Halve engine noise on RCT Spiegelgracht

By Joost Hellinga

In November 2018, the ship Leidsegracht of Rederij Cement Tankers (RCT) successfully switched to DEX QM oil. After the Caterpillar 3406E main engine was fitted with DEX QM MOTOR 10W40 and the gearbox with DEX QM GEAR 100, the crew immediately noticed that the engine noise produced was significantly lower. She appeared to have become much quieter. As a result, it was decided to carry out follow-up tests on another of RCT's vessels, the Spiegelgracht. On this ship, the crew observed increased noise in the accommodation. A reduction was therefore very welcome. The Twin Disc Marine gearbox was therefore fitted with DEX DP2 ISO VG100, and decibel measurements before and after should reveal that noise reduction. 

The Spiegelgracht's gearbox is of the Twin Disc type and is driven by a Caterpillar type 3406 DITA main engine.
It is from 2001 and had about 27000 running hours at the time. The current oil used is Total Caprano TD 30 and has been in it ca 1000 running hours as of September 2018.

• Brand: Twin Disk marine 
• Model No. MG5114 
• BOM No. S11106 
• Ratio No. 343 1 
• Serial No. 5GS060 
• Oil Capacity: 5.2 gallon ~ 20ltr 

Apart from the shipping company's desire to reduce noise at the gearbox, the cabinet shows no (specific gearbox) problems. 

Temperature measurement: The friction difference between the two oils, can be measured by recording the temperature in the gear. This was measured in two runs above the gearbox, running at full power (1800rpm): 

• Test 1 = Total Caprano TD30 - temperature measurement 83.9°C 
• Test 2 = DEX QM GEAR 100 - temperature measurement 77.2°C 

Conclusion: Directly above the gearbox, a sharp reduction in noise at all speeds was measured. We see the following noise reduction when using DEX QM GEAR 100 lubricating oil: 

• Idle speed 1650 rpm 1800 rpm 
• Noise reduction minus 1 dB 
• minus 3.4 dB 
• minus 3 dB 

The DEX QM GEAR 100 oil delivers a significant reduction in noise here, compared to the Total TD30 oil. The decrease in noise is a direct result of less friction in the implement. DEX QM oil claims to give less friction as a result of their Quantum Mechanics technology treatment on the base oil. This is seen in practice through a significant drop in temperature in the implement, reduction in noise, fuel savings and, in the longer term, noticeably less wear on the implement. According to the Decibel scale, a difference of 3.0 decibels represents a halving or doubling of noise. In this measurement of -3.4 decibels, the noise is more than halved. 

The decrease in noise experienced by the crew on Leidsegracht was clearly shown with underlying test on Spiegelgracht. On Leidsegracht, the reduction in friction in the CAT main engine and gearbox even leads to a reduced fuel consumption of over 5%.