Boat bounces on trailer.

[glenn property of pam]

Re: Boat bounces on trailer.

Ok lets see from the 1st post, even when the boat is up a couple more inches those straps still do angle out and a little forward. From my experiences with my dad and friends boat theirs do the same. Glenn im kinda confused on what your saying to do there but i didn't move the winch in the first place but the rust marks make me think someone else has. The trailer does jump more than id like it to but i really think the boat is shifting too. My buddy w the baja drove it around the block last week and his first response was "thats scary i wouldn't pull that very far" Ok here's something else i just thought of....when the boat is cranked up u can lift up the front of the boat very easily like its very back heavy. The guys who sold it to me said to crank the tongue all the way down when parked bc it will wheelie on u if u climb in the back. They said its bc of the motor swap and extra weight, and it does sit way low in the back in the water. ok any other opinions lol

what i was saying is the trailer is rear heavy so when you hit a bump its lifting the rear of the truck and thats a bad felling and dangerous. so you need to know how much weight is on the tow ball and that can be done with bathroom scales and a jack stand.

 

[akorcovelos]

Re: Boat bounces on trailer.

can you just move the post forward like that? Wouldn't that put the boat too far forward on the trailer and risk hitting the drive and any transducers hanging off the transom on the back of the try trailer?

 

[jkust]

Re: Boat bounces on trailer.

Ok so I presume then that you can pick the tounge off the ground if the trailer wheel wasn't down and hook it onto your hitch?
To me the leaf springs control the bounce of the boat on the trailer independently of the wheels bouncing off the ground. If the boat is bouncing up and down on the trailer and the wheels are bouncing off the ground, you've got two issues.

 

[WIMUSKY]

Re: Boat bounces on trailer.

Dump a few bags of sand or similar in the bow to increase tongue weight then take it for a ride to see if it is better. If so then it is time to make some adjustments.

I agree. It sounds like you're way light on the front. Throw in a couple hundred pounds, or so, of weight in the bow and see if that makes a difference. If it does, moving the winch forward a few inches to where it was originally "could" be the easiest fix. However, looking at your transom pic, the hull looks like it's sitting properly on the trailer in relation to the bunks. The bunk is already sticking out about and inch. Ideally, the hull and bunks would be flush. Although, I would think on a bunk trailer, the hull could be a little forward where you wouldn't do that on a roller trailer.

Also, are your tires properly rated for your load?

 

[UncleWillie]

Re: Boat bounces on trailer.

can you just move the post forward like that? Wouldn't that put the boat too far forward on the trailer and risk hitting the drive and any transducers hanging off the transom on the back of the try trailer?

You can only buy a few inches with the winch post move.
He will need to move the axle to the rear or re-engineer the entire setup.

Ok so I presume then that you can pick the tongue off the ground if the trailer wheel wasn't down and hook it onto your hitch?
To me the leaf springs control the bounce of the boat on the trailer independently of the wheels bouncing off the ground. If the boat is bouncing up and down on the trailer and the wheels are bouncing off the ground, you've got two issues.

The boat was not bouncing up and down on the trailer. It just appears that way to the observer.
There is more physics in a trailer than you may imagine.
The springs/suspension and the tires are not independent systems.
The tires and suspension have harmonic vibration frequencies.
If they get in phase with each other and the road, huge motions are produced.

It is known by very few people that the axle of a leaf spring trailer actually steers the trailer left and right as the load sways.
Yes, your trailer actually has steering! No Kidding!
If not designed and balanced properly, at a critical speed, the rocking of the load gets in phase with steering of the trailer axle and then the big fish tail action starts.
It seldom ends pretty.

With the center of gravity(CG) too far to the rear on the trailer, the critical speed lowers to the point that that it is possible to reach that speed in normal driving. (< 50 mph)
Moving the CG forward can raise the critical speed to a value large enough that you will never reach it. (100 mph+)

A 5-10% tongue weight has been demonstrated to be reasonable for most applications.

