A Question of Balance

Jackdaw · Mar 23, 2017

I get 800lbs of tongue weight. It's pushing down so hard it's lifting the front of the truck off the ground!

Center the keel over the axle (or just in front of that point) for a start.

If you really want the number, take the trailer off the truck and put a wood block under the hitch and measure that.

walt · Mar 23, 2017

If you really want the number, take the trailer off the truck and put a wood block under the hitch and measure that.

I dont think you can get the number that counts (weight right at where the trailer socket attaches to the ball on the vehicle) with the measurements you made without doing some fancy lever arm stuff. The important attachment point is NOT located at the rear wheels.

https://www.etrailer.com/faq-how-to-determine-trailer-tongue-weight.aspx

Benny17441 · Mar 23, 2017

If your vehicle is 6,100 lbs and the Truck and trailer are 9,740 lbs then the boat + trailer weigh 3,640 lbs. If the weight at the trailer axle is 3,300 the weight at the hitch (tongue weight) is 340 lbs or 9.34% which is slightly under the recommended 10% to 15% tongue weight to reduce trailer sway on the road. Your boat is not too far forward and any small adjustments can be made by raising or lowering the hitch ball with an adjustable assembly. You need to start with the trailer rails parallel to the ground on a level surface. Then the load needs to adjusted (balanced) until it yields a tongue weight of around 12%. Bear in mind not to exceed the load specs of the hitch . Raising the hitch ball from parallel trailer will reduce tongue weight and lowering it will increase tongue weight. You are already pretty close to adequate towing specs; now the tongue extension used for launching is just a different set of factors. I suspect if you are getting excessive bend on the tongue extender or the rails leading to the trailer tongue then the trailer might not appropriate for the boat and you could be exceeding its design load limitations. If it is just the tongue extender that bends then it might not be as critical as the extender is just used for a short time at crawl speeds. I think if you have no sway issues on the road and no bend on the trailer rails then it seems that you are fine. As far as the tongue extension for launching you could get a heftier one. If the trailer rails are now not parallel to level ground then the load distribution and ball height could indeed both be off. Understand that when the boat and trailer are in motion the tongue weight will vary with dips and rises on the road surface. Your homework is to determine if the trailer is adequate for the boat and to properly balance the load and tongue weight at level. Another way of attaining balance is by moving the trailer's axle backward or forward and it could very well be that the trailer could have previously been set for a different boat. At this time just set the trailer at level and then move the load forward or back ward until you attain the desired tongue weight. A quick way of checking is to get two people whose combined weight approximates 400 lbs and to get them to stand on the rear bumper of the truck and then measure the deflection in the suspension or distance from ground to bottom of bumper. Adjust the load until attaining the distance previously measured.

AaronD · Mar 23, 2017

walt said:
I dont think you can get the number that counts (weight right at where the trailer socket attaches to the ball on the vehicle) with the measurements you made without doing some fancy lever arm stuff. The important attachment point is NOT located at the rear wheels.

https://www.etrailer.com/faq-how-to-determine-trailer-tongue-weight.aspx

@LakeShark: It looks to me like you did exactly what that eTrailer link recommends under the 'commercial scale' section.

But I think something is off with the math. With the trailer attached, Front: 3300 + Rear: 3460 = 6760, or 300 lbs more than the 6460 you reported for the truck. We'd expect a little error/variance in the scale (note that the sum of the 2 axles in the no-trailer scenario is off by 20 lbs). But not nearly 300 lbs.

One possibility: could the rear axle weight with the trailer actually be 3160 (not 3460). Then the truck weight matches (3300 + 3160 = 6460, as you reported), and the total vehicle weight is within noise (3300 + 3160 + 3300 = 9760). If so, it sounds like you're about right on tongue weight. But if not, something is off somewhere.

