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trailering

Posted By: fin.

trailering - 04/04/06 01:06 AM

How do you judge proper tongue weight when trailering? If the hitch makes a good solid thunk, I figure thats enough!
Posted By: Anonymous

Re: trailering - 04/04/06 01:13 AM

Pete:

If I have to strain I move the boat back. I think you want about 100-150 lbs, but I am not sure? Need a expert here.

Doug
Posted By: Mike Fahle

Re: trailering - 04/04/06 01:16 AM

The general rule of thumb is to have 10% of the load weight on the tongue. Just use a bathroom scale to weigh what you have. If you do not already know the weight of the boat, trailer, and box with gear, then you can take it to a truck scale (many local businesses) for an accurate total weight - usually for just a few bucks. Easy way to adjust the tongue weight is by boat placement but it could mean moving the trailer axle if it is way off or the boat position is set.
Posted By: hobie1616

Re: trailering - 04/04/06 01:34 AM

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Easy way to adjust the tongue weight is by boat placement but it could mean moving the trailer axle if it is way off or the boat position is set.
Don't move the axle too far forward or the frame behind the axle will slooooowwwwwwly sag.
Posted By: Mary

Re: trailering - 04/04/06 07:48 AM

I think it is better to err on the side of too much tongue weight rather than too little. I was trailering two double-stacked boats to Ohio last year, and after having driven a couple hundred miles with no problem, suddenly the trailer started fishtailing badly. I was on a freeway, and I had to keep slowing down to about 40 mph to get the fishtailing under control each time it started.

So I stopped early for the night and I asked the advice of a trucker who was staying at the same motel. He checked out the trailer and said the axle is bowed down and the wheels are canted out and the bearings on the starboard side are probably going to disintegrate soon from the stress. He advised me not to drive far. I said, "Well, I have to go another 700 miles." He said, "No way. Go to a repair place and get a new axle and replace the bearings."

I did not take his advice. Instead, I decided that the boats had slid back on the trailer because of not being tied tight enough. (Not our boats and not our trailer.) Figuring the problem might be from not enough tongue weight, I pushed the boats forward a little, tied them down very tight, and had no problem the rest of the way to Ohio.
Posted By: hobienick

Re: trailering - 04/04/06 01:54 PM

The 10% rule is a good one. In teh case of most of our cats that is about 100-150 lbs of tounge wight. I know that class 1 hitches are rated for 200 lbs max tounge weight. Here is why balancing a trailer is so important:

1) If the weight is too far forward you will have too much tounge weight (obviously). This will cause the back end of your vehicle to lift the weight off the front wheels resutling in less ability to steer effectively on slippery road surfaces (or clean one depending on how bad it is). This is mostly dependant on your tow vehicle.

2) If the weight is too far aft (too little tounge weight) then the vehicle is "holding" the trailer down and the trailer wants to whip (like in Mary's case) which will toss the back end of your vehicle around and wear out the trailers suspension and bearings as well as your vehicles.

So, you want to lod the trailer such that the tounge weight does not depress the rear suspension of your tow vehicle too much, but just enough. I know this is not exact, but you can feel the difference between a properly balanced trailer and on that is not. Very tow vehicle dependant.

For example. On my VW Passat 1.8T (yes a 150 HP 4 cyl), manual. I tow the TheMightyHobie18 on a Trailex trailer. I line up the front cross bars of the boat and trailer. I usually have the mast top out as far as the rudder tips are when locked up. This gives me about 125 lbs of tounge weight and great balance. The car steers very well in all conditions.
Posted By: EasyReiter

Re: Fishtailing - 04/04/06 07:05 PM

Fishtailing is caused by the center of gravity not being forward of the axle.
tongue weight should be enough to make sure you do not fishtail, and be less than the limit of the hitch.
my old hitch had a 200# limit, and that is very uncomfortable to lift, so I use what is comfortable to lift at the hitch end, 75 to 100#.
Posted By: Mike Hill

Re: Fishtailing - 04/04/06 07:36 PM

All good info in here. A couple of points though.

Actually you are supposed to have 8% of the total trailer weight on the tounge of the trailer.

Also the weight is not nessessarily the same as the weight on the front wheel. Sometimes those trailer wheels can be set back from the tounge a good distance which would be different from the tounge weight.

So if your trailer weighs 1000lbs you need 80lbs on the actual tounge of the trailer.

Mike Hill
Posted By: _flatlander_

Re: Fishtailing - 04/04/06 07:50 PM

Thanks Mike for clarifying the 8%. I don't know what your source is but it makes common sense to me. I'm not the biggest or strongest guy around but I've pulled many different trailer/boat combo's with less than 100 lbs. of tongue weight and never had a problem (not double stacked mind you) and it's easier on my back. I've always adjusted the boat forward or back on the trailer to get a managable weight to lift.
Posted By: PTP

Re: Fishtailing - 04/05/06 06:02 AM

All great info! Now, how FAST do people feel comfortable towing a cat?
Posted By: Anonymous

Re: Fishtailing - 04/05/06 06:08 AM

I would say under 70. 60 might be better.
Posted By: C2 Mike

Re: Fishtailing - 04/05/06 08:36 AM

Hi guys,

I do around 35,000 miles per year and 90% of that is either towing around 3-4000 lbs for work or 2 f18's & associated stuff.

