A culvert plug with a different function- 12 by 5 ft.

I wanted to share what is happening at JPW as a result of us making different kinds of inflatable culvert plugs.

Most of the time they are for plugging culverts that lead away from a drainage area around a chemical plant or a refinery. Workers will plug the culvert and pump chemicals or oil out of this basin to keep it from going into a water way. It is important to note that most of the time the basin drains into a river or wetland, and that most of the time there are no leaks. These are strictly for emergencies.

Sometimes they are designed to test spillways. Two similar to this were used to test the seal around the spillway at the Animas Laplata Project in SW Colorado. Special parts are put on them to help hold them in place, and special valves, hoses and valve placements are used to make them easier to use.

We even made them to plug vent holes and truck access in the Ekati Diamond Mine in Canada. Ekati produces 6% of the world’s Diamonds. A couple of our plugs were 14 feet in diameter, and one was a 23.5 ft arch with a screen instead of being all the way inflatable. It tied to the framework of the truck tunnel.

Last year we produced plugs that sat alongside of large cement and Iron Gates at a water facility in Detroit. This one required that water be used so the tubes did not float out.

This year it was a project to actually plug a square 12 X 5 ft. culvert while there was water in the culvert. Once again we decided that water would be used to keep the unit from floating out of the culvert. Buoyancy effect can be a very large force. This is the one I wanted to concentrate on because it has some different features that we have not done before, and because of its size.
box 12 ft by 5 ft with 8 in haunch
Faced with a decision to purchase our plugs or a metal gate that sealed off the water, our customer opted to try this idea. While we were talking we came to the realization that the buoyant force would work against us, so we devised a way to support the weight of the water by using pipe and Channels and tie them up to carry some of the water weight. This is in a tidal pool, and the weight of the water in the plug can make it act like a big water balloon, so the channel and pipe idea was a good one.
3 inch bulk head fittings were added to the chamber to help get water in and out.
big pic plug em
At the end of the design phase we were asked to put in an area where a 12 inch and a 6 inch pipe could fit at the bottom of the culvert. We used closed cell ethafoam to help seal the spot between the fabric and the pipes.
stress em

We decided to use 3 psi Pressure relief valves, but this did not work out well in the testing process. We believe that we had a geometry problem. There were 2 different hoops, and pressure overcame the small hoop and turned the fabric around the 12 inch pipe relief causing it to pop out rapidly, and it ripped. We fixed that, and went to a 1 psi pressure relief valve. We had an explosion. This is when we learned a lot about geometry vs air pressure.

One of the ideas was to have air pressure on top of the water that would help wedge the plug into its cavity. Math is important here. 12 ft. x 4 ft. with 1 psi (assuming some distance at the top for air pressure) puts 6912 lbs of force on the inside surface of that plug. Buoyant force would be 14,980 lbs. This is equal to the weight of the water inside the container, and is the displacement force if air were being used to inflate instead of water. In other words it would take something that weighs 14980 lbs to sink this thing full of air all the way into the water. This is also called displacement, because the weight of the water being displaced is equal to the weight on top of the inflatable forcing it down.

What about the Explosion: It was not a pretty thing. This 100 lb. unit flew up in the air and spun at least 180 if not 540 degrees. The energy released at 3 psi from such a massive inflatable destroyed 2 picture windows in our shop. I personally flew a number of feet and fortunately did not hit my head.
window em
We are going to be real careful in the future testing for pressure. We now know that hydrostatic pressure testing is a superior way to test for pressure because water cannot be compressed, and does not hole kenotic energy the same way that air does. However it would not have been practical to test this hydrostatically. It is just too large for our shop.

The plugs are still doing their work, and we will have an update on this project’s success or failure in the very near future.

Here are some pictures of the installation:
thread pipe em
threading the pipe that holds some of the water weight via the fabric channel
water and air em
adding water and toping it off with air pressure
12 and 6 in pipe in place em
6 inch and 12 inch pipes in place under the plug

Here is a pressure bag that we made for BYU. The university is trying to develope a light weight lift bag that can lift up 25,000 lbs, but is not too heavy. this one was 14 lbs with the web. We had strap failure because the thread in the sewing was not strong enough. It is interesting to note that in the video many of the straps were broken before the inflatable broke. This is a hydro static test.
last corner sew a
See the vieeo of destruction on you tube.

I calculated without the straps the nflatable would break at 10 psi. We have a new one on the way that they will test without the straps. They were trying to get to 50 psi. It is possible that with Vectran web, and the proper stitching, it will make it to that mark before breaking. They only need 25 psi to make it lift 25,000 lbs, but they needed a 200 % safety margin to pass the test. This whole thing exploded at 34 psi. We will keep you informed on how it worked.

without the straps this one exploded at 23 psi.

