Trailer Hitch Question

[MAKC]

Hi all Im getting ready (although very reluctantly) to pull my boat out of the water for the seaon. I bought a new Venture bunk trailer and will be towing with a Ford F350 Supercab. My question is, should i get a lowering bracket for the receiver hitch? Ive seen as much as 3inch drop downs for the trailer ball and was wondering if i need or should use a drop down? Any hints/insights would be greatly appreciated.

 

[SkipBarnes]

You'll need to drop it down to where the trailer will be level. Use a carpenter's level and the jack on the front of the trailer, get it level, measure to the bottom of the trailer ball receiver, then measure the truck.

Another thing you'll need to do is set the triler up so that you have the proper tongue weight, 5-15% of the total weight of the boat and trailer. You can calculate this with a bit of engineering knowledge or if you know an engineer, have him draw a free body diagram to figure out the proper distance to pull the boat up. You'll need the weight of the boat and the location of the center of gravity (I got this info from Searay) relative to the stern.

Basically, you'll want the center of gravity to be forward of the halfway point between axles. How far is where the engineering comes in. You could just put the center of gravity about 6-12" forward of that point and see what the tongue weight is using a bathroom scale (that'll go to 300 pounds or so) and see where you are if the sliderule/pocket protector method doesn't appeal to you.

Hope that helps and good luck.

S

p.s., my propellor beanie has a stainless prop

:grin:

 

[chuck1]

Looks like Skip covered it pretty good. Should also have been address when the trailer was setup for the boat. Moving the boat just a couple inches back or forth really makes a big change in the tounge weight.

 

[Nehalennia II]

I just don't like the sound of putting it up for the year :smt089
But whether you squeeze a few more weeks out of it or put her up for the long nights.....you'll want the trailer to be level like SkipBarnes(AKA Skip-SlideRuleBranes :thumbsup: ) explains

 

[Dave M.]

I use ball mounts made by Curt. Here is a link.

http://www.sitepropreview.com/wwwroot/com/curtmfg/www/index.cfm?event=prodetail&id=143&categoryid=47

I pull several different trailers, so have mounts with different drops. I suspect your boat loaded will be in the 6500 lb range, and add 1500 for a trailer puts you at 8000 lb. So a 10,000 ball and mount are reasonable. Just try and make sure the trailer is level when pulling.

You will need to be careful loading the boat for the first time, if you have not already set things up. There is no guarantee that your prop will clear the ramp when trimmed normally. It is possible you will have to trim the outdrive up to load and unload.

Assuming you already have the trailer, you should read the manual for the hitch/brake actuator assembly. Below is a link for reference for an 8000 lb model, which you may have. Note that is specifies that the tongue weight be between 5% and 10% of the trailer weight. They caution that exceeding 800 lb may cause the surge brake system activate prematurly.

Look at page 4 of the link below, and you will see an exploded diagram of the hitch. Part # 5 is the roller kit. The upper pieces are rollers, and the roll on the shafts that are the lower pieces. The lower pieces are bolts, but drilled down through axially with grease fittings attached. After assembly, grease is pumped into the bolt, and it comes out between the bolt and the roller sleeve, so the sleeve can roll smoothly on the bolt. Make sure yours is already greased. Mine was not when I got it new.

Also, these two rollers carry the tongue weight, and must roll freely while doing so. The tongue weight upper limit guarantees that you don't put so much weight on these rollers that they don't roll smoothly. If they don't roll smoothly, then when you hit the brakes, the trailer will come forward and apply the brakes. But when you release the brakes, the assembly will hang up, and not release the brakes, or only partially release them. So make sure yours is greased and operates smoothly. Check the wheels assembly periodically to make sure they are not hot from dragging brakes. I say this because I already have the T-shirt!

http://www.tiedown.com/pdf/c178a.pdf

Dave

 

[MAKC]

This is all great info and i thank you so much for it. I just have a few more questions to make sure im understanding it all correctly.

For the tongue weight, the drop (or rise) of the hitch receiver itself isnt what i should adjust to get the proper tongue weight right? The thing i should check is to make sure its level and THEN adjust the boat on the trailer to get the right tongue weight? I think thats what i read but i just want to be sure. The trailer was set up with a 24' boat in mind but its also adjustable as they showed me. The dealer said that about 6 inches of the transom should hang over the back bunk supports and thats about the sweet spot for the calculation mentioned above. Should i bring a bathroom scale the first time i load the trailer? Sorry for the newbie questions but i really appreciate the help.

