*THE HULL TRUTH is the world's largest FREE network for the discussion of Boating & Fishing. Whether you're researching a new boat, or are a seasoned Captain, you'll find The Hull Truth Boating & Fishing Message Forum contains a wealth of information from Boaters and Sportfishermen around the world.
Welcome to the updated THT!
If you are having trouble signing in, please email feedback@thehulltruth.com with your username and we will help you. We thank you for your patience as we help you access the new site!
Random Quote: You know what they say about common sense-it ain't so common!
Well ... I think part of the problem is that I have the front of my truck raised a bit and the shocks are bottoming out with the tail of the truck pulled down. So that may explain the bouncing. So do you change the tongue weight by changing the height of the ball?
Please give a better discription of the truck and the weight of the boat trailer package with fuel and normal
gear.
For boat trailers generally about 7 to 10% hitch weight as a percentage of the total trailer weight
is about right.
Too much tongue weight tends to squat the rear of the truck and also reduces the load on the front
wheels, the rear axle is acting as a fulcrum just like a seesaw, you loose steering ability.
Too little tongue weight can cause the vehicle to be pitched up when traveling over bumps and dips,
also loss of rear wheel traction and tracking, can increase the possibility of jackknifing too.
To determine what it should be you need to go to a scale and get readings for the tongue weight and the
overall weight to know where to start.
Depending on the trailer you should be able to slide the axles forward to reduce the tongue weight or
slide the axles rearward to increase the tongue weight. If doing this you must keep the axles straight
too.
It is recommended that when hitched up the trailer should be level, especially a tandem trailer so that you
have equal loading on both axles or all three axles if thats the case. The truck should sit almost level too.
Then you need to know what the tow vehicle is rated for to see if you can safely tow this boat.
The USCG safe boating class recommends 5% - 7% of the boat weight be tongue weight.
If you do not have enough, then the trailer may tend to lift the rear of the vehicle. This can cause a situation where the trailer fish tails under tow, and can cause your rear tires to loose traction - which makes it harder to get up a slippery ramp.
Too much weight will push down on the rear of the vehicle, causing less weight to be on the front tires. This could result in a loss of steering control.
To change the tongue weight you slide the boat forward or backwards, and/or move the axles. Leaving the axles alone and moving the boat forward increases tongue weight, moving the boat back reduces tongue weight.
Leaving the boat alone and moving the axle forward reduces weight, moving the axle back increases the weight.
Small changes can result in large changes in weight.
You can measure tongue weight with a bathroom scale. Put the scale on some 2x4 or on any level hard surface. Then take a length of 4x4 long enough to go from the tongue to the scale. Weigh the 4x4 post, place it on the scale, and lower the trailer onto it. Now you know your tongue weight.
If you are way below the 5% or way above the 7%, then you may want to go to a trailer shop or boat yard and ask them to adjust the load. Or if you are comfortable with doing it yourself, go for it.
__________________ 1999 20 foot Seagull power cat
Single 135 Optimax outboard
The USCG safe boating class recommends 5% - 7% of the boat weight be tongue weight.
If you do not have enough, then the trailer may tend to lift the rear of the vehicle. This can cause a situation where the trailer fish tails under tow, and can cause your rear tires to loose traction - which makes it harder to get up a slippery ramp.
Too much weight will push down on the rear of the vehicle, causing less weight to be on the front tires. This could result in a loss of steering control.
To change the tongue weight you slide the boat forward or backwards, and/or move the axles. Leaving the axles alone and moving the boat forward increases tongue weight, moving the boat back reduces tongue weight.
Leaving the boat alone and moving the axle forward reduces weight, moving the axle back increases the weight.
Small changes can result in large changes in weight.
You can measure tongue weight with a bathroom scale. Put the scale on some 2x4 or on any level hard surface. Then take a length of 4x4 long enough to go from the tongue to the scale. Weigh the 4x4 post, place it on the scale, and lower the trailer onto it. Now you know your tongue weight.
