A Kettuvallams is about 67 feet in length and 13 feet wide in middle and is made of materials like bamboo poles, coconut fibers, ropes, bamboo mats, carpets and the usual wood Anjili. The hull is a series of wooden planks, long cut and carved and tied together using coir with coconut fibers stuffed in between. The hull which is made of hundreds of fine but heavy-duty planks of jack-wood and is held together by coir knots (not a single nail is used). This framework is then coated with a caustic black resin extracted from boiled cashew kernels which lasts for generations. The Kettuvallams is motorized and is steered in deep waters by means of oars. Long bamboo poles or 'punts' are used to propel in shadow areas. Bamboo beams sprouting off on the sides are used as foot holds for the same. Bamboo is used for the framework of the roof and splits of bamboo are used for weaving mat for roofing.
Basically the Kettuvallams was designed for transportation of materials and so many changes had to be made to make it a tourist vehicle like increasing the height of roof to get enough space for headroom, laying a plank all through to make it comfortable for walking and seating and like-wise providing sufficient windows and openings for light, airflow and view.
Today’s houseboats are designed by keep tourists in mind and so most of the features are comfortable and luxurious. Almost all houseboats have 2 bedrooms with private bathrooms. The bedrooms are fairly small and simple. A covered lounge will be there with open sides to make most of the views and an upstairs with uncovered deck for even better views. There are even huge luxurious houseboats with up to 10 bedrooms, including facilities like air- conditioning, televisions etc.