Thursday, December 1, 2011

N COMMANDMENTS OF NATIONAL CRATE DAY

All Crate Day supporters must abide the 10 Commandments of Crate Day. They're like laws, but more important. Cause if you don't follow them, you could die. And we don't want anybody to die. That just wouldn't look good. So read the rules below, and get your mates to read em over too.
COMMANDMENT #1:
Thou shall not be "that guy" - if you are not match fit don't try and act like you are.
COMMANDMENT #2:
Thou shalt support the "Crate Of Origin" – drink the beer where you came from (e.g. Dunedin - Speights, Auckland - Lion Red)
COMMANDMENT #3:
Thou shalt not drink warm beer.
COMMANDMENT #4:
Thou shalt open thy crate bottle with anything but a bottle opener.
COMMANDMENT #5:
Thou shall wear the attire of National Crate Day - black singlet, stubbies & jandals. If the weather turns tits up - swanny, jeans and red bands).
COMMANDMENT #6:  
Thou shall only eat chips, dip and anything cooked on the BBQ.
COMMANDMENT #7: 
Thou shall make sure mates get home safely.
COMMANDMENT #8:
Thou shall only listen to The Rock.
COMMANDMENT #9:
Thou shall only use thy crate as furniture.
COMMANDMENT #10:
Thou shalt always keep rules 1-9 top of mind, to ensure we continue the Crate Day legacy for years to come.

Monday, October 17, 2011

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.




Saturday, July 16, 2011

Cooling


Kinetic energy
Explain the terms ( Kinetic energy) Conduction,convection and radiation? Conduction is heat energy moving through a solid e.g. steel. Convection is the cycle ov heat through a liquid as the hot liquid rises the cold falls. Radiation is heat being transfered to the air from a hot object e.g. the engine


Indirect cooling
The coolant is in a closed cycle but still uses the raw water to cool the coolant further, this is a effective way of heat control because it works the same way as a car engine on a thermostat which means less corrosion and a faster warm up.

Direct cooling
The direct cooling method is to pump raw water up and through the water jacket then back out with the exhause fumes, this isnt as effective or practicle as indirect because of the corrosion and how long it takes for the engine to heat up - costing you more fuel.


Indirect and direct cooling propblems
What are the the problems you get with indect and direct cooling? Corrosion is the biggest problem because the raw water is so destructive, maintanance on the indirect cooling can be a mission - depending on how easy it is to get to the heat exchanger. You also have to regularly check the inlet valves because the can get blocked - causing over heating.

What is the puppose of a thermostate
To allow the engine to heat up to optimum running temp before letting the coolant pass through to be kept constant so the engine is always at the right temp.

Pressure cap? The pressure cap is a release valve for when/if the pressure in the radiator becomes to high for the specifications, it is also the way to top up the coolant.

Why is engines fitted with a core plug, and what is the purpose of a core plug? The manufacturors put them in so when they are moulded the can shake out all the core moulding sand. another reason for the core plugs is so if the water in the water jacket freezes it won't crack the block or head it will push out the frost plug instead.

What is the purpose of a heat exchanger? A heat exchanger is the equivelant to a radiator on a car except instead of cooling the coolant with air you cool it with raw water from the ocean which is also cycled to keep cold. It works by raw water circulating through pipes next to the circulating hot coolant the heat is transfered to the raw water leaving the coolant colder.

Thursday, July 14, 2011

Fuel injection

Eletronic control unit
The ECU is the brians of the motor and controls everything. it controls how much fuel can enter the motor, when the spark plugs spark, it dose this by reading the multidimen sional preformace maps. it uses engine sensors to control this.

Mass air flow sensor
A mass air flow sensor is used to find out how much air is entering the the fuel injetion system. The air mass in need so the computer can work out how mcuh fuel is need to be injected into the system so it has the wright balance of air/fuel mixture.

Air Temp sensor
The air temp sensor is used for two diffrent purposes. One is a warning system to warn the ECU if the air is to hot.There other purpose is to monitor catalyst functioning. they normally have have two sensors one befor the catalyti and one after to monater the temp after passing the catalytic core.

TPS throttle position sensor
A TPS is a sensor used to monitor the postion of the throttle in a internal combustion engine. The sensor is normally located on the buterfly so it an directly monitor the position of the buterfly.


