wrote in message
...

Ideally, the center of mass of the boat should be just ahead
of the axles, just enough to give you the tongue weight you're shooting
for. All else being equal/unchanged increasing the tongue length will
increase tongue weight by the amount of extra material in the tongue.

That's true, the tongue weight will increase by the weight of the
added material. (Actually, as Steven pointed out, some of that
added weight will also be supported by the whels.) But most
of it is nearer to the ball, and most will be supported there.

BUT, the weight of the added material is very small
and I believe can essentially be forgotten about. In our
example, an extra 3 feet of tonge would be maybe 20 lbs
of material. When we're looking for a tongue weight of
400#s, thats nominal.

What is ALSO true is that that longer tongue (all else
staying the same) moves the end of the tongue farther
away from the pivot point (axel). A longer arm (tongue)
gives more leverage. It would be easier to lift that
tongue off the ground or up off the ball. There would
be "less tonge weight".

Now I wonder how we ever made it to the moon, when a group of educated
intelligent men are debating the results of one of the most basic
engineering axioms. Also amazing is that so many people rush to proclaim a
known fact.......on a national stage............when they are exactly wrong.

I wonder how this thread would play out in Japan, or Germany?

Most people using and even building trailers are not engineers and the "rule
of thumb" is usually good enough for them. I've built 100s of trailers and
never needed to resort to a finite stress analysis or calculation of polar
moments to design a good trailer. However, knowledge of how these affect
the performance of the trailer is important.
BTW, I've seen trailers with very small tongue weight that tow just fine and
others with the "recommended" tongue weight but and unbalanced load (i.e.,
high polar moment) that sway all over the road.
The suggestion to: "Get the boat where you want it. Then make the tongue
the length you want
it. Finally move the axle to get 10% of the weight on the tongue.", is a
pretty good one... but 10% may be too little or too much depending on the
design and towing vehicle.
I've also build trailers with movable axle/spring frames to allow the
trailer to be blanced to carry different boats.


"Floyd in Tampa" wrote in message
om...
Now I wonder how we ever made it to the moon, when a group of educated
intelligent men are debating the results of one of the most basic
engineering axioms. Also amazing is that so many people rush to proclaim
a
known fact.......on a national stage............when they are exactly
wrong.

I wonder how this thread would play out in Japan, or Germany?

K Smith wrote in message ...
Snafu wrote:
Gary, I'm not understanding the part about "the longer the tongue, the
furthur back we can put the wheels." To maintain the ~10% of the weight on
the hitch rule, increasing the tongue length works the opposite way.

Absolutely the longer the tongue (drawbar?) the further "forward" the
wheels will by to keep the balance right.

K

Once again, you've proven you stick your nose where it doesn't belong.
You certainly don't understand simple physics. If you make the tongue
longer, you will need to move the wheels BACK to keep the balance the
same. Say you have the tongue 10' from the wheels, and the tongue
weight is 100 pounds, to say, at that 10', you need to resist 100
pounds to lift the tongue. Now, we extend the tongue, to 15'. Now you
have a longer lever, thereby LESS tongue weight. To compensate, you
need to move the wheels BACK.

"Gary Warner" wrote in message
...

So, any other problems with having a longer trailer tongue?

I have had this argument before, and don't wish to get back into the
mechanics of stability arguments again. BUT......


First word of caution: The 10% tongue weight is a "rule of thumb". Having
10% tongue weight won't necessarialy result in stable rig. Not having 10%
won't necessarialy make it unstable. Having too much will certainly load
down the tow vehicle, which could create problems. Not having enough will
certainly make a receiver type hitch rattle a lot more, and could make the
tongue pop off the ball when you hit bumps in the road.

What makes a trailer stable is the stiffness of the connection between the
axels and the load (springs, center of mass, trailer rigidity, etc.) and the
stiffness of the trailer with load to the tow vehicle (trailer rigidity,
distribution of mass).

For the purpose of discussion, take two trailers, each 20 feet long, axels
in the middle:

Trailer A has all its load located essentially over the axel Tongue weight
could be neutral. Other than the risk of the hitch popping off the ball,
this trailer could tow very nicely.

For trailer B the load is separated into two sections. A little more than
half of the load is centered 5 feet forward of the axels, the remainder of
the load is 5 feet back of the axels. This trailer has the "desired" 10%
tongue weight. Unfortunately, it is likely to sway terribly as you go down
the road.

The difference between these two trailers is the moment arm of the mass. It
isn't a "statics" problem, it is a "dynamics" problem.

To address your exact question: you could have possible problem with a
longer tongue if you don't compensate for the extra "spring". A short
trailer would be "stiff". If you use the same construction and stretch it,
the trailer will become more flexible. This can be very bad. You can avoid
this by making the tongue section more robust. When you figure the load on
the trailer you should consider more than just how gravity effects it. You
need to also consider the side loads during cornering, or when hit by the
wind blast of a passing truck.

You can have a long tongue, there is nothing wrong with that. But it is a
different trailer design than just taking a short trailer and extending it.

