Boat too long for trailer?

[dingbat]

Loadrite Trailer - #4800, tandem axle
Boat weight - ~#4300
Trailer weight - ~#1150
Tongue weight - ~#480

Rebuilt the trailer in the Spring. When changing the springs, I noticed that the trailer had 4 leaf springs in the front and 3 leaf springs in the rear. I called a local trailer dealer to inquire about my findings. He had never heard of such a thing and suggested that I put springs of equal weight back on.

I installed new 3 leaf springs, spring bushing and equalizer bushings. Lowered trailer to the ground and the equalizer all but bottomed out on the frame. I took it for a run around the block with no change in the position of the equalizer.

I went boating the following weekend. The trailer pulled well, but equalizer still out of position after a 50 mile drive. I dropped the boat in the water and the equalizer returned to its normal “equal” position. Thought all was well. We loaded boat back on trailer and same thing. Front equalizer almost bottomed out on the frame.

All indications point to the CG of the boat being too far forward on the trailer. The tongue weight is roughly 11% so I thought about moving the axles forward. Rough calculations for a 7.5% tongue weight (mfg. recommendation) has the axles moving roughly 13” forward. I may be able to move them 11” if I push the axle all the way to the forward cradle cross member, but then the boat would overhang the rear axle by almost 8 feet.

I’m beginning to think the trailer is too short for the boat and the PO made up for it with the heavier springs. I either get a new trailer or put 4 leaf springs back on the front.

 

[Tnstratofam]

Is the weight for your boat the actual weight or the mfg's quoted weight? Could be the boat is bow heavy due to other issues or how items are stored on board. You could also be carying allot of unseen water weight below deck.

 

[smokeonthewater]

The length of the boat has no bearing whatsoever on the springs or equalizers....If the boat were 6" long and weighed the same the springs would react the same..... your new springs are softer than your old springs.... you need 4 MATCHED springs

Your tongue weight at 10-11% was absolutely fine and IMHO perfect and I personally would leave it there... Changing it absolutely will not help the spring issue. If anything less tongue weight which means more axle weight will make it worse...... You either need to replace your newer pair of springs that match your old ones OR replace the old ones to match the new ones...

Number of leaves being equal does NOT make the springs equal..

As for the length of the trailer... regardless of weight, spring, or equalizer a good starting point is that the trailer should be AT LEAST 10% longer than the boat.

 

[dingbat]

Is the weight for your boat the actual weight or the mfg's quoted weight? Could be the boat is bow heavy due to other issues or how items are stored on board. You could also be carying allot of unseen water weight below deck.

The boat and trailer have been weighed. A Walkaround is bow heavy by design. No water below deck

 

[bruceb58]

Is the trailer absolutely level?

What style springs are front and back? Slippers on one end?

 

[smokeonthewater]

I just reread the first post.... If I understand you correctly the part of the equalizer attached to the NEW springs is hitting the frame... IF that is correct then it is the OLD springs that are too soft and you need to replace them with 2 more new ones to match what you just put on..

 

[dingbat]

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[smokeonthewater]

I should have specified that the fictional 6" boat would be placed on the trailer such that it's c/g was in the same place as your boat's c/g and also specified that things wouldn't change AS LONG AS the frame of the trailer did not flex due to the localized overloading.

But, again the LENGTH of the boat and weight distribution do not have ANYTHING to do with the equalizers....

I didn't catch that you replaced all four springs..... I now believe your issue is then most likely one of an unlevel trailer... either your tow vehicle is sagging excessively from more tongue weight than it can handle OR your hitch is too low... OR maybe your trailer is bent... measure frame to ground just in front of the front spring perch and behind the back one

Load right can specify what they want.... After many years of towing MANY trailers I still prefer 10%+ BUT I DID say IMHO on that part and it isn't in any way relevant to your equalizer problem.

you could have 100% tongue weight or 0% and the equalizers should stay in the same place...they SHOULD only move if the angles of the frame and the road change in relation to each other


Another oddball possibility is that MAYBE the length of the replaced springs were not the same... If for example one pair of old springs was shorter and the new longer springs are maxing out a shackle and then forcing the equalizer toward the other spring that might explain things.... you can easily measure from spring perches to equalizer perch

 

[smokeonthewater]

Only because your fictional 6" boat isn't long enough, in relation to the width of the axle, to cause a load imbalance. The equalizer helps compensates for the shifting of the center of gravity (of the load) in relation to the center of the axles. In this case, the center of gravity is too far forward of the axles causing excessive loading of the front axle. The problem could be resolved by moving the axles closer to the center of gravity, but the forward roller bunk is in the way. The alternative is to move the boat to the rear but that would give me excess overhang at the transom

You are misunderstanding the dynamics here... moving weight fore or aft is NOT the fix... moving the front of the trailer up or down IS....

This statement assumes that the trailer is assembled correctly with no structural problems.... If the brackets for the suspension are spaced incorrectly OR you have bent, mismatched, or broken components then there will be more to it.

 

[smokeonthewater]

Real world example... I put a 28' cruiser on a tandem trailer from a 23' bowrider... I had over 5' of overhang in the rear... the trailer was GROSSLY overloaded but I was only easing it (under 5mph with traffic stopped) to a neighbor's house...

It has about 250 lbs of NEGATIVE tongue weight as it took my full weight to push the tongue down to the ball...

all 4 tires were squatted and all 4 springs were compressed quite a bit BUT the equalizers were in their normal centered position and nothing was binding.

 

[bruceb58]

Assuming the trailer isn't bending and the trailer is level, the equalizer cares ZERO about the CG.

I would love to see a picture.

 

[GA_Boater]

Assuming the trailer isn't bending and the trailer is level, the equalizer cares ZERO about the CG.

I would love to see a picture.

A picture of a weight slip, too. :smile:

 

[dingbat]

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[bruceb58]

Expert advice from etrailer...take anything you see from them with a grain of salt. For example, he states that one axle will have more weight on it than the other. That is impossible assuming the equalizer isn't bottoming out.

On both of my tandem axle trailers, the equalizer is close to being level when the trailer is perfectly level.

 

[smokeonthewater]

It's on the internet so it HAS to be true..... uh.....bonjour

 

[dingbat]

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[smokeonthewater]

What we've got here is a failure to communicate..........

 

[bruceb58]

Good luck. Apparently you have it all figured out.

 

[dingbat]

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[Lou C]

Why would a 3500 axle need springs with a combined capacity of 4700 lbs? Your first post said that the carrying capacity of the trailer was 4800 lbs and the trailer weighs 1150 which equals 5950 lbs. So your axle capacity of 7,000 lbs means that the trailer appears to be adequate for the boat's weight. Those heavier springs would give you a total weight capacity of 9400 lbs which is way more than that trailer should ever carry. Now if the trailer came with 6 lug axles then that might make sense but that does not match the capacity rating of the trailer, it came with 5 lug axles I am assuming. And the boat actually weighs less than the trailer's carrying capacity of 4800 lbs by 500 lbs.
I'd like to see a pic of the boat as you normally have it loaded on the trailer. It sounds like you are saying that the boat needs to go back a bit relative to where the axles are, but then you will have too much overhang at the stern that is not supported. If this is a roller trailer, they make roller bars in different lengths. It may be possible to fit longer rear roller bars which would allow the rear rollers to go closer to the transom of the boat where they should be. I know for a fact that Load Rite sells longer than standard roller bars and I did this on my single axle trailer and it worked out fine.