Thanks for reading this.

comments will be added if you email me directly info@jpwinc.com I am experiencing way too much spam, and have turned off the comment feature to eliminate the automatic spam.


Grand Canyon National park and the government shut down

I just wanted to thank David Uberuaga, GC NPS Superintendent for understanding, and mitigating the losses from the government shut down. Many of us in the river business are absolutely blown away by the policy to make the best of this nasty situation. I know that Grand Canyon Outfitters lost a lot of money at that time, and some of that is the money they would have used to purchase our products. The fact that those losses were mitigated in the best possible way, made it a lot easier for companies like mine to keep and gain their business this year. On top of that I go on private Grand Canyon trips every few years, and I shudder at the prospect of a government shutdown, if I was about to start my trip. The Grand Canyon National Park has put the best possible face on this shut down disaster by making the these offers.

The Big Deal:

It is a big deal that someone in government knows what this kind of thing does to individuals and businesses effected by a needless government shutdown. The Park may have had their hands tied when it came to closing down the park, but when it opened again, they used some innovative thinking to make a bad situation much better, even if they could not make it perfect.
For all of us who worked there and still work and play there, the Grand Canyon is a magic place. People from all over the world go there to see it, and I still think the best way is on the river looking up. To say it is majestic is just putting words on an undefinable emotion I have when I think about the place. I often go there in my mind when things get really hard. I owe my lifestyle to the place. It is still the place where I can be in the moment for the entire time I am there.

I just had a conversation with Monty at Oars, and he told me about customers from New Zealand, and Northern Canada that were already here in the USA when the Government shut down. Those people missed their once in a life time shot, and no amount of mitigation can bring back the experience that was yanked away from them by our careless government bickering. However many people are able to regain the experience that otherwise would have been lost to them thanks to the policy that was implemented after the shutdown.
It is my understanding that Outfitter companies that lost trips and money because of the shutdown were given more days in the 2014 season to mitigate these losses. This means that they will be able to recover some and possibly a majority of the loss that they experienced because of the shutdown.

Private boaters were given a choice of days that they could take in 2014 or 2015.

I may not have this exactly correct, so I invite comments on this, but the bottom line here is that everyone appreciated this attitude, and the idea that our managing agency has put their best foot forward on making the best out of a nasty situation that was none of their doing. This is beyond admirable, it is spectacular, and it is why I am proud to be a citizen of this country.
Thanks to David Uberuaga, and the GC NPS for thinking about how to be the best partners they could possibly be.

Jack Kloepfer
Jack’s Plastic Welding

Big Environmental issues:

Here is a project that has come back to us for a second round.  Ken Calderia is a climate Scientist, and he studies the effect of atmospheric CO2 on coral reefs.

antacid tank2

This link is to an NPR article (written and audio) about what he is doing on the Great Barrier Reef In Australia, and also about what we made for him that helps him test his theory.    The yellow inflatable you see in this picture is a light weight tank that floats in the water, and it is a place where Antacid is mixed to spread over Coral reefs.  Hear or read the story here at this link.

NPR All Things Considered:  http://www.npr.org/2013/04/22/176344300/this-scientist-aims-high-to-save-the-worlds-coral-reefs  (broadcast 22 April 2013)

floating tank in service

The floating storage tank in service.   Note the red antacid material on the reef behind

tank in the shop

unit in the shop

 Other Coral studies JPW was involved in 2002


USGS Clear Plastic Chamber for Ocean Water Chemistry Studies
Nathan Smiley form the USGS in Florida commissioned us to build something we have never done before. To do this work we had to re think our process so we could weld unsupported vinyl film into a cataraft tube shape. The USGS be suspends this tube inflated with sea water under water for water quality analysis. We also built large clear tarps for the Sharq project. These studies will help find answers to why coral reefs are dieing world wide. This study is critical to our survival since 70% or more of our oxygen comes from healthy oceans. To learn more about the work that they do visit these web sites.


This is a picture of the new ring. Made of 20 oz urethane coated nylon. real tuff and light weight
new test tank ring


I recieved this email from a potential customer.   This is one of the most ambitious raft trips I have ever heard of.    If there is a cat that can do it, it is a JPW,  Read on to find out why. 

