Objectives Topics Resources & Notes GAIN ATTENTION Review Homework for chapter 5 Slide 1 OBJECTIVE

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1 6 Inboard Engine Drive Systems 59 COURSE LESSON TITLE PRESENTATION TIME PRESENTATION METHOD MATERIALS REQUIRED Chapter 6 Inboard Engine Drive Systems 2 hours Participative Lecture Ch6 PPT slides, computer, projector Objectives Topics Resources & Notes GAIN ATTENTION Review Homework for chapter 5 Slide 1 OBJECTIVE PRESENTATION Drive Systems Inboard Performance Systems Upon completion of the chapter, the student will have: an understanding of the various drive systems associated with inboard marine engines knowledge of the design of marine propellers and how the various configurations affect the boat s performance basic knowledge of how to perform routine maintenance of inboard drive systems 1. Reduction Gearing Optimizes engine speed and propeller speed Typically 1.5:1, 1.9:1, 2.1:1, etc. Example 2.1:1 means engine is running at 2,000 rpm while propeller is turning at 1,000 rpm Lower speed means higher torque 2. Straight Drive Train The entire drive system is angled to pass through the hull 3. Angled Drive Train Output shaft is offset 8-12 degrees 4. Vee Drive Permits engine to be placed further aft in hull 1. Propellers Blades o number of blades generally increases with power requirements Diameter o outside edge to outside edge across center o larger diameters need more torque to drive them Pitch o distance of advance for one revolution Other characteristics o shape, cupping, rake 2. Propeller Performance Boat speed and engine speed are key Optimize both! Best speed is the rated boat speed at wide open throttle Slide 2 Slide 3 Slide 4 Slide 5 Slides 6-7 Slide 8 Slide 9

2 60 6 Inboard Engine Drive Systems Objectives Topics Resources & Notes 3. Jet Drive Slide 10 Flush mounted for shallow water operation SUMMARY HOMEWORK 4. Specialty Drive Systems Trolling motors are electric motors used for low speed application Bow and stern thrusters are used for close-in maneuvering Routine Maintenance Oil level Transmission fluid level Impeller pump Transmission oil cooler (may clog with impeller bits) Water intake strainer Hoses and clamps 1. Vee Drive Maintenance Same as standard inboard, plus Keep an eye on the transmission 2. Propeller Maintenance Inspect for chips, nicks, dents, etc. Check for cavitation damage (small pits) 3. Jet Drive Maintenance Same as standard inboard, plus Special manufacturer s requirements for the drive unit. 4. Winter Storage Prevent freezing o Haul out o Run potable antifreeze through raw water system Warm the engine, then change the oil Maintain transmission fluid If hauled out, disconnect the drive shaft coupling 5. Spring Commissioning Check stuffing box If hauled over the winter: o Allow the boat to sit in the water for five days o Reconnect drive shaft coupling and check alignment Replace raw water impeller Check stuffing box again Slide 11 Slide 12 Slide 13 Slide 14 Slide 15 Slide 16 Slide 17

3 6 Inboard Engine Drive Systems 61 Homework Questions 1. The device which allows the engine rpm to match the load of the propeller is the: a. flywheel. b. distributor. c. skeg. d. reduction gear. 2. If an engine with a reduction ratio of 2:1 is running at 2000 rpm, at what speed does the propeller turn? a rpm. b rpm. c rpm. d rpm. 3. One advantage of the jet-drive system is: a. there is only one exposed rotating part in the water. b. adjustments to the engine are easy to make while operating in the water. c. it enhances shallow water operation. d. it requires little or no maintenance. 4. Side thrusters are used to: a. provide additional speed. b. provide a reverse gear. c. move the bow or stern either port or starboard. d. provide additional forward thrust to the propeller. 5. To provide for reverse motion, the jet-drive system uses a: a. steerable nozzle. b. side thruster. c. reduction gear. d. reverse gate. 6. Modern marine propellers have three distinct measurements. They are: a. number of blades, size of blades, and diameter of blades. b. diameter of blades, number of blades, and pitch of blades. c. pitch of blades, size of blades, and diameter of blades. d. size of blades, number of blades, and diameter of blades. 7. As a general rule, the number of blades on a propeller: a. decreases as power and weight of a boat increase. b. has no discernable effect on a boat s design. c. increases as power and weight of a boat increase. d. is strictly a matter of personal preference. 8. A propeller s design is always represented by two numbers. The first number always refers to the: a. weight. b. diameter. c. pitch. d. construction material. 9. The of a propeller is usually limited by the design of a boat. a. diameter. b. weight. c. pitch. d. construction material.

4 62 6 Inboard Engine Drive Systems 10. The two factors that are commonly used to determine the optimum performance of a propeller for a specific boat are: a. boat speed and speed over ground (SOG). b. boat speed and propeller speed. c. boat speed and engine speed. d. engine speed and propeller speed. 11. A preliminary view of a propeller s overall performance can be had by observing the: a. speedometer. b. boat s wake. c. boat speed as indicated on a GPS receiver. d. tachometer. 12. The usual cause of propeller cavitation is the propeller: a. turning at too low a speed. b. too far from the hull. c. blade dented or chipped. d. blades not painted. 13. The impeller used on the jet-drive: a. has a very high pitch. b. is located outside the hull. c. is always made of bronze. d. operates inside an enclosed housing. 14. If a propeller s pitch is too high, the engine will: a. not be able to reach its maximum rated speed at wide open throttle. b. reach its maximum rated speed before wide open throttle. c. run at its maximum rated speed at wide open throttle. d. over-rev at wide open throttle.

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