IMHO the 8-10% theory is ok up to 150lbs. Most car tow hitches are designed to have max 200lbs vertical load and up to 5000lbs gross trailer weight.

As for speed - if your trailer is loaded properly and the load tied down, speed is generally not an issue. (Have been guilty of making a TheMightyHobie18 do 120mph down a fwy late for a regatta many years ago . Common sense needs to apply though - you can't go around corners anywhere near as fast and stopping distances are longer.

Tiger Mike
Posted By: hobienick

Re: Fishtailing - 04/05/06 02:00 PM

Speed is also dependant on the tire diameter and how much you trust your bearings. The larger the tire the faster you can go since the bearing angular speed is reduced.

Again, drive so you can control your car and the trailer. Keep your distance from vehicles in front of you since you can't stop as fast (especially the smaller lighter vehicles that seem to stop on a dime).

I have found with my trailer and car I feel comfortable going about 70-75 mph on the interstates. When the wind is blowing I slow down since the trailer is relatively light and gets blown around.

Make sure everything is secured very well. I was coming back from a week long vacation in Vermont 2 years ago and was drivng behind my freind who was pulling his TheMightyHobie18. The front tie-downs failed and the bows lifted straight up in the air. While it was vertical it rotated around the rear tie down, landed on the pavement and was drug sterns first for about 500 ft until he could pull it off the road.

This all happened about 5 car lengths in front of me. Had the rear tie down not held it would have been a very painful (or very short) expereince for me. Fortunatly the only damage was to his keels and it was repaired.

It never hurts to have an extra tie down in place.
Posted By: Dan_Delave

Re: trailering - 04/05/06 05:49 PM

I pulled a Bobie 20 to Florida and back twice. I average about 70 when I have a clear road. Eileen does about 80...rock on girl! We pull it with a Mustang 5 liter (302). Knock on wood, no problems.

Dan
Posted By: ksurfer2

Re: trailering - 04/11/06 05:25 PM

Interesting info. The situations that scare me the most while trailering (I keep it to 60-65, after that my gas milage goes WAAAAAY down), is being passed by big rigs. The amount of air those thing push around is astounding and cause the trailer to weave all over. Any advise to keep the trailer in shape when being passed by these behemouths?
Posted By: Clayton

Re: trailering - 04/11/06 05:31 PM

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The amount of air those thing push around is astounding and cause the trailer to weave all over. Any advise to keep the trailer in shape when being passed by these behemouths?


When towing a lightweight setup like a cat, there is not much you can do. Just anticipate the surge and try to keep from getting blown off the road. Heavy trailers and boats move much less. For example my Stiletto 27 doesn't move when a rig passes by, I actually like the push to keep that thing moving . It probably about 2500#, boat, trailer and gear.

Nope they don't make beach wheels for that one!

Clayton
Posted By: Mary

Re: trailering - 04/11/06 05:37 PM

Which works better for trailer stability: having a wide axle with the wheels far apart or having a narrow axle with the wheels close together? And whichever way is better, WHY?
Posted By: Robi

Re: trailering - 04/11/06 07:11 PM

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Which works better for trailer stability: having a wide axle with the wheels far apart or having a narrow axle with the wheels close together? And whichever way is better, WHY?
Mary, I think we can apply the same principle from sports cars with excellent road gripping abilities. The wider the wheelbase, the better.

I do beleive is the wheel base is wider, the center of gravitiy is stationed towards the center and barely shifts. If the wheel base is narrow the center of gravity is more substantial to shifts, left right for and aft.

Also another thing that works good with trailors is to have bigger wheels/tires. Bigger wheels and tires will lessen the rotation on the bearings. Making them rotate less, causing less wear and tear through reduced heat.
Posted By: hobienick

Re: trailering - 04/11/06 07:19 PM

Mary,

When you say stability what, exactly, do you mean? It is resistance to tipping over sideways? If yes, then a wider stance in better, i.e. a cat vs a mono.

Or do you mean how much the trailer "dances" around behind the tow vehicle? If yes, then a longer distance from the trailer hitch to the axel will have a much greater affect than a wider stance. That distance being longer will cause the trailer to follow your tow vehicle better (it will center it self better) and it will make backing up much easier.
Posted By: Mary

Re: trailering - 04/11/06 08:25 PM

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Mary,
When you say stability what, exactly, do you mean? It is resistance to tipping over sideways? If yes, then a wider stance in better, i.e. a cat vs a mono.

