Positioning of trailer axle

[gruntahunta]

My boat is so heavy at the towing point that I can barely lift it (and I am fairly strong). I know I need to move the axle forward to fix this but my question is.... How far forward????

Is it to the point of balance or somewhere between that and where I am now?

At the moment there is no chance of it ever coming off the tow ball but it kills me trying to lift it up onto the jockey wheel etc.

Does anyone know the correct positioning of the axle to get the best and of course maintain safety balance?

[Axl]

You dont want to move the axle to far forward if you do you wont be able to get into the boat (when it is not hooked up to the tow vehicle) and not have the front tilt up and the motor leg hit the ground (concrete ouch).

My last rig did this and it was a pain when I wanted to clean and or work in the boat I had to hook it up to the tow vehicle.

[finga]

Give and take matey.
Move it forward 6 inches and try that. If still too heavy then move some more.
I'll probably get shot down in flame but I only have about 20-30kgs weight on the towball for the big boat and I don't have a problem standing at the back of the boat and it doing a wheelie.
I've never had an issue towing it.

[dreemon]

I cant move my weight anymore forward without moving the axle to the rear, same as finger I only have about 35 kg on the towball and never a prob,

[ifishcq1]

The recommended weight that should go on the tow ball is around a tenth of the total gross trailer and boat weight
this point virtually stops swaying and the chance of jack knifing the trailer
so depending on your boat size, maybe you should have difficulty in lifting the front if you want to be safe on the road
cheers

[Moonlighter]

5 to 10% of the BMT weight on the towbar is the generally accepted range.

Subject of course to the proviso that you do not exceed the car manufacturers max towbar downforce rating. Yes, manufacturers do specify a max towball downforce, or weight on the towball. Look it up in your owners manual or contact our cars manufacturer and they will tell you.

Too little weight on the towbar is the cause of trailers swaying on the highway, which is a dangerous thing. I wouldn't go less than 5% in your case, assuming a BMT weight around 1000kg, that would be 50 kg as an absolute min.

So Grunta, there are 3 things to consider.

1. The position of your boat on the trailer. You can move the winch post back or forwards to adjust weight distribution. So, in your case, you could look at moving the winch post backwards -ie away from the car. This will move the boat backwards and thus shift the balance point to the rear. But you need to consider that ideally, the last row of rollers on your trailer should be close to the transom so they support the motor's weight. So have a look at his and see if it is feasible to move the boat bacwards a bit.

2. The axle position. Looking at your avatar picture, it seems we are dealing with about a 5m alloy runabout, correct? If so, I would agree with Finga, start by moving it 6" forward and check. Take careful measurements from each end of the axle to the end of the coupling and make sure it is the same distance from both sides, that will keep the axle parallel.

3. Weight in the boat. Can you move heavy things towards the back of the boat? Batteries, fuel tank, anchors, etc? It all helps.

You might end up doing a bit of all of these things.

But it really is try it and see.

Cheers

ML

[Fed]

You'd better duck Finga the Googleboys will getcha!

[cormorant]

If moonlighters suggestions aren't possible or don't solve it have you got a couple of car stands and a length of 4*2. Just jack it up and put in the stands and 4*2 a couple of times and it will resolve where it might have to go to. Then check if it can go there as with brakes and brackets or places to put guards it might not be possible . Bit more rather than a bit less weight is better as long as it isn't affecting car handling or over towbar limits.

[SunnyCoastMark]

My boat is so heavy at the towing point that I can barely lift it (and I am fairly strong). I know I need to move the axle forward to fix this but my question is.... How far forward????

Is it to the point of balance or somewhere between that and where I am now?

At the moment there is no chance of it ever coming off the tow ball but it kills me trying to lift it up onto the jockey wheel etc.

Does anyone know the correct positioning of the axle to get the best and of course maintain safety balance?

Gruntahunta, When you say that" it kills you trying to lift it up onto the jockey wheel" - what do you mean? Do you have a clamp on Jockey wheel or swingaway?

It really is better to have that extra weight on the towball - in your case (looking at your avatar) it should be at least 50 kg - ideally up around 70 - 80kg.

I would be looking at changing the jockey wheel set up, before doing anything else.....

Mark

[Feral]

probably need to move it forward around a foot.

can you get access to the frame underneath with axle stands?
Easiest way to judge how far to move the axle is to wait until the missus goes out, then put the boat onto axle stands at roughly the point your thinking of moving the axle to , and her set of bath room scales under another axle stand under the tow hitch, unless your using a 4wd with a large tow bar, you dont want more than 80 odd kg weight on the scales, preferable a lot less. (Most standard towbars are rated for no more than 90kg down weight)

Try lifting it before putting the missus scales under it, you wont do your self any favours if its 150kg and you bugger the scales

oh and wipe the grease off the scales before you put them back, dont want to get caught!

