When writer and explorer Thor Heyerdahl led a team of rafters across the Pacific Ocean in 1947, their Kon-Tiki vessel was built out of nine balsa tree trunks tied together.

The local organisers of a charity Kon-Tiki Challenge reckon participants won't have to go to those lengths to make their way across Balluta Bay - though their imagination is the limit.  

Rotary Club Malta, Round Table Malta and Sliema local council have invited clubs and groups of friends to design and build their own homemade raft and race it across the bay on Saturday 16 July, with proceeds going towards Dar il-Kaptan, a respite care centre for people living with disabilities.

The rules are simple. Engines are banned, as are shop-bought paddles (handmade ones are fine). Craft must be built out of chemical-free materials, and any vessel that might pollute the sea in any way will be banned. Any sharp edges must be covered and protected, and vessels which use parts from existing boats will also be banned.

Companies with a keen eye for promotion are in for a treat, as vessels can be branded with logos. 

Provided participants adhere to these rules, wear life jackets and are all able to swim, their design creativity is the only limit on their choice of vessel, said Round Table chairman Simon Soler. 

Vessels will be divided into two classes depending on their size. Rafts which take between 3 and 5 people will be placed in class 1 races, with rafts taking between 6 and 8 racers in class 2. 

The race will get underway at 1pm on Saturday 16 July. Donations to Dar il-Kaptan can be made by sending an SMS to the following numbers: 

5061 7308 - €2.33
5061 7914 - €4.66
5061 8998 - €6.99