Trailering - sway. The tail wags the dog

[rorkin]

Think about the problem like a lever.. That is what it is..

A boat is not a simple lever. It has mass! When you change the height of the tongue on the trailer, the weight distributed over its axis changes. Think about a half-filled fuel tank! Mine sits just about over the axles. A hundred gallons could be either weighing down the bow or stern. Fill her up and everything changes! Hundreds of pounds shifting from front to rear depending on the height of the mount. And it will also shift in transit. So getting the right height from the start is rule one!

Everyone's rig is different and all problems are not solved by one simple answer. That's why we love this site and all who participate :wink:

It is still a lever.. When the tank is filled it changes the weight either in front of the fulcrum point or behind.. depending where the tank is on the boat.This will then increase the tongue weight if in front of the fulcrum and decrease if in back. If the tank is precisely located over the fulcrum point, then I guess if it is half filled and and then all sloshes to the back if the trailer is tilted then it can affect the tongue weight. I don't think you will find that to be the case. In either event tongue weight should be determined with normal towing load.. Gear and fuel
The normal towing weight is the total of loaded boat and trailer
The tongue weight will change with load positioning
I don't want to appear stubborn .
but the ball height does not affect tongue weight.. It only affects stability and driveability if there is too much deviation from level.

Suppose you started with a level trailer at a given ball height.
You then found that the tongue weight was only 2 % of total.
So you then move the boat forward on the trailer to achieve the proper tongue weight (as acurately measured on a scale).
But if the increased tongue weight caused the rear of the truck to drop
3 inches .. Would you run it that way ??. I hope not. That is why ball height can't be rule one.
Perhaps this is a chicken and egg problem. The tongue weight should be a given percentage of GVW (trailer and loaded boat).. and the
trailer should be level. Levelness of the trailer is a function of ball height and your truck's suspension when the trailer is hooked up.
I would set the constant (tongue weight) which is determined by position of the boat on the trailer first. Again.. ask a trailer manufacturer.
When they design an adjustable trailer, they cant worry about the receiver height of every tow vehicle. The trailer is designed to be towed level with the proper tongue weight for the given load. I rest my case

 

[Hookup1]

Trailer

I don't treat the ball height as a variable. The trailer MUST be level when hooked up to the vehicle to distribute the load evenly to the tires on a dual or tri-axel trailer. After you adjust your trailer tongue weight you need to get the ball mount with the correct lift/drop.

If your going to adjust the trailer here is how I get the tongue weight. Put a jack stand on a bath scale under the trailer ball. Crank the trailer down to put the weight on the scale. If the scale can't handle the weight use a couple of boards - scale on one side, jack stand in the middle and block the other side to divide the weight.

http://www.boatus.com/trailerclub/upkeep/backyard.asp

 

[rorkin]

Re: Trailer

I don't the treat ball height as a variable. The trailer MUST be level when hooked up to the vehicle to distribute the load evenly to the tires on a dual or tri-axel trailer. After you adjust your trailer tongue weight you need to get the ball mount with the correct lift/drop.

If your going to adjust the trailer here is how I get the tongue weight. Put a jack stand on a bath scale under the trailer ball. Crank the trailer down to put the weight on the scale. If the scale can't handle the weight use a couple of boards - scale on one side, jack stand in the middle and block the other side to divide the weight.

http://www.boatus.com/trailerclub/upkeep/backyard.asp

100 percent right . The height is not a variable.. The draw bar drop or rise you buy to get it level is the variable. Which you can only discover once the tongue weight is properly established Then figuring what if any drop
exists at the hitch point when the weight is applied.(truck springs and shocks)
Which is then used to figure the proper drop or rise in the draw bar
when added to the height of the ball alone gets the trailer level .

Step one. Get boat on trailer with transom as fully supported by last roller or board as possible. Remember, the outboards will stress the transom so you want as much support as possible at the transom

Step 2 get tongue weight by using scale method as noted in link above or
other method

step 3 Adjust tongue weight if wrong by moving boat front or back or
axles back or front. Your trailer adjustment may vary by
manufacturer.

Step 4 see if hitch point is above or below level when weight of trailer
is applied.

Step 5 get correct draw bar to make trailer level if needed

step 6 Go fishing .. whew !!

 

[Grog]

The 100 pounds per inch of height difference is an extreme example. If the trailer was six feet long I can believe that but you're talking of a pivot point 20 feet away.


You don't need a machinests level but get the right drop/raise for the reciever to get the trailer to sit fairly level. Without the trailer being level, you're pissing in the wind trying to solve any problems.

 

[journeyman]

Rorkin,

I'll defer to my original reply to this post

The height of the hitch ball had a lot to do my sway issues and was the easiest thing to adjust. The trailer manufacturer will have recommendations as to hitch height to make the trailer level and once I fell in the 'Window' by increasing the drop, I can now safely cruise at 60. Truck is a 2500 HD Silverado and sits quite high so I had to look for a ball mount with a pretty good drop. I suppose hitch height and tongue weight are closely related.

Having a trailer sway on you can be reeeeeel scary

Nowhere did I discount the importance ot tongue weight! The purpose of this Forum is to help each other out with knowledge and/or experience.


When you come on and slam somebody with;

Just went throiugh this with mine.. Get that tongue weight right..
Fooling around with ball height is not the answer..
You want the trailer level when hooked to truck

You do a disservice to all who come here to look for help. In all your posts and, in fact, quite a few of the other replies here talk of the importance of a level trailer. Again, how do you keep a trailer level without the proper ball height. SOMETIMES with an already properly balanced rig, ball height is all that is needed to be adjusted as was in my case.

We can debate forever the question but, for other's sake, this will now end. I would suggest you don't so readily discount other's experience as "not the answer", pass on your experience and knowledge, and allow everyone freedom to post.

 

[rorkin]

I did not slam anybody... as I said. Do what works for you

I give up.

Rorkin,

I'll defer to my original reply to this post

The height of the hitch ball had a lot to do my sway issues and was the easiest thing to adjust. The trailer manufacturer will have recommendations as to hitch height to make the trailer level and once I fell in the 'Window' by increasing the drop, I can now safely cruise at 60. Truck is a 2500 HD Silverado and sits quite high so I had to look for a ball mount with a pretty good drop. I suppose hitch height and tongue weight are closely related.

Having a trailer sway on you can be reeeeeel scary

Nowhere did I discount the importance ot tongue weight! The purpose of this Forum is to help each other out with knowledge and/or experience.


When you come on and slam somebody with;

Just went throiugh this with mine.. Get that tongue weight right..
Fooling around with ball height is not the answer..
You want the trailer level when hooked to truck

You do a disservice to all who come here to look for help. In all your posts and, in fact, quite a few of the other replies here talk of the importance of a level trailer. Again, how do you keep a trailer level without the proper ball height. SOMETIMES with an already properly balanced rig, ball height is all that is needed to be adjusted as was in my case.

We can debate forever the question but, for other's sake, this will now end. I would suggest you don't so readily discount other's experience as "not the answer", pass on your experience and knowledge, and allow everyone freedom to post.