Hello
I am planning on building a pontoon single-person boat capable of
being disassembled and carried in the back seat and trunk of a
passenger car. The capacity needs to be 300 lbs and the deck will be
4x6 inches. FYI the unit will be powered by a low-power motor. I do
have a few questions:
1)Where can I get materials such as pipe or cylinders in plastic or
fiberglass (seeking 10-12 inch diameter)?
2) Is it necessarily unwieldy to have two pontoons on each side in
tandem? Longer than four feet may not fit my vehicle's interior.
3) Would an outrigger design be necessary to avoid toppling over of
the craft? It will be on freshwater only.
Thanks
Ken

Sounds like a fun project!

As long as you have you pontoons aligned, you shouldn't have any
problems. As far as material, you could go to Home Depot and look at
their PVC selection. They have some big stuff. A little heavy though.

Not sure I understand you decking. You mean 4 x 6 feet?

--
Matt Langenfeld
JEM Watercraft
http://jem.e-boat.net/

KA Turner wrote:
Hello
I am planning on building a pontoon single-person boat capable of
being disassembled and carried in the back seat and trunk of a
passenger car. The capacity needs to be 300 lbs and the deck will be
4x6 inches. FYI the unit will be powered by a low-power motor. I do
have a few questions:
1)Where can I get materials such as pipe or cylinders in plastic or
fiberglass (seeking 10-12 inch diameter)?
2) Is it necessarily unwieldy to have two pontoons on each side in
tandem? Longer than four feet may not fit my vehicle's interior.
3) Would an outrigger design be necessary to avoid toppling over of
the craft? It will be on freshwater only.
Thanks
Ken

KA Turner ) writes:

3) Would an outrigger design be necessary to avoid toppling over of
the craft? It will be on freshwater only.

If one pontoon can support your weight, and if each pontoon is under the
outer edge of the platform, it should be fine. It all depends on the
bouyancy of the pontoons. You want to be able to shift you weight enitrely
over one pontoon without having it sink very far into the water. You can
figure this out with geometry. Assume you know fresh water weighs 62.4 lb
per cu ft?

Interesting project.

Considered a larger folding platform?


--
------------------------------------------------------------------------------
William R Watt National Capital FreeNet Ottawa's free community network
homepage: www.ncf.ca/~ag384/top.htm
warning: non-freenet email must have "notspam" in subject or it's returned

1)Where can I get materials such as pipe or cylinders in plastic or
fiberglass (seeking 10-12 inch diameter)?

considered styrofoam wrapped in tough plastic or tyvek for light weight
pontoons? pontoons could be glued up from rigid closed cell house
insulation and shaped to reduce water resistance. could be extra protected
by wood stringers or longitudinal plywood midsection if desired.

--
------------------------------------------------------------------------------
William R Watt National Capital FreeNet Ottawa's free community network
homepage: www.ncf.ca/~ag384/top.htm
warning: non-freenet email must have "notspam" in subject or it's returned

KA
I built pontoons for a gold dredge a few years back but the style I used
could be refitted for your needs

Feel free to contact me privately and I'll draw you up a set of plans.

"KA Turner" wrote in message
om...

1)Where can I get materials such as pipe or cylinders in plastic or
fiberglass (seeking 10-12 inch diameter)?

wrote in message link.net...
KA
I built pontoons for a gold dredge a few years back but the style I used
could be refitted for your needs

Feel free to contact me privately and I'll draw you up a set of plans.

"KA Turner" wrote in message
om...

1)Where can I get materials such as pipe or cylinders in plastic or
fiberglass (seeking 10-12 inch diameter)?
As far as dimensions of the user platform I seek to have it 4x6 or I
can go 6x8 inches. Per the weight of water being 62.4 lbs how do I
figure buoyancy needed and use of materials?
Thanks
Ken

KA Turner ) writes:

As far as dimensions of the user platform I seek to have it 4x6 or I
can go 6x8 inches. Per the weight of water being 62.4 lbs how do I
figure buoyancy needed and use of materials?

for anything to float it has to displace a volume of the medium (water)
equal to its own weight. so if your boat and everything on it including
yourself weighs 250 lb it has to displace 250/62.4 or 4 cu ft of water.
therefore the volume of the pontoons below the surface has to be 4 cut ft
or 2 cu ft each. if the pontoon is circular in cross section the volume is
the cross sectional area immersed times the length of the pontoon. the
area of a chord of a circle is 0.5 x r x r x (angle - sine(angle)) where
"r" is the radius of the circle (pontoon) and "angle" is the angle at the
centre of the circle which subtends the arc, measured in radians. however
you really want each pontoon to support your weight alone so you can, say,
sit on the edge of the boat without it that side sinking. if you've ever
made log rafts as a boy you'll recall that when you walk to one side how
it goes down and the other side comes up as you slide off into the water.


you can also calculate how much pontoon surface is in contact with the
water for frictional drag by calculating the length of the arc submerged
as the radius times the angle in radians and multiply that by the length
of the pontoon. however if you are going to put the pontoons inside the
car they will be too short for the boat to go very fast. as the boat
approaches a speed of 1.34 times the square root of the length of the
pontoon (waterline length) the amount of power required to made it go any
faster rises exponentially with the speed. if you could carry the pontoons
on the roof of the car and make them 12 ft or longer the craft would
be more practical for a motor to push at a decent speed

as for the weight of materials you can weigh them yourself (as sheet of
1/4 inch plywood weighs anything from 17 to 23 lb in the kinds of wood
most boatbuilders use), or look the weights up in a boatbuiling book such
as the popular "Elements of Yacht Design" by Skene which is avaiable in
some public libraries. (Skene does not give weights of plywood)

for a pontoon boat everything except the pontoons will be above the
waterline so you don't have to worry about costly "marine" grade. just
make sure its "exterior" grade.