Or do you mean how much the trailer "dances" around behind the tow vehicle? If yes, then a longer distance from the trailer hitch to the axel will have a much greater affect than a wider stance. That distance being longer will cause the trailer to follow your tow vehicle better (it will center it self better) and it will make backing up much easier.

By "stability" I meant how well it tracks behind the towing vehicle and how little it gets thrown around when big vehicles pass it.

So you are saying that this is not necessarily specifically related to the width of the axle, but is also related to the length of the trailer tongue?

I'm not an engineer, so bear with me on this. If you have a narrow axle and your trailer wheels are close together, does that mean you should have a shorter tongue. And if you have a wide axle (wheels far apart), you need a longer tongue? Or is it vice versa?

I know I have followed some trailers with very wide axles, carrying ATV's, and they seem to be all over the place. And I have followed one of our trailers with the narrow axle carrying three boats, and it seems to track very true.

So is this all a function of relative tongue length vis-a-vis axle width? (Assuming proper weight on the hitch.)
Posted By: Andinista

Re: trailering - 04/11/06 08:29 PM

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.....He checked out the trailer and said the axle is bowed down and the wheels are canted out and the bearings on the starboard side are probably going to disintegrate soon from the stress. He advised me not to drive far. I said, "Well, I have to go another 700 miles." He said, "No way. Go to a repair place and get a new axle and replace the bearings."

I did not take his advice. Instead, I decided that the boats had slid back on the trailer because of not being tied tight enough. (Not our boats and not our trailer.)

so basically you didn´t mind risking other peoples boats, trailer and perhaps other peoples lives on the highway..
Posted By: steveh

Re: trailering - 04/11/06 09:03 PM

Quote
By "stability" I meant how well it tracks behind the towing vehicle and how little it gets thrown around when big vehicles pass it.

So you are saying that this is not necessarily specifically related to the width of the axle, but is also related to the length of the trailer tongue?

I'm not an engineer, so bear with me on this. If you have a narrow axle and your trailer wheels are close together, does that mean you should have a shorter tongue. And if you have a wide axle (wheels far apart), you need a longer tongue? Or is it vice versa?

I know I have followed some trailers with very wide axles, carrying ATV's, and they seem to be all over the place. And I have followed one of our trailers with the narrow axle carrying three boats, and it seems to track very true.

So is this all a function of relative tongue length vis-a-vis axle width? (Assuming proper weight on the hitch.)


Exactly. However, you do need width to add stability if your load is higher to keep it from tipping over.
Posted By: Mary

Re: trailering - 04/11/06 09:18 PM

Andinista,
Well, it was all in the family. My sister and her husband had bought them, and I was bringing them up to Ohio to help form our new Wave fleet. They had bought them from another friend of ours down here in Florida who had been sailing Waves with us and who is impeccable about maintaining his boats and his equipment and had been trailering his boats all over Florida with this same trailer with no problems whatsoever.

The only problem was that he does not hogtie things down as much as I do, and the boats had slid back a little bit. No big deal. It was just common sense to redistribute the load, and I'm sorry I even consulted that so-called trucker.

As far as risking the lives of other people on the highway, I don't think so. Based upon his analysis, the worst thing that could have happened was that the bearings might go on one of the trailer wheel hubs, which would have left me possibly stranded alongside the road for a while.

Have you ever heard a high singing noise when you are pulling a trailer? That's the sound of wheel bearings starting to seize up. Rick and I have experienced that twice, and both times we have ended up staying overnight in unplanned places.

Doesn't endanger others, but it's not something I wanted to experience all by myself pulling a trailer through the mountains.

Fortunately, shifting the load forward and tying it down better solved the problem. Although, I still worried about the bearings all the way north.
Posted By: Andinista

Re: trailering - 04/11/06 09:39 PM

Ok. The sentence "Instead, I decided that the boats had .." sound like the theory came out just as an easier alternative than hearing the guy's advice.
Posted By: Mary

Re: trailering - 04/11/06 10:15 PM

Hey, I heard the advice, and I passed it on to my sister, the new owner of the boats and trailer, in case they ever want to take it anywhere off the island, which is unlikely.

Now, the interesting thing about all this is that the wheels on that particular trailer were very far apart, wide axle. It was always carrying two Waves double-stacked. And, as I mentioned, the axle was bent (bowed down a little bit), which caused the wheels to cant outwards a little bit, which caused more pressure on the wheel bearings.

SO, I am just wondering whether there is also some engineering ratio to determine where the wheels should be under the load so that it will not stress the axle. Is more in better than more out?
Posted By: hobienick

Re: trailering - 04/11/06 10:19 PM

The tracking of the trailer has very little (if anything) to do with the stance of the wheels. It is the longer tounge that will keep it tracking behind the two vehicle. It will still blow around when a semi passes you, or you the semi, but it will not jerk the tow vehicle around as much and will recenter in a much more gentle way than a short tounged trailer will.