[finga]

Take careful measurements from each end of the axle to the end of the coupling and make sure it is the same distance from both sides, that will keep the axle parallel.

The point Moonlighter has made is very important.

If it was me I'd be servicing the bearings at the same time and I'd be doing some simple measurements before any moving of the axle has started to make sure all is good in the way the trailer frame has been made.
Grab a string line and attach it to the centre of the rear crossmember. Get the centre by measurement and don't rely on the weld to be centre.
Run the stringline through to the centre of the drawbar at the very front. Does the stringline pass over the centre of the other crossmembers??
Stand at the side and look across the trailer. Can you see the 2 long bits the crossmembers are attached to?? Make sure they're parallel to each other. If there are any questions how to do this ask.
When the hubs are off measure from the centre of the front of the coupling to the ends of the axle and see if they're the same before you move anything.
I've seen this measurement to be waaaaaaay, way, waaaaaay out. I'd do this just for curiosities sake.

And when finished I bung a simple sticker sort of thing or a niko maker line at the front and rear of the spring/mudguard hanger as a reference point. Sometimes the axle will move, especially if you hit a gutter or something, and if you have a reference point then it's an easy thing to notice and an easy thing to rectify.

[gofishin]

My boat is so heavy at the towing point that I can barely lift it ...but it kills me trying to lift it up onto the jockey wheel etc.

Gruntahunta, When you say that" it kills you trying to lift it up onto the jockey wheel" - what do you mean? Do you have a clamp on Jockey wheel or swingaway?...

I would ask the same question - why not let the jockey wheel do the job it's designed for? Is there a reason you are lifting?

Yes, definitely check the towball down weight as suggested, and note, the scales under the jockey wheel will not be the same as the scales under the towball hitch.

Most home scales only go to 130kg (some to 150kg), but for your boat this should be ample. If you are not sure how to do this…with the boat on a nice level slab, first chock both wheels of the trailer front and back with something decent. Adjust the jockey wheel so the hitch is a smidgen higher than it is when secured to your tow vehicle.

Place the scales under the hitch and find something sturdy that fits nicely in between the scales and hitch (piece of timber, whatever). If it is heavy(steel, bricks etc) note the weight on the scales. Gently lower the jockey wheel until all the weight is off the jockey wheel.

Q1.What did the scales read (less any steel/bricks as above etc)? Note: items stored in the boat not where they are supposed to be, or the motor trimmed down instead of up, etc will change the ball weight compared to how you tow the boat. The smaller the boat, the more it is affectedby these things.

Q2. What size of boat and what engine? It’s a Quinny Coast Runner or runabout, I can see that, but can’t tell what size. I’m guessing 4.55 – 4.75 model.

Q3. What are the trailer ATM and TARE weights (off the plate).

Do the above (before moving the axle) and report back! If it does need moving, and won’t affect the towing stability, you can trial different COG positioning by simply disconnecting the safety chain to the boat, slackening the winch wire/belt a little, and moving the boat back on the trailer a few inches at a time. Note: Chock the wheels both sides, hose the skids/rollers and the boat will move easily.

This won’t provide an exact measurement, but it will be close (we are cheating as we are not changing the trailer frame COG in relation to the axle, only the boat COG). Also, as suggested, make sure the boat is positioned correctly on the trailer in the first place re winch post positioning and transom overhang, plus axle is square to trailer CL.

Also note, moving the axle forward will make it harder to reverse the trailer!
Cheers
Brendon

[Bros]

My boat is so heavy at the towing point that I can barely lift it (and I am fairly strong).

Sounds like you have got it right. If you are just towing around town in the 60klm speed limit ONLY move it further forward if you are going to tow at higher speeds at any time leave it where it is.

Caravans are heavy on the ball and you never ever see people lifting them just use a windup jockey wheel.

[johncar]

I agree, fix up your jockey wheel set up and you shouldn't need to be manually lifting it at all, that's the job of the jocky wheel. Moving your axle foward or boat rearwards can lead to unstability on the road and although many may get away with it with regular driving, an emergency brake or swerve, hitting a big pot hole may cause some grief. I recommend staying in the range of 5 - 10% of the total BMT mass on the ball, so it would be OK to make weight distribution adjustments to the axle or boat if you can remain in that range on the towball.
I prefer to be closer to the 10% personally for a better safety factor. My BMT at just over 3T has approx 300KG on the ball so no I can't manually lift it and any boat much over a tonne I wouldn't expect to be able to easily manually lift.

[finga]

My BMT at just over 3T has approx 300KG on the ball so no I can't manually lift it and any boat much over a tonne I wouldn't expect to be able to easily manually lift.

What sort of trailer is it?
What vehicle do you tow it with?
What rating is the wheel on the jockey wheel?