Rod McInnis

On 10 Dec 2003 09:00:31 -0800, (basskisser) wrote:

K Smith wrote in message ...
Snafu wrote:
Gary, I'm not understanding the part about "the longer the tongue, the
furthur back we can put the wheels." To maintain the ~10% of the weight on
the hitch rule, increasing the tongue length works the opposite way.

Absolutely the longer the tongue (drawbar?) the further "forward" the
wheels will by to keep the balance right.

Once again, you've proven you stick your nose where it doesn't belong.
You certainly don't understand simple physics. If you make the tongue
longer, you will need to move the wheels BACK to keep the balance the
same. Say you have the tongue 10' from the wheels, and the tongue
weight is 100 pounds, to say, at that 10', you need to resist 100
pounds to lift the tongue. Now, we extend the tongue, to 15'. Now you
have a longer lever, thereby LESS tongue weight. To compensate, you
need to move the wheels BACK.

It really pains me to see the lack of understanding of basic physics by
a lot of people that this thread has exposed. For example, take the
argument above. Both of you may be right, both of you may be wrong, you
can't tell from the information given. In the specific example above of
a tongue weight of 100lbs with a tongue length of 10' from axle to
hitch, if you extend the tongue another 5' you may have to move the axle
forward, backward, or not at all to keep that 100lb hitch weight.
That's because in addition to changing the lever length, the weight on
the hitch also depends on what the weight of the additional 5' of tongue
did to the balance point. Since that hasn't been specified, the answer
is unknown.

Steve

On 10 Dec 2003 09:00:31 -0800, (basskisser) wrote:

K Smith wrote in message ...
Snafu wrote:
Gary, I'm not understanding the part about "the longer the tongue, the
furthur back we can put the wheels." To maintain the ~10% of the weight on
the hitch rule, increasing the tongue length works the opposite way.

Absolutely the longer the tongue (drawbar?) the further "forward" the
wheels will by to keep the balance right.

K

Once again, you've proven you stick your nose where it doesn't belong.
You certainly don't understand simple physics. If you make the tongue
longer, you will need to move the wheels BACK to keep the balance the
same. Say you have the tongue 10' from the wheels, and the tongue
weight is 100 pounds, to say, at that 10', you need to resist 100
pounds to lift the tongue. Now, we extend the tongue, to 15'. Now you
have a longer lever, thereby LESS tongue weight. To compensate, you
need to move the wheels BACK.

Tell ya what I'll do, I'm not going to give you the answer, but I'll
define a problem and let basskisser and Karen come up with solutions and
see if they come up with the same one, and then hack out their
differences.

Let's go with the situation above. Assume you have a trailer where the
distance from hitch to axle is 10' and the tongue weight is 100lbs.
Also, assume that the trailer is level because if it isn't, it will
affect the answer. Also assume that the tongue extension has a constant
weight per unit length.

Now increase the length of the tongue to 15' from axle to hitch. Just
from the difference in leverage, what is the new, lower weight on the
hitch?

Since we assumed that the extension has a linear weight/length, the
center of mass of the extension is 2.5' from the hitch and 12.5' from
the axle. So what percentage of the weight of the extension is
supported by the hitch?

Knowing the percentage of the weight of the extension that's supported
by the hitch, how much does the extension have to weigh to exactly
counteract the decrease in weight due to leverage and keep the weight on
the hitch at 100lbs?

If the extension weighs any more than the answer you come up with, then
you have to move the wheels forward to keep the weight 100lbs. Any
less, then you have to move the wheels back.

Bonus question: assume that the original level trailer with the 10' from
axle to hitch weighs 1000lbs and the hitch weight is 100lbs, or 10% of
the trailer weight. You extend the tongue by 5' using an extension that
weighs 10 lbs/ft. How far and in what direction do you have to move the
axle to keep the hitch weight 10% of the new trailer weight?

Have fun!

Steve

Everybody else seems to have gone off on the relative tongue weight.

Other factors:

A longer tongue will back up more stable, but be less maneuverable when backing.

A longer tongue will help keep your truck out of the salt water.

With a long tongue, I'd consider adding trailer running lights under the bow
somewhere. It can be a long way between the back of your truck and
the first running lights on the trailer. Several years ago, I damn near
center-punched a Corvette on a trailer with no lights between the back
of the truck and the back of the trailer. He came out of a blind side street
on a rainy night, and it sure looked like just the tow vehicle. I got all kinds
of sideways avoiding the trailer, no harm, no foul, but some running lights
on the trailer would have kept my adrenaline level down. My Shorland'r
trailer has a long tongue from the factory, and I added running lights under
the bow (there was already a set at the front of the trailer fenders).

Finally, several folks have said 10% on the tongue. I've seen lots of recommendations
of 5-10%, mine is 5% and OK.


--
Chuck Tribolet

http://www.almaden.ibm.com/cs/people/triblet

Silicon Valley: STILL the best day job in the world.


"Gary Warner" wrote in message ...

Designing our trailer it looks like for our 22' boat we could have the
tongue as litle as 2' from the bow -- or 24' total rig. But we'ld like to
put the wheels (tandem) as far back as possible so less boat and
less weight is hanging out past the wheels. This should help
stability. SO, the longer the tongue, the furthur back we can
put the wheels. ~ Storage of the trailer is no problem and though
a longer rig makes tight manuvering harder I don't think we'll
have any major prolems with that.

