"Tinkerntom" wrote in message
oups.com...
Hey Wilf, You never said that I can find, what sort of roof rack do you
have? Is it a Commercial unit? If so, most of them have some sort of
extender system already made. No point in reinventing the wheel.

The problem with electrical conduit is two fold. First it is steel and
would begin to get nasty fast when exposed to salt water. Secondly, it
is designed to bend, which is great in some projects, but you would not
want it to decide to bend when you have the kayak on it and lifting
other end. It would result in a loud crash, and possibly a broken boat
or twisted back as you try to keep the loud crash from happening. Any
of these scenarios being bad.

I think you will also find that the commercial extender systems do not
extend as far as you are thinking like up to 28". So, though they use
extruded, hardened Aluminum, which is amazingly strong, they only go
out like maybe 15". Go out any further, and they don't bend, they break
right of, and you end up with a similar scenario as above.

So it may be time to go back to the drawing board! You might think in
terms of Titanium, and then you begin talking real money, though with
the aircraft industry up there, you may have a cheaper source!

What you need is a material that can take the extended end loading, you
might think of a fiber glass or Kevlar pole, which could be extended
out beyond the side of vehicle, and supported in the middle folcrum on
the roof gutter independent from the existing rack. This pole could
extend across the top of the vehicle and be attached for loading to the
other end of the rack. Think in terms of a teeter-totter, with one end
held down, and the other end sticking out beyond the side of your car.
The right material can carry a significant load.

The right material could even be just a clear of knots, straight
grained piece of Douglas Fir. A hand selected 2x4, from the local
lumber yard. Trees are subject to end loading by the wind, and are
incredibly strong.

When you are done loading your boat, the system will not fold up all
nice on top like a commercial unit would, but you could pull it and
place inside vehicle, or lash along side the kayak on top.

Now your car begins to look like a kayakers car should look. Check out
the pictures on Wilko's website, and you will get a better idea of
where this is headed. :-)

My only other suggestion also, is that when you lift the front end up
on the extension, that you tie a loop of rope around it to act as a
safety to keep it from slipping off the extension as you lift the back
end. this would be especially important if it is windy, or you are
parked on a slope, which could result in the front end sliding off or
deciding to take a lesson in "flying like a kite!" and you are holding
on to the little end of the kite.

I am sort of like a bull, when it comes to loading stuff as you know
(:-), and I just lift my 70 lb boat onto the top of my Caravan. One
time the wind caught the boat as I had it overhead and did a windvane
number on my back. I am re-thinking my loading procedure even as I
write this all to you. It is amazing how you get smarter each time you
try to break something. TnT


How about seeing if you can get a section of Schedule 40 pipe about 3ft long
by 1 1/2 to 2 inches and attach it to the rack (no rust). Then get a good
length of hardwood dowel that fits inside. It could be very loose fitting if
you have 3 ft of it inside the pipe. I'm thinking 1 1/2 inch OD pipe should
work great with a 1 inch or 1 1/4 inch dowel - like you buy to hang the
cloths up in your closet. Toss the dowel inside the car when done (if the
paddles fit, so will it). A dowel this size with 3 ft of support should hold
for most boats. I would think it would hold 100 lbs distributed across the 2
ft or so you have sticking out. -- Stress test away from the car - I don't
want to get blamed for a paint job after it breaks ;

The beauty of using wood is you should hear it start to fail before it lets
go. Unlike the conduit which may just fold-up without a sound.

Ken

No Spam wrote:
"Tinkerntom" wrote in message
oups.com...
Hey Wilf, You never said that I can find, what sort of roof rack do
you
have? Is it a Commercial unit? If so, most of them have some sort
of
extender system already made. No point in reinventing the wheel.

The problem with electrical conduit is two fold. First it is steel
and
would begin to get nasty fast when exposed to salt water. Secondly,
it
is designed to bend, which is great in some projects, but you would
not
want it to decide to bend when you have the kayak on it and lifting
other end. It would result in a loud crash, and possibly a broken
boat
or twisted back as you try to keep the loud crash from happening.
Any
of these scenarios being bad.

