off.
If you are not a member of the NGB you probably should be as in the event of an incident, the first thing your club will be asked is if it is a member of NGB - clubs outside NGBs are looked on very unfavourably as NGBs usually make sure their members conform with best practice.