Weighing trailer tongue weight

[John Jones]

Here is a way to weigh the trailer tongue weight up to 600 pounds.

Most bathroom scales peak at 300 lbs but you can double the capacity with this little setup.

Note - I'm not responsible for what happens if you don't do this on level ground, chock the trailer wheels securely, or don't use a beam heavy enough to handle the tongue weight!

Just make the wooden block the same height as the scale and try to have the trailer about the same attitude of levelness that it is when hooked to your tow vehicle.  

You will have to re-zero the scale to allow for the weight of the beam.  
Just double the scale reading and you have your tongue weight.

[Skoot]

So I weighed my trailer tongue this weekend with a bathroom scale.  It weighed right at 140lbs.

Does that sound right for a 1975 19-6 with a 90hp motor?

[John Jones]

I don't know what your rig weighs but if it doesn't sway at highway speeds you are good.  

That's about the tongue weight of my 15' flats skiff which I'm guessing weighs 1400 total with boat, motor, trailer, 3 batteries, 16 gal. gas, trolling motor, jack plate, and more tackle than I will ever use.

[Glock Diver]

So I weighed my trailer tongue this weekend with a bathroom scale.  It weighed right at 140lbs.

Does that sound right for a 1975 19-6 with a 90hp motor?

That sounds mighty light.  Recommended tongue weight is 5% - 10% of the total weight.


I just adjusted my trailer, as my tongue weight was too low.  It was about 290 lbs on the tongue (used a bathroom scale).  My boat+trailer= 6300 lbs with a full tank of gas, so I want to be closer to 10%.  Today I adjusted the winch stand forward 6 inches.  Dunked the trailer, cranked the boat up 6" closer, and I now have 410 lbs of tongue weight. I guess a rough formula (for my boat at least) is 6 inches = 120 lbs, or 20 lbs per inch. Your results will vary.

I'm closer, but still not quite 10%.  I'll have to see how she does on the highway later this week, and adjust further if needed.  Oh well, at least I got the nuts loosened up already...  

[wingtime]

There is a couple of tricks to weigh your tongue weight with just a single bathroom scale.  You build a lever to multiply it's capacity.  At the end of this article they have an example of how to do it:  http://auto.howstuffworks.com/auto-part ... eight1.htm

Here is a link to a trailer towing guide.  Note that it says for a single axle trailer you should have 10% minimum TW with a 15% max.  Tandem trailers can have a 9% minimum.
http://www.sherline.com/lmbook.htm



There is a good picture of the scale lever trick here:  http://www.etrailer.com/faq-trailertowtips.aspx

[GoneFission]

So I weighed my trailer tongue this weekend with a bathroom scale.  It weighed right at 140lbs.

That sounds mighty light.  Recommended tongue weight is 5% - 10% of the total weight.
I just adjusted my trailer, as my tongue weight was too low.  It was about 290 lbs on the tongue (used a bathroom scale).  My boat+trailer= 6300 lbs with a full tank of gas, so I want to be closer to 10%.  Today I adjusted the winch stand forward 6 inches.  Dunked the trailer, cranked the boat up 6" closer, and I now have 410 lbs of tongue weight. I guess a rough formula (for my boat at least) is 6 inches = 120 lbs, or 20 lbs per inch. Your results will vary.

Be careful - the 10% basic rule is based on lighter boats.  You also have to pay attention to the vehicle's allowable hitch weight - not gross towing capacity, but the weight on the hitch (or tongue weight).  Many class III and class IV hitches limit weight to 500 lbs on the hitch.  For example, my tow vehicle has a 9200 lb. towing capacity, but a hitch weight of 500 lbs. max.  Check your specs, but in most cases, once you go over 500 lbs. hitch/tongue weight, you should be using a weight equalizing hitch.

[GoneFission]

My boat+trailer= 6300 lbs with a full tank of gas

 

Are you sure about that weight?  That seems very heavy for a 225.

[Glock Diver]

My boat+trailer= 6300 lbs with a full tank of gas

 

Are you sure about that weight?  That seems very heavy for a 225.

   Doesn't it sound heavy?  I was shocked too, but I took the boat to the truck scales and had it weighed, because I wanted to know for sure.

Boat + Motor & accessories = 4600 lbs
105 gal fuel = 600 lbs
Tandem axle Trailer = 1100 lbs (yes, I had that weighed alone too)

Grand Total of 6300 lbs


My tow vehicle (2010 F150 SCrew) has a tow capacity of 9600 lbs, but like someone just mentioned, the tongue capacity is only 500 lbs, so I can't go too much higher than where I'm at now at 410 lbs.  We'll see how she trailers on the highway Thursday.

[Glock Diver]

There is a couple of tricks to weigh your tongue weight with just a single bathroom scale.  You build a lever to multiply it's capacity.  At the end of this article they have an example of how to do it:  http://auto.howstuffworks.com/auto-part ... eight1.htm

Here is a link to a trailer towing guide.  Note that it says for a single axle trailer you should have 10% minimum TW with a 15% max.  Tandem trailers can have a 9% minimum.
http://www.sherline.com/lmbook.htm

There is a good picture of the scale lever trick here:  http://www.etrailer.com/faq-trailertowtips.aspx

Maybe I'm over-simplifying things, but whats wrong with just using about a 14" long piece of 2x4 lumber, set perpendicular under the coupler, resting directly on a bathroom scale?  

[John Jones]

What he is talking about or the diagram I drew in the top post lets you weigh 600# on a 300# scale.

[Glock Diver]

What he is talking about or the diagram I drew in the top post lets you weigh 600# on a 300# scale.

Hmmm... mine is a 300 # scale.

I just watched as the needle went around one more time, after hitting 300 lbs. Hope it's still accurate!

[wingtime]

Actually the link I posted will allow you to multiply the max capacity of the bathroom scale to say 900 lbs.  Same idea as what JJ posted  but you increase the length of the fulcrum.

No 6300 lbs doesn't sound heavy at all.  As I mentioned on the thread about the single or tandem trailer choice I think Aquasport was a tad conservative with the empty weights of the boats.  Plus all the accessories we add on today add up real fast!  Also the four stroke motors are much heavier that the two strokes.