Throttle body
In fuel injected motors the thrttle body is part of the air intake system. The throttle body is in respons with the accelaraotor pedal. The throtle body is normaly mounted in between the air fitter box and intake manafold. The biggest part on the throttle body is the throttle plate.

Carburators

 2 stroke Carburetors works the same way as  4 stroke carburbtors do. There are fuel lines that go into the float bowl,  the float valve inside the float bowl controls how much fuel that can go into the float bowl. The fuel then enters a jet that jet sprays the fuel into a venturi which adds pressure so the fuel and air mixes together. Above the jet is the air intake, The  air/fuel mixture then passes though the throttle plate. When the throttle plate is fully open it lets as much fuel as it can pass though. The throttle plate is never fully closed because if it was the motor would not iddle witch means it will not run. After that the muxture goes down the carb throat and into the combustionchamber.



Emulsion TubesThe air from the air bleeds enters the main circuit through the emulsion tube. The emulsion tube has a series of small holes from top to bottom, and it is through these holes that air enters the main circuit. At low engine speeds, when fuel demand is low, these holes are submerged in fuel, and so no air can flow through them. As engine speed increases, the fuel level in the float bowl drops, uncovering these holes, and allowing air from the bleeds to enter the main circuit, thus leaning the mixture. As the engine speed increases further, the fuel level in the float bowl continues to drop. This uncovers even more of the holes in the emulsion tube, which makes the air bleed have a greater effect on the mixture


Manual and automatic choke
A manual choke is opparate manualy by pulling a lever that closes the choke buterfly that is at the beggeing of a carburtor. A automatic choke is controled by a thremostic coil which the buterfly sharft is attcaed to. When the heat for the motor running the coil releases and the choke is then opened.

Float valve
The float valve is there to control the amount of fuel that can enter the venturi. As fuel getts used the level of fuel in the float boul drops causing the float to drop and open the needle valve letting more fuel into to the float boul.
Float valve

Mechanice lift pump
A mechanide lift pump is used to pump fuel into the carburtor. A mechanice lift pump is bolted to the head or to the block. This is because the camshaft has an extra lobe on it witch pushes on the lift pump rocker arm. When the pistons travel down to bottom dead centre it sucks fuel into the mechanice lift pump. When the pistons travel to top dead centre the fuel is forced out of the lift pump into the carburtor.


Vacuum fuel pump
The carburtor is not strong enoff to suck fuel into the carburtor so there is a vacuum pump just befor the carb to pump the fuel into the carb. The vacuum pump work by diaphrame.  The diaphrame works on piston strokes. There is also a one way valve in the pump witch make sure the fuel can only go one way and allows no air in the system.
What presure did you get from these pumps?? you gett around 2 - 4 PSI


Diffrents between diesel and petrol
Diesel runs on C.I compression igintion, this is compression to heat, there is enough heat and compreesion to cause an explotion forcing the pistons down.
Petrol runs on S.I spark igintion, petrol is highly flamable so with a small spark it will egint easly. forcing the pistol down.

Fuel cut off switch
The fuel cut off switch works on a copper coil causing a magntice force controling the swith.

What is the four stroke cycle
Intake,
compreesion,
power,
exhaust,

what dose S.I mean?
spark igintion

What dose C.I mean?
cpmpreesion igintion

When taking a carb apart what should you be really carefully with?
You have to be extra carefully and not turn the arb upside down. when turning it upside down the float needle valve can come out and wont go back in propally

When dismantling a carb what precaution should you take? do not turn it upside down because the small springs and valves will change position/alinement.
How does a bimetallic spring work in a automatic choke work? A bimetallic spring that helps with cold starting.when the engine is cold the sping holds the butterfly valve closed, as the engin heats up it slowly opens the valve producing a progressivly leaner fuel mixture. At the same time the high idle gradulay drops back to normal, when the engin is warm the butterfly valve will be fully open, ( standing up) producing the right mixture of air and fuel for the warm engine.