I was all prepared to pull the trigger on a set of Aire Leopard tubes when I started discussing my summer plans with Ellen Dela Cruz at a party a couple of weeks ago. She informed me that she is Jack’s cousin and told me that I really needed to contact Jack’s Plastic Welding before I purchased tubes. OK, so that’s what I’m doing. This summer, I’m planning a trip down the Liard River (class III/IV, sand bars, floating trees) in the Northwest Territories, Canada. From the Liard, I’ll take the Mackenzie River (class I) to Tuktoyaktuk on the Beaufort Sea. My plan is to float/row the Liard, but when I get to the Mackenzie, I’m going to deploy sails, leeboards, and a rudder and sail down river. When there is no wind, I’ll row. The trip should take less than 6 weeks, but I’ll load on feed for 8. 

 I own a 72″ x120″ NRS Fat Cat frame and am modifying it to accept sails, leeboards, sleeping cockpit, etc. In looking at your offerings, it occurs to me that an El Tigre (17′x28″ blunt) might  suit my needs and the longer waterline will probably improve sailing performance when beating into the wind in waves. If the tubes really weigh 45 lbs as spec’d, the might even pass airline baggage without a penalty. Any thoughts that you care to share regarding the relative suitability of the El Tigre would be much appreciated.

This is the reason why you should consider using our catarafts 

There is another option to that is made in the USA…..  JPW Catarafts.  and in particular the Eltigre models

lighter because thy do not have a bladder, or extra coatings.  They Fold up smaller because they do not have extra coating on the surface, that can make them too stiff to roll easily.  they are made with fabric specifically made for inflatable boats.   This results in lower maintenance, and storage issues.  There is no bladder to remove and dry out at the end of the season, and it folds up into a small package to take up less space in your garage.  Simply store it away from rodents after washing off the PB and jelly from the past year. Our warranty is good for 10 years, we have boats on the water that were made in 1988.  We do not have a no question warranty.  But instead we like to educate our customers.   This is one reason why we have so few warranty issues with our boats.

I like the NRS frame.  We used it to take cats across lake powell twice in 2012, under solar power,  Once with daddy cat set and 2 cutthroats in tow, and once with an eltigre set with 1 more solar panel.  No gasoline or oars for that matter were used.  A extra long El tigre will be on the great Salt lake for the whole summer under solar power in the North arm.  This is an art adventure.  The water is pink from the brine shrimp eggs and salt.    There are abandoned oil wells up there and a sculpture of some kind out in the middle of Nowhere.    The project is a collaboration between Texas Tec, and the Univ of Chicago.   Other customers include the Alaska dept of wildlife, and Dave Jones Alpenglow lodge in Kodiak AK.  Our boats have been up in that neck of the woods before on numerous hunting trips.  look at some of the immages that are links in this blog.

I think the NRS frame is a good choice for setting up a mast situation.  Riley Dunn sailed our first 28 inch set of tubes around the Yucatan Penninsula in the early 90’s.  His frame was made of  speed rail.  Our friend Charlie took a Long 25 inch diameter set of tubes from above Minneapolis to Memphis Tennesee.  His frame was made of speed rail.  Our solar cat solar frame was made with speed rail, that is the same size as the NRS frame tubing.  Each year for the past 5 or so, I have at least 1 customer talk to me about running the length of the Yukon.  But I am not certain that has really been done, but I would not doubt that one of our Alaska customers has.  We do sell a lot of tubes to gold miners in Nome who do placer mining in the Yukon Delta.  So we have a lot of experience with all of these issues.  Motors sails, and all kinds of things.


our cat tubes used to make an air boat.   Air boats West.


one of our larger cat tubes with a sophisticated sluice box for the Yukon river delta.


this cat went up the Escalante arm of lake powell in 70+ mph winds to pick up a pack cat trip.  I should write a blog about that experience.


Riley duns boat that sailed around the Yucatan (sorry I do not have a picture of the sail.


John snyders boat – home in Fiji.  This one does have a sail.


Charlies rig he used to go down the Mississippi from above Minneapolis to Memphis.


My insurance man told me never to do this again


A 36 in dia snout type rig in the lower grand canyon

So you can not get a better set of tubes for the weight, and the warranty, and the experience of the builders.  Besides we absolutely love the idea that you have an adventure like this with our tubes.

We once had a Kodiak bear bite the end of a cat tube off.  The owner had some vise grips and some glue and folded the end over and clamped it shut so he could get home.  You can not take guns to Canada, so Please learn all you can about the Grizzley up there.  We want to see you return safely.

I forgot to tell you about our tubes goint to the summit of Greenland, and to the south pole.  Serious duty.  We learned a lot about cold weather.


My favorite setup for the grand canyon the produce rig.


Std Eltigre in Lava falls mowing down the V wave


Sam tucks hunting trip in Alaska somewhere. Note all the caribou horns

Kent Greens cataract canyon Super Eltigre.  Look at all the cargo and a fairly big motor.

