trailer suspension? boat bouncing on trailer

[since1791]

Is there a good way to tell if the leaf springs on my boat trailer are bad? Not sure if this is related to this issue or not: I'm having issues with the rear of my 14 foot flat bottom G3 1442 bouncing on the trailer while driving over bumps in the road. The boat sits on 2 carpeted bunks 8 foot long with a jon boat carpeted bunk support up near the front of the boat for additional front support. The boat is secured to the trailer with a bow stop & winch hook in the front, 2 straps in the middle of the boat, and 1 transom strap at the rear. I quit using 2 transom straps since 1 would always come loose. It's only the rear of the boat that bounces, usually like a wobble bounce back near the transom from left to right, or right to left. I can't quite tell if the boat is coming off of the bunks when bouncing, but I seriously doubt it since the straps are all tightened really good. So I'm wondering if maybe the leaf springs are bad & just not absorbing any of the bumps at all??

 

[Deeppowder]

Re: trailer suspension? boat bouncing on trailer

I had a similar problem. The boat was strapped down to the 8 foot bunks and not the trailer. The bunks were not attached very well to the trailer. I started to strap the boat down by putting a ratchet strap around the boat and trailer towards the stern of the boat. I had no problems with the boat bouncing after that.

 

[tomdinwv]

Re: trailer suspension? boat bouncing on trailer

Is the rear of the boat overhanging the bunks? Do you know how much the boat trailer combo weighs? What is your tounge weight? (Should be about 10% of total loaded trailer weight) If the tounge weight is too light it can cause quite a bit of bouncing around. May be as simple as moving your winch post forward. If you have any pics, post them on here and these guys can help get you fixed up.

Deeppowder brings up a good point also. Check the bunks and make sure they are tight and that the straps are going to the trailer and not the bunks.

 

[since1791]

Re: trailer suspension? boat bouncing on trailer

Thanks DP & Tom! I'll go take some pics & post them. The trailer has had some major mods done to it to put it mildly, so I'm not going to be surprised at all if there are a couple of issues that are noticed. I'm just a rookie & have been doing the best i can to learn from the veterans on this forum. As to the trailer tongue weight & bunk position: not sure about the tongue weight, never measured it but my guess would be that it is on the light side. However, the boat & trailer itself are very light too. The boat sits with about 1 inch of bunk hanging out where the transom sits. I think I have some room to move the winch post forward a little bit while still leaving 10% of the total length in front still (read on another thread where a vet recommended trailers be 10% longer than the boat. Lastly, I'm pretty sure my axle can't be moved- but maybe someone else will have an idea or see another way. Pics coming soon- need to go take them & post.

 

[dockwrecker]

Re: trailer suspension? boat bouncing on trailer

May seem silly but balancing the tires will take a lot of the vibration out that's causing your boat to jump around especially with a light rig.

 

[since1791]

Re: trailer suspension? boat bouncing on trailer

post 1 of 2 with pics. This was a utility trailer that was modified for a 14 ft. semi-V hull with center rollers only when I bought it. I've since gotten the G3 & had to modify it from rollers to carpeted bunks. The PT wood on the trailer rails is due to the 1 1/4 rails that were stock on the trailer & inability to find decent strength loaded U-brackets at that size. So I took some PT 4x4's & used a table saw to make custom cuts as needed so that the 4x4 was trimmed down enough to accommodate the standard sized U-brackets while snugly fitting the PT cuts to the original steel frame. i'll paint it this fall when the PT wood has had enough dry time. Yes, it is probably overkill on the mods but it beats the heck out of spending $ I don't have to get a new trailer. Any help on improving anything seen here is welcome & appreciated. thanks again!

 

[since1791]

Re: trailer suspension? boat bouncing on trailer

post 2 of 2 with pics. The leaf spring holders are both welded onto the frame. Other than putting weight inside the boat up near the front & maybe moving the winch post forward a little, I'm not sure what else i could do to increase the tongue weight. Dockwrecker has a great suggestion too that I didn't think of. The tire on the driver's side does seem to wobble a bit.

 

[tomdinwv]

Re: trailer suspension? boat bouncing on trailer

It looks to me that most of your boats weight is forward of the axle. I dont think moving the boat forward will help much. It does appear that the boat sits pretty high up off the trailer. The higher the center of gravity, the more unstable its going to be. I cant tell by the pics, was that a tilt trailer? It doen't look like it but I can't really tell. When you use transom straps, what part of the trailer were you securing them to? You mentioned earlier that one of your transom straps kept coming loose. They should be secured to the the metal on the trailer (with a heavy eye bolt or something similar) and not the wood supports. If the straps are old, it may be just a matter of replacing them with new ones.

Another question for you. When securing the front of the boat with the winch, do you also have a safety chain? Nothing to do with stability but you should have one to hook to the bow eye, along with the winch strap when towing.

 

[lckstckn2smknbrls]

Re: trailer suspension? boat bouncing on trailer

Are the bunks Pressure treated wood?

 

[O-fishal]

Re: trailer suspension? boat bouncing on trailer

Reduce the tire pressure!!

