Trailer Design Guidelines

[woody619]

I know it may be too late. But we've repaired and welded our boat trailer. I was just wondering what the rules are to doing it. To see if there's anything we need to grind off and redo. I was at the launch ramp today and someones said it should be level when connected to the truck. I noticed that there's more weight on the back tire than the front (dual). What does that mean? Are there anymore rules to consider? I'll add pics this weekend.Thanks

 

[MTboatguy]

Re: Trailer Design Guidelines

I know it may be too late. But we've repaired and welded our boat trailer. I was just wondering what the rules are to doing it. To see if there's anything we need to grind off and redo. I was at the launch ramp today and someones said it should be level when connected to the truck. I noticed that there's more weight on the back tire than the front (dual). What does that mean? Are there anymore rules to consider? I'll add pics this weekend.Thanks

In a perfect world, yes you should be level with even distribution of weight on both axles, I would not cut and start welding again, often times you can distribute the weight by simply picking up a drop draw bar, of course if you need to raise a tongue you can also turn it upside down, and mount the ball. They make draw bars to fix virtually any leveling situation you might need.

Another thing to take into consideration, do you have brakes on the trailer, if so, are they on one axle or both axles, you want the weight distributed correctly so those brakes can work efficiently.. I have seen quite a few boat trailers with brakes only on the front axle, so with the weight biased to the rear axle your not getting the maximum braking power you would want..

 

[jeeperman]

Re: Trailer Design Guidelines

And a dual axle trailer with the torsion type suspension must be setup to be level when on the road. They do not have the equilizer between the axles like leaf sprung axles.

 

[109jb]

Re: Trailer Design Guidelines

In a perfect world, yes you should be level with even distribution of weight on both axles, I would not cut and start welding again, often times you can distribute the weight by simply picking up a drop draw bar, of course if you need to raise a tongue you can also turn it upside down, and mount the ball. They make draw bars to fix virtually any leveling situation you might need.

Another thing to take into consideration, do you have brakes on the trailer, if so, are they on one axle or both axles, you want the weight distributed correctly so those brakes can work efficiently.. I have seen quite a few boat trailers with brakes only on the front axle, so with the weight biased to the rear axle your not getting the maximum braking power you would want..

I too have seen boat, utility, carhauler, etc. with tandem axles with only brakes on the front axle. This is absolutely wrong if the trailer is leaf sprung with equalizers. If this is the case, the braked axle should be the rear axle. It may be a little counter-intuitive, but it has to do with how the equalizers work.

 

[dockwrecker]

Re: Trailer Design Guidelines

I too have seen boat, utility, carhauler, etc. with tandem axles with only brakes on the front axle. This is absolutely wrong if the trailer is leaf sprung with equalizers. If this is the case, the braked axle should be the rear axle. It may be a little counter-intuitive, but it has to do with how the equalizers work.

Correctomundo!

 

[rwidman]

Re: Trailer Design Guidelines

I know it may be too late. But we've repaired and welded our boat trailer. I was just wondering what the rules are to doing it. To see if there's anything we need to grind off and redo. I was at the launch ramp today and someones said it should be level when connected to the truck. I noticed that there's more weight on the back tire than the front (dual). What does that mean? Are there anymore rules to consider? I'll add pics this weekend.Thanks

Let me see if I understand. You built a boat trailer and now you are asking how to design it? Someone said?

How did you notice that there's more weight on the back tire than the front? Did you weigh the trailer?

A few things you should know:

A tandem axle trailer should be level when connected to the tow vehicle.

5%-7% of the total weight (with the loaded boat) should be on the tongue where it connects to the tow vehicle. The rest of the weight should be pretty much evenly divided between the two axles.

The frame, axles, and tires should be rated for the weight of the trailer and loaded boat. Also, the brake actuator and the hitch and ball on the tow vehicle.

For safety there should be working brakes on all wheels (both axles)

The trailer must have safety chains and lighting according to the laws of your state and the federal government. Also, reflectors.

The boat should be secured at the bow with a safety chain and/or strap as well as the winch strap and it should be secured to the trailer at the stern with straps.

Hope this helps.

 

[gozierdt]

Re: Trailer Design Guidelines

First, state what your boat is- size, I/O-inboard-outboard, weight. Show us the pictures, both side views of the rig (truck and trailer), and underneath views of the axle setup. I think you'll have several options, as stated above, you can pick up drop (or raise) drawbars for on the truck to help level the trailer frame. You can also often move the boat forward to move weight forward onto the front axle. The goal is to get the rig set up well balanced for maximum safety.

 

[109jb]

Re: Trailer Design Guidelines

The OP said it wasn't level with more weight on the rear wheels. No real need in my opinion to overcomplicate things. From that description we have all we need.

The OP simply needs to make sure the trailer is level when hooked to the truck. If he has a receiver type hitch then it is just a matter of getting a draw bar with the right drop. There are draw bars with adjustable drop and ones with fixed drop. I would simply unhook the trailer and set it level. Measure from the ground to the bottom of the coupler. Next measure from the ground to the top of the square receiver hole. The difference in these 2 measurements is the drop you need. Now if you are not using a receiver hitch, get one.

