Author Archives: jpwinc

About jpwinc

President of Jack's Plastic Welding

Low water science trip on the Gila River- how to carry a lot of gear on little water.

Keith Gido from the biology department at Kansas State University contacted us this spring and asked us how one may get 200 lbs of gear down a river that is only carrying 50 cfs. We talked about using the Cutthroat as a gear vehicle and how one can “flintstone” down the river when there is very little water. In other words, one can stand up in the middle of the boat, and lift the boat and gear over the rocks, while still getting a relatively large gear load down the river. We added an extra foot of length to each boat to give more load capacity.

This is what Keith had to say about the boat and the trip:

The boats have been fantastic! The open bottom has been ideal for flintstoning in low to medium flows on the Gila River. The boats ride nice and high on the water with the extra foot we put on each tube. We are getting ready for another trip this sunday. Flows are higher than normal, so should be a hoot. Attached are a couple of photos from our low flow trips. Feel free to use them as you wish.

We’ll let you know if there are any failures, but at this point, only successes!

Flows were 45 – 50 cfs. It was nice in some spots but we had to drag the boats across rocks pretty much at every riffle. Don’t know the exact weight. I’m 200lbs, plus 100 lbs of gear, plus the frame.

Here are a couple of pictures. One shows how low the flow was when you look back upstream and see the second boat, and how much water there is in the river. The second picture shows the boats parked in an eddy, and how much gear they are carrying.

in the pool looking back up at 2nd boat em
all that gear em

The new D7 valve from Leafield

The new D7 valve from leafield is a most wonderful thing for inclusion in Drop stitch panels such as raft floors, and stand up paddle boards. One of the best features that is not included in this link, or a picture of it, is the screen that keeps drop stitch threads out of the way of the seal. The O ring and the sealing surface around the top that does not use the black ring of the C7 makes this fantastic.

I personally do not want to stop using the C7, because I like the way the seal works in normal applications, because I have not used the D7 without the screen. The screen does increase inflation and Deflation time slightly.

We are using the D7 on some of our Paco Pads for those customers who just cannot live without this kind of valve. Note that some of our pad competitors use leafield valves, and so when they request this, we use the D7 because of the shorter length of the valve nut, which is the part that goes on the inside that you can not see. We recommend the screen be removed, because when using it on a pad, it really does not inflate or deflate any faster with the screen in place. This image shows the valve with the screen in place, and alos shows the O ring.
d7 and screen em

So here are some images of the D7 at work in Drop stitch fabric.

With the O ring sealing system we are able to cut a smaller hole and slip the nut inside of the Drop stitch and clamp directly to the inside surface of the Drop stitch. This reduces the area and the dome effect where there is no drop stitch under the valve opening.
2014-05-10 19.02.59
2014-05-10 19.03.41
2014-05-10 19.02.20

Note that the back surface of the drop stitch is almost flat because of this application method. We still apply a backing to the valve sealing area, and we still seal the edge of that backing, as we always have. Sealing the edge reduces micro bubbling issues that happen at the edge of that backing material, regardless of the type of valve or the type of drop stitch that is used.

I think the engineers at Leafield have done a marvelous job with this. We can build drop stitch panels that hold air for incredible amounts of time, and they are stronger and more reliable than ever. Like this one.
curved ds floor


Rapid deployment emergency spill containment for big trucks.

Rapid deployment spill containments are one of the best ways to protect the environment and save money at the same time.
We have been making these for the local division of Baker Hughes (an oil and gas service company) for 5 years now. They have saved thousands of dollars by avoiding environmental cleanups. We are hoping that they will go companywide with this idea.
Please have a look at this demo video we put together.

We left some questions unanswered in the video, and so I am going to address them now.
Cost around 500.00 see the industrial price list for this 180 gal and a 300 gallon option.
Clean up of the spill containment will vary depending on the location, but in our area of the oil patch the cleanup costs about 120.00 and to re fit the unit for another round of duty will cost another 160.00. Therefore there is a little saving in using them twice or possibly 3 times. WORD OF CAUTION: If petroleum products are allowed to stay in contact with the coated fabric for a long period of time it can cause the fabric to become brittle. When we repack them, we may decide that they are now out of commission. Regardless the used spill containment must be cleaned by professionals who specialize in this sort of work. There is a bright side to all of this. 180 gallons of diesel or hydraulic fluid can be recovered. That alone can save enough money to make this all worthwhile.

