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Old 04 January 2010, 22:50   #1
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Trailer Setup

Howdy,

For a while now I've struggled at the ramp getting the boat to sit straight, until I realised one of the rear guide roller/wheel sets was about 3 cm further out than it's partner on the other side, and they were actually too far apart for the width of the boat...

So now I have pulled it in a bit, and also lowered both rear guide wheel sections about a cm as bring it in made it higher.

But it's still really hard work both getting it off (needs a good strong push) and pulling up (really works the winch)... I see other boaties making it look like a baby's bottom sliding down a buttered bannister...

Looking at it now, as you can see from the pics hopefully, the boat still sits with its rear weight on the tow rear guide rollers, and about 1cm above the rear cente roller,

Up front, the box weight is on the central roller.

I've heard that the weight should be on the central roller... is this the case for all trailers... ie should I lower the two rear guide rollers so that the bottom of the stern hull sits on the central roller?

So weight on central and then adjust two side guides so they are snug?

Any thoughts/advice, most appreciated...

Cheers
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Old 05 January 2010, 06:06   #2
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Hi and a happy new year to you. I had the same problem when recovering so this summer I dropped the back cradle to the very bottom hole and when I recovered in October the rib came on a treat. Hope this helps.

J
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Old 05 January 2010, 14:19   #3
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Hey,

Cheers for the reply - and happy new year too!!

So was the main body weight sitting on the rear central roller, or still on the side guide wheels, just lower?

Cheers!
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Old 05 January 2010, 17:09   #4
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My trailer does not have central rollers as such it has two main cradles back and front consisting of 4 indepandent sets of four and the wt is mainly on the rear one because that is where the engines are.
Hope this helps.
J
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Old 12 January 2010, 15:43   #5
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Quote:
Originally Posted by jambo View Post
My trailer does not have central rollers as such it has two main cradles back and front consisting of 4 indepandent sets of four and the wt is mainly on the rear one because that is where the engines are.
Don't suppose anyone has central rollers like mine (and straight axle)... how are your heights setup?

Cheers
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Old 13 January 2010, 04:28   #6
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Does that entire rear beam (the one with the rollers on) swing independantly of the trailer chassis?

If not, then I suspect you may be on the proverbial hiding to nothing. If that beam swings, the rollers will completely self align. If the beam is fixed, then you are relying on simply the rear two rollers to align everything.

If you look at this http://www.indespension.co.uk/b2c/ap...ANO=640&slnk=1 , the pic for the 3.5 version shows what I mean - the whole rear beam pivots to cradle the bow, then gravity centres it as you winch on where the hull is still relatively pointed so that when you get to the "flat" bit, it's already centred.


Any chance of a "zoomed out" pic, ideally from a slight angle to get a better feel for what's under the back of your boat?
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Old 13 January 2010, 13:37   #7
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it would be good if you get all the rollers with the same amount of weight on them, spread the load so to speak, if your rollers are on posts put the jack under them to adjust the height
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Old 13 January 2010, 14:16   #8
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Quote:
Originally Posted by 9D280 View Post
Does that entire rear beam (the one with the rollers on) swing independantly of the trailer chassis?

If not, then I suspect you may be on the proverbial hiding to nothing. If that beam swings, the rollers will completely self align. If the beam is fixed, then you are relying on simply the rear two rollers to align everything.

If you look at this http://www.indespension.co.uk/b2c/ap...ANO=640&slnk=1 , the pic for the 3.5 version shows what I mean - the whole rear beam pivots to cradle the bow, then gravity centres it as you winch on where the hull is still relatively pointed so that when you get to the "flat" bit, it's already centred.


Any chance of a "zoomed out" pic, ideally from a slight angle to get a better feel for what's under the back of your boat?
Hey,

Thanks for the reply.

Yeah, my side rollers look like those in the 3.5 version -- Front & rear 8 Rollers swing beam assemblies (16 x ribbed rollers in total) as they call it, or 'wobble rollers'. Each assembly, left, right, front rear, has 4 rollers, each set of two swings and adjusts independantly.

And then in the centre, there is two (front and back) of these type things: http://www.smartmarine.co.nz/rp12-ur...mm-p-8949.html

Out of interest (?!?!) what would cause "If not, then I suspect you may be on the proverbial hiding to nothing. "....