If you are way below the 5% or way above the 7%, then you may want to go to a trailer shop or boat yard and ask them to adjust the load. Or if you are comfortable with doing it yourself, go for it.
Very similar to my above post but,
Did you notice his signature is a 30+ Contender? Also no mention of what size truck, so I suggested
that he scale the trailer to determine his weights and provide more information about the truck.
cyncwby - 12/13/2007 7:37 PM Sounds to me like you need a new pair of rear shocks. Usually you need 10-15 % of the total weight of your boat/tailer on your tongue
10-15% is incorrect for trailer boats. It should be around 1/2 that.
__________________ Grady White SeaFarer 226 w/Yamaha F225 - SOLD
So do you change the tongue weight by changing the height of the ball?
Changing the height of the ball will change the height of the ball. You change tongue weight by a) moving the axle forwards or backwards or b) moving the boat forwards or backwards.
Sounds like your bouncing is being caused by too little tongue weight. Does the back of your vehicle squat a bit when you lower the hitch onto the ball?
Assuming you're towing a weight within your tow limit. Check your owner's manual.
The truck definitely squats. I am pretty sure that the reason it is bouncing is because my front shocks are topping out on the rebound. Nothing a longer set of shocks wont fix.
So ... do I worry about tongue weight? The boat and trailer should be well within the limits of my boat so I dont think its an issue there.
The truck definitely squats. I am pretty sure that the reason it is bouncing is because my front shocks are topping out on the rebound. Nothing a longer set of shocks wont fix.
So ... do I worry about tongue weight? The boat and trailer should be well within the limits of my boat so I dont think its an issue there.
Sounds like you have too much travel in your suspension; weak springs? tires rated correctly? lifted truck? wrong shocks?
So ... do I worry about tongue weight? ..................
Yes. Set it between 5% and 7% of the total weight of the loaded boat and trailer. Don't be tempted to use a "published weight". Tow it to a scale and weigh it.
You've already been given good advice on how to change the tongue weight so there's no need to repeat it.
Make sure the trailer is parallel to the ground whem connected to the tow vehicle.
Once you have made these correctiions and adjustments, if you still have problems you will need to troubleshoot your tow vehicle. Don't waste your time and money on the tow vehicle until the trailer is set up correctly.
Changing the ball height WILL affect tongue weight. Anyone who tells you differently does not understand basic physics. Generally, raising the ball height will lessen tongue weight, and lowering the ball height will increase tongue wieght. That said, you want your trailer to be level anyway, so fiddling with the ball height is not a recommended way of adjusting the tongue weight.
Let's say you are shooting for 7%. First,you need to figure out what 7% of your trailer weight is using a truck scale. Weight the truck + trailer and weight the truck alone. Now that you have your real trailer wieght, multiply this times .07 to get 7%. This is the amount of wieght you want to be placed on your truck while the trailer is level. If this amount of wieght squashes the rear end of your truck down, you need to modify your suspension. If the amount of weight is far above or below 7% while holding the trailer level, you need to fix the trailer. Moving the axle forward will decrease tongue wieght, and moving it back will increase tongue wieght.
Sounds like he may be towing with an independent front suspension truck with the torsion bars cranked up. Probably rides fine empty, but with a load it pulls the front suspension up enough that when you hit a bump it either maxes out the front shocks or hits the mechanical limit on the a-arms.
If that is the case, you could try losening the torsion bars a turn or two (hopefully you still have enough tire clearance) or you could cough up the dough for a real lift kit.
Well, it might be and it might not be. First and foremost, the boat has to be supported correctly on the trailer. That means bunks or rollers directly under the transom. You don't want bunks too far past the transom because they could hit the trim tabs or make the boat harder to load and unload. And rollers sticking out past the transom wouldn't be supporting anything at all and just get in the way.
I set my boat up on my trailer by moving the winch post, then adjusted the tongue weight by moving the axles. It's easy if everything is done with U bolts as mine is. It would be more difficult with a drilled frame and nearly impossible with welds.