What is the purpose of the venturi and how does it work? it works on the same principles as a aeroplane wing - so it bottlenecks to make the air presure rise and flow faster and the fuel an air to mix more effectively


 


Monday, June 27, 2011

trailers

TYPES OF TRAILERS:
there are two main types of trailers single axle and tandom axle trailers. there are also triple axle trailer which arnt as commen as they are only used on really hevay boats. then there are roller style trailers which are the most commen where as skid trailers arnt as commen because they have to be samuged to take the bost off the trailer and to retrive the boat. with the roller trailer you dont have to put it as far under the water as you do with a skid trailer because for easy launching with a skid trailer the trailer has to be under the water alot more then a roller trailer.


tandom trailer with rollers

single axle trailer with skids

TRAILER MATERIALS:
there are two main types of trailer materials galvanized steel and aluminium. there is also steel trailers but there arnt as commen as there rust alot easier. galvanized steel is the most strongest materal to use when making a trailer and  has very good protection againest salt water. aluminium trailers are made of high quality aluminium which is still strong but they weigh alot less than galvamized steel trailers. aluminium trailer arnt as durable as galvanized steel trailers however aluminim trailers have alot more protection than steel trailers

galvanized steel

aluminium

steel

Overal dimentions and regulations:



  • If you are towing a boat you can tow a trailer that can be 2.5m wide, up to 4.25m high when the boat is sitting on the trailer, and 11.5m long, however the trailer and truck must not be more than 20 meters all up.










  • when towing a trailer the maxim weight you are aloud to tow is 3.5 tonne (3500kgs). if the load on a trailer is more then 2 tonne(2000kgs) you have to have a braking system.








  • Braking systems:
    The main and relly only braking system when towing a trailer is hydrolic braking. hydrolic braking comes in to forms disk and drum brakes. there are to main ways of controling them. you can have them hooked up to your braking system so when you put your foot on the brakes it also brakes on the trailer aswell. You can also have the hydrolic coupling braking system which provents surging with the trailer. so when you put your foot on the brakes theres a hydrolic in the coupling and then this acdivates the brakes on the trailer.
    hydrolic coupling


    Types of suspension:
    There are two types of suspensin there is leaf spring (most comen) and coil springs. leaf suspension is the most comen type of suspension and been around for 100's of years. leaf suspension sprends the weight over 4 equal points on a chasie. they are very easy to set up as its reely only a few bolts in the middle and at each end of the leaf spring. however they are alot more difficult to adjust. coil spring suspension is alot harder to set on trailer as you need to set up torsion bars which make them a pain. they are also very bouncey on a light trailer.
    Leaf suspension

     Coil suspention

    Winches:
    trailers are used to haul goods that are very heavy in weight or huge is size. Trailer winches are made to make the loading and un loading of trailes smoother and easier. If you where loading and un loading boats from there trailers with winches it would be come very hard and the risk of  damage will incress o shit load.
    The advantage of having an electric winch is that there is hardly any phisicaly strenth need to opperate. where as with a manuel winch you will have to be quite fit to winch in a big boat.

    manaul winch

    eletric winch

    Hubs and Bearings.
    Most new bearing have bearing protectors that are called bearing buddys. when your driving down the road your bearings on a trailer heat up. when you stick them in fresh or salt water they cool down and shrink. with old bearings when this use to happen they sucked the water into the bearing and this would could it to rust and damage the bearing. now with the new bearing buddy it is a sealed metal chamber thats attacers to the bearing. They are packed with greass and has a spring in it is when it go's in water and shrinks insteed of salt water been sucked in it suks greass in. this inrcesses the life in a bearing alot. bearings without bearing buddys
    bearing buddy
    Your hubs on traliers are normaly inderpendent hubs. witch means they are not attached with one another.
    your hubs are also for bracking. this is for disk and drum breaks. drum breaks are old and are becoming outdated noe disk breaks are coming in.

    Lights
    LED lights last alot longer than ordinary bulbs an LED bulb can last for over 10,000 hours while remaining with the same quality of light. The actual quality of light is better than an ordinary bulb and less energy is lost in heat. trailer lights are expossed to water and need to be able to enjor alot.
    ordinary trailer lights
    LED trailer lights

    Couplings

    Most trailers have ball and socket coupling systems. These are fine for a small trailers. anything over about 4.5 tonn you will need a heavey duty coupling system. most cars and 4X4's these days have the ball for the ball and socket coupling system.