Texas tec tubes with 30 ft of water line.  Longest cat yet.  These will be on the GSL all summer 2014 on a solar rig.


Finally this is the video add that the currents guys did for our boats .  You can see the solar rig at the end of it.  It is pretty cool.


Get us an order now and we can have your boat in about 4 weeks.  And we can customize it to make it work the best for your situation.  Go to this site if you would like to do that.


We already have 28 and 30 inch eltire cat designs in 12.5, 15, 20, and 30 ft waterlines,  for unbelievable cargo capacity.  The one above could easily take 2 of the NRS frames you are talking about.

One last thing.  We removed the last 18 inches of tube that did not do anything.  Now you can aim for the cliff and get bounce from the end of your tubes.  More capacity, less length.

If you want to know more about us, you may see some of the interesting projects we make by going to our news letter web site.  Jacks or better NEWS FROM THE WILD CARDS AT JPW

 A note from Carmie Hull… 

BTW, when pondering my cataraft options, I was initially concerned about

the wind resistance of the blunted tubes on the El Tigre, so I began researching

the problem and discovered something surprising. The info below applies

to nosecones that are symmetric about the central axis of rotation of the tube,

so it doesn’t exactly apply to the nose of the El Tigre which curves off axis.

Also, the analysis applies only to low density fluids, like air (not water), and to

nosecones moving at less than the speed of sound. So as long as the nose of

a cataraft is floating above the surface of the water, the analysis is suitable.


It turns out that the drag coefficients for a pointed conical tip and for a spherically

rounded tip are the same and have the value of 1/2.


The drag coefficient for a parabolic nosecone is about 0.4


But, though it is no doubt well known to those who know it well, I was surprised to

find  that the drag coefficient for a conical nosecone with a flattened tip can have

a drag coefficient as low as 0.38. Better than the rounded, pointed, and even parabolic

nose shapes.


The optimal nosecone shape was first described by Isaac Newton in volume II of Principia 

Mathematica over 300 years ago. See Proposition XXXIV on page 327. I have to admit that I don’t really follow

his argument, but evidently most of his peers couldn’t either, correct though it was.




Solution of Newton’s nosecone problem using more cogent modern analytical techniques is provided

by C. Henry Edwards:




The analysis in the references above ignore the importance of laminar vs turbulent

airflow, vortex shedding, etc, etc, etc, … but I thought you might still find the results

interesting since they suggest another (surprising) benefit to the flat nose shape.


Best Regards,




February 12, 2014

Self bailing white water rafts

JPW self bailers in the Middle fork of the Salmon

Greetings blog readers. This is my frist attempt at blogging, and although I have been adding stuff to our web site (and unofficially blogging because of it) this medium is new to me, It is an interesting way to keep in touch with customers and let them know what is new. So Now I can send people to the blog. We ill see how this whole thing works.

I picked one of my favorite pictures from last year, and used that in the post.  You will probably see this again when I have content to add.  This is just a test for now.   Thank you for being patient with the new blogger.

How I think blogs work, and what I am going to try and do:

There is a lot of information that I have generated over the years, and I want to start putting some of that back in the blog format.  I like the search engine functionality of this, and it makes for a friendly way for people to get information from JPW and for me to reply back and still have many people following the thread.

We have been in business for 30 years now,   There is a lot of water under the bridge.  still things keep comming up over and over again.  I cover a lot of those things in our web site in these three areas.

The related information page

River stories page

Photo gallery

So for this reason you may find a lot f the same content that you have searched the web site to find.  What I realize is I have been blogging all along.  But without the use of a search engine, that makes the information harder to find.  This way I can simply send customers to the blog if there are some issues that I know are there.

I want to write about river trips that I have taken over the past few years, and what are the most significant things I have learned about boating, and myself.

I want to bring up things like maintenance issues, repair issues, how to fix your wet paco pad for instance.

We get a lot of customers who want boat repairs, when is it a good idea to not take that free boat from your friend.

Why we feel that our boats work better than the competition.

I want to blog on the environmental, industrial, medical, and space products that we make.

I want to show our customer from what ever persuasion, that we have a lot to offer, and this system will give you a chance to reply.    so there it is in a nut shell.  Lets see where it goes from here.

There may be times when I would like to have a private email conversation, and I hope I can figure out how to do that.  You can always contact me by going to the bottom of our web pages my email adress info will always be there.

One more note.  In the 90′s I was pretty sharp about the internet.  In the 2010′s I am not so sharp, and the mobile devices are harder for me to follow because i always have my computer with me, and can always do work from just about anywhere.  So I have not become mobile phone literate as computer literate.   I appreciate any feed back that I can get on this subject.

Thanks and I will see you all in the blogesphere.