We would also like to recommend that once the unit is deployed, that the spill not be left alone. In the unit there is a rapid CO2 inflation cartridge. That CO2 cylinder will not inflate the unit at -40 F, because that is the temp that CO2 turns solid. Hopefully there is a hot thermos of coffee nearby that will heat the cylinder up. It is possible that the plastic will actually crack at those cold temps. The alternative to not trying is a large environmental cost, so give it a go anyway. what do you have to loose. If that does not work, and there is compressed air on the rig, there is an alternate Schrader (tire valve) valve that can be used to inflate, or top off if necessary.

We also supply 2 absorbent snakes to help with the immediate area around the containment. These are there just in case there is some over flow or the containment is not perfectly level. The main idea is to keep fluids off the ground and minimize damage.

Inflation at altitude:
We have tested this fabric to very high pressures. We double seal all seams. We have calculated that these diameter tubes will burst above 50 psi. Yet the CO2 cylinder will put the unit at 6 psi in Aztec NM (5000 ft. elevation) and at 4 psi at sea level. We test inflation for 1 day before completing the system.
rapid d spill parts

This image shows the main parts of the containment. Top left corner is the inflatable manifold, (jerk to inflate pull tab) that serves as the inlet for the CO2. On the upper right are the handles used to place the inflatable under the leak. In the bottom right corner is a Schrader (tire) valve for emergency inflation if necessary, and for a backup. This is also how the unit is deflated. The tire stem is removed to allow the air to come out of the inflatable. At the bottom are 2 Snakes (absorbent material) that help soak up fluid that sloshes out of the containment, or for immediate catchment of diesel BEFORE it leaves the asphalt and gets into the ground.
packaged em

Containments in the bag ready to be picked up.
closure em
A close-up of the bag closure.
The original containment (note it only has 2 handles today) being filled with water so one can see how the skirt is pulled upward by the buoyant force of the inflatable.

The orriginal press release about this product, because I still may have forgotten something

The destruction test of a 33 inch diameter inflatable at 23 psi At Brigham Young University. No seams were destroyed. this was a hydrostatic test.

Remember to give us a call if you are interested. 1800 742 1904, or visit our main web site for more information – visit this web site for more environmental products from JPW

Thank you for reading this.

inflatable boat design- Animas Amazons, and Jack’s Plastic Welding INC

This Blog is about customer participation in designing a customized self-bailing whitewater raft. I have attempted to inject some humor and history into it, to make it easier to read thanks for indulging me. If you care to skip to the main points behind this article, please go to the first meeting.

designers em
Animas Amazons Design Team

Animas- Without a soul. As in “Rio de los Animas De perdida in pergatorio” the official name of the river that flows through Durango, Co and Aztec, NM. It was named by Escalante and Domingues, two Franciscan Spanish priests trying to find a better way to get from Santa Fe NM to Monterey CA in the late 1500’s. It means river of lost souls forever stuck in purgatory. It received that name when they came to Bakers Box, (link is a video of kayaks in the box**) and they could go no further. They abandoned hope of baptizing any more Natives that lived upstream. They turned to the west and found the Delores River (our lady of sorrows). These days, the Animas River has a lot of soul, and there is a lot of happiness generated around it. However that is another story. We have just shortened the name of the river to the Animas. That is how the Animas and Purgatory Ski resort got their names.

Amazons- a tribe of wild women – a matriarchal society- Women warriors. They would often cut off their right breast so they could throw the lance better. Legend has it that men were taken as slaves. I do not suppose that was too much fun for the men, but you know men may fantasize about such things anyway.

Put the two together -Animas Amazons- A wild tribe of women that have no souls. Once again the definitions do not fit the team. The team is instead a collection of local ladies that like rafting, and down river race competition. Most if not all have been customers for years, and Cody and her Father took a trip down the Nahanni River in N W territories Of Canada using our Culebra frameless catarafts (with break down row frames), last year. Stacey has paddled our Dragonfly raft in Westwater Canyon. There are a host of other connections to the group, because I do not know all the women. There are about 20 of them in the group.
On with the story- Why did we decide to create a down river racing raft? What knowledge to these ladies have that we can use to build a better boat, and is there a reason why Jack would put out so much energy to see a project finished?

We have been building customized Self bailing rafts since 1993. The first ones went to San Juan College in Farmington. In these past 20 years, we have learned a lot about raft design, and the largest lesson is that we do not have a handle on everything there is to know. Therefore knowledge from experience is valuable to us, and we want this product to be a floating advertisement to our ability to create what our customers want. We put that much energy into a product to see if it will work, but also to show that what we design is what you will get. It is that simple. This design was not easy. It has all the components that make a Self-bailer design difficult. Yet we pulled it off the first time, and to the exact specs that they required.

