Does anyone know of any software, web site, or formula that helps
determine how long a drawbar should be for a given trailer weight,
size, and axle positions?

Thanks in advance,
Dennis.

Does anyone know of any software, web site, or formula that helps
determine how long a drawbar should be for a given trailer weight,
size, and axle positions?

The correct term is 'ball mount'. There is a discussion about these
questions at:
http://www.timberman.com/RIG/trailer...omparisons.htm

Note that minimum 'ball mount' length has to be such that the tow and towed
vehicle will not collide during a maximum turn.

HTH

The welder who modified my power boat trailer into a sailboat trailer,
used a bathroom scale to see how long the trailer tongue had to be to
give a downward force of 200 pounds on the ball. He had to add 18
inches to the trailer tongue to get the rig to balance out but it was
really worth the effort and cost because the trailer & sailboat now
pull very well. The trailer tracks like it was on rails and the 18
inch addition means that, even in a very tight turn, the boat and tow
car never touch. In addition, the rig even backs much better than
previously.

I hope this helps.

Mike


wrote:
Does anyone know of any software, web site, or formula that helps
determine how long a drawbar should be for a given trailer weight,
size, and axle positions?

Thanks in advance,
Dennis.

wrote:
The welder who modified my power boat trailer into a sailboat trailer,
used a bathroom scale to see how long the trailer tongue had to be to
give a downward force of 200 pounds on the ball. He had to add 18
inches to the trailer tongue to get the rig to balance out but it was
really worth the effort and cost because the trailer & sailboat now
pull very well. The trailer tracks like it was on rails and the 18
inch addition means that, even in a very tight turn, the boat and tow
car never touch. In addition, the rig even backs much better than
previously.

I hope this helps.

Mike



Another advantage... you can back the trailer that much further into the
water without your tow vehicle wheels touching. Important for salt
water launching.

wrote:
The welder who modified my power boat trailer into a sailboat trailer,
used a bathroom scale to see how long the trailer tongue had to be to
give a downward force of 200 pounds on the ball.

Serious questions coming up: How does a power boat trailer differ from
a sailboat trailer; isn't the "downward force" known as "tongue weight;"
and why could not the boat (whether power or sail) be repositioned on
the trailer so as to provide the (presumably) requisite tongue weight
regardless of type of load?

I ask the latter because, first of all, I do have a (ski) boat and
trailer (which I might like to use for a different boat), and I also
have an open frame trailer set up to haul several four-wheel rail
"speeders" (one at a time of course, but of varying weights), and I have
simply created wheel chocks to be placed at appropriate points on the
trailer frame depending on which speeder I am towing, so as to assure a
tongue weight of 150 pounds.

Ken Harrison

I would assume that the boat couldn't be loaded forward enough to get the
proper tongue weight without adding length to the front of the trailer.

--
JerryD(upstateNY)

Serious questions coming up: How does a power boat trailer differ from a
sailboat trailer; isn't the "downward force" known as "tongue weight;" and
why could not the boat (whether power or sail) be repositioned on the
trailer so as to provide the (presumably) requisite tongue weight
regardless of type of load?

"JerryD\(upstateNY\)" wrote in
:

I would assume that the boat couldn't be loaded forward enough to get
the proper tongue weight without adding length to the front of the
trailer.


Hm.. I would have thought the opposite.
A longer tongue length inceases the cantalever leverage.
Therefore since the Sailboat does not have a heavy motor over the wheels,
or hanging off the back (if it was an outboard), you are now carrying more
weight in front of the axle making for a heavier tongue.
Extend the length out to increase the leverage and reduce the tongue
loading?

"Ken Harrison" wrote in message
news
wrote:
The welder who modified my power boat trailer into a sailboat trailer,
used a bathroom scale to see how long the trailer tongue had to be to
give a downward force of 200 pounds on the ball.

