US company takes tank testing to open sea

US naval architecture and research company M Ship Co says that its REI (rapid empirical innovation) technology allows it to take hull testing away from the towing tank and test scale ship models at sea.

The company says that its REI approach allows models to be towed in real-life weather conditions by a self-powered FLOWT (fast, low-cost, open-water testing) platform. Among other claimed advantages, this is said to save designers, naval architects and builders 50%-80% of the cost of using a conventional towing tank, without sacrificing accuracy or waiting for tank access.

“The REI programme certainly is an unconventional approach to conventional tank testing,” said M Ship Co executive director and co-founder Bill Burns, describing the FLOWT platform’s 6m pontooned hull, which employs knife-edged hulls, multiple computer work stations and various adaptable structures, “but the implications of it are of far-reaching importance to the people who shape our industry.”

Burns explained that two different hull models can be evaluated in tandem, providing direct hull-to-hull comparisons. After the hulls are fabricated they are outfitted with identical high frequency accelerometers that provide comprehensive motion and acceleration comparisons. The models are then tested on the FLOWT platform, providing real-time force, trim and acceleration measurements and analyzing parameters such as power, speed, payload, fuel efficiency, range capability and ride quality.

“We can offer test programs that can use a constant baseline with a new design or test two new designs at the same time,” said Burns. “Fully instrumented, rough water testing at the same time is unique and offers immediate and unequivocal comparison of ride quality performance between designs.”

REI applications include validating CFD; comparing different designs with instant results; developing designs for market differentiation; and proving concepts for patentability and investment. The company says that accuracy of data has been validated at the US Navy’s David Taylor model basin.

“The REI results exceeded our 95% threshold,” said Burns. “The REI calm water resistance measurement has been shown to have an absolute accuracy of 4% at 5 knots model scale and improves to 3% at 15 knots model scale. The results are well within the scatter range you would expect between different tow tanks.