The houseboats of today - huge, slow moving, exotic barge used for leisure trips - are the reworked kettuvalloms of olden times. The original kettuvalloms were used to carry tonnes of rice and spices - a standard kettuvallom can hold up to 30 tonnes - from Kuttanadu to the Kochi port.
The kettuvallam or 'boat with knots'- was so called because the entire boat was held together with coir knots only - not even a single nail is used during the construction. The boat is made of planks of jack-wood joined together with coir. This is then coated with a caustic black resin made from boiled cashew kernels. With careful maintenance, a kettuvallom can last for generations.
A portion of the kettuvallom was covered with bamboo and coir to serve as a restroom and kitchen for the crew. Meals would be cooked on board and supplemented with fresh fish from the backwaters. Today, the tradition is still continued and the food from the local cuisine is served from the Kuttanadu localities, on board.
When the modern trucks replaced this system of transport, some one found a new way that would keep these boats, almost all of which were more than 100 years old, in the market. By constructing special rooms to accommodate travelers, these boats cruised forward from near- extinction to enjoy their present great popularity. Now these are a familiar sight on the backwaters.
Today, the houseboats have all the creature comforts of a good hotel including furnished bedrooms, modern toilets, cozy living rooms, and kitchen. Parts of the curved roof of wood or plaited palm open out to provide shade and allow uninterrupted views. While some boats are poled by local oarsmen, most are powered by in board engine. Boat-trains - formed by joining two or more houseboats together - are also used by large groups of sight-seers.