So, any other problems with having a longer trailer tongue?

It is a great suggestion regarding adding lights to the extended tongue. I
never thought of the sideways "blind spot" due to an extended trailer
tongue. I added 3 feet onto my little trailer and do NOT have any lights
forward of the aft end of the boat. You've given me a project for the
weekend. .......thanks....

p.s. regarding an extended tongue making backing up "less
maneuverable"...yes, but, the longer the trailer/tongue, the BETTER the
trailer backs up. Think of an 18 wheeler backing up in Wal-Mart's parking
lot and think of you backing a short boat on a short trailer down a ramp. It
is true that the 18 wheeler needs MORE ROOM to maneuver ( and that is
probably exactly what you said) but I'll back down an 18 wheeler anytime
versus a 14 foot boat trailer. regards. RichG


"Chuck Tribolet" wrote in message
...
Everybody else seems to have gone off on the relative tongue weight.

Other factors:

A longer tongue will back up more stable, but be less maneuverable when
backing.

A longer tongue will help keep your truck out of the salt water.

With a long tongue, I'd consider adding trailer running lights under the
bow
somewhere. It can be a long way between the back of your truck and
the first running lights on the trailer. Several years ago, I damn near
center-punched a Corvette on a trailer with no lights between the back
of the truck and the back of the trailer. He came out of a blind side
street
on a rainy night, and it sure looked like just the tow vehicle. I got
all kinds
of sideways avoiding the trailer, no harm, no foul, but some running
lights
on the trailer would have kept my adrenaline level down. My Shorland'r
trailer has a long tongue from the factory, and I added running lights
under
the bow (there was already a set at the front of the trailer fenders).

Finally, several folks have said 10% on the tongue. I've seen lots of
recommendations
of 5-10%, mine is 5% and OK.


--
Chuck Tribolet

http://www.almaden.ibm.com/cs/people/triblet

Silicon Valley: STILL the best day job in the world.


"Gary Warner" wrote in message
...

Designing our trailer it looks like for our 22' boat we could have the
tongue as litle as 2' from the bow -- or 24' total rig. But we'ld like
to
put the wheels (tandem) as far back as possible so less boat and
less weight is hanging out past the wheels. This should help
stability. SO, the longer the tongue, the furthur back we can
put the wheels. ~ Storage of the trailer is no problem and though
a longer rig makes tight manuvering harder I don't think we'll
have any major prolems with that.

So, any other problems with having a longer trailer tongue?

(Steven Shelikoff) wrote in message ...
On 10 Dec 2003 09:00:31 -0800, (basskisser) wrote:

K Smith wrote in message ...
Snafu wrote:
Gary, I'm not understanding the part about "the longer the tongue, the
furthur back we can put the wheels." To maintain the ~10% of the weight on
the hitch rule, increasing the tongue length works the opposite way.

Absolutely the longer the tongue (drawbar?) the further "forward" the
wheels will by to keep the balance right.

K

Once again, you've proven you stick your nose where it doesn't belong.
You certainly don't understand simple physics. If you make the tongue
longer, you will need to move the wheels BACK to keep the balance the
same. Say you have the tongue 10' from the wheels, and the tongue
weight is 100 pounds, to say, at that 10', you need to resist 100
pounds to lift the tongue. Now, we extend the tongue, to 15'. Now you
have a longer lever, thereby LESS tongue weight. To compensate, you
need to move the wheels BACK.

Tell ya what I'll do, I'm not going to give you the answer, but I'll
define a problem and let basskisser and Karen come up with solutions and
see if they come up with the same one, and then hack out their
differences.

Let's go with the situation above. Assume you have a trailer where the
distance from hitch to axle is 10' and the tongue weight is 100lbs.
Also, assume that the trailer is level because if it isn't, it will
affect the answer. Also assume that the tongue extension has a constant
weight per unit length.

Now increase the length of the tongue to 15' from axle to hitch. Just
from the difference in leverage, what is the new, lower weight on the
hitch?

Since we assumed that the extension has a linear weight/length, the
center of mass of the extension is 2.5' from the hitch and 12.5' from
the axle. So what percentage of the weight of the extension is
supported by the hitch?

Knowing the percentage of the weight of the extension that's supported
by the hitch, how much does the extension have to weigh to exactly
counteract the decrease in weight due to leverage and keep the weight on
the hitch at 100lbs?

If the extension weighs any more than the answer you come up with, then
you have to move the wheels forward to keep the weight 100lbs. Any
less, then you have to move the wheels back.

Bonus question: assume that the original level trailer with the 10' from
axle to hitch weighs 1000lbs and the hitch weight is 100lbs, or 10% of
the trailer weight. You extend the tongue by 5' using an extension that
weighs 10 lbs/ft. How far and in what direction do you have to move the
axle to keep the hitch weight 10% of the new trailer weight?

Have fun!

Steve

I know damn well what the outcome is. But, I don't have to show/prove
to you a damned thing. I solve baby **** like that on a daily basis.