My boat dances on trailer

[salmonee]

when I hit a bump/pot hole in the road going 20+mph. I'm replacing the coupler this weekend. My boat sits on roller and I tied the stern down with straps. Is this normal? I'm afraid it's going to come crashing down on the trailer one day. What kind of checks should someone do on an old trailer? Mine is an '85. I replaced the entire axle/hub last summer. I'm putting new tires and jack on as well.

 

[RL Gman]

Re: My boat dances on trailer

If the boat is dancing around, you probably have some rollers too high or some too low, causing an uneven distribution of weight. Not only would that be bad for the "dancing" boat coming crashing down, that extra strain on the hull in certain areas is definitely a bad thing. I would say, find the "pivot point" for the dancing, that area is either too high, or the rest of the rollers are too low.

Without pics, that's the best I can think of...

OT: thats why I prefer bunks to rollers...distribution of weight!

 

[jtexas]

Re: My boat dances on trailer

yup, boat should be made fast bow & stern.

Wheel bearing inspection is a good idea, if you haven't done so within the past couple years.

 

[Thundra]

Re: My boat dances on trailer

Get one of these for the bow-eye;

And get one of those big straps to go over the back of the boat to help.

Also, make sure your trailer tires are balanced when you get new tires.

 

[180shabah]

Re: My boat dances on trailer

Pics of your setup would help.

Your boat and trailer should be one, when travelling down the road.

 

[kenmyfam]

Re: My boat dances on trailer

Somethings wrong, photos would be a big help.

 

[dave11]

Re: My boat dances on trailer

If the boat is dancing around, you probably have some rollers too high or some too low, causing an uneven distribution of weight. Not only would that be bad for the "dancing" boat coming crashing down, that extra strain on the hull in certain areas is definitely a bad thing. I would say, find the "pivot point" for the dancing, that area is either too high, or the rest of the rollers are too low.

Without pics, that's the best I can think of...

OT: thats why I prefer bunks to rollers...distribution of weight!

I would agree. I prefer bunks, also.

 

[salmonee]

Re: My boat dances on trailer

Here are pics of the boat. I noticed that it wobbles when I climb into the boat.

 

[RL Gman]

Re: My boat dances on trailer

If it's wobbling side to side, I think I see the problem...

All of the rollers (obviously not the keel rollers) need to be raised about an inch to and inch in a half.

It looks like too much weight is sitting on the keel. I bet those rollers have all worked themselves down a bit after years of towing. Stick the boat in the water, rais the rollers, take a little weight off the keel and I bet you can put the boat's dancing shoes away!

Edit: Looked again at the side picture and I might have been wrong above...The rear rollers may need a good 2 - 2 1/2 inches raised...or, dont change the front rollers and just raise the rear rollers about 1 - 1 1/2 inches...

Which way does it wobble, fore and aft, or port to stbd, or all around?

 

[salmonee]

Re: My boat dances on trailer

If it's wobbling side to side, I think I see the problem...

All of the rollers (obviously not the keel rollers) need to be raised about an inch to and inch in a half.

It looks like too much weight is sitting on the keel. I bet those rollers have all worked themselves down a bit after years of towing. Stick the boat in the water, rais the rollers, take a little weight off the keel and I bet you can put the boat's dancing shoes away!

Edit: Looked again at the side picture and I might have been wrong above...The rear rollers may need a good 2 - 2 1/2 inches raised...or, dont change the front rollers and just raise the rear rollers about 1 - 1 1/2 inches...

Which way does it wobble, fore and aft, or port to stbd, or all around?

It wobbles side to side. The boat is stern heavy. The motor is a 115 Yamaha 4 stroke, very heavy ~500lb. There is nothing in the bow, the entire compartment is empty space besides junk that I throw in there.

I think you might be right about the roller adjustment. I know that I can wobble the boat if I push up on the bow. It doesn't take to much force either. It will bob up and down if I push up at the bow.

 

[RL Gman]

Re: My boat dances on trailer

It wobbles side to side. The boat is stern heavy. The motor is a 115 Yamaha 4 stroke, very heavy ~500lb. There is nothing in the bow, the entire compartment is empty space besides junk that I throw in there.

I think you might be right about the roller adjustment. I know that I can wobble the boat if I push up on the bow. It doesn't take to much force either. It will bob up and down if I push up at the bow.