Next time I put the boat in, I'll try remember to get a pic of the trailer empty to give a better idea...

Here we go - this is the closest I can quickly find on google...

http://www.oceantrail.co.uk/shop/ima...%20590_LRG.jpg

Kind of like that, but

a) the two rear wobble sets are further apart on mine (because I guess this pic is set for a narrow boat...!)
and
b) there is a central roller (like that black central keel roller), at the back, inline with the two rear rollers
and
c) my axles are straight.

Hope that helps!!!!!

Oh, and the height and sideways positions of the wobble rollers is adjustable. Central rollers fixed.
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Old 14 January 2010, 05:05   #9
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OK, I maybe didn't ask that as well as I could......

Does the entire rear cross beam that your rear rollers are fixed to swivel on an axis parallel to the trailer axle, the roller sets rigid fore / aft to the beam, but each individual roller axle pivot independantly? Or is youre beam fixed, and the two banks of rollers tilt fore & aft independently?


Now to try a better explanation of what I was trying to say. Yopu'll need your 3d imagination hat on here......

If that entire rear beam swivels , rigid with the two sets of rear roller assemblies, what happens is the "v" of the beam is pushed forwards out the way as the two rearmost rollers meet the hull. (they are pushed down, whioch swivels the entire beam so the bottom of the "V" moves forward out the way) With a centre (keel) roller, the keel will hit first, and the boat will then want to "capsize" until the side rollers touch the hull. This is especially so if you have a rigid straight rear cross beam, as the keel roller will not move "out the way", and gravity means that it will want to go sideways for longer (until the side trollers touch). this phenomenon is ineviable with any "pointy bow" boat. Hence, the "hiding to nothing" because it's inevitable the boat will overbalance on the keel roller before it is supported by the side rollers.

If you look closely at the Oceantrail pic, or the one on here shows it better: http://www.indespension.co.uk/b2c/ap...ID=1090&slnk=1 you'll see the rear rollers are welded solid relative to the beam (can adjust left / right to suit the hull) and the entire beam is hung from a couple of large bolts at the chassis - the whole lot pivots as one.

If the whole beam swings and there is no centre roller, as you winch on, the rearmost rollers touch the bow first, and the weight on them swings the whole beam so that the rear roller banks are at a silly upwards angle. (as per the indespension pic) As you winch further on, the bow starts to widen out to form the main hull, gravity takes over, and gravity takes the boat to the lowest point (which prety much parks the keel dead centre betwween the rollers. Once the rollers are past the "pointy" bit of the bow, the beam aligns itself relative to the keel, and as you winch further on, the hull rolls up this self aligning slope until it starts to overbalance (the centre of gravity of the boat passes the pivot) and the whole beam and boat then swivels in unison to "horizontal" and the bow is caught by the forward rollers. (forward rollers don't need the whole beam to pivot because the boat is by definition already lined up when they touch the hull). Once that has happened, you have a full set of rollers aligned & you just keep winching 'til lit stops.

You say your rollers are further apart. On a full swinging beam, the spacing will depend mostly on the shape of your bow, as a "bulbous" bow will get to "hull" size quickly, so they can be further apart whereas a narrow bow will need the rollers closer together to prevent the keel form hitting the beam. Mine are probably on a spacing where the inner rollers are not too far off your keel roller width, and I have the forward ones set as far out as possible to stabilise it.

Looking at your trailer, your rearmost cross beam (the one that holsds the rollers) looks straight from those photos. I can't easily tell form the photos, but I think your fore & aft roller beams on the rear beam pivot relative to the beam rather than them being rigid to the beam & the whole beam swinging? Thing is that there is a relatively small angle the roller sets can swing through if tyhey pivot relative to the beam, so you inevitably end up with just the rear two doing anything at the beginning. Couple that with the narrowest point of the hull (the bow) which means that the rollers are "too far apart" to hold the bow off the metalwork, the bow will inevitably hit the beam, I assume that's why the keel roller is there, and as discussed already that instantly gives you an instable system.


Lots of words, hope they make more sense than last time.
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Old 14 January 2010, 06:42   #10
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... put the jack under them to adjust the height
NZ is a bit of a long trip for Codprawn.
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