Screen-shot of a predicted swim time based on a particular time of commencement and swim direction


OceanCurrent ‘game’ helps Rotto swimmers plan their race

Swimmers in tomorrow’s annual Rottnest Channel Swim in Western Australia will be able to plan a tactical race thanks to a new tool created by IMOS OceanCurrent.

A new online tool allows swimmers to interact with data on predicted currents in a game-like situation. By selecting the time the swimmer will set off from Cottesloe beach, and then entering the direction in which they’ll head off, the tool predicts the time it will take them to reach Rottnest Island.

Developers of the swim planning tool, Dr Madeleine Cahill and Roger Scott, wanted participants in the race to be able to access the ocean current data in a way that was fun, intuitive and most importantly, useful.

“We’ve presented data on current forecasts in such a way that swimmers can easily understand it and apply it directly to their individual race.

“Swimmers know when they’ll be heading out from Cottesloe so we’ve helped them plan the optimal direction in which to swim out from the beach,” said Dr Cahill.

The OceanCurrent swim planning tool uses current forecasts from the Oceans Institute of the University of Western Australia. The final update to the Rottnest Island channel forecasts occurred this morning, so the data that is live now is the best predictor of currents the swimmers will get. 

Today’s updated forecast is for weaker northward currents than previously forecast and only occurring in the morning. Later in the day, the forecast is for westward flow providing a small boost to slower swimmers and those starting in the later wave times. The westward flow, however, is highly dependent on small scale weather features which are hard to predict.

Looking at the forecast currents throughout the day, Dr Cahill believes for the early wave times, heading slightly south may still pay off but for anyone who will be still be swimming after noon, then heading straight for the finish line is probably their best bet.

Dr Cahill acknowledges that there are multiple factors influencing an open water swimming event but believes that the new online tool will still help swimmers to optimise their race.

“Of course the weather on the day is a big factor and each swimmer’s ability and fitness counts for a lot, but at least we can help them use the currents to their advantage,” she said.

The tool is easy to use and with a click of the mouse swimmers can see what the current is predicted to do at hourly intervals throughout the day.

Dr Cahill believes that the tool developed for the Rottnest Channel Swim can be adapted for all sorts of ocean events and applications. 

“There are open water swims all over Australia that could use such a tool and we’ve been thinking about how we could incorporate other data, such as winds, to make this a valuable resource for yachting,” said Dr Cahill.

The IMOS OceanCurrent portal provides up-to-date maps of surface currents and temperature in Australian waters. The OceanCurrent team point out that sea surface temperatures in this region are slightly cooler than normal for this time of year and that swimmers should prepare appropriately.


OceanCurrent Rottnest Island swim planning tool: 

Categories:  WAIMOS, news, Node, Facility, IMOS OceanCurrent