After reading that, sounds like the adjustment is all you will need. Should be a fairly short job...after you get the boat off the trailer. :redface:

Do you have good tongue weight? The boat/trailer distribution looks good, but if as you said, all that weight is in the back, that may contribute to the problem. Adjusting the bow catch just a little will help there, but like I said, it looks like it is distributed correctly.

 

[salmonee]

Re: My boat dances on trailer

After reading that, sounds like the adjustment is all you will need. Should be a fairly short job...after you get the boat off the trailer. :redface:

Do you have good tongue weight? The boat/trailer distribution looks good, but if as you said, all that weight is in the back, that may contribute to the problem. Adjusting the bow catch just a little will help there, but like I said, it looks like it is distributed correctly.

I'm not sure what tongue weight means. If your asking about the weight at the tongue, there is hardly any weight at all. I can lift the boat easily at the tongue. Maybe 5lb of weight.

Raising the rollers don't sound so easy to me. It almost sounds like I may be required to adjust the other rollers as well just so that it hugs the bottom of the boat when the rear rollers are raised.

 

[RL Gman]

Re: My boat dances on trailer

I'm not sure what tongue weight means. If your asking about the weight at the tongue, there is hardly any weight at all. I can lift the boat easily at the tongue. Maybe 5lb of weight.

Raising the rollers don't sound so easy to me. It almost sounds like I may be required to adjust the other rollers as well just so that it hugs the bottom of the boat when the rear rollers are raised.

2 distinct thoughts, both of which probably affecting the ride of the boat...

1. Tongue weight: should be about a tenth of the weight of your rig (anywhere from 9% to 15% really). Looking at the rig, you're probably at about 1500-1700 lbs (at least with the gear)? You should have about 150 pounds on the truck. That will help the sea-saw affect I'm sure you're getting while pulling. (Remember that axel is the lever point, you want the "fat kid" on the truck side.) To fix this, you can do a couple of things, move the bow catch foward, or move the axel back. Obviously moving the catch foward some is the easier of the two (four bolts loosened and move it). All you need to ensure is that the furthest rear roller still has some boat to sit on it...

2. Adjust the Rollers: To ensure not to much weight is on the keel, and to ensure no roller is holding to much weight, I would start my moving them up an equal distance. This whole part is a bit of a guess and check, but shouldnt take to much. If it were my trailer, I would start by moving the front rollers up (by up I mean a vertical change, not up on the trailer) 1 inch, and the furthest back rollers up 2 inches. This will take some weight off the keel, and distribute it better on the rollers, making them cradle the boat.

In the pictures I didnt see the adjustmetn type for the rollers, but I cant imagine that would be a difficult change, probably two bolts loosened and them move it up. And yes, you need to move them all at the same time. And then recheck for any dancing.

This is getting longer than I expected So I'll stop here and wait for an update! Perhaps some other guys will also chip in and thow some advise your way...I know Smoke is huge on towing, and has some good info, he'll prolly chime in...

 

[marlboro180]

Re: My boat dances on trailer

I think RL touched on something with the tongue weight here.

Salmonee,
Tongue weight is the amount of weight at the very front of the trailer, measured at the ball . If you can lift it really easily, you do not have enough weight on the front of the trailer.If you only have about 5 # at the ball, that is way too light. The trailer will want to sway around a bit, bounce up and down at the coupler, etc. and will contribute to dancing around

Common practice is to have 8-15% of the total weight of you boat, trailer and contents ( ice, coolers, gear, etc) on the tongue. SO if your rig weighs 1000#, you would want 80-150# on the tongue. I am using a hypothetical number here, so find out what your boat weighs and go from there.

A bathroom scale is a very useful tool for setting up your trailer.

It seems as though you may want to change where you stow your gear
( further forward) and / or move the boat forward on the trailer.

Heres a link for further readinghttp://auto.howstuffworks.com/auto-...acity/information/tongue-weight.htm/printable

 

[jtexas]

Re: My boat dances on trailer

In my experience, a tongue-light trailer sways like crazy, while a tongue-heavy trailer tends to shake the tow vehicle. Moving the bow stop by one inch can make a big difference.

