Trailer seems to fishtail

[cyclops2]

Re: Trailer seems to fishtail

Bingo.

The boat / trailer has ....2.... problems now.

Center wear is from the wind lifting the boat at high speeds.

Edge wear is from the underinflated tires at low speeds & turning.

That boat is a in a bad spot. It is flying with under inflated tires.

A car following you at all your speeds should see the springs unloading very easily. Same with the tires. Use 2 people in each vehicle so the drivers ONLY DRIVE & the talkers only talk.
They sould see see fishtailing at highway speeds passing trucks. Video that. Should make for a few laughs after you make all the corrections & ADD 500 pounds of weight to the frame OVER THE axle area.

Your problem is common with big lightweight boats. Shovelnosed hydros. kneeldown hydros. Flat bottomed Garverys. Almost any of them made to be light & out of plywood or Aluminum.

My 73 is showing on speed of recall on the past.

Piece of cake now.

 

[smokeonthewater]

Re: Trailer seems to fishtail

Bingo.

The boat / trailer has ....2.... problems now.

Center wear is from the wind lifting the boat at high speeds.

Edge wear is from the underinflated tires at low speeds & turning.

That boat is a in a bad spot. It is flying with under inflated tires.

A car following you at all your speeds should see the springs unloading very easily. Same with the tires. Use 2 people in each vehicle so the drivers ONLY DRIVE & the talkers only talk.
They sould see see fishtailing at highway speeds passing trucks. Video that. Should make for a few laughs after you make all the corrections & ADD 500 pounds of weight to the frame OVER THE axle area.

Your problem is common with big lightweight boats. Shovelnosed hydros. kneeldown hydros. Flat bottomed Garverys. Almost any of them made to be light & out of plywood or Aluminum.

My 73 is showing on speed of recall on the past.

Piece of cake now.

You can pretty much disregard this... I can't even figure out where this is coming from.... Your boat is not flying at 55 and even the tongue being up or down a few inches wouldn't make a fiberglass bow rider do so.... Since you have given no indication that you have odd tire wear and have not stated what pressure the tires are rated for there is no reason to assume causes of tire wear issues.

Your tongue weight is marginal at best and since there are no signs of other issues then adjusting tongue weight is the prudent choice.... definitely do NOT add 500 lbs or any other amount over the axle or anywhere else... Also don't worry about how many inches the center of gravity is from the axle... That 6" thing is just somebody's starting point for a guess on where to find a good tongue weight.... get the percentage right and ur GTG

EDIT: I just figured out that cyclops meant to reply to a different thread and this wasn't intended for you.... My advice stays the same though....

 

[sschefer]

Re: Trailer seems to fishtail

Completely agree with smoke. I think you have your trailer setup pretty well after what you've said in previous posts. A little more tounge weight might help but it is possible that the suspension on your Trailblazer is just not all that great and may be contributing to your problem. You may want to talk to your Chevy dealer about available towing package options that would enhance the vehicles towing capabilities. If it was mine, I would hook up with a bigger vehicle and see how it handled. If the problem cleared up you would know the correct actions to take.

 

[cyclops2]

Re: Trailer seems to fishtail

DO NOT GET OLD !!!!! Or go on medications.

Smoke is right.

Cross posted . Hate SLIDING DOWN the old farts side of the hill.

 

[j_martin]

Re: Trailer seems to fishtail

For Cyclops, every day is a new adventure.

I've pulled my bass boat ('bout the same) with all kinds of vehicles. With light ones (Dakota PU, Caravan) if everything isn't just right, as in tire inflation and steering geometry, it gets pretty goofy sometimes. With a real truck (Cummins dually 1 ton) the trailer and boat could be upside down and I wouldn't notice.

Yer running light on the towcar, so it's gotta be pretty right.

When I was running auto tires on the boat trailer, it was more touchy than when I switched to ST tires.

hope it helps
John

 

[cyclops2]

Re: Trailer seems to fishtail

J

My best trailering adventure was in 1980 ??

Took wife , daughter & new 16' Lowe Aluminum on a 2 week trip. Going was fine in a 1976 Honda Civic sedan. The tiny first ones in the USA.
Almost home. 1 lane bridge. I am 100' from it. So is the other car. He floors it to beat me. I stand on the brakes. Nothing happens with about 1,000 pounds behind me. Suddenly he jams his brakes on & lets me coast slowly across the bridge.