Serious questions coming up: How does a power boat trailer differ from a
sailboat trailer; isn't the "downward force" known as "tongue weight;" and
why could not the boat (whether power or sail) be repositioned on the
trailer so as to provide the (presumably) requisite tongue weight
regardless of type of load?

I ask the latter because, first of all, I do have a (ski) boat and trailer
(which I might like to use for a different boat), and I also have an open
frame trailer set up to haul several four-wheel rail "speeders" (one at a
time of course, but of varying weights), and I have simply created wheel
chocks to be placed at appropriate points on the trailer frame depending
on which speeder I am towing, so as to assure a tongue weight of 150
pounds.


Sounds like you've got the problem cured on your "speeder" trailer! However,
boat trailers aren't quite so conducive to moving the weight around.
Difference between motor and sail(boat) trailers . . often the sail
trailer carries the boat much higher to account for a weighted keel. Doing a
complete rebuild of a trailer such as converting sail/motor you can do some
tongue weight shift in the design, but a longer tongue might be the more
practical way, plus giving you the advantage of the longer tongue.
To the guy who says his boat trailer tracks better and is "easier to
back" with the longer tongue . . absolutely! Many yrs. as an OTR driver
teaches you that a 48' trailer backs much nicer than a 45', and a 53' is
better yet. Never tried one of those 28-30' "pups" but know from talking to
others they are a "bi*ch" to back up.

--
Nahmie
The only road to success is always under construction.

Norman D. Crow wrote:

trailer carries the boat much higher to account for a weighted keel.
Doing a complete rebuild of a trailer such as converting sail/motor
you can do some tongue weight shift in the design, but a longer
tongue might be the more practical way, plus giving you the
advantage
of the longer tongue. To the guy who says his boat trailer tracks
better and is "easier to back" with the longer tongue . .
absolutely! Many yrs. as an OTR
driver teaches you that a 48' trailer backs much nicer than a 45',
and a 53' is better yet. Never tried one of those 28-30' "pups" but
know from talking to others they are a "bi*ch" to back up.

I can attest to the fact that the 28' OTR trailers are a "bi*ch" to
back, UNLESS it's with a "yard jocker".

Tom J

Lengthening the trailer tongue is a different matter from lengthening the
distance from the ball on the ball mount to the tow vehicle.

In the former, the center of gravity of the boat/trailer is farther from the
center of gravity of the tow vehicle, but that by itself doesn't make much
difference in towing and handling (all else being equal).

However, if the distance from the tow vehicle to the ball mount is longer,
any sway in the trailer has much more of an effect on the handling of the
tow vehicle. Think of a lever and fulcrum. The longer the lever from the
fulcrum, the more movements are magnified.

Common lengths, from the hitch pin hole to the ball hole, are around 8
inches, with the longest I have commonly seen about 11 inches (and the
shortest something like 6 inches). Not all hitches have the same distance
from the back end of the hitch to the end of the vewhicle (bumper...), and,
of course, not all vehicles have the same distance from the center of
gravity or the rear axle to the hitch. Therefore, I would imagine that the
length of the ball mount in the ranges commonly available will not have much
effect on towing. The most important factor is probably tight turns, with
the trailer not running into the tow vehicle (pretty hard to do with a
standard pop-up configuration!).

Note that there are hitch ball mount 'extenders' available in lengths up to
18". These usually state in the fine print that the maximum towed weight
should be reduced by 1/3 if using these, and I would also imagine that any
sway in the trailer could be dangerously amplified.

The welder who modified my power boat trailer into a sailboat trailer,
used a bathroom scale to see how long the trailer tongue had to be to
give a downward force of 200 pounds on the ball. He had to add 18
inches to the trailer tongue to get the rig to balance out but it was
really worth the effort and cost because the trailer & sailboat now
pull very well. The trailer tracks like it was on rails and the 18
inch addition means that, even in a very tight turn, the boat and tow
car never touch. In addition, the rig even backs much better than
previously.