I think you will also find that the commercial extender systems do
not
extend as far as you are thinking like up to 28". So, though they
use
extruded, hardened Aluminum, which is amazingly strong, they only
go
out like maybe 15". Go out any further, and they don't bend, they
break
right of, and you end up with a similar scenario as above.

So it may be time to go back to the drawing board! You might think
in
terms of Titanium, and then you begin talking real money, though
with
the aircraft industry up there, you may have a cheaper source!

What you need is a material that can take the extended end loading,
you
might think of a fiber glass or Kevlar pole, which could be
extended
out beyond the side of vehicle, and supported in the middle folcrum
on
the roof gutter independent from the existing rack. This pole could
extend across the top of the vehicle and be attached for loading to
the
other end of the rack. Think in terms of a teeter-totter, with one
end
held down, and the other end sticking out beyond the side of your
car.
The right material can carry a significant load.

The right material could even be just a clear of knots, straight
grained piece of Douglas Fir. A hand selected 2x4, from the local
lumber yard. Trees are subject to end loading by the wind, and are
incredibly strong.

When you are done loading your boat, the system will not fold up
all
nice on top like a commercial unit would, but you could pull it and
place inside vehicle, or lash along side the kayak on top.

Now your car begins to look like a kayakers car should look. Check
out
the pictures on Wilko's website, and you will get a better idea of
where this is headed. :-)

My only other suggestion also, is that when you lift the front end
up
on the extension, that you tie a loop of rope around it to act as a
safety to keep it from slipping off the extension as you lift the
back
end. this would be especially important if it is windy, or you are
parked on a slope, which could result in the front end sliding off
or
deciding to take a lesson in "flying like a kite!" and you are
holding
on to the little end of the kite.

I am sort of like a bull, when it comes to loading stuff as you
know
(:-), and I just lift my 70 lb boat onto the top of my Caravan. One
time the wind caught the boat as I had it overhead and did a
windvane
number on my back. I am re-thinking my loading procedure even as I
write this all to you. It is amazing how you get smarter each time
you
try to break something. TnT


How about seeing if you can get a section of Schedule 40 pipe about
3ft long
by 1 1/2 to 2 inches and attach it to the rack (no rust). Then get a
good
length of hardwood dowel that fits inside. It could be very loose
fitting if
you have 3 ft of it inside the pipe. I'm thinking 1 1/2 inch OD pipe
should
work great with a 1 inch or 1 1/4 inch dowel - like you buy to hang
the
cloths up in your closet. Toss the dowel inside the car when done (if
the
paddles fit, so will it). A dowel this size with 3 ft of support
should hold
for most boats. I would think it would hold 100 lbs distributed
across the 2
ft or so you have sticking out. -- Stress test away from the car - I
don't
want to get blamed for a paint job after it breaks ;

The beauty of using wood is you should hear it start to fail before
it lets
go. Unlike the conduit which may just fold-up without a sound.

Ken

Ken, the only thing I would question, is that where the dowel comes out
of the pipe, would represent a sheer line. All the load on the extended
dowel would be concentrated at the sheer line as a breaking force. You
would not be able to take advantage really of the flex of the dowel
inside the tube, to dissipate the energy as a flexing force, and it
would tend to break at that sheer line.

You are right on though about hearing the dowel break.

Another function of the safety line that I recommended, is that if the
extension collapses, the boat would not fall clear to the ground.
Considering the car paint though, it might be equally important to use
some cushions in strategic spots in case the boat fell. You could just
hang a long noodle on the side of the car to take the bang.

or like Cyli indicated, you just don't worry about the paint! TnT

"Tinkerntom" wrote in message
oups.com...
Snip

Ken, the only thing I would question, is that where the dowel comes out
of the pipe, would represent a sheer line. All the load on the extended
dowel would be concentrated at the sheer line as a breaking force. You
would not be able to take advantage really of the flex of the dowel
inside the tube, to dissipate the energy as a flexing force, and it
would tend to break at that sheer line.