 

[MLauman]

The thing i should check is to make sure its level and THEN adjust the boat on the trailer to get the right tongue weight?

Correct!

Should i bring a bathroom scale the first time i load the trailer?

You can do the bathroom scale thing with some success but you should plan a trip to a truck scale some time to get the whole picture - truck, boat, tongue and total (GVW).

 

[SkipBarnes]

For the tongue weight, the drop (or rise) of the hitch receiver itself isnt what i should adjust to get the proper tongue weight right?

Correct, the leveling of the trailer is independent of tongue weight

The thing i should check is to make sure its level and THEN adjust the boat on the trailer to get the right tongue weight?

You'll have to get the boat on the trailer, put the scale under the trailer jack, unhook the tow vehicle, jack up the trailer to get the tongue weight. It won't be exact because you're not right under the hitch part, but it'll be close enough. If you want it to be exact, get a 4x4 and use that between the hitch part on the traile and the scale. It doesn't have to be level at this point.

I think thats what i read but i just want to be sure. The trailer was set up with a 24' boat in mind but its also adjustable as they showed me. The dealer said that about 6 inches of the transom should hang over the back bunk supports and thats about the sweet spot for the calculation mentioned above.

It's a good starting point. All boats are different, but in general, their experience speaks volumes.

Should i bring a bathroom scale the first time i load the trailer?

Correct.

Sorry for the newbie questions but i really appreciate the help.

No problem!

 

[chuck1]

Sorry for the newbie questions but i really appreciate the help.

Just remember the only dumb question is the one you don't ask. That is what this board is all about. Owners helping Owners :thumbsup: The more questions the better. This is a great topic. I've been dealing with some of the same issues.

Skip,
Have you ever dealt with Weight Distribution systems. Been looking into installing one on my boat trailer but can not seem to get any straight info about how they work with surge brakes. Some say its ok and other says it will not work :huh: I had it on one of my RV trailers worked great. It was my understanding you should have it on any trailer over 5000lbs :huh:

 

[SkipBarnes]

Have you ever dealt with Weight Distribution systems. Been looking into installing one on my boat trailer but can not seem to get any straight info about how they work with surge brakes. Some say its ok and other says it will not work :huh: I had it on one of my RV trailers worked great. It was my understanding you should have it on any trailer over 5000lbs :huh:

You're right, I didn't consider that this rig would be over 5000 pounds.

I never got this far with my trailer, I did buy a system at one point and took it back when I realized I'd have to make some modifications to my trailer to make it work.

(anybody who knows more about trailers, step up. I'm no expert. The following is based on my interpretation of the subject and may not be worth poo)

The idea behind these systems is to apply a moment between the trailer and the tow vehicle to distribute the load. The rear axle takes most of the load and if you can imagine taking the normally single point universal joint type of attachment and convert it to more of a solid joint that allows rotation when turning the vehicle, and at the same time applies a torque to the frame that serves to force the front wheels down, that's basically what you've got.

As I recall, you're right, anything over 5000 pounds should have this type of setup. I towed my 250 Sundancer without the load distribution system and kept the tongue weight closer to 5%. I have an Expedition, rated for 5000 pounds without the WDS and about 10000 with a WDS.

I read into the same thing on the surge brakes. I have no idea which side is right.

 

[Dave M.]

MAKC

You need to look at the capability and needs of your tow vehicle before you invest in load leveling stuff. With an F350, I doubt that 1000lb of weight in the bed of your truck is much of an issue, and more than likely make it drive better and have better traction. Having 650-750 lb of weight on the trailer ball is probably about the same weight applied to the rear truck axle. The Curt Manufacturing D104 Ball Mount, or 'stinger', is rated for 10.000 lb load, and 1,000 lb ball weight. This will easily handle your boat and trailer without weight distributing. So then you just need to make sure the receiver on your truck is also adequate.

