see sawing

[floater212]

how do i figure out what's wrong with my boat (too far foward or too far back) or trailer (new spring and tires), on the highway i take to get to the water bumps big, of course, and small the boat starts a seesaw action that drives me crazy...short drive! it had this from the start of when i got it. the tow vehicle is a 2012 ford 150 4x4 so it's stout enough, i changed rear shocks to high pressure gas and added a sway bar which helps but still there. i have never changes position of the bow stop because i don't know which way , i am thinking of the load leveler coilover shocks. which way should i go for? my boat is a 2005 rinker 212 ( 3500lbs) and single axle trailmaster, they call it a heavy single.

 

[Alumarine]

What's your tongue weight on it?
It should be 10%-15% of total weight.

 

[MTboatguy]

I agree with Marc, check your tongue weight.

 

[roscoe]

Trailer frame should be level when hooked to the truck, you may need to buy a different tow bar to achieve this.

And yes, you need 350 + pounds of tongue weight on the ball.

Move the boat forward or the axle rearward, to increase tongue weight.

 

[GA_Boater]

If it hasn't been said - Increase your tongue weight. Can you pick up the tongue?

 

[floater212]

i don't know the tongue weight, how can i find that out, i don't have a scale to go up that high so how do i do it?

 

[floater212]

it also took 3 tries to get the levelest ball/drop set up.

 

[MTboatguy]

Do you have a picture of your trailer hooked up to your tow vehicle? as was already asked, can you pick the tongue up by hand, if it is off balance, which what a light tongue will do, it will cause that oscillation you are describing when it hits ripples in the road. The boat and trailer being heavy in the back is trying to pull it off the ball which causes it to "see saw" back and forth.

 

[Scott Danforth]

move your bow stop forward or move your axle backwards

you need more tongue weight

 

[Alumarine]

i don't know the tongue weight, how can i find that out, i don't have a scale to go up that high so how do i do it?

I googled how to determine trailer tongue weight and it found this among others.
http://hildstrom.com/projects/tonguescale/index.html

 

[H20Rat]

It should be 10%-15% of total weight.

Don't think I'd personally ever run 15% on a boat trailer... To much of a good thing applies to tongue weight, you risk overstressing the front members of the frame as well as reducing the handling of the tow vehicle.

Shorelandr recommends 5-7%, and they give corrective steps if it is >7%.
https://www.shorelandr.com/pages/pf_trstep3.htm

 

[khe]

If there is a CAT certified truck scale near you (it seems like they're everywhere) you can weigh your truck and boat as a unit - your weigh ticket will show: Steering, Drive, and trailer. Once you have your weigh ticket, move to the parking area, unhook the boat and weigh just the truck. With the two weigh tickets, you can do the math and figure the tongue weight: Add the steer axle and drive axle weights together from the weigh ticket with the boat hooked up. Add the steer and drive axle weights for the truck only. Subtract the truck only weight from the truck only with the boat hooked up and you have your tongue weight. To calculate the weight of the boat and trailer, subtract the gross weights. Divide the tongue weight by the weight of the boat & trailer to obtain the percentage.

EZ Loader recommends 5-7%

 

[Silvertip]

You do not need a 400# scale to measure 350 pounds. If you have a bathroom scale, it will likely measure in excess of 200#. You obtain a 2x4 about 3 feet long. Place a mark exactly in the middle of that 2x4. Place one end of the 2x4 on the scale and the other end on a block (wood, concrete, etc). Just make sure the 2x4 is level. Now set the coupler (or the tongue jack) on the center of the 2x4. The scale will read 1/2 the tongue weight. This isn't rocket science so an error of 5 - 10# is not critical. It is meant to give you an idea what the tongue weight is. Right now you don't have any idea.

 

[JASinIL2006]

Whatever you do, find out what the tongue weight should be and fix it. You can go from see-sawing to out of control before you know it.

 

[M2HB]

As a general rule, 10% is a minimum tongue weight.

Too little tongue weight can rip the trailer off the tow vehicle if the sway gets bad enough.
I try to keep it over 10% since I pull with a one ton truck.

The problem with low tongue weight is if something shifts or weight is added in the back, like water in a boat, it can cause a wreck.

 

[floater212]

how would it act if there is too much weight on tongue? just for fun i tried to lift hitch up and there has to be about 400lbs +, couldn't even budge it at all.

 

[Alumarine]

how would it act if there is too much weight on tongue? just for fun i tried to lift hitch up and there has to be about 400lbs +, couldn't even budge it at all.

Unless you can lift 400 lbs you won't be able to budge it.

 

[M2HB]

Extra tongue weight won’t create issues if the tow vehicle can handle it and the tongue can handle it. In many cases, one or the other may not handle the extra weight.

 

[MTboatguy]

Actually if you are heavy in the tongue where it is actually dragging down the back of the tow vehicle, it can cause a seesaw effect on concrete slab roads, the joints of the slabs sit higher than the middle of the slab and as you go over the joint the extra weight of the tongue will load the springs more and cause a opposite rebound causing the tongue to spring upon unloaded state. It does not take much release and rebound to make them seesaw if things are out of balance.

If you have a few cinder blocks around you can shift your load to see if you can't smooth it out a bit, I would put a few in the stern on the floor then take out and drive on the type of road that you experience this situation and it will help you determine which direction to go to correct it.

 

[floater212]

moved bow stop towards truck 1", seems alot better, we'll see after a few more hauls...