It's like the wheel base on a car. If you ride in an old CJ5 Jeep dow the highway, every little bump in the road will rock the jeep. If you ride in a road boat station wagon with the really long wheel base, you don't feel the bumps as much. (For those of you who will jump on me and point out suspension differences, assume they are using the same suspension).

For a more nautical reference imagine sailin a small 8' dinghy in 1' seas. Then imagine sailing a 16' dinghy in the same seas. Much smoother. Rotate the plane of motion 90 deg and you have your trailer. Instead of your contact points being the bow and stern causing pitch they are the hitch and wheels causing yaw.

I hope this cleared things up and didn't make it more complicated.
Posted By: hobienick

Re: trailering - 04/11/06 10:21 PM

You needed a beefier axel. It sounds as if it was overloaded. Most small boat trailers are good for about 600 - 1000 lbs. The only way to remove the torsion you saw on the wheel bearings is to apply your load to both sides of the wheel.
Posted By: acdavis

Re: trailering - 04/11/06 10:56 PM

I'm pulling this out of a vehicle stability class that I took while studding Mechanical Engineering in college. It's been a few years so if I'm mistaken feel free to correct me.

From what I remember, there are three areas of stability:

Stable, under normal speeds when disturbed the trailer will always follow behind the towing vehicle and any oscillations (bumps in the road) will dissipate.

Critically stable, the vehicle will remain stable under a threshold speed and any oscillations will dissipate. Over this speed the oscillations will increase until you loose control of the vehicle (fishtail).

Unstable, at any speed any oscillations will increase and you will loose control at even the smallest speed.

Warning, if you’re not an engineering nerd you may want to skip this next paragraph:

Stability has to do with where your eigen values are located when plotted on a real vs imaginary graph. For fundamental stability the eigen value must be in the quadrent located above the real axis (x axis) and to the left of the imaginary (y axis). Critical stability occurs when any eigen value is located on the y axis and above the x axis, and fundamental unstability occurs when the eigen value is located to the right of the y axis.


When it comes to trailers this is a direct function of where the center of mass is in relation to the axel of your trailer.

If your center of mass is in front of the axel the trailer will remain stable.

If the center of mass is right at the axel, your trailer will be critically stable, over the threshold velocity it will oscillate out of control. This type of loading should be avoided because there is really no easy way to know what the threshold velocity is. Unless you like finding out the hard way.

The trailer will be unstable if the center of mass is behind the axel. This is unsafe at any speed.

I remember a demonstration we had in class where we had a bicycle with a trailer which had a 2 lb weight in it. Just putting this little amount of weight behind the axel was enough to throw someone off the bike at a walking pace.

It's super easy to know what kind of loading you have. If the tongue of the trailer is on the ground before you hitch up and take off you'll be fine, just make sure the load can’t shift. If the tongue is balanced evenly or up in the air, you're screwed.

Of course the easiest way to make a trailer unstable is to simply put your car in reverse.

I’ll put my pocket protector away now.

Adam
Posted By: ReefedOne

Re: Wheel SIZE 8" v. 12" - 04/11/06 11:22 PM

Before you put your Mech. Eng. texts and SAE handbooks away, please re-assure the folks that 8" wheels are just fine (for single cat trailers, anyway), and will not "overheat" the bearings at speeds under 100mph. Wheel bearings must meet minimum DOT/SAE/etc. standards, which generally have LOTS of margin built-in. What makes bearings overheat is EXTREME OVERLOADING (or overtightening during installation) and (*ta-DAH*) INSUFFICIENT LUBRICATION, period. Spring loaded hubs, which maintain positive grease pressure, i.e. no air voids, thereby keeping water out, go far in this regard. So does periodic maintenance.

I've had trailers with both size wheels, and in retrospect, I like the 8" better because the boat was lower to the ground, ergo easier to launch, recover, and hop up on to step the mast.

I too worried about the THEORETICAL overspeed of the bearings with my 8" wheels, so once after driving 120 miles non-stop at 70MPH, I pulled over to the shoulder, hopped right out and felt both hubs in quick succession... air temperature. NO problemo...


Of course all of the above applies only to bearings made in the G8 industrial countries. If you buy bearings made in Red China, well, I hope you enjoy the $2.86 savings while your $20,000 A-cat gets a terminal case of road rash.
Posted By: hobie1616

Re: trailering - 04/12/06 01:05 AM

\
Quote
From what I remember, there are three areas of stability…
One other factor is how much fuel is in the towing vehicle’s tank. Fuel weighs 5.8 to 6.5 lbs. Ethanol is 6.59 lbs. Diesel is 7.0 to 7.3 lbs. If a vehicle has a 20 gallon tank you mat see stability change as the fuel is used.
Quote
Of course the easiest way to make a trailer unstable is to simply put your car in reverse.
When I was in the Army, I had a signal group with a bunch of M151A1 Jeeps (pre Hummer) equipped with trailers. None of the guys in the section had ever pulled a trailer before. After I finished with them they were doing figure-eight races in reverse around two warehouses. The major I worked for freaked out until I got him into a Jeep. He turned out to be a pretty good competitor.
Posted By: Andrew

Re: trailering - 04/12/06 06:04 AM

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Fuel weighs 5.8 to 6.5 lbs. Ethanol is 6.59 lbs. Diesel is 7.0 to 7.3 lbs.