You are right on though about hearing the dowel break.

Another function of the safety line that I recommended, is that if the
extension collapses, the boat would not fall clear to the ground.
Considering the car paint though, it might be equally important to use
some cushions in strategic spots in case the boat fell. You could just
hang a long noodle on the side of the car to take the bang.

or like Cyli indicated, you just don't worry about the paint! TnT


You are correct about the shear at the point of entry but I think a hardwood
dowel of this size will take this force without complaint. My uncle used to
hang an old wood extension ladder on dowel pegs and it took 2 people to lift
that thing down. The flex in the exposed dowel would take the force of the
jolt of rough handling of the boat though. I did some google searching but
cannot find the shear strength of a dowel but I would guess that a 1 inch
hardwood dowel would take at least 500 pounds of pure shear force before it
would break. I have a 1 1/2 inch dowel here and I just stood on the end of
it with the other end wedged under my work bench -- yep lifted the bench
right up - the dowel flexed a little but easily handled me 275 lbs out about
a foot from the support.

Ken

No Spam wrote:
"Tinkerntom" wrote in message
oups.com...
Snip

Ken, the only thing I would question, is that where the dowel comes
out
of the pipe, would represent a sheer line. All the load on the
extended
dowel would be concentrated at the sheer line as a breaking force.
You
would not be able to take advantage really of the flex of the dowel
inside the tube, to dissipate the energy as a flexing force, and it
would tend to break at that sheer line.

You are right on though about hearing the dowel break.

Another function of the safety line that I recommended, is that if
the
extension collapses, the boat would not fall clear to the ground.
Considering the car paint though, it might be equally important to
use
some cushions in strategic spots in case the boat fell. You could
just
hang a long noodle on the side of the car to take the bang.

or like Cyli indicated, you just don't worry about the paint!
TnT


You are correct about the shear at the point of entry but I think a
hardwood
dowel of this size will take this force without complaint. My uncle
used to
hang an old wood extension ladder on dowel pegs and it took 2 people
to lift
that thing down. The flex in the exposed dowel would take the force
of the
jolt of rough handling of the boat though. I did some google
searching but
cannot find the shear strength of a dowel but I would guess that a 1
inch
hardwood dowel would take at least 500 pounds of pure shear force
before it
would break. I have a 1 1/2 inch dowel here and I just stood on the
end of
it with the other end wedged under my work bench -- yep lifted the
bench
right up - the dowel flexed a little but easily handled me 275 lbs
out about
a foot from the support.

Ken

Ken, Wilf, is talking about extending the dowel out 28", see what
loading the dowel breaks under now. This will prevent Wilf from falling
off his workbench, and you seemed more inclined to do this sort of
stuff! I mean testing, not falling off your bench! TnT

Tink says:
===========
Ken, Wilf, is talking about extending the dowel out 28", see what
loading the dowel breaks under now. This will prevent Wilf from falling
off his workbench, and you seemed more inclined to do this sort of
stuff! I mean testing, not falling off your bench! TnT
==============

I'm with you on this Tink -- as far as a 275 pound guy is concerned.
The question is, as you point out, what happens when the dowel is
extended out 28" and approx 50 pounds is placed essentially at the 14"
mark (although, what with twisting and turning, the full 50 pounds
could, momentarily anyway, be way out there at the 28" mark)?

Tink, you mentioned that you're an electrician: do you think 50 pounds
could bend the larger diameter conduit?

Cheers,
Wilf

BCITORGB wrote:
Tink says:
===========
Ken, Wilf, is talking about extending the dowel out 28", see what
loading the dowel breaks under now. This will prevent Wilf from
falling
off his workbench, and you seemed more inclined to do this sort of
stuff! I mean testing, not falling off your bench! TnT
==============

I'm with you on this Tink -- as far as a 275 pound guy is concerned.
The question is, as you point out, what happens when the dowel is
extended out 28" and approx 50 pounds is placed essentially at the
14"
mark (although, what with twisting and turning, the full 50 pounds
could, momentarily anyway, be way out there at the 28" mark)?