On my truck, I would not want weight distributing, I want all the rear axle weight I can reasonably get with my boat trailer. I am limited by how far I can move the boat foward, and by how much weight the coupler/surge brake system can bear. I am at a bit less than 800 lb, I think. With this small amount of weight added to the rear of my truck, and pulling 10,000 lb (my boat and trailer), I have had rear tire spin on wet Portland OR streets in 2nd and and I think 3rd gear by accident while getting moving at stop lights. I need more rear axle weight, not less.

I doubt that you can measure enough weight with a bathroom scale to get to where you want to be. I think MLauman is right, you need to find a convenient truck scale where you can make the measurements of your truck, your trailer, and then how much weight the trailer is putting on the truck.

When figuring out how much drop you need for the ball, be sure to take into account how much the rear of the pickup will drop when you put the trailer weight on it. You want the trailer level when the truck is carrying the load.

Whether or not tongue weight is independent of the leveling of the trailer is dependent on the type of springing you have in the trailer. If you have leaf springs with a center pivot, then it is independent. If you have torsion tube suspension in your trailer, and multiple axles, then it probably is not independent. In this case, as you move the tongue lower, it takes less weight to hold it up, as more weight is transferred to the front axle. Take your measurements with the trailer level, and you will get the right numbers.

You might imagine that regardless of the trailer axle suspension, if you just drop the tongue to the ground, it would sit on the ground. Most everybody knows that. Here are pictures of the trailer tongue of my boat dropped down with nothing holding it off the garage floor. The tongue does not rest on the floor.

 

[SkipBarnes]

What he said :grin:

(I knew there was more to it... )

 

[MAKC]

This is all great info and i cant tell you how much i appreciate it. This is my first boat and my first year boating. Ive learned so much already this year and realize how much more there is to learn. I look forward to it though.

Thanks again!
Mike

 

[SkipBarnes]

Dave -

I agree with everything you said, it is a bit more complicated than I considered, but here's a couple of points to consider:

Isn't the issue the amount of lift to the front axle due to the moment applied about the rear axle by the trailer? 1000 pound on the rear axle is probably not an issue, but the lifting of the front axle can affect handing quite a bit, which is why (as I understand it) you want the load leveling.

You could still use the bathroom scale, but it's a bit more complicated and requires another sliderule method. If you predict that you'll have about 1000 pounds tongue weight, you could place the load on a horizontal 4x4 with the scale supporting it on one end and a block of approximately the same height of the scale on the other end. A steel pipe between the 4x4 and the scale will give you a precise measurement, same on the other end. Place the load 3/4 of the way toward the block and the block will be supporting 750 pounds and the scale about 250. However, I don't know how much the wood would will take before it splinters. A real truck scale is a better solution.

What are you pulling? I am considering whether or not I want to invest in a triple axle (I ran across a pretty serious deal on one) and a tow vehicle for my 340 Sundancer. It'd be nice to be able to store it closer to my house and I'd also like to plop in Lake Michigan once in a while (I'm in Lake Huron).

I assume you lift in and out. What would you consider adequate for a tow vehicle for an 11000 pound boat?

 

[Dave M.]

Dave -

Isn't the issue the amount of lift to the front axle due to the moment applied about the rear axle by the trailer? 1000 pound on the rear axle is probably not an issue, but the lifting of the front axle can affect handing quite a bit, which is why (as I understand it) you want the load leveling.

You make a good point. I am suggesting maybe 700 lb on the ball, or even 800, but not more for the boat in question in the post. I went and measured my PU. From the rear axle to the ball is about 5 ft. From the rear axle to the front axle is about 13 ft. When you put 700 lb on the ball, you apply a turning moment around the rear axle of 700lb * 5 ft, or 3500 ft-lb. This moment gets applied to the front axle over the distance of 13 ft. So the weight removed from the front axle is 3500 ft-lb / 13 ft = 270 lb. The total weight added to the rear axle is the weight added on ball plus the weight removed from the front axle, which is 700 + 270 = 970 lb. Correct me if my thinking is wrong here, but I think I am right. So anyone could substitute their own numbers here for their own vehicle. It is evident that for a shorter wheelbase rig, the weight removed from the front axle will be more.

For an F350, I doubt that removing 270 lb from the front axle would make much difference, but it really depends on the weight of the truck, the stiffness of the springing, and the normal front axle weight.