Then fuel weighs 5.8 to 7.3 lbs (per gallon), right?
Posted By: hobienick

Re: trailering - 04/12/06 01:53 PM

Wow, this thead just got really complicated for a simple question. Let's assume for all of my previous posts the trailer was balanced correctly (weight on the tounge of the tow vehicle). With a longer distance between the hitch and the axel the trailer will track behind the tow vehicle better.

Since most of us trail with bows forward cat trailer have this "advatage" built in.

I would say that the chagne in weight of fuel in a tow vehicle is not going to make it unstable. It's not like we are flying in a small airplace with a fuel tank aft of the rear baggage compatement that when the fuel is burned completly changes the handling of the airplane.

As far as tire size goes, 8" tires will work fine. I like the larger tires because I feel better with that extra margin given by reduction in angular velocity of the bearings. I also really like the larger tire diameter for handling bumps in the road.
Posted By: _flatlander_

Re: Wheel SIZE 8" v. 12" - 04/12/06 02:03 PM

Quote
Before you put your Mech. Eng. texts and SAE handbooks away, please re-assure the folks that 8" wheels are just fine (for single cat trailers, anyway), and will not "overheat" the bearings at speeds under 100mph. Wheel bearings must meet minimum DOT/SAE/etc. standards, which generally have LOTS of margin built-in. What makes bearings overheat is EXTREME OVERLOADING (or overtightening during installation) and (*ta-DAH*) INSUFFICIENT LUBRICATION, period. Spring loaded hubs, which maintain positive grease pressure, i.e. no air voids, thereby keeping water out, go far in this regard. So does periodic maintenance.

I've had trailers with both size wheels, and in retrospect, I like the 8" better because the boat was lower to the ground, ergo easier to launch, recover, and hop up on to step the mast.

I too worried about the THEORETICAL overspeed of the bearings with my 8" wheels, so once after driving 120 miles non-stop at 70MPH, I pulled over to the shoulder, hopped right out and felt both hubs in quick succession... air temperature. NO problemo...


Of course all of the above applies only to bearings made in the G8 industrial countries. If you buy bearings made in Red China, well, I hope you enjoy the $2.86 savings while your $20,000 A-cat gets a terminal case of road rash.


Ditto, Amen and all that. There's a lot of real estate between lakes around here, not so breathtaking that one would want to drive slow to take it in (driven at 75 - 80 mph) and never a problem. Specifically the advantage of having the whole "kit" lower far outweighs the supposed advantage of 12" setup. I've pulled and have both sizes and while pulling I can discern no difference.
Posted By: _flatlander_

Re: Trailering wind resistance - 04/12/06 02:15 PM

Pardon me, maybe this should be a new thread?

With soaring fuel costs and lots of miles slated for this season, I like the lower idea (8" wheels), from the wind resistance standpoint. I'm about to take the old school, overblown cooler style box OFF my 16 trailer (sail tube only). Nothing in it can't be kept in the vehicle. Thinking of doing something to the front of the box on the 20 trailer (along the lines of Thull) to cut down wind resistance. Or is this useless? Engineers? I dunno, maybe I can tape some smoke bombs to my bumper. Will a significant amount of air go under a tow vehicle at 70 mph?
Posted By: hobienick

Re: Trailering wind resistance - 04/12/06 05:53 PM

I don't think you will see any increase in fuel economy if you take the tool box off your trailer. Remember how much quieter it gets in your car when you tailgate a tractor trailer. The same thing happens behind your vehicle but on a smaller scale. The increase in drag is mostly (at least for me) due to the boat being wider than my car. So, my car has not moved the air out of the way yet.

I don't think a couple inch difference in height of the trailer will increase your fuel economy either for the same reason. Most of the drag comes from the boat being wider than the tow vehicle. Your best bet would be to dissassemble to the boat so it can fit within the width of your tow vehicle. Then you will have better fuel economy.

My 2 cents
Posted By: steveh

Re: trailering - 04/12/06 06:02 PM

Quote
The tracking of the trailer has very little (if anything) to do with the stance of the wheels. It is the longer tounge that will keep it tracking behind the two vehicle. It will still blow around when a semi passes you, or you the semi, but it will not jerk the tow vehicle around as much and will recenter in a much more gentle way than a short tounged trailer will.


