"Rod McInnis" wrote:


Anyway, my 170 or so lbs didn't change the tongue weight at all.

How far behind the blocks were you sitting?


I was sitting on the transom of the boat which is directly over the
farthest back part of the trailer. Maybe MY center of gravity was
in 6" or 8" or however big half my ass is? The blocks were at 7'


I am not sure I have the geometry right: Blocks are 7' forward of the
very
back. The base frame is 23.5 feet long, so there is 23.5 - 7 = 16.5 feet
of
frame ahead of the blocks. The tongue extends 3 feet beyond that, or a
total of 19.5 feet


Yes, that's it.


If you were sitting at the very, very back, then your weight would create
a
moment about the blocks of 7' x 170 lbs = 1190 ft-lbs. Due to its
leverage, the tongue will see this as 1190/19.5 = 61 pounds.

I would have expected that you would notice that. If you weren't all the
way to the back, or you did this when the blocks were farther back, then
the
difference would be much less.


I was all the way at the back, maybe in 6 or 8" or so. I'm also 90% certain
we
did this test when the blocks were at 7'. But everything is still there in
the shop
so I think I'll go down there tomorrow and double check because I too was
surpried that my weight didn't have any effect.


Another issue you should be aware of is the size of your blocks. If your
block is a 12"x12" you could be introducing a significant error in your
measurements. As the trailer flexes and the scale depresses the trailer
frame will rock forward on the blocks, which can shift the contact point
on
the block to the forward edge, effectively moving the pivot point forward
up
to 12 inches. This would make a huge difference.


Yes, the size of the blocks was about 7". I can see what you mean and think
I'll try it again. The axle that goes across (well, I guess we've
determined that
shouldn't really be called the axle - but I don't know what to call it)
ANYWAY
that tube is about 3" or so wide. So it seems to me using a 3" block would
be
about the same thing.


Rod,

Thanks VERY much for the comments and taking your time. I think some others
here know as much, but the way you explain it - and some of your
suggestions -
make sense to me.

Gary