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Woodsy · 10-07-2016, 08:34 AM

Dbreskin...

You have it wrong.... and you could get seriously hurt or hurt someone else. Let me explain.

Levers & Fulcrums are pretty much the oldest machine known to man. All trailers are essentially a lever and a fulcrum. Trailers are designed to carry a certain amount of weight over the fulcrum (Wheels). That weight carried by the lever is divided over the fulcrum point fore and aft such that that the weight exerted on the tow vehicle hitch is 10% to 15% of the total load. So you have to add up the boat weight, trailer weight, extra weight (gas, tubes, coolers etc) and multiply by .125 (12.5%) to get proper tongue weight.

When you shorten the lever arm (trailer tongue)... you change it all up.

The only thing you got right was the increased tongue weight for because of the shorter tongue (lever arm) there are 2 reasons for this. First, there is a certain percentage of the boat weight forward of the fulcrum point. Second, because you haven't yet moved the fulcrum point. Shortening the lever arm increases the force (weight) exerted by the boat weight on the forward side of the fulcrum. This INCREASES the tongue weight or downward force exerted by the lever.

In order to decrease the tongue weight, and keep the proper balance of the weight over the fulcrum (wheels) you have 2 options... Both essentially move the fulcrum point.

1. Move the weight (boat) towards the rear. This will decrease the amount of downward force or tongue weight.

2. Move the fulcrum point (wheels) forward. This will also decrease the amount of downward force or tongue weight.

Moving the axles rearward seems like a great idea, but in reality it puts a larger percentage of weight on the forward side of the fulcrum (wheels) so thus will INCREASE your tongue weight.

Google it.... use a ruler as a lever arm and a marker as a fulcrum and some quarters for weight... move the fulcrum around. This isn't rocket science.

What I would do is get the tongue weight for your current (shortened) setup and do the math on the overall weight to see if you fall within the 10%-15% guideline for tongue weight. But make sure you get accurate weights. You might be OK. If not, you can do the math and figure how best to change it. Because a lever and fulcrum multiply force, the change you may have to make is a small one. You may only have to move the boat 6" or so aft to get it right.

Hope this helps... Not trying to be a jerk, just passing on the engineering.

Woodsy

10-07-2016, 08:34 AM	#27
Woodsy Senior Member Join Date: May 2004 Location: Weirs Beach Posts: 1,949 Thanks: 80 Thanked 969 Times in 432 Posts	Dbreskin... You have it wrong.... and you could get seriously hurt or hurt someone else. Let me explain. Levers & Fulcrums are pretty much the oldest machine known to man. All trailers are essentially a lever and a fulcrum. Trailers are designed to carry a certain amount of weight over the fulcrum (Wheels). That weight carried by the lever is divided over the fulcrum point fore and aft such that that the weight exerted on the tow vehicle hitch is 10% to 15% of the total load. So you have to add up the boat weight, trailer weight, extra weight (gas, tubes, coolers etc) and multiply by .125 (12.5%) to get proper tongue weight. When you shorten the lever arm (trailer tongue)... you change it all up. The only thing you got right was the increased tongue weight for because of the shorter tongue (lever arm) there are 2 reasons for this. First, there is a certain percentage of the boat weight forward of the fulcrum point. Second, because you haven't yet moved the fulcrum point. Shortening the lever arm increases the force (weight) exerted by the boat weight on the forward side of the fulcrum. This INCREASES the tongue weight or downward force exerted by the lever. In order to decrease the tongue weight, and keep the proper balance of the weight over the fulcrum (wheels) you have 2 options... Both essentially move the fulcrum point. 1. Move the weight (boat) towards the rear. This will decrease the amount of downward force or tongue weight. 2. Move the fulcrum point (wheels) forward. This will also decrease the amount of downward force or tongue weight. Moving the axles rearward seems like a great idea, but in reality it puts a larger percentage of weight on the forward side of the fulcrum (wheels) so thus will INCREASE your tongue weight. Google it.... use a ruler as a lever arm and a marker as a fulcrum and some quarters for weight... move the fulcrum around. This isn't rocket science. What I would do is get the tongue weight for your current (shortened) setup and do the math on the overall weight to see if you fall within the 10%-15% guideline for tongue weight. But make sure you get accurate weights. You might be OK. If not, you can do the math and figure how best to change it. Because a lever and fulcrum multiply force, the change you may have to make is a small one. You may only have to move the boat 6" or so aft to get it right. Hope this helps... Not trying to be a jerk, just passing on the engineering. Woodsy __________________ The only way to eliminate ignorant behavior is through education. You can't fix stupid. Last edited by Woodsy; 10-07-2016 at 09:18 AM.

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