All other things being equal, for an equivalent disturbance, the wider trailer will have larger oscillations in the disturbing, restoring and damping forces due to the longer moment arm from the tow point to the tire contact point. In particular, the component of the tire side force that resolves to a force pointing directly aft and acting on the moment arm, sin(yaw)*(axle length), will have a much larger impact on the system on a wider trailer than on a narrower trailer.

Assume a wind vane with a pivot arm of length 1 ft from the pivot point to the center of lift of the vane. Assume a second wind vane with the mid point of an arbitrarily long cross bar attached to the same 1 ft arm with a vane at each end of the cross bar. Any length cross bar will be less stable than the zero crossbar case and with a long enough cross bar, the wind vane will be unstable.

Looking at it qualitatively, an absurdly long crossbar (axle) will, in effect, result in a very short pivot arm (tongue length).

Please don't make me draw a free body diagram.
Posted By: Mary

Re: trailering - 04/12/06 06:11 PM

So am I right in my totally subjective impression that, in general, a narrower axle will tow better than a wider axle, if the tongue length is the same for both and they are both carrying the same load and with the same tongue weight and same percentage of weight forward of the axle?
Posted By: steveh

Re: trailering - 04/12/06 06:20 PM

Nick says no, I say yes. These guys also say yes, though they don't show equations to prove it.

Quote
Trailer length and length with respect to width is another factor. Longer trailers typically tow better -- or more accurately, a greater separation between the rear most wheels of the tow vehicle and the fore most wheels of the trailer. A long tongue as discussed in the Strength section can help in facilitating separation. The point here is really the distance with respect to the width. Look at the width of the trailer with respect to the tow vehicle and with respect to the axle separation. The wider the trailer, the more it will benefit from length.


If you feel like dropping $12, you could most likely find the definitive answer in this ... Analytical Methods and Test Procedures
Posted By: acdavis

Re: Trailering wind resistance - 04/12/06 06:49 PM

As far as wheel sizes go I feel confident with 8" tires. True a 12" wheel spins 30% less than an 8". Typically 12" tires are wider than 8" tires, which means more rubber is on the road, which means more traction.

In mechanical design we tend to deal with cyclical loads. Funny things happen when a load occurs over and over again. Think about bending a paper clip, you can do it once or twice but if you do it over and over again eventually it breaks. The goal of mechanical engineering is to design paper clips that don’t break. Bearings are designed to have an “infinite” life (on paper any way). On the box it never says “replace after 1 million revolutions.” Industry standards such as SAE are set up to make sure that machine parts don’t have a finite lifespan.

What is more important than wheel size is that your hubs are well maintained. Well maintained bearings with an 8" wheel will last for years and years and miles and miles. Poorly maintained bearings regardless of wheel size can be extremely dangerous. It is all about lubrication and maintenance.

A friend of mine was towing his Boston whaler from Tiburon (just across the Golden Gate from SF) down to Monterey. He didn’t know about bearings or how to pack his bearing buddies. Just south of San Francisco he noticed his trailer was smoking and pulled over right away. A bearing had seized and when he jacked his trailer up the wheel fell right off. The heat had softened his axel and the seized bearing has sheared the wheel right off. I guess the moral of the story is to check your bearing buddies regularly.
Posted By: PTP

Re: Trailering wind resistance - 04/12/06 07:10 PM

I have brand new springs/bearings/hubs/tires (12) that were installed about 6 months ago and I have maybe trailered 100 miles since. Do I need to do anything to the bearings before a long trip?
Posted By: acdavis

Re: Trailering wind resistance - 04/12/06 07:15 PM

I totally agree with Nick here. Your trailer essentially drafts behind your car in NASCAR and bicycle racing. An easy way to tell what is causing an increase in drag is to look at the front of your car dead on and see what sticks out above and on the sides.

As far as designing some type of cowl to increase your fuel efficiency it is extremely difficult and I think you’d end up spending much more building the stupid thing than you’d ever see in fuel savings in a hundred years.

Awhile back there was a group of the best of the best engineers working for Porsche that had supposedly used all of this new cutting edge technology to cut down on drag on some new sports car. When they did the wind tunnel tests they found that they did cut down on the drag. Just for fun they put the car in the wind tunnel backwards and the test results were phenomenally better with the car backwards than forwards. Aerodynamics is difficult for even the best of the best.
Posted By: acdavis

Re: Trailering wind resistance - 04/12/06 07:25 PM

PTP,

You're probably fine. Just look at your bearing buddies, if they're sunk into the hub a bit then add some grease, if they're popped out all the way then you're fine.

I don't know if it's bad or not, but before a long trip I always give mine a shot of grease till it oozes out a bit, then I wipe the excess off. I also always have some type of grease gun with me for long trips, my bearings are older and the seals tend to leak a bit. You can get a whole tube of marine grade grease at the big orange home improvement store for about 2 bucks and a grease gun for less than $10. With all the money we dump into our boats, this is one of the cheapest and most important investments we can all make.