I still tense up thinking about that one.

Moral..............Luck beats the crap out of skill, knowledge or experience.

 

[cyclops2]

Re: Trailer seems to fishtail

I found out on that trip home that the trailer did have a steering wheel.
Big pot hole on the Interstate. I cut the wheel left then right. The trailer cuts the rear of my Civic left then right. That was my first lesson on high speed evasive turns.

 

[j_martin]

Re: Trailer seems to fishtail

Were you going commando by the time you got home?

 

[JDA1975]

Re: Trailer seems to fishtail

We got a contract in New Mexico once, to work on a road, and took 5 of our trucks out there with pneumatic trailers, Since our rigs were not set up with PTOs, we mounted 2 diesel engines and PTOs with 100 gallon fuel tanks on 2 small flat bed trailers. I was running a Nissan Frontier pick up with one, the other was pulled by our mobile home.. Needless to say mine fishtailed at 55 MPH, his did not. Your tow vehicle, and its suspension will play a lot into fishtailing, adjusting tongue weight may help some. Still haven't got a good picture of what your tow set-up looks like, a picture is worth a thousand words. Looking forward to see if/how you end up solving this problem. It is vital to solve it too...don't try to pull it by keeping your speed below the fishtail point, because while it may not fishtail at 45, it could still do it when you have to slam on your breaks, swerve to miss a deer, or have a blowout.

 

[Scott Danforth]

Re: Trailer seems to fishtail

You can pretty much disregard this... I can't even figure out where this is coming from.... Your boat is not flying at 55 and even the tongue being up or down a few inches wouldn't make a fiberglass bow rider do so.... Since you have given no indication that you have odd tire wear and have not stated what pressure the tires are rated for there is no reason to assume causes of tire wear issues.

Your tongue weight is marginal at best and since there are no signs of other issues then adjusting tongue weight is the prudent choice.... definitely do NOT add 500 lbs or any other amount over the axle or anywhere else... Also don't worry about how many inches the center of gravity is from the axle... That 6" thing is just somebody's starting point for a guess on where to find a good tongue weight.... get the percentage right and ur GTG

EDIT: I just figured out that cyclops meant to reply to a different thread and this wasn't intended for you.... My advice stays the same though....

actually, the 6" rule comes from the engineering standards at one of my old jobs for building genset trailers. Never less than 10% tongue weight, and CG no less than 6" forward of axle to prevent towing instability, ie "fishtailing"

 

[sullmate]

Re: Trailer seems to fishtail

Fed,
I have been towing different rigs for 30 years. The trailer is level with the tongue.This rig used to tow well but not now. The axle is straight, I get white knuckles when towing on the highway. I don't tow very often anymore. I used to tow about 200 miles up to Lake George, N.Y.
I want to thank everybody for their input. I boaters are the best and have always been very helpful
I not too computer literate and would have no idea how to post a picture of my rig.
Sullmate

 

[cyclops2]

Re: Trailer seems to fishtail

You mention the rig towed OK before.

You may have a bunch of worn out rubber bushings in a lot of the suspension parts. Worth a look underneath with a Gorillia mechanic shoving & yanking everything.

Check the color of the paint / rust marks, where the trailer leaf springs are bolted....frame & spring / axle also. Something has changed, as you noticed in the handling.

EDIT

Heaven forbid this.
Check the play in each wheel bearing. Jack the wheel side up to really feel any odd noise or feel while yanking it all over.

The fistailing IS GOING to occur at a lower speed. That should be a given. Find the cause / causes before we lose you.

Post back when you find the problems.

 

[smokeonthewater]

Re: Trailer seems to fishtail

actually, the 6" rule comes from the engineering standards at one of my old jobs for building genset trailers. Never less than 10% tongue weight, and CG no less than 6" forward of axle to prevent towing instability, ie "fishtailing"

which makes it just what I said, It is a starting point but it does not apply across the board to all trailers.... a certain distance (6" here) only applies to a certain wheelbase trailer.... The CG on my 30'' trailer might be 24" forward and on my jetski trailer it might be 3".... The percentage will put the CG location where it needs to be.... That may very well be 6" but if it isn't then don't sweat it.