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 by the Kuttanad localites, 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 and in Alleppey alone, there are as many as 120 houseboats.
While converting kettuvallams into houseboats, care is taken to use only natural products. Bamboo mats, sticks and wood of the arecanut tree are used for roofing, coir mats and wooden planks for the flooring and wood of coconut trees and coir for beds. For lighting though, solar panels are used.
Today, the houseboats have all the creature comforts of a good hotel including furnished bedrooms, modern toilets, cozy living rooms, a kitchen and even a balcony for angling. Parts of the curved roof of wood or plaited palm open out to provide shade and allow uninterrupted views. While most boats are poled by local oarsmen, some are powered by a 40 HP engine. Boat-trains - formed by joining two or more houseboats together - are also used by large groups of sight-seers.
The new generation Houseboats are renovated forms of original Kettuvallams. The modern type House Boat have all the creative comforts like a Hotel ie well-furnished bedrooms, modern hygienic toilets, cosy living rooms, dining area, beautiful kitchen and in some cases even a balcony for angling. Most of the Houseboats are powered by remarkably unobtrusive inboard diesel engines and use solar energy for power requirements.