July 16, 2001. Copyright 2001. Graphic News. All rights reserved.

A fishy tail to power boats

LONDON, July 16, Graphic News: Everyone knows the Japanese are crazy about fish, and now a Japanese inventor has built a boat that ÒswimsÓ like a fish.

Akira Tomizawa, 72, is convinced that Òfish power,Ó or a motor rigged to a device that wiggles like a swimming fishÕs tail, can do the job better than a conventional propeller.

Tomizawa has attached a large realistic, articulated fish -- modelled after a tuna -- under a catamaran. The fish swims powered by a motor and pushes the boat along.

ÒI would like to use this fish motor and enable a real boat to travel at speeds of 60-125mph (100-200km per hour), just like a bullet train. IÕd like to see that happen,Ó said Tomizawa at a recent sea trial off central Japan. The test proved that TomizawaÕs fish-boat can travel up to 1.5 mph (2.4 km per hour).

Tomizawa started researching his fish-boat idea when he was 20-years-old. He bought himself an 8mm movie camera and shot hours of footage of swimming fish from all angles to figure out how they can swim so deftly.

He then got to work drawing up the blueprints for his fish-shaped motor, choosing a tuna as a model, because tunas are capable of swimming at speeds of up to 50 mph (80km per hour).

Tuna fish with streamlined bodies and a stiff, crescent-shaped caudal fin and tail, move rapidly through the water by contracting and relaxing a succession of muscle blocks, called myomeres, alternately on each side of the body.

Starting at the head and progressing down toward the tail the contractions result in a series of waves travelling down the fishÕs body. The rear part of each wave thrusts against the water and propels the fish forward. 

Over the decades Tomizawa has put up with the sceptical remarks of curious onlookers and scientists. His successful full-scale test swim has now proved the concept that his six-foot (two-metre) long mechanical fish can swim just like the real thing -- but it dosenÕt taste as good as a plate of maguro sushi.
/ENDS