Tink, you mentioned that you're an electrician: do you think 50
pounds
could bend the larger diameter conduit?

Cheers,
Wilf

Wilf, you say you are with me on this, do mean the testing, or falling
off the workbench?

I am not sure what you mean by large diameter. We bend conduit all the
time with bending tools up to 1". Beyond that we have hydralic benders.
This is mainly to provide a standard radius that the wire can be pulled
through inside. Otherwise if you were to take the conduit, and bend it
over a sharp edge, as soon as the radius of the tube is broken, the
tube will easily collapse. There is a certain structural strength to
the tube, but once it is compromised, the tube material is pretty soft
and malleable.

One person that you might check with, is Michael Daly. Recently I saw
him post, that he is a structural engineer. He could probably give some
good suggestions on real data base. I mostly figure stuff off the seat
of my pants, hence the Tinker. My name is a double or triple entendo
(sp)! Given enough time, as a practical engineer, I can usually cobble
something together! Though it is the sort of stuff you might see on the
Red/Green Show.

I guess one thing I might ask you though, is how did you come up with
the 28" number? Also is your rack a commercial unit, or is it standard
Ford issue on Aerostar?

As you load the kayak, can you come in at a larger angle to get the bow
more up on the vehicle to start. That way the extension would not need
to be so long. You would then be standing further out from the vehicle
as you lift the stern, lift it higher so that the front does not get
pivoted off the front rack, and swing the stern up on the rear rack.

Also did you understand about the safety line, which should help keep
the bow in place. TnT

Tinkerntom wrote:
BCITORGB wrote:
Tink says:
===========
Ken, Wilf, is talking about extending the dowel out 28", see what
loading the dowel breaks under now. This will prevent Wilf from
falling
off his workbench, and you seemed more inclined to do this sort of
stuff! I mean testing, not falling off your bench! TnT
==============

I'm with you on this Tink -- as far as a 275 pound guy is
concerned.
The question is, as you point out, what happens when the dowel is
extended out 28" and approx 50 pounds is placed essentially at the
14"
mark (although, what with twisting and turning, the full 50 pounds
could, momentarily anyway, be way out there at the 28" mark)?

Tink, you mentioned that you're an electrician: do you think 50
pounds
could bend the larger diameter conduit?

Cheers,
Wilf

Wilf, you say you are with me on this, do mean the testing, or
falling
off the workbench?

I am not sure what you mean by large diameter. We bend conduit all
the
time with bending tools up to 1". Beyond that we have hydralic
benders.
This is mainly to provide a standard radius that the wire can be
pulled
through inside. Otherwise if you were to take the conduit, and bend
it
over a sharp edge, as soon as the radius of the tube is broken, the
tube will easily collapse. There is a certain structural strength to
the tube, but once it is compromised, the tube material is pretty
soft
and malleable.

One person that you might check with, is Michael Daly. Recently I saw
him post, that he is a structural engineer. He could probably give
some
good suggestions on real data base. I mostly figure stuff off the
seat
of my pants, hence the Tinker. My name is a double or triple entendo
(sp)! Given enough time, as a practical engineer, I can usually
cobble
something together! Though it is the sort of stuff you might see on
the
Red/Green Show.

I guess one thing I might ask you though, is how did you come up with
the 28" number? Also is your rack a commercial unit, or is it
standard
Ford issue on Aerostar?

As you load the kayak, can you come in at a larger angle to get the
bow
more up on the vehicle to start. That way the extension would not
need
to be so long. You would then be standing further out from the
vehicle
as you lift the stern, lift it higher so that the front does not get
pivoted off the front rack, and swing the stern up on the rear rack.