Moving things around in the boat might help on a small boat but if the boat weighs several thousand pounds, there's not much to move that would make a difference.
Changing the ball height WILL affect tongue weight. Anyone who tells you differently does not understand basic physics. Generally, raising the ball height will lessen tongue weight, and lowering the ball height will increase tongue wieght.
There seems to be some clarification needed here. On a single axle trailer, raising or lowering the ball can alter the tongue weight only by the cosine of the angle of the trailer. The cosine effect is the same if the trailer is moved above or below center. What is "the cosine effect"? As the angle increases, the load decreases. Obviously, if you raised the trailer until it was resting on its tail, there would be zero tongue weight. As you move the trailer from being vertical to horizontal, the tongue weight goes from zero to its maximum. That applies if the trailer is moved up or down. Raise OR lower the ball and the weight does change. But it changes very little and changes exactly the same if you are going up or down from level.
On a multi-axle trailer, the load will change because raising it tends to unload the front axle and add that load to the tongue. Lowering the tongue will unload the rear axle(s) and decrease the tongue weight - but it takes more than an inch or two to make a significant difference.
So, back to the original question. There are lots of theories about how much tongue weight you should have, but there is also a good test. Does the trailer begin to sway at speed or is it stable? If it does not sway, your tongue weight is fine for your combination. Get it too light and the boat will act like a happy dog's tail. Get it too heavy and it will bottom the tow vehicle's suspension but will not sway. So, what should your tongue weight be? Enough that the trailer tracks properly and does not sway. Is the ball height right? Usually the trailer should be level. But you can check it. First, make sure that all the tires are inflated to the same pressure. Then tow at high speed for a few miles and check the temperature of the tires very quickly after you stop. You want to check to tire temps, which indicate the load, not the braking energy. You cannot do this if you've been doing a lot of braking, which will transfer heat into the tires. You need to do it after one clean stop.
If you've jacked up your front end, the additional load of the trailer will make the front end even higher. You do not want to be out of shock travel on either end.
Kerno - I believe we are saying the same thing. I think you just clarified it a bit. I was trying to limit the amount of geometry.
When I said that raising the ball would decrease the wieght, I was going on the assumption that the ball height would be at or above the level. You are correct in that the weight would decrease the farther you go from being level.
The point point I respectfully disagree with you is the magnitude of change, based on my real life experiences of lifting a trailer tongue on a short snowmobile trailer. Using a straight hitch, the tongue of my snowmobile trailer was six inches too high. I could easily lift the trailer off the ball with my own two hands. After I replaced the hitch with a 6" drop hitch, the snowmobile trailer sat level, but I was no longer able to easily lift it. On a side note, it also trailered much better.
Things are much more noticeable on a snowmobile trailer due to the short length. They also sit lower to the ground as the tires have to be underneath the trailer rather than on the sides. While trailering up north with some other couples, I noticed that one individual had issues with trailer sway and had trouble towing above a certain speed, despite the fact that he was driving a full size 1/2 ton truck. He was discussing upgrading to a 3/4 ton because of the scariness of the tow. I was pulling a similar trailer with my little S-10 and the ride was far more pleasant. Keep in mind that sleds weigh around 500 lbs, so a 2 up trailer with 2 sleds & gear weighs around 2500 lbs, a lot less than many boat trailers.
At a gas stop, I asked him to rearrange stuff in his trailer. He slid his plastic bin full of clothes all the way to the back and was able to move the sleds forward about 12 inches. He also relocated his gas cans to the front of the trailer. He could not believe the difference. I am not saying that you can make up for lack of a big truck just by tongue weight, but a level trailer with proper tongue weight does make a huge difference.
The secrecy regarding the tow vehicle suggest that might be the problem
Sorry ... been away from the computer for a while. The tow vehicle is a GMC 2500 HD Duramax. I can adjust the winch post back and forth but it seems that I need to determine what my current tongue weight is prior to making any adjustments.
Towing tongue weight question. 
