Guidelines for adjusting trailer tongue weight

[mrmamiller]

I have a new to me Century 1700CC boat. The trailer is a Performance (defunct) galvanized bunk trailer. As received, the tongue weight was excessive, my rough initial guess was 400+ pounds, based on how it sucked down my truck. My scale bottomed out at 352. I am a "snowbird" in Florida and without my arsenal of tools and available space to perform my anticipated changes, so I am going to try a "one-shot" change to adjust the tongue weight. Details: The boat and equipment should weigh approximately 1800-1900 pounds. The batteries are under the counter console and the in-floor gas tank is apparently located under the console as well. Other equipment is an electric trolling motor mounted on the bow. The trailer has a sliding carriage for the axle (single axle) and the trailer is approximately 22 feet from coupler to end of bunks. I'd like to move the carriage only one time (yeah, right) and hope to get it somewhat close to the recommended 10% (190#). I thought of moving the axle a foot, others tell me 6 inches at most. Any ideas as to whether there are guidelines based on boat type, weight distribution and trailer type/dimensions? It would be a REAL pain to keep repeating the adjustment until I get it right. I'll be working on the ground with fire ants and other critters around. No pics available right now, maybe later. I can supply other dimensions if I think that it would help. I'm looking to do the work in the next few days, getting itchy to get on the water. Thanks

 

[hungupthespikes]

Re: Guidelines for adjusting trailer tongue weight

Get the coffee pot going. It will take a couple of reads to get your head around this, but it works like a charm thanks to a guy named Jerry Townsend.

Classic Whaler: Boston Whaler: Reference: Trailering: Calculations

 

[mrmamiller]

Re: Guidelines for adjusting trailer tongue weight

Holy Calculations, Batman! That really looks interesting. I'm a math guy, so I think I can get through it. Coffee is the drink to have for reading the article, certainly nothing any stronger. Thanks for the info!

 

[Bamaman1]

Re: Guidelines for adjusting trailer tongue weight

Most people change their tongue weight by moving the boat back slightly on the trailer. They move their winch support back--usually by loosening two U bolts holding it to the trailer frame.

Moving axles is certainly a last resort to changing the tongue weight.

 

[gm280]

Re: Guidelines for adjusting trailer tongue weight

Just a dumb thought, but why not take a couple jack stands and a jack and lift the boat trailer up and set it on the jack stands at different places to see the tongue weight change before removing anything? The proper point will be the center line of the axle after locating the balance point you want for tongue weight. One move of the axle and you are finished... Or am I really too stupid to make such a suggestion? I don?t know, but that is how I would solve that problem...and quickly too! Please reply if that is not a probable idea because I may be missing something...honestly... I do realize that if you have the balance point too far from the present axle setup you have to take that weight into consideration but it would have to be pretty close either way...

 

[rbh]

Re: Guidelines for adjusting trailer tongue weight

If you can not move the boat back, then yup the axle has to come forward.
The axle is the balance point, and of course you do not want a completly balanced trailer as you need some tongue weight, the 10-15% rule of thumb.
Moving the axles more than 6 inches at a time is alot, think about balancing a ruler on your finger, you know the balance point should be at the 6 inch mark.
Jack and block up the rear of the trailer till the wheels are off the ground with the leg down but still on the ball.
Move the axle ahead 6 inches tighten and drop the trailers tires to the ground, chalk the wheels and put the scale under the leg and check the weight.
Repeat till its where you want it.

 

[smokeonthewater]

Re: Guidelines for adjusting trailer tongue weight

don't guess... get it weighed

I have taken a boat to a truck stop to be scaled and pulled the bolts out of the (sliding) undercarriage except for one or two finger tight I paid my $9 for the first weigh and used a come along to slide the axles a bit and reweighed a couple of times (reweighs are usually $1) till I had it perfect.

An hour or so at the truck stop beats the heck out of doing the whole job lots of times.

 

[UncleWillie]

Re: Guidelines for adjusting trailer tongue weight

Just a dumb thought, but why not take a couple jack stands and a jack and lift the boat trailer up and set it on the jack stands at different places to see the tongue weight change before removing anything? The proper point will be the center line of the axle after locating the balance point you want for tongue weight. One move of the axle and you are finished... Or am I really too stupid to make such a suggestion? I don?t know, but that is how I would solve that problem...and quickly too! Please reply if that is not a probable idea because I may be missing something...honestly... I do realize that if you have the balance point too far from the present axle setup you have to take that weight into consideration but it would have to be pretty close either way...

Not dumb! A perfectly sound idea!
The technique is included in the link in Post #2.

 

[JB]

Re: Guidelines for adjusting trailer tongue weight

Moving axles is certainly a last resort to changing the tongue weight.

I really disagree with that. Moving axle cradles is usually the last thing done in correctly rigging a trailer. Positioning of the boat and winch stand follow very different rules than adjusting tongue weight.

The boat is positioned by the support for the transom. The winch stand is positioned to fit the boat. The axle cradle is positioned to adjust tongue weight.

 

[smokeonthewater]

Re: Guidelines for adjusting trailer tongue weight

i really disagree with that. Moving axle cradles is usually the last thing done in correctly rigging a trailer. Positioning of the boat and winch stand follow very different rules than adjusting tongue weight.

The boat is positioned by the support for the transom. The winch stand is positioned to fit the boat. The axle cradle is positioned to adjust tongue weight.

absolutely true

 

[jimbo_jwc]

Re: Guidelines for adjusting trailer tongue weight

I was tought 100# per 1000# than they came out with those load leveler arms and I had the pleasure to lift my rear drive tires off ground . Heck with front wheel drive might have worked .

 

[mrmamiller]

Re: Guidelines for adjusting trailer tongue weight

Finally got axle adjusted. Had to move it a whopping 14 inches, and unfortunately had to do it by the trial and error method. Would have like to do it by math, but time was of the essence. The method by where you place jacks under a precise point and measure tongue weight sounded like the plan for me. But when I approached that part, I found that the sliding carriage prevented that method. So, I did the job using trial and error. Fortunately, this 10 year old galvanized trailer had bolts that loosened very freely (after having penetrant on them for 1 week). Thanks for the advise. Mark

 

[hungupthespikes]

Re: Guidelines for adjusting trailer tongue weight

Way to Get-r-done.
The math one-n-done does take some time to get all the numbers together. (that's the hard part)
Thanks for the update, see you in Florida
huts