Nothing is 'greener' than a nozzle
10 May 2016
Nozzles are good for the environment and for your wallet. It was long ago demonstrated that a nozzle improves thrust and/or increases speed, saves fuel and greatly reduces vibration – and has ‘saved' many marriages on board.
Damen Marine Components is based at Nijverheidsstraat in Hardinxveld. It was here that former ‘Van de Giessen’ made a name for itself with its nozzles. In fact, this 150-year-old company was manufacturing under the Damen umbrella as long ago as 1979. The name Van de Giessen disappeared in 2006; but the knowledge remained with DMC!
The question is: which nozzle suits your ship and the type of cargo you carry? A DMC Optima nozzle type, for example, can bring a large push tug, like Veerhaven III, with six loaded barges from full speed to a standstill within the prescribed stopping distance. Nothing special? Winning the class certificate with two engines (one stationary) is telling!
Ins and outs
We talk to René van Middelkoop of Sales & Marketing and sales engineer Kees Oevermans, who both know all the ins and outs of nozzles. How is it possible that a nozzle increases thrust when moving forwards but also in reverse?
"The Optima nozzle is a type 19 A (forward) and 37 (reverse) combination. The working area of the propeller is shifted towards the rear. It is a design arrived at through practical experience and by listening carefully to users. Our experience shows that a nozzle delivers a 20 to 25 percent improvement in thrust compared to an 'open propeller' configuration."
"We manufacture specifically for each customer. When it comes to custom fitting or if the installation deviates from the norm, we provide advice and aim for the most profitable solution. We don't promise anything we can't deliver. Our work doesn't stop with a quotation; we are there at delivery and follow the performance of our products on board for some time afterwards."
The Optima, Wing and VG 40 are standard types. A number of these are in stock and immediately available in 1,500 to 1,900 millimetres. DMC has a strong partner in Damen Gorinchem. Nevertheless, Middelkoop and Oevermans work independently and privately. Over the years, they have become accustomed to customers dropping by to talk about thrust.
The Damen Optima nozzle has been granted an international patent. This type is also the most commonly installed. A quick glance at the river reveals a handful of vessels fitted with Optima nozzles.
Damen has a long tradition in shipbuilding and components, such as nozzles, rudders and marine winches. The company installs these products worldwide in ships, ASD tugs and large and small work boats. Quality is all about sheet thickness. The philosophy behind this is that the nozzle frequency needs to be higher than the blade frequency. Stiffness is the philosophy; that's why DMC manufactures products with high dimensional stability and an entirely stainless steel internal form from one single sheet. This reduces the amount of welding required and consequently the price. Strategically positioned zinc pieces increase durability and counteract galvanic corrosion.
Source: De Binnenvaartkrant no. 25, Maritime Industry special, 10 May 2016