Minium tongue weight question

[lrak]

Re: Minium tongue weight question

Lets say you have two 25' long trailers of the same weight. You want the center of gravity to be at least 18" in front of the axle so the trailer doesn't have a tendency to sway.

Trailer 1 is a cargo trailer with the a COG 13.5' back and an axle (fulcrum) 15' back from the ball.
Trailer 2 is a boat trailer with a COG 19.5' back and an axle (fulcrum) 21' back from the ball.

13.5' / 15' means 90% is on the axle and 10% is on the ball.
19.5' / 21' means 93% is on the axle and 7% is on the ball.

Same overall trailer weight. In both cases the COG is 18" in front of the axle. The difference is the axle (fulcrum) is further back on the boat trailer. You could get the cargo trailer tongue weight down to 7% by adding an extra 6' on tongue to the cargo trailer, but in most cases it is just easier to deal with the higher tongue weight.


I know from practical experience that I need very little tongue weight on my boat trailers. I've had utility and cargo trailers sway like crazy with higher percentages of tongue weight than were fine with boat trailers. I guess we'll just have to disagree.

 

[bruceb58]

Re: Minium tongue weight question

You are right, we disagree, especially about laws of physics.

 

[H20Rat]

Re: Minium tongue weight question

It's a physics thing and has nothing to do with the overall length of the trailer. It's where the CG is placed that determines stability.

Irak beat me to it already, but you posted on manufacturer of non-boat trailers who recommends it. He posted from all the boat trailer manufacturers, none of which recommend 10% minimum.

Different trailers all react differently. Trailers that have high wind drag are going to need more tongue weight also. Even tire size and construction can contribute to sway.

 

[smokeonthewater]

Re: Minium tongue weight question

Lets say you have two 25' long trailers of the same weight. You want the center of gravity to be at least 18" in front of the axle so the trailer doesn't have a tendency to sway.

Trailer 1 is a cargo trailer with the a COG 13.5' back and an axle (fulcrum) 15' back from the ball.
Trailer 2 is a boat trailer with a COG 19.5' back and an axle (fulcrum) 21' back from the ball.

13.5' / 15' means 90% is on the axle and 10% is on the ball.
19.5' / 21' means 93% is on the axle and 7% is on the ball.

Same overall trailer weight. In both cases the COG is 18" in front of the axle. The difference is the axle (fulcrum) is further back on the boat trailer. You could get the cargo trailer tongue weight down to 7% by adding an extra 6' on tongue to the cargo trailer, but in most cases it is just easier to deal with the higher tongue weight.


I know from practical experience that I need very little tongue weight on my boat trailers. I've had utility and cargo trailers sway like crazy with higher percentages of tongue weight than were fine with boat trailers. I guess we'll just have to disagree.

The bulk of this statement is based solely in fantasy....

agreed that a trailer with a high frontal area is more prone to sway but that doesn't mean that there is anything special about a boat trailer that makes it immune from the physics laws that affect all other trailers.