We expect the front axle to be unloaded somewhat when adding weight behind the rear axle (with the weight being transferred from the front axle to the rear). The 120 lbs you saw (3420 - 3300) sounds reasonable. But I engineer software, not machinery, so take my $.02 for what it's worth...

Scott T-Bird · Mar 23, 2017

I think Benny has explained it well, and it also sounds like a good balance across all three axles. I think that I would be satisfied with that. My oh my ... did summer come early to Minnesota?

Bill Roosa · Mar 23, 2017

You have most of the numbers to do the math. you will need the following to accurately determin toung weight.
Distance from front axle to tongue
Distance from rear axle to tongue
Distance from trailer axle to tongue

Get me those numbers and you can have a professional engineer confirm that the tongue weight is in fact really close to 360 lb

CloudDiver · Mar 23, 2017

Sorry guys... I just skipped all the math and I'm just going to eyeball it because that actually works 95% of the time; Boat looks like its in the correct position with the keel just forward of your axle. Your tongue extension is bending because the square tube is too small dimensionally or the wall thickness is too thin.
Forget the math, just get a new extension tube in a heavier wall dimension. Moving the boat back will only take a few pounds off the tongue weight and the extension tube will still be too thin.

Daveinet · Mar 23, 2017

I think the original number should be pretty close, but if you need to move the boat, that is very easy. throw a 4X4 under the keel and jack the hole boat up. Then use the truck to move the trailer. I temporarily moved my boat farther forward so I could work on my swing keel. Didn't take but just a few minutes to do.

CloudDiver · Mar 24, 2017

LakeShark said:
Here is a close up of the Wing position to the axle currently (before I removed the tarp). I agree that the tongue weight if not where it should be is close but if moving the boat back toward center on the axle will not change weight much but will ease in loading etc... will it make the tongue too light?

Currently the tongue is a 2X2 square tube (unknown wall) with the boat weighting 3640 empty with the trailer and your awesome welding and metallurgy knowledge what wall and size tube would you recommend going to? Is there a 2X2 tube with a wall that could extend 10 feet without deflecting too much? That makes the span from hitch to trailer axle 319" (26.58")

Sorry I forgot to write this yesterday, saw it right before I left work and was going to post when I got home. By the looks of the way your trailer is constructed I would guess there is no way you can add a larger size tube, the extending tongue needs to stay 2x2 to fit back in the socket. You are correct that you need a wall thickness that will not deflect over 10 feet. The wall dimension of the tube that is bending is probably 1/8" or an even less gauge, common in steel tube is 13, 14, and 16 gauge... all of that is considered 'thin' in terms of steel tube that size. The thickest 2x2 tube commonly available is 1/4 inch, and next down 3/16", both very strong but if you want safest and heaviest duty go with 1/4". They are typically available in common lengths up to 24 feet (10 and 20 are most common), and you need the longest you can. I would start by supporting the front of the frame with jack stands and remove the tongue tube, unbolt the hitch coupler. Measure what you have, put calipers on the wall thickness (not in a rusty spot). 16 ga (I hope its not this thin, jeeze) is .065, 14 ga .083, and 13 is .095. After that common sizes in fractional are 1/8th wall (1.25) which very close to DOM .120 wall, then 3/16" (1.875) and 1/4" (easy .250). You want to be as thick as possible so 1/4" will be your best bet without thinking, but a 20 foot section will be 108 pounds (nothing wrong with that). A 3/16" wall thickness at 20 feet will be 87 pounds and I think would be adequate, but I don't have the math in front of me to calculate deflection on a 10 foot section. All I can say is measure what you have and you go up a size or two it should be much better/safer. I'm betting what you have is .120 wall or standard 1/8" wall. So 3/16 will probably handle it, but 1/4" would be a huge safety factor. You'd only need to cut the section to length and re-drill any holes required. I'd suggest having it professionally hot-spray galvanized, plenty of people will tell what happens when an extendable tongue rusts inside of it housing tube (not pretty).

