TRAILERS

     There two main types of boat trailers.

• single axle: are for smaller boats and have the advantage of better maneuverability however they have a limited weight capacity.
• tandem axle: These are for larger heavier boats but have a disadvantage of having to maneuver in larger turning circles.
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single axle for smaller boats and tandem axle for larger and heavier boats

Boat length     gross vehicle weight rating( This is the maximum and vehicle axle can handle)

15'-17'            3500lbs

17'-19'          

3500lbs  

17'-19'            5200lbs

19'-21'            3500lbs

19'-21'          

 5200lbs

  

DESIGNS.


There are many boat trailer designs but the two main ones are bunk type and roller type.
Bunk type: 
Bunk types have marine carpet covered planks/skids. Are very stable but usually used smaller lighter crafts

Roller trailers:
Can be used for all types of crafts with and have the advantage of being able to adjust the rollers for the hull shape and the weight. The Disadvantage is the roller maintenance and replacement of rollers.

The trailer designs come in many shapes and forms depending of personal choice and the boat owners choice. A frames balance the center point of weight over the axle. The draw bar is to support the bow and has the winch attached to it.




Materials:
Boat trailers are usually made from Galvanised steel Aluminium.

DIMENSIONS restrictions:

The rules are as follow form New Zealand land transport:

It is not wider than 2.5 metres if they're loaded side by side.

Is not higher than 4.25 metres if they're loaded one above the other.

Is not longer than the standard length or rear overhang limits for that vehicle if they're loaded one behind the other.

If you have an over size load you will need special permission to transport it with pilot and safety vehicles.

SUSPENSION TYPES

Leaf springs fixed and floating

Coil springs with damper

Air bags

Wheels and tyres

Wheels are made from alloy or steel. Types have a recommended load capacity so you should always use the recommended tyre your trailer is going to carry.

A dolly wheel 

Hubs:

These are on the end of the axle and provides a place for the brakes bearings and tyres to be mounted to.

Stubs: These are a tapered steel rod welded to axle to house inner and outer bearings.

Breaks: Are only necessary after a certain weight is being towed and come in:

Disk breaks

Drum Breaks

Electric drum breaks.

Couplings:

These are and the front end of the trailer to lock the trailer on the towbar These can also houses break regulator system for the trailer. They come in two sizes 

50mm and 1/78 inches


Winches:
These to pull the boat onto the trailer to make life easier or if the boat is to heavy.

Lights:
Trailers have a power cord connected to the vehicle that makes the break lights or indicators come on when the car breaks.
Submersible lights are a must on marine trailers.