 

[since1791]

Re: trailer suspension? boat bouncing on trailer

No PT wood on the bunks as I was concerned about the PT chemicals corroding the aluminum. Yes, with the marine bunk carpeting it would be a long shot that the PT chemicals would go through the carpet's rubber barrier except in the event of a worn or torn spot; but why take a chance? the 8' foot lengths are cedar that was painted with 2 coats of paint since nobody here in this area had cypress. got the idea from reading several posts on bunks when I was considering using trex. Cedar seemed to be the best recommended alternative when cypress was not available.

 

[since1791]

Re: trailer suspension? boat bouncing on trailer

tire states a max of 65 psi & I think I have 50 as the usual setting. What would be the best psi?

 

[since1791]

Re: trailer suspension? boat bouncing on trailer

Yes, it does sit high but it's as low as I can get it in the rear with the existing brackets. The bunks each have a total rise of 1.5 inches over the entire length of back to front on the 8 foot span. The boat dealership guy recommended a small incline from back to front but I can't remember why. A guess is that it makes unloading the boat into the water easier? The trailer was not a tilt trailer so far as i can tell. The transom straps were hooked to the handles at the top of the transom on each side & hooked into the black i-bolt holders located in the center of the trailer frame right where the center of the transom would be. The straps are pretty new (ratcheting type). never used the bunks to hook too- always used the trailer frame. the frame used to be a utility trailer so it has the square holes all the way around the outside of the frame for where those wooden fence-looking box frames can be dropped in. The ratchet clamps fit perfect into them

 

[since1791]

Re: trailer suspension? boat bouncing on trailer

Just did a tongue weight measurement- 67 lbs. The boat is 200 stock & I'm guessing the trailer is about 350. By the time I add a motor & accessories, it should be close to about 10% of total weight

 

[tomdinwv]

Re: trailer suspension? boat bouncing on trailer

Hmmmm. I'm not sure what is happening with your setup. Don't worry though. Someone will chime in here with the right answer to your problem. You are definately in the right place to get help. Stay tuned and good luck!

 

[tomdinwv]

Re: trailer suspension? boat bouncing on trailer

Another question that may help someone else figure this out. Do you know what your spring/axle setup is rated for? Some utility trailers I have used have road like the axle was welded straight to the frame until you get enough weight on it to compress the springs some. If your axle/springs are rated for, say 2000 or 2500 lbs and you only have 500 or 600 lbs on board that might cause it to ride rough and bounce around.

 

[Thalasso]

Re: trailer suspension? boat bouncing on trailer

Is there a good way to tell if the leaf springs on my boat trailer are bad? Not sure if this is related to this issue or not: I'm having issues with the rear of my 14 foot flat bottom G3 1442 bouncing on the trailer while driving over bumps in the road. The boat sits on 2 carpeted bunks 8 foot long with a jon boat carpeted bunk support up near the front of the boat for additional front support. The boat is secured to the trailer with a bow stop & winch hook in the front, 2 straps in the middle of the boat, and 1 transom strap at the rear. I quit using 2 transom straps since 1 would always come loose. It's only the rear of the boat that bounces, usually like a wobble bounce back near the transom from left to right, or right to left. I can't quite tell if the boat is coming off of the bunks when bouncing, but I seriously doubt it since the straps are all tightened really good. So I'm wondering if maybe the leaf springs are bad & just not absorbing any of the bumps at all??

Your leaf springs have nothing to do with your issue.

#1 The rear of the boat should be tied down to the trailer( not the bunks ) either with a strap over the boat from side to side or transom straps.
#2 The bow of the boat should have a strap or chain from the bow to the tounge of the trailer for two reasons. 1. to keep it down in case of a quick stop and 2. Will help to keep bow from bouncing. You coud rig a ratchet strap for this purpose.

 

[oregoncruiser]

Re: trailer suspension? boat bouncing on trailer

Thalasso is hitting on another important issue. I the bow is not 100% secure, it can allow the boat to shift back and forth on the trailer, or up and down. This will be mirrored at the rear of the trailer, and could allow the transom straps to loosen, i.e. you could loose them.

As has been stated, you need to secure the bow down to the trailer tongue in a fashion that eliminates any possibility of movement in any direction. Then secure the transom starps to the trailer frame as well.

A final thought is that the transom straps, and the bow strap need to pull in opposite directions. If both sets of straps are pulling the boat forward, this would allow the boat to bounce around. So... if transon straps are putting forward tension on the boat, I would put the bow to trailer tongue strap opposite, so that it is pulling the boat mostly straight down, and if anything slightly backwards.

 

[River_Lizard]

Re: trailer suspension? boat bouncing on trailer

Your leaf springs have nothing to do with your issue.

#1 The rear of the boat should be tied down to the trailer( not the bunks ) either with a strap over the boat from side to side or transom straps.
#2 The bow of the boat should have a strap or chain from the bow to the tounge of the trailer for two reasons. 1. to keep it down in case of a quick stop and 2. Will help to keep bow from bouncing. You coud rig a ratchet strap for this purpose.

I agree with Thalasso.... you should have the boat tied to the frame of your trailer while you're towing it.

 

[since1791]

Re: trailer suspension? boat bouncing on trailer

Great suggestions- thanks everyone! I'll try the method of strapping suggested above & see how it does when I drive it tonight about 10 miles. will post afterward with the results