CloudDiver · Mar 24, 2017

You mentioned that the trailer was not built for your boat... looking at your pics it does have pretty nice heavy duty construction, although its obvious the tongue extension is tiny. The trailer was probably made for some type of aluminum boat. Anyway, long and short of it is I wouldn't move the boat backward at all, you want good tongue weight so you don't get death wobble when towing. Your position just 'looks' ideal from the pic. Upgrade to thicker wall tube on the extension tongue, problem solved. You calculated your current tongue weight at 360 pounds which is actually ideal. My C22 is on a dual axle trailer so I have not measured actual tongue weight. My Toyhauler is also a dual axle, aluminum, and 3300 pounds dry (measured on truck scale), and I get 600 pounds on the tongue weight. So I think your boat position is actually in the near perfect range. The only other thing I consider checking and possibly upgrading is the leaf springs, considering the light boat that it was built for the trailer could have light duty springs. Is the trailer bottomed out just by having the boat sit on it? On a single axle trailer for a 2400 pound C22 you should use 3500 to 4000 pound rated leaf springs (both common sizes). The springs should be rated to support the weight of the boat and the trailer, so I go higher than lower. The boat weight would effectively pre-load the springs to half or better of their rated strength. A 5000 or 6000 pound set of springs would be too stiff and not effectively preloaded with the boat weight. Its worth checking and a cheap upgrade, $50 to $60 for a set. just jack up the trailer on stands so the springs are not loaded and measure the eye-to-eye length. I get my springs from etrailer.com

CloudDiver · Mar 24, 2017

LakeShark said:
Had a thought come to mind this morning. If my tongue weight is about correct and the extension is what is causing the issues with the bending. Can I simply replace the 2" extentube with a .25 wall 2" tube and run an 1.5 inch C channel down the center of the tube (1.5"ID) to add the strength I need without having to use another larger tube? Or is this a bad idea and will not affect the deflection enough to matter. 2"od Square tube is all that will fit in the current 3 inch trailer center bar.

Yes, if you go with 1/4" wall you'll be good but no need to add a C channel down the center. What size is the 'center bar'? 3 inch? Are you sure? There are typical 'nesting' sizes of standard tube that fit inside one another, and if the socket that the tongue goes in is 3 inch O.D. than you should be able to get a larger size in there.

CloudDiver · Mar 24, 2017

LakeShark said:
I will doublecheck the nesting tube size as they are tight on tolerance and were painted / rusted together when I first got the boat (I measured the extension at 2"od but not nesting tube). I will likely go with just upgrading to 1/4 inch wall tube but since I like things being overbuilt and a 1.5inch C channel is relatively affordable will it affect anything if I run it down the tube and just tack weld the ends? Or will it change nothing of the strength and only add weight?

1/4 inch wall on the tube will be beast, the C Channel will only add weight and expense plus be something else that will rust. The C channel will also be something else you have to drill through for the bolts on the coupler and securing pins on the tongue. As mentioned before, highly recommend getting the new cut to size and drilled tongue hot spray galvanized to avoid it rusting in the future. A good coating of waterproof grease in the nest tube helps too, re-apply every season.

CaptDon01 · Mar 24, 2017

I'll agree with everything CloudDriver said, except greasing the trailer tongue extension. As a confirmed trailer-sailor, having towed our C-22 multiple times across the country west to east, east to west, north to south, and south to north, launched in saltwater, freshwater, and brackish water, towing literally thousands and thousands of miles, the worst thing you can do is grease the tongue extension. It will only collect dust and grime from the road, and the grease soon turns into a brown sticky mess that bonds the trailer extension nicely into the trailer frame. Plus, the grease makes it impossible to walk on when extended to clip the trailer winch strap onto the boat. The galvanized coating gets polished from use, and as you can see in the photos, it doesn't rust, and we launch probably 90% of the time in saltwater.

Just a tip from your Uncle Don.....

A Question of Balance

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