marine gearboxes

explain the diffrent types of gear selection types found in

outboard gearcases and sterndrive:
the gear selector system in a gear case is quite simple only having a forward and revers.  forward and revers are selected by  a dog clutch. this clutch has three big teath on either side and are used to grab hold of either the forward or revers gear.the dog clutch is located inbetween the two gears. the dog cluth has movement as it is needed to lock in one gear. in order to lock in the gear the shift rod needs to be minoverd ( pulled up or pusshed down). doing this shifts the dog cluth on its slide locking its teath into the teath on the inside of a drive gear.  this is also the same in a stren drive but in a bigger scale and slightly more heavy dutey equipment. forward and revers can either be selected from the controll pannel in the boat or on the out board depending on the size of the engin or design of the boat.

inboard marine gear selectors:
gears are selected either by hydrolic or cable systems wich can be controlled from the main controll pannel. the reason why an inboard has this system compared to an outboard is because the engin is under the floor and would cause problems having to go down to the engin and back to change the gear, also inboard gearboxes are alot more heavy duty and there for need more pull to change. instead of a dogcluth system like a outboard it has a cluth pack wich is sevral clutch plates and spacers.when a inboard gear box is shifted it locks a sertan shaft or gear wich makes outside gears or plantintry gears rotate a spacifictway selected by the oporater.

what type of gears are used in outboards and strenlegs? give an explanation of why manafactures choose this types of gear.
there are two types of gears in a gearcase and stern leg, those gears are a pinion gear and two drive gears, theres only a forward revers and neutral because having more than one forward means that more moving parts need to be made, housed and mounted so they work smothly. doing this  would make the gear case harder to service. also there would have to be a type of clutch installed and a bigger gear case would need to be made bigger wich would cause more drag in the water making fuel econimany alot worse .

duo prop
 a duo prop is basicly two props on the same drive shaft on one  gear case. the shaft that holds the two propellers is designed so one prop spins the opposite direction to the other propellor. the reason for the props spinning opposite directions is to remove  thrst and disturbistance in the water. the propellor shaft that the two props run off is made so one end is fixed an one  rotates the opposite direction on bearings.

jet unit vs surface drive unit:
a jet unit drive system is used by drawing water in and pushing it out at a high pressure through a smaller hole it came through. jet units re used quit alot on small race boats wich are not on wavey surfaces. a surface drive unit is designed so two out of three blades on the prop are under water and the other out above the water. having a surface drive can work to some advantages on diffrent types of boats. boath these types ofdrive systems dont realy work well on wavey or ruff surfaces as if the boat leaves the water just slightly all power and drive stops as there is no water to be driven off. there for these types of drives  are used on heavy boats or for boats on  flat water for full power. i would chosse a jet unit over  surface drive because how simple the system is and  how much power can be created.