On my truck, with just me in it, the front axle weight is 4400 lb. I cannot tell the difference in the front end height or steering when I put the trailer on. But I have the weight of the Cummins diesel in front, a gas rig would be lighter in front. My 77 1/2 ton Chev PU weighs about 4800 lb total!

So I would say you are right, and you have to consider each tow vehicle individually, and see what makes sense, and what the manufacturer specifies.

 

[Dave M.]

Dave -

You could still use the bathroom scale, but it's a bit more complicated and requires another sliderule method. If you predict that you'll have about 1000 pounds tongue weight, you could place the load on a horizontal 4x4 with the scale supporting it on one end and a block of approximately the same height of the scale on the other end. A steel pipe between the 4x4 and the scale will give you a precise measurement, same on the other end. Place the load 3/4 of the way toward the block and the block will be supporting 750 pounds and the scale about 250. However, I don't know how much the wood would will take before it splinters. A real truck scale is a better solution.

Skip, that would all work, I think. I don't know that I have tried it, but I think I have. One issue I can think of, and it may come from experience, is one with an electronic scale. With one, you need to put a weight on the scale to turn it on, then remove the weight so it can calibrate. Then when it reads zero you put the weight back on. This is easy then it is you getting on and off the scale. When it is you trying to move the front of your boat tongue up and down off the scale at just the right time, maybe it is not so easy!

I admit to being spoiled. I have a highway truck scale about 7 miles away that I can use anytime I want. It is not normally manned, maybe 1 day in 5, but they leave it on for people to weigh. So I use it quite a bit.

 

[SkipBarnes]

For an F350, I doubt that removing 270 lb from the front axle would make much difference, but it really depends on the weight of the truck, the stiffness of the springing, and the normal front axle weight.

Your math looks correct. I just thought of something else - when you go over a bump, there's a lot of weight transfer going on on the trailer, so it's conceivable that your tongue weight could increase significantly as the weight transfers. This is another benefit of the load leveling system, it reduces the indendent rotation of the two vehicles.

And God help you if you get in an accident (I work with automotive occupant safety and biomechanics for a living) but I'll stop preaching for today - nothings really gonna help you there anyway.

I am intrigued by your rig. I have a line on a tri axle trailer for very little $ but question whether or not I want to buy a bigger truck to pull it. My boat is a 340 with a near 12' beam, so there's a lot of added hassle factor to pulling that monster around, but with the price of this trailer.... how does trailering work out for you?

 

[SkipBarnes]

I admit to being spoiled. I have a highway truck scale about 7 miles away that I can use anytime I want. It is not normally manned, maybe 1 day in 5, but they leave it on for people to weigh. So I use it quite a bit.

Definitely the way to go. I'd do this before I tried to fool around with 4x4's and pipes :thumbsup: Seems more prudent and I wouldn't have to wonder if I did the math correctly on the way to the lake :grin:

 

[Dave M.]

Your math looks correct. I just thought of something else - when you go over a bump, there's a lot of weight transfer going on on the trailer, so it's conceivable that your tongue weight could increase significantly as the weight transfers. This is another benefit of the load leveling system, it reduces the indendent rotation of the two vehicles.

Just going over bumps in the road will transfer weight, but I don't think that load leveling equipment will make any difference here. Going over places where the level of the road changes is something else. For example, pulling in or out of a Safeway parking lot. There can be some significant changes in the slope of the road. The load leveling equipment will try and make the tow vehicle and the trailer not rotate, when the road tries to make them rotate. So you will get unintended and undesired weight transfer.

I am intrigued by your rig - It looks like you're towing about a 310? I have a line on a tri axle trailer for very little $ but question whether or not I want to buy a bigger truck to pull it. My boat is a 340 with a near 12' beam, so there's a lot of added hassle factor to pulling that monster around, but with the price of this trailer.... how does trailering work out for you?

I am just pulling a 270 with an 8' 6" beam. I can pull without a permit or wide load signs. My mirrors are wide enough I can see back beside the boat. Gross trailer weight as I mentioned is about 10,000. Without the trailer the truck is at about 7200 lb, with it about 17200, roughly. I keep my speed down to 60 normally when pulling, and slow down if anything looks questionable ahead. The combined gross weight rating for my rig is 20.000, so I am easily under that.