 

[HopinImFloatin]

Re: Boat bounces on trailer.

ill give this a bump because i have the same issue. A pic from the side of the full boat and trailer, with the axle position shown could shed more light on everything. Moving the axle rearward will help the tongue weight but you will still have the same concern with the bow being too light on the trailer, mine is both also. The boat is probably really stern heavy causing both issues, if you can get the boat stable on the trailer by moving it forward, both problems will probably be solved. I cannot move my boat any farther forward as the rear rollers are only about 2" from the transom. For mine, i was considering moving both batteries to the bow but im not sure if thats the best idea. It is possible the transom is wet and causing excess unseen weight in the rear. Hopefully i added some insight and didnt totally hijack this thread.

 

[72Cutter]

Re: Boat bounces on trailer.

Here`s my BUMP on this issue...I believe that moving the axle to the rear should remedy the issue with the tongue weight.. By moving the axle to the rear it automatically gives the front of the trailer more weight...Many trailers have pre-drilled holes for that application....I like the idea of adding weight to the nose of the boat just to see if it does the trick....(It should) Hence, eliminating all other leaf and tire issues....

 

[KX6D]

Re: Boat bounces on trailer.

You need 7-10% of the total boat/trailer weight on the hitch ball. If not, it will bounce and wander all over the place on the highway, creating a quite dangerous situation. If your boat/trailer combo weighs 3500 lbs (you may weigh more), you should have 250-350 pounds on the hitch ball. Get the rig weighed then adjust the front post / boat forward till the 7-10% requirement is met and you should be good to go, if the boat is sitting on the bunks properly.

Actually, you need 10% to 15% if set up correctly. Boats tend to be more heavy on the back, but trailer physics don't change. Also, and I haven't read everyone's posts, your boat is hanging too far off the back of the trailer. As pointed out, your straps should go straight down. Also, back up when you take a picture so we can see the whole story!

Dino - KX6D

 

[T_Herrod]

Re: Boat bounces on trailer.

Figure out how much your rig weighs then set the jack on your bathroom scale (most go up to 300 lbs). See how much tongue weight you have. If your way off an axle move may be required. If it's off just slightly then moving the winch may do the trick.

 

[jestor68]

Re: Boat bounces on trailer.




I'll suggest two things to correct most of your problem. First, move the winch stand forward as much as possible. It only takes a few inches to shift a couple hundred pounds. It may be necessary to move the trailer jack forward a tad. It makes no difference how much bunk sticks out the back as long as there is no interference with a transducer, etc.

Moving the entire boat forward should shift the CG enough to put a decent weight on the trailer hitch. Since your boat weighs about 2500 lbs, you need about 250 lbs of weight on the trailer hitch. You should not be able to easily pick up the front of the trailer with the boat positioned properly on the trailer.

Go to HD(or where ever) and buy a heavy duty ratcheting tie down strap to tie down the bow to the trailer frame(in addition to the regular winch strap that pulls the bow against the bow stop). Position the additional tie down so that it pulls down and about 30 degrees forward, to hold the bow hard against the bow stop.

This will eliminate the boat's tendency to bounce on the trailer with every little bump in the road.

I use this method on my Bayliner/Escort trailer and it works. Without the additional tie down, the bow wants to bounce. This is due in part to the design of the Escort trailer; it flexes too much going down the road.

Insure the tires are properly inflated. Low air pressure will give them more of a tendency to bounce too.

The axle is most likely not adjustable. The spring shackles are welded to the frame on my Escort trailer.

 

[glenn property of pam]

Re: Boat bounces on trailer.

need a side shot.

 

[jestor68]

Re: Boat bounces on trailer.

That's a file photo, not of his actual boat. It's a 2050 on the standard Escort trailer, which is what he has.

 

[scott8058]

Re: Boat bounces on trailer.