Posted By: hobie1616

Re: trailering - 04/12/06 07:42 PM

Quote
Quote
Fuel weighs 5.8 to 6.5 lbs. Ethanol is 6.59 lbs. Diesel is 7.0 to 7.3 lbs.


Then fuel weighs 5.8 to 7.3 lbs (per gallon), right?
Depending on whether is gas, gas/alcohol or diesel.
Posted By: Mary

Re: trailering - 04/12/06 08:35 PM

So far from this thread I have gleaned that a narrower axle will tow better than a wider axle, if the tongue length is the same for both and they are both carrying the same load and with the same tongue weight and same percentage of weight forward of the axle.

So, it sounds like the wider the axle, the longer the tongue you need to maintain the same towing stability, as far as tracking straight behind the tow vehicle.

AND, it also sounds like you are better off with a narrower axle because it is easier on your bearings if most of the weight is distributed to the outside of the wheels rather between the wheels and directly over the axle.

Am I getting this image correctly? This is really interesting stuff .
Posted By: hobienick

Re: trailering - 04/12/06 09:30 PM

Steve,

I never said a narrow axel will tow better or worse than a wider one. I said that a longer tounge length will have more effect that a change of a few feet in the axel width.

I think you and I are on the same page here:

Longer tounge = more stable trailer.
Posted By: hobienick

Re: trailering - 04/12/06 09:40 PM

Quote
AND, it also sounds like you are better off with a narrower axle because it is easier on your bearings if most of the weight is distributed to the outside of the wheels rather between the wheels and directly over the axle.


Mary, It doesn't matter how wide or narrow your axel is. The wheel are cantilevered (supported on only one end) no matter what. You need to have an axel/bearing/wheel combo that is designed for the appropriate weight.

Quote
So, it sounds like the wider the axle, the longer the tongue you need to maintain the same towing stability, as far as tracking straight behind the tow vehicle.


That is correct. And as Steve's formula confrimed the longer the tounge the better it will track. In real work application a few foot change in the width of the axel will not have an appreciable effect on the stability of a trailer with a 16' tounge length.
Posted By: steveh

Re: trailering - 04/12/06 10:02 PM

Quote
The tracking of the trailer has very little (if anything) to do with the stance of the wheels.


I took stance to mean width. If you meant camber, well, having the tires cambered inward helps stability, too. So does toe-in.

Posted By: ReefedOne

Re: trailering - 04/12/06 10:24 PM

PTP:
Quote
I have brand new springs/bearings/hubs/tires (12) that were installed about 6 months ago and I have maybe trailered 100 miles since. Do I need to do anything to the bearings before a long trip?


Its not so much the mileage (minimal in your case), but how many times have they been SUBMERGED IN WATER at the boat ramp, DEEP puddles, etc. during those 6 months? Axle grease is water RESISTANT, to a point, but if water STAYS in there, the churning at 80MPH will eventually cause the soap-base of the grease to "mayonnaise" and break-down... then, the "bad thing" happens... almost always at a very inconvenient--and even dangerous--time and place.

You're probably fine, but hey, pump some MORE grease in there and CHECK closely if the overflow that oozes out is grease... or WATER? Even if they have NOT been dunked during that period, if you live in a humid climate, there's condensation too...
Posted By: ReefedOne

Re: bearing buddy CAPS - 04/12/06 10:31 PM

Is it just me, or am I seeing more and more bearing buddy type hubs withOUT the rubber slip caps on them? No, they don't keep out water, but they do keep out SAND, which is important, given the sliding piston, the need to keep grease nipple clean, etc.
Posted By: bvining

Re: trailering - 04/12/06 10:32 PM

Quote
Longer tounge = more stable trailer.


longer tongue makes it easier to back it up.

Ever tried to back up a short little trailer? very hard if you're used to a long tongue.
Posted By: pdwarren

Re: Trailering wind resistance - 04/12/06 11:56 PM

Quote

Awhile back there was a group of the best of the best engineers working for Porsche that had supposedly used all of this new cutting edge technology to cut down on drag on some new sports car. When they did the wind tunnel tests they found that they did cut down on the drag. Just for fun they put the car in the wind tunnel backwards and the test results were phenomenally better with the car backwards than forwards.


So that's why the boxster looks the same which ever end you're looking at...

Paul
Posted By: SunnyZ

Re: Trailering wind resistance - 04/13/06 12:21 AM

Quote
Quote

Awhile back there was a group of the best of the best engineers working for Porsche that had supposedly used all of this new cutting edge technology to cut down on drag on some new sports car. When they did the wind tunnel tests they found that they did cut down on the drag. Just for fun they put the car in the wind tunnel backwards and the test results were phenomenally better with the car backwards than forwards.


So that's why the boxster looks the same which ever end you're looking at...

