Marine Transmission

 Marine Transmissions

Explain the different types of gear selection systems found in an: 
Outboard gearcase:
Outboard gearboxs use a dog clutch system which slides forward and back, seleting ether foward or reverse gear. This system is nosiey and rough. when damage is done to this gear system it normaly means the gearbox is gone.
Sterndrives:
Sterndrive gearboxs use a completely diffrent gear selection method. it is near the top of the stern leg and is vertacal not horezontal. It uses a tapped brass cone that slides up and down selecting forward or revese gear. This is smoth and dosn't damage the gear as much.What type of gears are used in outboards and stern legs.
Give an explanation of why manufacturers choose this type of gear.
Outboard and stern drive gearboxs are constant mesh, which means all gears are moving even when not engaged. This means all the gears are close together and dont take up much room allowing them to make a compactd gearbox 

Explain what a duo propeller system is and how it works.
The duo prop was invented by volvo and has two props that rotate in the opposite direction,
It has the sharfts that spin in opposite direction, You have the main sharft that spins clockwise and a counter rotating sharft thats inside the main sharft spining in the opposite direction.
Why would a ''V'' drive be used instead of a standard shaft drive system

A 'V' drive system is use to bring the weight of the motor to the back of the boat and to turn the motor the other way around. This make more easer accses to the main drive parts. I think you would loss alot of power in a 'V' drive system as you are nearly driving it 180 degrees on itself.
 
Compare a jet unit with a surface drive unit and give reasons why you would choose one system over the other.

Jet units use an intake system which sucks the water in from under the boat and squits it out the back of the boat. It has an inpeller which draws the water in and preserises it thoughs it out the back at high speeds give the boat drive. if somthing gets stuck over the intake or gose into the intake it can do a shit load or damage. E.G, if something gets stuck over it there will be no drive and it can burn the inpeller out, if something gose it the intake it will cause alot of damage to all the drive parts.
A surface drive unit is on top of the water at all times, they usealy have alot of blades on the prop as only 2 or 3 of them are in the water at the same time. surface drives are normally found on race boats as there give very fast plaining and alot of acclaration. 
Jet and surface drive units don't have anywhere as of good handling as other drive systems.
If i had to pick which system i was to use i would pick surface drive as it is a very fast drive system and i love speed.