--
------------------------------------------------------------------------------
William R Watt National Capital FreeNet Ottawa's free community network
homepage: www.ncf.ca/~ag384/top.htm
warning: non-freenet email must have "notspam" in subject or it's returned

Mr. Watt et al :
I have the boat conceptual diagram posted on
http://kturnerga.tripod.com/boat.jpg

The main idea is to make the unit portable in a passenger vehicle.
Should this be a pipe dream I may have to wait until I buy the Ford
Explorer
Ken

(William R. Watt) wrote in message ...
KA Turner ) writes:

As far as dimensions of the user platform I seek to have it 4x6 or I
can go 6x8 inches. Per the weight of water being 62.4 lbs how do I
figure buoyancy needed and use of materials?

for anything to float it has to displace a volume of the medium (water)
equal to its own weight. so if your boat and everything on it including
yourself weighs 250 lb it has to displace 250/62.4 or 4 cu ft of water.
therefore the volume of the pontoons below the surface has to be 4 cut ft
or 2 cu ft each. if the pontoon is circular in cross section the volume is
the cross sectional area immersed times the length of the pontoon. the
area of a chord of a circle is 0.5 x r x r x (angle - sine(angle)) where
"r" is the radius of the circle (pontoon) and "angle" is the angle at the
centre of the circle which subtends the arc, measured in radians. however
you really want each pontoon to support your weight alone so you can, say,
sit on the edge of the boat without it that side sinking. if you've ever
made log rafts as a boy you'll recall that when you walk to one side how
it goes down and the other side comes up as you slide off into the water.


you can also calculate how much pontoon surface is in contact with the
water for frictional drag by calculating the length of the arc submerged
as the radius times the angle in radians and multiply that by the length
of the pontoon. however if you are going to put the pontoons inside the
car they will be too short for the boat to go very fast. as the boat
approaches a speed of 1.34 times the square root of the length of the
pontoon (waterline length) the amount of power required to made it go any
faster rises exponentially with the speed. if you could carry the pontoons
on the roof of the car and make them 12 ft or longer the craft would
be more practical for a motor to push at a decent speed

as for the weight of materials you can weigh them yourself (as sheet of
1/4 inch plywood weighs anything from 17 to 23 lb in the kinds of wood
most boatbuilders use), or look the weights up in a boatbuiling book such
as the popular "Elements of Yacht Design" by Skene which is avaiable in
some public libraries. (Skene does not give weights of plywood)

for a pontoon boat everything except the pontoons will be above the
waterline so you don't have to worry about costly "marine" grade. just
make sure its "exterior" grade.

Your diagram shows the two bullet-shaped pontoons on each side
arranged nose-to-tail. Why not place them tail-to-tail, butting against
each other, to present a tapered bow and stern to the water? For
that matter, you could add a barrel-shaped third section between
these two, to make the pontoon 10 or 12 feet long.

Alex

"KA Turner" wrote in message
om...
Mr. Watt et al :
I have the boat conceptual diagram posted on
http://kturnerga.tripod.com/boat.jpg

KA

Your plans are showing a 6 foot by 8 foot platform, but you are asking for a
6 inch by 8 inch.

As I said before, I have a set of plans that will do what you are wanting,
providing it is actually the 6 foot by 8 foot you are wanting to build.
Contact me privately and I'll get a set drawn up for you.


"KA Turner" wrote in message
om...
Mr. Watt et al :
I have the boat conceptual diagram posted on
http://kturnerga.tripod.com/boat.jpg

The main idea is to make the unit portable in a passenger vehicle.
Should this be a pipe dream I may have to wait until I buy the Ford
Explorer
Ken

(William R. Watt) wrote in message
...
KA Turner ) writes:

As far as dimensions of the user platform I seek to have it 4x6 or I
can go 6x8 inches. Per the weight of water being 62.4 lbs how do I
figure buoyancy needed and use of materials?

for anything to float it has to displace a volume of the medium (water)
equal to its own weight. so if your boat and everything on it including
yourself weighs 250 lb it has to displace 250/62.4 or 4 cu ft of water.
therefore the volume of the pontoons below the surface has to be 4 cut
ft
or 2 cu ft each. if the pontoon is circular in cross section the volume
is
the cross sectional area immersed times the length of the pontoon. the
area of a chord of a circle is 0.5 x r x r x (angle - sine(angle)) where
"r" is the radius of the circle (pontoon) and "angle" is the angle at
the
centre of the circle which subtends the arc, measured in radians.
however
you really want each pontoon to support your weight alone so you can,
say,
sit on the edge of the boat without it that side sinking. if you've ever
made log rafts as a boy you'll recall that when you walk to one side how
it goes down and the other side comes up as you slide off into the
water.


you can also calculate how much pontoon surface is in contact with the
water for frictional drag by calculating the length of the arc submerged
as the radius times the angle in radians and multiply that by the length
of the pontoon. however if you are going to put the pontoons inside the
car they will be too short for the boat to go very fast. as the boat
approaches a speed of 1.34 times the square root of the length of the
pontoon (waterline length) the amount of power required to made it go
any
faster rises exponentially with the speed. if you could carry the
pontoons
on the roof of the car and make them 12 ft or longer the craft would
be more practical for a motor to push at a decent speed

as for the weight of materials you can weigh them yourself (as sheet of
1/4 inch plywood weighs anything from 17 to 23 lb in the kinds of wood
most boatbuilders use), or look the weights up in a boatbuiling book
such
as the popular "Elements of Yacht Design" by Skene which is avaiable in
some public libraries. (Skene does not give weights of plywood)

for a pontoon boat everything except the pontoons will be above the
waterline so you don't have to worry about costly "marine" grade. just
make sure its "exterior" grade.