Also did you understand about the safety line, which should help keep
the bow in place. TnT

Sorry Wilf, I answered your second post before I saw the first, will
reread and get back to you later, TnT

Tink says:
=============
I am not sure what you mean by large diameter. We bend conduit all the
time with bending tools up to 1".
=================

Right, but even to bend 1" pipe, surely you use a "bending device" (my
family would disown me for that... both father and brother are
electricians and I spent a few summers as an electrician's helper, but
am a complete nerd about practical matters... so, I don't recall what
that fulcrum thingy is called). Anyway, I'm guessing that the larger
diameter pipes cannot be bent, readily, without mechanical assistance.
Hence my thought that, if a human can't readily bend it, a 100 pound
kayak is not likely to bend it either (even at 50 pounds times, let's
say, 30 inches). But, as I say, I'm not the electrician, I'm the geek.

Tink says:
================
My name is a double or triple entendo
(sp)! Given enough time, as a practical engineer, I can usually cobble
something together! Though it is the sort of stuff you might see on the
Red/Green Show.
===========

And you likely thought ALL Canadians were like Red Green, eh? GRIN

Cheers,
Wilf

"Tinkerntom" wrote in message
oups.com...

No Spam wrote:
"Tinkerntom" wrote in message
oups.com...
Snip

Ken, the only thing I would question, is that where the dowel comes
out
of the pipe, would represent a sheer line. All the load on the
extended
dowel would be concentrated at the sheer line as a breaking force.
You
would not be able to take advantage really of the flex of the dowel
inside the tube, to dissipate the energy as a flexing force, and it
would tend to break at that sheer line.

You are right on though about hearing the dowel break.

Another function of the safety line that I recommended, is that if
the
extension collapses, the boat would not fall clear to the ground.
Considering the car paint though, it might be equally important to
use
some cushions in strategic spots in case the boat fell. You could
just
hang a long noodle on the side of the car to take the bang.

or like Cyli indicated, you just don't worry about the paint!
TnT


You are correct about the shear at the point of entry but I think a
hardwood
dowel of this size will take this force without complaint. My uncle
used to
hang an old wood extension ladder on dowel pegs and it took 2 people
to lift
that thing down. The flex in the exposed dowel would take the force
of the
jolt of rough handling of the boat though. I did some google
searching but
cannot find the shear strength of a dowel but I would guess that a 1
inch
hardwood dowel would take at least 500 pounds of pure shear force
before it
would break. I have a 1 1/2 inch dowel here and I just stood on the
end of
it with the other end wedged under my work bench -- yep lifted the
bench
right up - the dowel flexed a little but easily handled me 275 lbs
out about
a foot from the support.

Ken

Ken, Wilf, is talking about extending the dowel out 28", see what
loading the dowel breaks under now. This will prevent Wilf from falling
off his workbench, and you seemed more inclined to do this sort of
stuff! I mean testing, not falling off your bench! TnT


Unfortunately I don't have enough dowel to anchor it and have 28 inches left
over or I would gladly give it a try - I've ended up on my backside in the
name of learning before. I think it would break if I were to put my full
weight at 28 inches out, but that is not what we are talking about when we
are loading a boat. You will have much less than half my weight and it will
be more distributed. At any rate I think the schedule 40 pipe on the car is
the ticket because it will not rust and it should hold just fine. The only
thing to do now is find something that fits inside it that will take the
weight. Get some conduit and some dowel and anything else that is lying
around and see what happens. Good luck.

Ken

Again, thanks to everyone for all your input.

While in the shower this morning, I had a flash of brilliance as my
father's words came back to me: "avoid moving parts whenever possible
and shun automation!". While this little project hardly concerns
automation, and not much in the way of moving parts, the general gist
of his admonition was KISS.

So, along those lines, I started thinking simple (and crude). Here's
what I'm going to try. Take a 8'-2X4 and place it across the front of
the van roof, by the front roofrack crossbar. Now lash it into place
along the crossbar. Now I should have about 3.5' of 2X4 jutting out
past the side of the van. While I know I'm an idiot in terms of things
practical and mechanical, but I can't see a 2X4 not holding up this
kayak. What do you guys think?

Then, when I'm done, the 2X4 stays up on the rack next to the kayak.

Are there any flaws in this crude version of an extension bar?

Cheers,
Wilf
==================