Twin Axle trailer

About the important piece of kit under your Cape Cutter 19 when on the road.....

Twin Axle trailer

Postby Julian Porter » Mon Sep 02, 2019 11:46 am

The axle of my South African trailer is approximately half way along the length of the boat. I’ve seen a twin axle trailer where both axles are within the last 1/3 of the trailer (pretty much filling that section of the trailer. How can I determine if the weight on the hitch will be too great?


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Re: Twin Axle trailer

Postby Greybeard » Mon Sep 02, 2019 12:21 pm

You can use a trailer nose weight guage. Milenco do one that is certified as accurate - about £45 for a new one, under half that 2nd hand. Unfortunately I sold mine after I sold Falcon. If you find it's too heavy on the hitch then move the axle forward.
Im not sure about setting up a double axle trailer for nose weight though.

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Re: Twin Axle trailer

Postby erbster » Mon Sep 02, 2019 6:38 pm

Can’t you just put the jockey wheel on some bathroom scales?


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Re: Twin Axle trailer

Postby Julian Porter » Mon Sep 02, 2019 7:37 pm

Sorry I didn’t make my question clear. I don’t want to measure the weight I want to estimate it before buying a trailer with a particular configuration.


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Re: Twin Axle trailer

Postby Greybeard » Mon Sep 02, 2019 8:45 pm

It's a little more difficult with a twin axle because as you lift or lower the hitch it you start to feel the effects of loading /umloading the springs on each axle, although the degree of effect will depend on the 'mathematical' pivot point between the two. I would try to measure it with the hitch at the same height as your towball. If you are using a gauge or scales then it might need packing to get that height - check that the tyre pressures are correct too.
If the trailer hitch sits almost level with your towbar height and the jockey wheel lifted then there's not enough nose weight. It needs to be nose down and 75kg should be needed to lift it to the correct height.
As a first estimate then I would be satisfied just by lifting it an inch or two by hand above that height. 75kg is liftable without having any childish accidents :)
I know Dennis has considerable experience when it comes to towing though I can't recall whether his caravan is a twin axle or not. I'm sure he'll be along shortly - if he's not still on his hols.

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Re: Twin Axle trailer

Postby Dennis » Wed Sep 04, 2019 4:50 pm

Julian Porter wrote:The axle of my South African trailer is approximately half way along the length of the boat. I’ve seen a twin axle trailer where both axles are within the last 1/3 of the trailer (pretty much filling that section of the trailer. How can I determine if the weight on the hitch will be too great?


The sort of trailer you are describing is typically used with powerboats with a couple of huge outboard motors sitting on the transom. In other words the centre of gravity of the boat is well aft, hence the position of the wheels on the trailer.

I suggest you measure the actual nose-weight of your existing trailer with the boat loaded as it will be for trailing on the road. Ideally it should be approx 7% of the total towed weight (trailer + boat) for stability. However, you cannot exceed the maximum allowed for either the coupling on the trailer (typically 100 Kg) or the towball on the car, this can range from typically 70 Kg for a saloon to 250 Kg for some large 4x4s.

If the result is reasonable, you should aim for the two axles of the new trailer to be positioned equally either side of the position of the axle on your existing trailer. Assuming that the distance from the coupling to the axle(s) is the same.

If the result is too light or too heavy you can calculate using simple maths (moments) where the axle(s) should be, to give your desired noseweight.
Cheers

Dennis

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