 

[salmonee]

Re: My boat dances on trailer

I don't think I can move the boat any more forward as it is. The stern sits only about 1-2 " past the last roller.

 

[salmonee]

Re: My boat dances on trailer

2 distinct thoughts, both of which probably affecting the ride of the boat...

1. Tongue weight: should be about a tenth of the weight of your rig (anywhere from 9% to 15% really). Looking at the rig, you're probably at about 1500-1700 lbs (at least with the gear)? You should have about 150 pounds on the truck. That will help the sea-saw affect I'm sure you're getting while pulling. (Remember that axel is the lever point, you want the "fat kid" on the truck side.) To fix this, you can do a couple of things, move the bow catch foward, or move the axel back. Obviously moving the catch foward some is the easier of the two (four bolts loosened and move it). All you need to ensure is that the furthest rear roller still has some boat to sit on it...

2. Adjust the Rollers: To ensure not to much weight is on the keel, and to ensure no roller is holding to much weight, I would start my moving them up an equal distance. This whole part is a bit of a guess and check, but shouldnt take to much. If it were my trailer, I would start by moving the front rollers up (by up I mean a vertical change, not up on the trailer) 1 inch, and the furthest back rollers up 2 inches. This will take some weight off the keel, and distribute it better on the rollers, making them cradle the boat.

In the pictures I didnt see the adjustmetn type for the rollers, but I cant imagine that would be a difficult change, probably two bolts loosened and them move it up. And yes, you need to move them all at the same time. And then recheck for any dancing.

This is getting longer than I expected So I'll stop here and wait for an update! Perhaps some other guys will also chip in and thow some advise your way...I know Smoke is huge on towing, and has some good info, he'll prolly chime in...

Shouldn't I move the center rollers up higher than the stern? This would put more weight center of the trailer as appose to the back.

 

[RL Gman]

Re: My boat dances on trailer

Shouldn't I move the center rollers up higher than the stern? This would put more weight center of the trailer as appose to the back.

wow, great question, especially considering everything we've discussed...but I would say no.

Ideally, you want all the rollers to hold the same amount of weight, so that no one part or area of the boat is feeling more strain. Also, you dont want to be shifting the weight of the trailer (to help tongue weight) by placing more stress on one roller over another (as I get the feeling your asking in that question, again, good question, but I dont think so).

Right now, it looks like the keel rollers are taking the brunt of the weight (thats what I see in the pics, and what you dont want! In fact, I dont even let my boat touch keel rollers!) and I was saying raise all of the rollers up, with the back a little higher, to level the boat more on the trailer.

Now, with all that weight on the back, are you able to create equal strain across all the rollers? Probably (read definitely) not, but you still dont want any of the rollers to be a pivot point where they can place a moment (read torque) on the hull. So although they will not be hold the same amount of weight, the trailer will still cradle the boat and not allow any movement (read dancing).

Obviously the trailer was designed to hold more weight on the transom (as evident by the double rollers in the back) so raising them will not be a bad thing.

As for the tongue weight, you have to fix that by the 3 ways mentioned earlier, moving the bow stop foward, axle backward, or more weight on the front (stuff loaded in the boat). NOTE: not by making the front rollers hold more weight!

If adding weight to the front of the boat isnt enough to give sufficient tongue weight, you will need to move the bow catch...but since the rollers are within an inch of the transome, you would also have to move those rollers more foward on the trailer.

I'm realizing this is getting more and more complicated!! lol And I know that's what you were trying to avoid!

Problem lies: Trailering a boat is a critical part of the recreational boat user, and having the trailer supporting the weight correctly can easily be the difference between a safe and unsafe trip...

Let me know what you think so far!

 

[kenmyfam]

Re: My boat dances on trailer

All your rollers should "share" the load. Tongue weight is critical as well. 10% is a good ballpark figure to begin with. Fine tune from there. An extra strap holding everything down just in front of the motor well would do no harm either.
My 2 cents.

 

[Mi duckdown]

Re: My boat dances on trailer

If you can pick up the tongue, you are way too light.
from the looks of your trailer you can easily move the winch post a couple inches forward and crank the boat forward.
Back off the side rollers. using only the keel rollers.
measure the tongue weight as you crank it forward with a scale at the ball with trailer level 18, 19 inches.
than reset side rollers.
That may require jacking up the boat to reset.
no biggy