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Old 15 January 2007, 12:31   #11
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For 7m I'd look at a twin unless you will regularly be moving it by hand into a tight spot. (Even then you can make life easier by putting a bit more air into the tyres)

Mine's a twin and I managed to drive it a few miles on 3 wheels without any drama after one of the suspension units failed.

With 4 wheels sharing the load obviously less wear and tear on each bearing.
So how come one of the suspension units failed?....

A trailer with twin axles will have suspension/hub/tyres that are (in simplistic terms) rated for 1/4 of the carrying capacity of the trailer, whilst on a single axle its 1/2.....
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Old 15 January 2007, 12:39   #12
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Tim, twins take more charge of the car, tripples more so again. They are more akin to a vehicle in their own right which you are towing, whereas a single is more like an extension of the car. The nose weight varies more over undulating surfaces with the twin or tripple rig. With my tripple set up, I can get a situation where there is almost no nose weight if the road is a small brow, eg. the car is on the level and the trailer is on the hill.

Hand manoeuvring a twin is very difficult and a tripple is impossible. It follows that there must be increased side loads on the draw bar when turning and that there is tyre scrub, also wheel fatigue and hub fatigue can be an issue and these loads are also transferred to the trailer so it too must be fully sound.

However, twins and tripples are far superior at riding poor road surfaces, consequently they give the boat a nicer ride. They may be essential for a large boat simply because you will not get a single axle which can carry the load.
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Old 15 January 2007, 12:40   #13
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No contest, on a little rib like yours it would have to be a single!
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Old 15 January 2007, 12:47   #14
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Originally Posted by jwalker View Post
Tim, twins take more charge of the car, tripples more so again. They are more akin to a vehicle in their own right which you are towing, whereas a single is more like an extension of the car. The nose weight varies more over undulating surfaces with the twin or tripple rig. With my tripple set up, I can get a situation where there is almost no nose weight if the road is a small brow, eg. the car is on the level and the trailer is on the hill.

Hand manoeuvring a twin is very difficult and a tripple is impossible. It follows that there must be increased side loads on the draw bar when turning and that there is tyre scrub, also wheel fatigue and hub fatigue can be an issue and these loads are also transferred to the trailer so it too must be fully sound.

However, twins and tripples are far superior at riding poor road surfaces, consequently they give the boat a nicer ride. They may be essential for a large boat simply because you will not get a single axle which can carry the load.


It is not impossible with a triple - just bloody difficult. My brother and I managed to swing our rig through 90 degrees and push it along a corridor until it was parked nicely - wouldn't like to repeat it though!!! It did help it was a very smooth sealed concrete floor.

Good point about the trailer taking control - hadn't thought about it quite like that but spot on about the changing weights at the back etc. There is a good saying amongst railway men - "the engine pulls the train but it's the train that stops the engine".
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Old 15 January 2007, 13:06   #15
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so it too must be fully sound.
Quote:
Originally Posted by Jono
So how come one of the suspension units failed?....
Errr . . .not quite sound enough!

Box section on one of the suspension units corroded out underneath and one corner too many pushed the bar through. Anyone else with those units I'd suggest close inspection of the underside as you can't really see this from a quick look. Give it a good poke with a screwdriver to be sure.

. . . so twin axle is no reason to be complacent
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Old 15 January 2007, 13:39   #16
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Galvanised suspension units can be purchased.....
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Old 15 January 2007, 14:44   #17
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Double the number of bearings to rust up and need changing and double the number of brakes to stick on when you don't want them too.

Yep. Ours is going nowhere right now. Most or all of the brakes are stuck on and couldn't move it an inch even with the car in low box giving it some.
Didn't use the handbrake either so we didn't expect that.

Harry
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Old 15 January 2007, 14:46   #18
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Double the number of bearings to rust up and need changing and double the number of brakes to stick on when you don't want them too.

Yep. Ours is going nowhere right now. Most or all of the brakes are stuck on and couldn't move it an inch even with the car in low box giving it some.
Didn't use the handbrake either so we didn't expect that.

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Old 15 January 2007, 15:22   #19
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Twin for me on the rough roads here and also it means that if a wheel bearing jacks in and spits a wheel off then you don't end up with a road full of bits of boat cos there is still one left

I have watched a single axle trailer going down the gravel road to the slipway where I launch mine and it was bouncing and leaping all over the place. My trailer runs on 4 x 7.50R16 Land Rover tyres and hardly notices on the same bit of road
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Old 15 January 2007, 15:44   #20
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2, 4 or 6

Whats wrong with carrying spare wheel with Tyre bolted to trailer along with two sets of Bearings and Bearing Pullers and finally an Inflate spray.

Add all of the to two wheel trailer and presto.

I also agree with previous writer which mentions 4 wheels is double the trouble for Hubs and Brakes etc.

Never a dull moment to take a few hours extra before getting launched.

And as for Trailer side crawling, just slow it down...
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