Paul


I have noticed that cars are starting to resemble jelly beans. What is with that body style? The next time you drive down the street look at them. Jelly beans...Mine is Kiwi.
Posted By: hobie1616

Re: Trailering wind resistance - 04/13/06 12:25 AM

Quote
I have noticed that cars are starting to resemble jelly beans. What is with that body style? The next time you drive down the street look at them. Jelly beans...Mine is Kiwi.
Aerodynamics. Less drag means lower fuel usage. Vans have the same aerodynamic characteristics as a sheet of plywood.
Posted By: C2 Mike

Re: trailering - 04/13/06 12:40 AM

Quote
Which works better for trailer stability: having a wide axle with the wheels far apart or having a narrow axle with the wheels close together? And whichever way is better, WHY?


The further apart your wheels are, the more stable you are on the road. As somebody else mentioned, draw bar length (how far back the wheels are relative to your car) will reduce any tendancy for the trailer to weave all over the road.

Furthermore, larger diameter wheels are better than the smaller ones as the bearings are not working anywhere near as hard. I use 15" car rims on mine. Went to a wrecker and found 3 mag wheels with good tyres for $25 the lot The negative is your boat is higher off the ground but then if you match the trailer wheels to your car, you can use the car spare if you ever get a flat

Tiger Mike
Posted By: hobienick

Re: trailering - 04/13/06 01:01 PM

I did mean width, but I as said in a later post the 2-4 foot difference in width is not going to make any appreciable difference on a trail with a 16 foot plus tounge length. On a much shorter (5-6 feet) utility trailer, yes the width will have a profound difference.

An easy was to exaggerate the effect of axel width and tounge length is to back the trailer up. The easier it is (removing practice and skill at backing trailers up from the variables) the more stable it will be behind your tow vehicle.
Posted By: MauganN20

Re: trailering - 04/13/06 01:06 PM

just heard from Trey last night on his way down to spring fever. One of the TheMightyHobie18 trailer axles blew up. Not the bearings, he said the axle just folded in three places.
Posted By: Seeker

Re: trailering - 04/13/06 08:25 PM

"I use 15" car rims on mine. Went to a wrecker and found 3 mag wheels with good tyres for $25 the lot"

I don't know with a light weight cat trailer if it makes much difference...but for trailers in general you are not suppose to use car tires because the sidewalls are too flexible in comparison to trailer tires.


Regards,
Bob
Posted By: C2 Mike

Re: trailering - 04/13/06 10:56 PM

Quote
"I use 15" car rims on mine. Went to a wrecker and found 3 mag wheels with good tyres for $25 the lot"

I don't know with a light weight cat trailer if it makes much difference...but for trailers in general you are not suppose to use car tires because the sidewalls are too flexible in comparison to trailer tires.

Regards,
Bob


The average car tyre will have a working load of approx 1200 lbs and my trailer weight is around 1000 lbs per wheel so the loadings will be similar. (I usually have 2 boats and all my stuff in the trailer). You should use a tyre designed for whatever load you are putting on it.

Tiger Mike

Attached picture 73299-AustBite.JPG
Posted By: Seeker

Re: trailering - 04/14/06 02:27 AM

"The average car tyre will have a working load of approx 1200 lbs and my trailer weight is around 1000 lbs per wheel so the loadings will be similar. (I usually have 2 boats and all my stuff in the trailer). You should use a tyre designed for whatever load you are putting on it."

Hi Mike
It's not so much the load, as the flex of the sidewall...from what I have read on the subject, the sidewalls are much stiffer on dedicated trailer tires which helps to keep trailer sway to a minimum...granted this is a much bigger issue with a heavy utility or power boat trailers.

Regards,
Bob
Posted By: SteveT

Re: trailering - 04/14/06 03:55 AM

So here's a little twist: How many people tow a train, as in a camper and the boat or a fifth wheel and the boat. A few of our fleet members do this successfully with the fifth-wheel types having better luck. Also, how many people use a sway brace. Reese makes a really good one that I'm thinking of installing.
Posted By: C2 Mike

Re: trailering - 04/14/06 05:56 AM

Quote
"The average car tyre will have a working load of approx 1200 lbs and my trailer weight is around 1000 lbs per wheel so the loadings will be similar. (I usually have 2 boats and all my stuff in the trailer). You should use a tyre designed for whatever load you are putting on it."

Hi Mike
It's not so much the load, as the flex of the sidewall...from what I have read on the subject, the sidewalls are much stiffer on dedicated trailer tires which helps to keep trailer sway to a minimum...granted this is a much bigger issue with a heavy utility or power boat trailers.

Regards,
Bob


Well I used the above rig to travel from Melbourne to Perth 2400 miles (each way!) at Christmas just gone with not so much as a puncture. The photo was taken at the Great Australian Bite after about 18 hours of driving when we stopped for fuel.

Tiger Mike
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