Trailering the 270 is pretty much a non-issue for me. Probably the biggest difference is if coming down a several mile 5% or 6% downgrade, I shift down so I don't descend the hill on brakes. As a rule of thumb, I descend hills in the same gear I would climb them. Diesels don't have throttle plates, so there is not nearly as much braking force just backing off the throttle as there is with a gas engine. An exhaust brake would be nice, but I don't have one.

Not sure if your boat weight of 11,000 is the published weight or the real weight. I would expect the real weight to be 1,000 more than the published weight, at least. Say your boat really is near 11,000, and you have a trailer that weighs 2500. Then you are pulling 13,500. For a PU GCVW of 20,000, that leaves 6500 for the truck weight. So I think you are borderline here with what you can do with a 3/4 ton or 1 ton truck. Mirrors are also an issue. You want to be able to have them wide enough that you can see down alongside the trailer.

I remember someone from the old site about a year ago saying it was fairly common to see 310's and 330's being launched in the desert southwest. It if were me, with a boat that size, I think I would want the trailer to have a 5th wheel connection to the tow rig. It is much more stable, allows you to put the weight directly over the rear axle, and pretty much requires you to use a separate vehicle mounted brake controller. Turning radius at a boat launch is an issue though, a 5th wheel trailer will cut more to the inside of a corner, and when doing a 180 turn like I have to at the boat launch, it would drag the front and rear axle tires sideways more in the turn. This happens to me to some degree anyway, but has not caused any sort of problem. Just what happens when you turn a three axle trailer in a sharp turn.

I don't use a lift. The photos of took of the trailer tongue I took yesterday in my shop, where my boat lives. I haul the boat to the boat launch and launch it like any smaller boat when I go boating. I commonly do this single-handed, it is no harder than with a 20 ft boat. I can't speak for a 330, I think it is very dependent on the construction of your trailer. On my bunk trailer, I always power the boat onto the trailer when loading. It self centers much better than my old 17 ft Glasspar, it is actually easier to load.

 

[Sundancer]

I'm just catching up on this thread, but noticed a dealer suggested it was OK if the boat hangs off the back of the trailer bunks by 6 inches or so? There is a LOT of weight on the transom and not supporting the last six inches will create a hook in your hull! It sounds like someone was just trying to get ride of a trailer. Either move the bunks back or get longer bunks or move the jackstand, but make sure the boat is supported the full length of the hull!

We tow our 250 with a Suburban and a 3500 crew cab diesel. We've towed it with one of our Burbs for the past 5.5 years and it's does just fine. At least I thought anyway. I made a lane change while it was raining. I was traveling about 35 MPH and it scared the daylights out of me! I tapped the brakes and it grabbed just enough to do move it over but I hadn't experienced that before. Maybe it was an extremely slippery section of road, but I was extremely cautious after that! We tow every weekend and like Dave said, there really isn't any difference launching or loading. I just have a LARGE right arm during the season!

With the 3500 Duallie Diesel, we're good to 16,500 pounds. After 12,000 pounds I think the law requires a gooseneck for weight distribution purposes. The back end doesn't sag more than an inch or inch and a half and with that long wheel base and Diesel engine up front, you'd have to a number of links off the weight distribution bars! I don't know how much you'd gain, but at some point the rear axle sticks up like a stink bug! Then you know you've gone too far.

There are WD hitches that will work with surge brakes and some folks have good luck with them. After the Burb incident, I was seriously thinking about it. With the truck, I doubt we'd even notice it.

I agree with Dave, if your dry weight is 11,000 I'd add at least 1,000 pounds or more! Wet weight with half full fuel tanks would easily add another 1,000 lbs and the trailer for something that big is probably 2,000 - 2,500. I would be uncomfortable towing anything over 80% of my GCWR! I think the Ford has a 4:11 rear end on their diesel and they claim close to 30,000 lbs, but I can't imagine that's good for longevity! Even just a few times a year. I would think something along the lines of a Kodiak 5500 or the International F70 would be up to the task, but then you need the overwide permits, can't tow on holidays, after dark, on every odd Wednesday and and what do you do with the tow vehicles when you aren't using it? If you have a construction business it might come in handy, but I don't think my wife would want to take that to Starbucks! I think the F70 is pushing $100K! That would make a nice down payment on some waterfront property somewhere!