New Trailer Design/Type

[swifty]

Come on we are talking light trailers here.

[CBBR]

After building many trailers and not only boat trailers.. Rocker box's will not lift the hight of your trailer much ( The pivot point of the box )... Rocker box trailers are only good for high load carrying,,, As thay Spread the load over both Springs/Axle's..
Holder and Slipper per axle ( Ie spring and Hanger) will not spread the load as a rocker box but is way easier to shift around...But i only work with heavy transport trailers so what would i know... Cheers JNR

that's the closest thing to the truth i have every seen you write  good to see you know your limitations 

[Hacky]

After building many trailers and not only boat trailers.. Rocker box's will not lift the height of your trailer much ( The pivot point of the box )... Rocker box trailers are only good for high load carrying,,, As thay Spread the load over both Springs/Axle's..
Holder and Slipper per axle ( Ie spring and Hanger) will not spread the load as a rocker box but is way easier to shift around...But i only work with heavy transport trailers so what would i know... 2cCheers JR

For a spring to work properly the spring needs to sit flat. so if you drop the centre of a tandem set up for a rocker box you should drop the front and rear mounts the same distance.  Thus you end up raising the trailer 75 or 100 mm or so. Not a great deal but on some launch sites it can make a difference.

[Matthewf/Norbert/TuiDog]

alko suspension is great  http://www.alko.com.au/vehicle-technology/product-catalogue/axels/independent-rubber-suspension-irs/

(this is not the same as the kiwi durotorque which fails!!).  Off road 4x4 community now uses this due to its durability and being sorted in aus. i fitted this to steelos trailer and its really good stuff and over engineered to the max, nice bit of kit, tows great.

[Blondeone]

Didn't mention a rocker box as I don;t have one , but great that JR brought it into the discussion.
Just Have IRS with the wheels close together.ex USA.
No issue on soft river banks, were I have had issues with a single axle.
Obviously it comes's down to personal preference but you can't go past a tandam for towing.

[Carl]

Anyone got any idea roughly what sort of downward weight should be on the drawbar of your trailor? I have 101kg. Im thinking thats way to much. Its a tandom trailor.

[Paul]

Your car owners manual should tell you the max tongue weight.  For me, it's got to be easily liftable, so 30kg maybe.

What type of suspension does the tandem have?  If it's not load-levelling type suspension, then the towbar on the car, maybe set too high for the drawbar on trailer (which increases trailer tongue weight).

[swifty]

* It is recommended to use a jockey wheel ,the trailer hitch should have a weight of about 10% of the weight of the trailer and load on it.

* Most vehicles have tow ratings unbraked and braked,we are not required to follow these in nz.

* The requirement we have is for the trailer/tow car combination to be able to stop from 30km in 7metres.
So the maximum allowable weight of an unbraked trailer is decided by the weight and braking ability of the tow vehicle.

* The maxium  weight of an unbraked trailer should not be more than three quarters of the unladen weight of the tow vehicle,This combination can be expected to have double the stopping distance of the towing vehicle alone.

[Carl]

Your car owners manual should tell you the max tongue weight.  For me, it's got to be easily liftable, so 30kg maybe.

What type of suspension does the tandem have?  If it's not  type suspension, then the towbar on the car, maybe set too high for the drawbar on trailer (which increases trailer tongue weight).

Thanks Paul. My random setup is not load levelling which could have some influence on it all. Suspension is to be done up over winter while boat is being straightend. Thanks swifty for all that info.

[PM]

* Most vehicles have tow ratings unbraked and braked,we are not required to follow these in nz.

Check your insurance policy, they will try to wrangle their way out of the claim if the tow vehicle of bar isn't rated for the load towed. While it is perfectly legal to operate the rig in such manner you may find something quite different should something untoward happen...

[xplorn]

I have always gone with a tad more weight on the tongue than normal to give that extra traction weight to the drive axle, I go with the big shank 21mm(from memory) 50mm tow ball as your tow point can take a beating over river beds and towing out of rivers specially if you get towed as well because your trailer is bogged in the river

also if your boat isn't over a ton dont overdo it a sindle will be fine just use big stubs and a good size 15 or 16 inch wheel for rolling radius over big rocks/stones otherwise your will have more parts more tyres etc that wont really be required .Remember river beds are hard on lite gear(stubs and spings)

[agh]

Hi, I am also looking to purchase or build a trailer(4.5mt boat) , did you have any luck getting ideas, plans?