1.1 the principle of Marine diesel engine selection

Except according to the sailing ship type, load, speed, regional factors such as the design host power ship size, but also in accordance with the purposes, work time, work mode determine the host load size, choose different reinforcement degree of wood oil machine.
As a ship machine propeller matching diesel engine power reserve, to reasonably consider when should give full play to the dynamic performance and fuel economy of diesel engine, and diesel engine to prevent overload.

1.2 Marine diesel engine spectrum and use is recommended

Marine diesel engine is based on the characteristics of all kinds of vessels and their own ability of power calibration, with the configuration of the diesel engine, calibration of different speed and power, make up the department of Marine diesel engine.
The user needs to according to different purpose and use features on.

The select principle of all kinds of ship propeller, gear box

1.3.1 all kinds of Marine propeller speed range (recommended)

In order to play the best efficiency of propeller, analysis and statistics of all kinds of Marine propeller speed range is as follows: type (check the professional classification) speed range r/min large cargo ships 60 ~ 120 small and medium-sized ship 250 ~ 360 medium-speed passenger high-speed passenger ship 600 ~ 400 ~ 500, 1200 fishing boats in 250 ~ 360 trawlers 360 ~ 150 diesel engine with gear box, the calibration speed divided by the gear box of the ratio of diesel engine propeller speed should be attached to the scope of the above requirements, otherwise unable to achieve the ideal effect.
 

1.3.2 selection of gear box

Different USES of the ship, the gearbox reduction ratio and propeller diameter is not the same: cargo ships and fishing gear box reduction ratio and propeller diameter value is relatively large;
Passenger ships and official ship numerical is relatively small.
 

Four kinds of main points of the match of the ship

1.4.1 high-speed passenger ship matching points.
 

High-speed passenger ship generally refers to the speed of 16 (more than 30 km/h) of the ship, is characterized by light weight, work time is generally not long, the tail shaft speed is high, the higher requirements on diesel engine weight.
So when selection to choose high speed to strengthen high degree model.
Main engine revolution to choose 1800 ~ 2300 r/min.
Gear ratio generally choose 2 ~ 3.
Should retain 10% of the power reserve of high speed, so should ensure that the host in full throttle when matching propeller while sailing the high speed of 103% power speed per hour.
According to the rated speed and navigation is to make sure that the load diesel engine about 90% of the total load, speed still can guarantee the same when the hull resistance increased.
If the ship is run continuously for a long time, in 2400 hours of work time (e.g., the long-distance passenger ships), should be chosen with the configuration with a power transmission speed small hosts.
 

1.4.2 commercial ship load matching points.
      

Commercial load ship is the feature of gravity and load is larger;
Inland commercial load boat commonly used speed under 10 ~ 12 km/h, run continuously for a long time (years working time in more than 4000 hours);
Commercial load the ship on the efficiency and reliability are concerned.
   

Diesel engine power matching: the data provided by the ship design unit shall prevail, and design units or the user can also use 1 horsepower with 2 tons of weight (not including the weight) experience as the basis of preliminary selection, and then check the actual speed can achieve.
The Yangtze river and coastal commercial ship load due to operational speed (10 section above), high power need to match bigger, usually can use 1 horsepower with 1.5 tons of weight, and the grand canal need speed lower section (7), power can be smaller, but the best don't more than 2.5 tons load horsepower.
       

Unless there is a small load (below 50 t) high-speed transport, to consider the fuel economy, general download heavy carrier not recommend the use of more than 1800 r/min speed models.
      

Gear box choice: because of the Marine gearbox is only one speed ratio, load when the ship started in light load, overload, propeller characteristic is different, can be both difficult to match.
The selection of screw and the gear ratio to choose to the overloading conditions shall prevail.
Recommended gear box ratio 4.5 :1 ~ 5:1 ideal, it is not recommended to choose gearbox under a 4:1 ratio, speed ratio too low, with ideal a light load, overload, the torque output is insufficient, diesel engine is easy to show weakness and overload phenomenon of smoking.
 

Propeller matching: should ensure diesel engine at the top of the do check boat shore test, calibration speed diesel engine full throttle speed reached 80% ~ 85%.
Commercial tug and barge carrier reference trawler matching.

1.4.3 the trawler matching points.
 

Chinese fishing boats, 27 meters of fishing vessels is given priority to with wooden boat, 27 ~ 32 meters have a wooden boat, there is also a steel ship, 32 meters is given priority to with steel ship.
Wooden boat construction are individual shipyard, there is no formal design and drawings.
Power matching is user to matching, according to need and experience the trawler including light ship, slip net, fishing boat, etc.
Similar to commercial ship load working condition, the condition for sailing conditions commonly used, the highest speed section 10 ~ 13, operational speed section 7 ~ 9.
According to every tons gross tonnage (load + self-respect) with 1 ~ 1.2 horsepower more appropriate.
Is equipped with large power in low load condition, the following network with wide oil consumption is too big, make the economy worse.
Recommended gear box ratio 4.5 :1 ~ 5:1 ideal, is not recommended to choose the gear box under the speed ratio 4:1.
Speed ratio too low, can't both light load and overload conditions.
With ideal a light load, overload, the torque output is insufficient, diesel engine is easy to show weakness and overload phenomenon of smoking.
In addition ratio is too low, when idle speed too fast, let down the nets or XiaDiao operation.
     

Propeller matching should ensure diesel engine at the top of the do check boat shore test, calibration speed diesel engine full throttle speed reached 80% ~ 85%.
Light boat is light to trap phototaxis fish, usually need a high-power diesel generating auxiliary power.
Auxiliary power required for motor power present efficiency (0.85 ~ 0.92).

1.4.4 trawler matching points.
 

Trawler power main consideration trawl needs, various areas because of practices (double or single drag), mesh size, towing speed is different, the drag force size difference is very big.
Available, so you need to size without ready-made formula can only according to the local model or experience of the mature with a choice of size, power, of course, also to meet the power limitation of fishing inspection bureau.
Trawler commonly used condition for boating and trawl two conditions, so the ship form a complete set of machine blade is different from general fishing boats.
Trawlers trawling for a long time, generally continuous operation for more than a week.
Trawl speed in commonly 3 ~ 4 day, under low speed in order to be able to get a larger drag force, must match the oar diameter propeller (relative with the trawler type).
Diesel engine at low speed torque is small, in order to obtain larger torque output, must match a large speed ratio gear box, on the one hand to improve trawl speed in the cases of diesel engines, diesel engine torque increase, on the other hand to improve torque amplification ratio, increase the torque output.
Recommended gear box ratio above 6:1, if propeller limit diameter is enough big, can match 7:1 even one.
Less than 5.5 :1 ratio gear box is not recommended.
Because the trawler is according to the working condition of trawl to match the gearbox and propeller, and only a speed ratio, gear box in the navigation condition of propeller is bound to be too light, the machine's power cannot allow play, in the process of the sail speed slower.
To solve this contradiction, need to improve diesel engine calibration speed to solve, choose in selection model selection of the calibration speed is higher than the maximum torque speed a lot of models, such as for series YC6M, YC6A series diesel engine maximum torque speed of 1400 r/min, choose 1800 r/min calibration model is superior to the rotational speed of 1500 r/min.
YC6T maximum torque speed of 1100 r/min, YC6T series to choose 1500 r/min model is superior to 1200 r/min. On the matching of propeller, the ideal matching is to ensure that at the top of the static pull test or shore test at full throttle speed diesel engine calibration speed can reach 80 ~ 85%.