Has anyone else experienced problems with trailer suspension (or rather the lack of it) damaging their boat?

I have repaired several grp dinghies which have been used on 'normal' indespesion type trailers of various sorts and which have had considerable damage done to their bilges by excessive impact from the trailer. When I inspected the trailer I found that in every case the force needed to deflect the suspension arm was greater than my weight (12stone) - Having gone round numerous dinghy parks and tested trailers, frankly most of those with these systems are pretty stiff and unyeilding and would give light or fairly light (under 300lbs) dinghies a very tough ride. I ditched my own 'x' brand nearly new trailer as a result and have resurected an old Snipe with a transverse leaf spring - fine but over 60mph it occellates and causes a vibration - whats the answer? who makes a trailer with soft suspension by which I mean one which would deflect if one pressed firmly on the side of the boat when its loaded and got a nice response and which will be able to deflect at least 3" without much persuasion. I would really like to hear from a suspension manufacturer who I can use to make up a new 'soft trailer' . Aeolus

I'm a trailer builder (professionally) in Australia...sorry.

I assume you mean by "normal" independent type suspension you are talking about the rubber block "alko" style.

If you are, these are not "tunable" like normal Leaf Springs. with light boats, Most of these suspensions start at an axle load of 850kgs+. if your trailer and boat weighs less than this DON"T bother.

DON"T get conned into asking for a light trailer due to the following.

1. More weight helps with the spring rates
2. more weight keeps the trailer "glued" to the road.

As for your oscillation are you talking about the trailer swaying from side to side as you tow it down the road. If so, check the alignment of the axle in relation to the coupling. You should be able to do this with a tape measure.

Vibration could be caused by sway, unbalanced wheels, loose wheel bearings, bent/buckled wheels, loose wheel nuts,

If you are going to build a new trailer tell your trailer builder what weight YOU intend to carry so he can help you.

With the damage on the boats you mention are they tied down/ or tied down firmly?

P.S. 300lbs is not light, 45kgs(100lbs)  for a 12 foot skiff

I have towed my own trailers at over 130km/h, however this is not legal in OZ(I've got the tickets to prove it) on roads,our major hwys, that the northern blokes would consider Goat tracks, WITH NO PROBLEMS. It all can be done , however DON"T BE CHEAP on your trailer.

It should be layed down by your version of the "Roads and Traffic Authority". you should be able to find out the following

1. Brakes/braking systems required
2. Maximum towing weight for YOUR tow vehicle
3. Maximum Length of your combination
4. Maximum rear/front overhang
5. combination lengths
6. etc.

As for noise from your tie down straps, simply put a half turn( so the bottom of your strap becomes the top) this stops the fluttering

Hi Tim,

I saw a similar discussion to this somewhere, and someone provided the following link, so I kept a note of it:

http://www.ntta.co.uk/law/index.htm - http://www.ntta.co.uk/law/index.htm

I hope that this helps.

Ian  (Yorkshire Dales S.C.)

Tying the boat on is of course very important, getting the correct weight capacity of trailer to boat is important and issues of speed and whether or not the trailer tows safely at speed is important, but I would still reitterate my original query which was 'why is is that we have hundreds of trailers out there with suspension which is not deflecting when the trailer hits bumps?'

If the suspension is not 'suspending' then you might just as well dispense with it and have a solid axle - has anyone thought of designing a car like this? No. so why have trailers that effectively have no springing either? Sorry folks but this is the real issue as far as I am concerned and I would be grateful to hear from someone who knows of a decent suspension unit which really does what its supposed to -

Not to derail this thread but while we are on the subject of towing what is the law on lighting?

I read somewhere that if you car's light are visible while towing you don't need any on the boat. I can't be arsed to install all the electrical stuff into my car or buy a lighting board. Can anyone confirm this?  I haven't ben pulled over so far...

Back onto topic. Despite the fact the suspension doesn't deflect when the boat is on it or you jump on it doesn't mean it doesn't do anything.

F = ma

So you will get a very high force if the magnitude of the acceleration is very large, which is what happens when you hit a big bump or hole in the road. The force will be enough to make the suspension deflect and save the boat from damage and is likley to be greater than you jumping up an down on it.

There are problems with oscillations occuring at high speeds with a softer suspension and no damping.

Not sure what boat you sail but just visualise for a second another car dissapearing through the transom of your boat (accompanying sound of splintering wood/carbon/foam...delete as appropriate) and all the fun you will have with your insurance company not buying you a new boat and the third party deciding "where there's blame there's a claim" for inadequate lighting, plus all the great spectating you'll be able to do at your club for a few months!

Really not wishing to get up on my soapbox, but I've seen a Mirror that got rear-ended, not pretty at all, and it really is dead easy to wire in trailer electrics, get yourself a plug kit and scotch-locks from Halfords, refer to your car wiring diagram (Haynes manual or similar) and you'll be done in 30 minutes.  There's even a huge amount of info available on the net for this stuff, or even pop to a breakers yard and see if there is a car like yours with the kit wired in, just chop the wiring loom out and match it one wire at a time to your motor.

Air suspension is great but if you are towing it with a standard car not a Volvo FH16 truck.... where are you going to get the to resupply the air bags/tanks. Light versions of air bags are available down here but need an CONSTANT air supply to run it.

For my 12 footer trailer the suspension is as follows

1. 4 leaf 45 x 8mm eye to eye springs
2. 40mm solid axle fitted with HT Holden bearings
3. 14" Ford Falcon pattern wheels
4. 185/14x8ply light truck tyres

For the people who don't know what I'm talking about.

Eye to eye means a bolt at each end of the spring with a couple of (shackle)plates on one end. These springs ARE tunable for ride characteristics, IE soft or FIRM.

the axle is the biggest light trailer axle available and more than up to the job. It will carry 1200kgs with this bearing combination which is very common in Australia

The rims and tyres are LARGE this is for the following

1. owning a couple of Ford Falcons used for towing I have 2 spares for going away 1 for the trailer and 1 for the car and are interchangeable
2. as someone mentioned earlier larger tyres handle bumps/potholes better
3. for long trips (I mean here anything over 1 hour up to 14-16 hours driving) the wheel bearing do LESS rotations than on a smaller wheel for the same road speed, therefore running COOLER and less likely to fail. (this however doesn't stop them failing, maintenance is still required)
4. makes the center of gravity over your trailer lower for better stability and th e track width wider for the same.

As for not running your trailer without lights, I HAVE NO SYMPATHY FOR YOU IF YOUR BOAT GETS WRITTEN OFF FOR SUCH A SIMPLE THING. Next time you are driving at night have a look for a car or trailer with ineffective lights and good lights and YOU work out which you would rather be behind.

Compared to the cost/hassle of fitting a tow bar the electrics are a piece of cake, I did mine by trial and error (no wiring diagram) and it only took me an hour!

At the very least you should fit some decent reflectors at the rear and/or outermost points of your boat/trailor until you can fit electrics. In my experience people drive far too close to the back of boats with lights/reflectors on so without you're just asking for trouble.