 

[NHGuy]

Re: Trailer Design Guidelines

Widman, don't bet the guy up, he's doing the right thing asking.
And ps. he didn't build the trailer, he fixed it.

 

[woody619]

Re: Trailer Design Guidelines

Thanks for the help guys. Here's some before and after pics. B ythe way the brakes are on the rear axle thank god.

Here's the info on my boat

26' Searay. Inboard. 350 Chevy Engine w/ Pre Alpha Outdrive. Weight i believe will be around 9-10,000 lb's

Here's the pic of how the back tires carry more weight than the back, but i think it's because the front is on blocks (lifted) still from when we were welding. I'll let you know if it levels off after we lower it.

Thanks for the input guys!

 

[woody619]

Re: Trailer Design Guidelines

Also, there's only like a 3 or 4 inch clearance from the fenders to the the boat. Sorry for the noob question. But my boat's never seen the water. That won't hit at the launch ramp right?

Regarding how much weight is at the front, how do you measure that? At the weight scales? You just make sure the front is on the scale and the 4 tires are off?

 

[rwidman]

Re: Trailer Design Guidelines

Also, there's only like a 3 or 4 inch clearance from the fenders to the the boat. Sorry for the noob question. But my boat's never seen the water. That won't hit at the launch ramp right?

Regarding how much weight is at the front, how do you measure that? At the weight scales? You just make sure the front is on the scale and the 4 tires are off?

Pull the boat onto the scale with the truck wheels clearing the scale. Get a weight (example: 6,000 lb). Now put the tongue jack down onto the scale with the other wheels still on the scale, disconnect from the truck, and get another weight (example: 6,450 lb).

The second weight is the total weight and by subtracting the first weight from the second, you have the tongue weight (450 lb in this case).

 

[gozierdt]

Re: Trailer Design Guidelines

You can also weigh the tongue weight at home if you have a fairly accurate bathroom scale. The diagram below shows how to do it without overloading your scale. For your boat 7-10% of the gross trailer weight will give you about 700 to 1000 lb tongue weight. So if you measure 200 lbs on your scale, the tongue weight would be 800 lbs.

I'd also suggest you look into a weight distributing hitch for that heavy a tongue weight, and you should have a 2 5/16" ball. Both need to be rated for both the tongue weight you have and the gross towed vehicle weight. You also need a tow vehicle rated for that much towed weight and tongue weight.

 

[rwidman]

Re: Trailer Design Guidelines

You can also weigh the tongue weight at home if you have a fairly accurate bathroom scale. ...............

Yes you can, but if you don't know the (accurate) weight of the loaded boat and trailer, the actual tongue weight is not much use.

Once you have weighed the entire rig, the bathroom scale method should work for the tongue weight.

 

[bruceb58]

Re: Trailer Design Guidelines

Looks like the brake actuator is the 7500# model. Which one did you buy?

Also, brakes on one axle is not adequate for 9000#.

So, what kind of welder did you use for your welding?

 

[woody619]

Re: Trailer Design Guidelines

Thanks for showing me how to get the tongue weight guys.

Re: The actuator, it is the 7500 lb one. I ordered it from pacific or champion. I forget

DICO/TITAN? - MODEL 6

7500# GVWR CAPACITY
FITS 2 5/16" COUPLER BALL
ZINC PLATED
FITS 3" WIDE BOX TUBE TONGUE
ORDER REVERSING SOLENOID SEPARATELY

Re: the weight, I don't really know because I've never weighed it. Kinda guessing from what I've read. (Or think I've read)

I'm actually thinking about swapping out @ least one of the axles anyway (leaf springs and everything too), so i'll put brakes on it. I'll have to swap with a different type of axle right? That supports brakes? Their kinda rusty.

We used a Arc/Stick Welder. We have a friend who's a welder at the ship yards over here in San Diego who welded it for us.

We couldn't even take the boat or trailer anywhere to get it worked on. The guy we bought it from lived down the hill from us. We had to install extra breakers in the house to support the new welder.

 

[bruceb58]

Re: Trailer Design Guidelines

I hate to say it, but you probably should have bought the next model up which is the 10,000# model. You might be ok but you are going to be at the limit with that coupler.

As far as the welding, it is good that someone knowlegable did the welding with the proper equipment. There are many on here that do welding themselves with a 110 MIG which have thoughts that it would be adequate.

The only difference between an axle that is designed for brakes is if it has the square brake flange with the four holes in it. The picture you took shows you don't have it.

 

[bruceb58]

Re: Trailer Design Guidelines

Also, there's only like a 3 or 4 inch clearance from the fenders to the the boat. Sorry for the noob question. But my boat's never seen the water. That won't hit at the launch ramp right?

Jack up one axle until the equilizer reaches the distance of its travel. You need to still have some room left for spring travel.

 

[rwidman]

Re: Trailer Design Guidelines

It shouldn't have to be said, but, both axles should be the same. Don't replace one with a different type.

 

[woody619]

Re: Trailer Design Guidelines

Man, I wish i knew that. What can possibly happen with it being too small? It may not brake right? Just so I know what to look out for, so I don't overlook any signs. Thanks Bruce