Ok first chance ive had to check back here and thanks for all the replys. Here is the only pic i have from the side right now ill try to get another one tom or this weekend. Ok lets see, first when i said the boat bounces around i don't mean its jumping up off the bunks i just mean its not in the same position as when i left my driveway. Im gonna check the springs too bc i had a slip for a while and the trailer by itself hops pretty good on bumps. Im gonna have to try the jack and bathroom scale thing bc it def doesn't take 250 - 350lb of force to lift it. Its hard to see from the pic but i don't think i can move the axle to much further back. The last time we had the boat out we found water in the drive oil so the alpha is off until Saturday when my buddy can help me put new gaskets and seals in her. Hopefully sat afternoon i can put her in the water and try moving the winch.

 

[scott8058]

Re: Boat bounces on trailer.

what do you mean thats a file photo? which pic are you talking about?

 

[04fxdwgi]

Re: Boat bounces on trailer.

Ok first chance ive had to check back here and thanks for all the replys. Here is the only pic i have from the side right now ill try to get another one tom or this weekend. Ok lets see, first when i said the boat bounces around i don't mean its jumping up off the bunks i just mean its not in the same position as when i left my driveway. Im gonna check the springs too bc i had a slip for a while and the trailer by itself hops pretty good on bumps. Im gonna have to try the jack and bathroom scale thing bc it def doesn't take 250 - 350lb of force to lift it. Its hard to see from the pic but i don't think i can move the axle to much further back. The last time we had the boat out we found water in the drive oil so the alpha is off until Saturday when my buddy can help me put new gaskets and seals in her. Hopefully sat afternoon i can put her in the water and try moving the winch.

1st thing I see in your pic, it your winch is actually pulling up on the bow eye when the bow is resting against the stop, trying to lift the weight off the bunks. Not a good thing that will amplify the bouncing on bumps. Pay out your winch strap and wind it back up so it enters the bottom of the reel, making it pull straight or slightly downward on the bow eye. 2nd thing I see is there is alot of boat behind the axle (where most of the weight is) and more weight needs to be in front of the axle. Moving boat forward or axle back will shift the weight to where it needs to be.

Mine is a tandem axle, but you can see how much boat is in front of axles on mine and my boat is way front heavy, where yours is light in the nose. Also you can see I have the cable coming off the bottom of the spool to keep a slight downward pressure on the bow eye.

......

 

[captain zac]

Re: Boat bounces on trailer.

You are going to have to follow a few steps to correct your problem:

1. determine wt. of boat and trailer
2. determine the tongue wt. (like said above bath scales should work google HOW TO WEIGH TRAILER TONGUE WITH BATH SCALES)
3. like said above the tongue should be very close to 10% of the total wt.
4. If you are light on the tongue (which appears to be the case) then its time to get your tools together and head to the ramp
5. when you get to the ramp slide the winch stand forward (its a guess but try 4 inches)
6. back into the water and float the boat up to the new winch position
7. pull the boat out to a level spot and reweigh (its all a guess)
8. repeat until you get the desired tongue wt.
9. after you get the tongue wt. right now you can adjust the bunks (not sure about your trailer but some bunks can be moved forward if not you might have to cut them to fit

This will take some time but it will take care of your problems

Harry

 

[oldjeep]

Re: Boat bounces on trailer.

Looking at your side picture, it looks like you need a lower hitch. Trailer appears to be tipped back rather than level.

 

[cooleyo]

Re: Boat bounces on trailer.

+1 old jeep. I just dealt with these same issues. I had to move the winch 6" foward to get the weight distribution corrected. A 3"-4" move foward of the winch post, and a 2" drop hitch. Moving the boat foward some will also make the trucks rear end squat some more too.

 

[WIMUSKY]

Re: Boat bounces on trailer.

+2 Using a drop hitch will lower the tongue which in turn moves more weight to the tongue. Add that to moving the winch forward 3 -4 " may just solve your problem..... As mentioned, readjusting your strap is also a good idea.....

 

[scott8058]

Re: Boat bounces on trailer.

It does ride a little incline with the straight hitch, the only other one i have right now is a 4" drop, would that be to much?