trailers

[capt lar]

when dragging one of my boats around, my trailer will start to fishtail at speeds above 60 mph. i can adjust the boat on the trailer. would someone remind me if this condition means too much weight forward or back. i thought it meant i needed to move the boat forward, but don't want to overload the receiver. thinking to make a florida run in november. capt. lar

[delmarrey]

The proper tongue weight for towing is 7-10% of the trailer assembly gross weight, perferably on the 10% side.

Also the tow vehicle must be rated for the gross weight of the trailer assembly. No matter how big the engine is, the suspension has to be able to keep the front wheels in control.

And trailer brakes are a plus, especially down hill. Not much to worry about there, in FL.

[Alan Wheeler]

This is a complicated situation. Do you have duro torque or leaf spring suspension on the trailer. What type tyres and are they at the correct pressure. Has the toe and camber attitude of the tyres been set up correctly when the trailer was made. All these have an affect on the tracking stability.
For a general weight distribution, you divide the entire trailer/load balance into a 60/40 ratio. Yeah I know, how do you do that? But anyway, 60% of the overall weight should be forward of the trailer axial.
Here are some effective and possible remedies. Depending on the exact problem, each may or may not have an affect. Depending on tire type, try changing the inflation pressure. Try a much harder inflation and then try a very soft inflation and see which has the better effect. Try taking the weight in the boat further forward. A very effective mod you can do, is to fit shock absorbers to the trailer axial. That makes such a difference to how any trailer sits behind a vehicle. Ensure Springs, if fitted, have no shackle slop and the springs themselves are not too extreme in their curve.
Hope this helps.

[capt lar]

dual axle, surge brakes, leaf spring suspension. 5400 lb capacity. truck or jeep both rated for 5500 lb. longer wheel base on truck helps a little, but same problem - violent sway and loss of control. pot hole or uneven pavement can start the motion.
boat (3,000 lb.), motor (500 lb), fuel (up to 135 gal =800lb.) and gear (not much when towing) means i am well under those #'s.
tires are correct pressure. ratio seems correct @ 10% - maybe higher. this is a center console with t-top and a 225 h.p. merc that hangs a lot of weight off the back, so i may be too far forward. when setting up i wanted to prevent risk of tip when trailer is not attached to car and 2 guys are @ stern - seen it many times - expensive - damage skeg.
capt. lar

[Jentine]

If the tail is wagging the dog at highway speeds, your tongue weight is insufficient. The tongue weight should be ~ 10% of the gross weigh of the trailer and load. Any less and the trailer wanders, more and the tow vehicle is unbalanced causing hard steering.
Your tongue weight should be in the 500- 600 pound region. You didn't mention the 1300-1500 pounds for the trailer. That figure added to the total listed brings the gross weight up to the limit of the tow vehicle. You may need a load equalizing hitch to raise the rear of the truck while maintaining the proper tongue weight.
Jim

[BC Mike]

You need more hitch weight. You need to check the axel alignment, they should be at 90 degrees to the main frame. That 500 to 600 pound hitch weight sounds about right to me. Get a cheap tongue jack to lift the hitch. Check the tyre pressure on the trailer. Sometimes radial tyres wander more than the other kind. Is the boat on the trailer power or sail. If it is sail the hull could be flexing under the pads and that starts a nasty wander.
When Mike Hailwood was asked how the Honda moemcycle handled he replied " Like a pregnant cow in quicksand " If it does that there are other issues and you may need a bigger tow vehicle.
Michael

[capt lar]

well, okay then - i will check out tongue jack. it is easy enough to move boat forward on trailer, and through your comments, i am also thinking stronger tie down straps to avoid possible shift on rollers and empty fuel tank to reduce shifting weight that could aggreviate swing. this is a 23 foot boat, and as big as i would want to get and still trailer. no question it is max for a jeep or 1/2 ton truck. capt. lar

[BC Mike]

A sail boat with what kind of keel ?? or is it a power boat ??
Always have straps to tie it down, forward and aft for a sailboat, at the transom for a power boat, at the trailer winch area for both, and something to hold the boat back in case you run into something solid. Do that for either type of boat.
Michael