What knowledge do the Amazons have that would make them great boat designers?

In 2013 we had a 13 ft. boat that was returned because of shipping damage. The Amazons used this boat to race with. They called it white lightning, and they thought it was pretty good, but we all thought we could make one that was faster on the water. Their experience in racing, their experience with inflatable boats in General, and the fact that we could meet at my house and discuss this made them the obvious choice for a demonstration of capability. The fact that they are racing with our boat and promoting the design and racing experience are frosting on the cake. Please read about the 2013 experience. The Piedra River had some surprises for them.

What makes this boat unique?

I have been working on drop stitch inflatable floor designs since 1993, and with the addition of Inflatable Stand Up paddle boards, we have learned how to curve them. We know that one of the big problems with hull speed, in a self-bailing whitewater raft, are the ribs in the I beam floor, grommets, bail holes, and anything that resists the flow of water under the boat. The reality is that a non-bailer is usually faster on the water until it gets water inside. Before last year, drop stitch floors did not curve upward to fit inside of the bottom of the raft. Many rafts actually take in water at the bottom and hold it inside of the floor of the boat so they are heavier on the water. This makes them harder to accelerate. What we wanted to do was make a self-bailer that maximized the flow of the river under the raft, maximized the flotation of the self-bailing floor, and minimized the amount of water that was taken with the boat down river. Then I met with these ladies, we addressed those issues, and we added even more features.

The first Design meeting:

We had been talking about designing a new boat for the Amazons for about 6 months. I thought we had some production time coming up soon. I called a meeting to get ideas for the design. We took a serious look at the original boat (white lightning) that they used in 2013, and used it to discuss what should change and why.

Smooth floor design:

The smooth floor design was an idea that I was keen on from the beginning. White Lightning (the 2013 race boat) had about as smooth of a floor design as we could get at the time. But when that boat was built we did not know how to curve the drop stitch into the space properly, and I wanted to showcase that capability. The Amazons agreed with that proposal, but were concerned about the ability of the boat to bail fast enough. That is when we decided to have cutouts in the middle of the floor to enhance bailing.

Other floor performance issues:

We wanted to have the maximum amount of flotation from the drop stitch floor as possible. We know that a shallow draft can enhance speed. We also know that the boat needs to track well. So there were some tradeoffs. To increase floor flotation, we made the boat as wide as we thought possible, and we filled the entire cavity of the floor area with drop stitch floor to increase flotation. To increase tracking effect, we raised the floor as high as the floor on a dragon fly raft. Stacey had used one in Westwater canyon, and was impressed with the tracking and speed of that boat.
The floor fits very snuggly between the main tubes. So much so that we feel foot entrapment between the drop stitch floor, and the main tubes is not an issue. I want to follow up with the team at the end of the race season about this to see if there were any issues. However let it be known that we are not stuck on designs that use this concept, and we can build any kind of floor system that a customer would like. To us this seems to be the best of both worlds, and we welcome the opportunity to discuss this with anyone who would like to give us feedback on this design.

Wind resistance:

We tackled this performance issue by making the main tubes a small diameter of 19 inches. We also decided that a low kick would be beneficial, but that it would not be beneficial in big waves. The compromise was to give the boat an 8 inch kick, (white lightning had a 9 inch kick and 19 inch tubes) and to make it with tapered tubes to reduce the amount of kick on the end at the top, where the wind would effect it, but allow for the 8 inch kick on the bottom so the boat could get over the waves. The taper was not extreme because the team wanted the paddle captain to have a strong and wide enough seat in the stern. The main tube tapers from 19 inches to 15.5 inches at the bow and stern to accomplish these tradeoffs in design.

D ring and handle placement:

I know that chicken lines around the outside of rafts can present a problem for someone who wants to paddle, and especially when the line runs right under a paddlers butt. That is not comfortable. We designed the D rings low enough so that would not be an issue, but high enough so the ropes would be obtainable if someone needed to grab them. The Amazons wanted 3 handles on each side to make running starts to the water with the boat more efficient.

Foot Thwart design:

We finally talked about the original foot thwart design, and the team agreed that the 9.5 inch diameter tubes used on white lightning, made great foot holds. We then talked about placement, and we designed a tapered end tube in the very front to get the most comfort and support for the front paddlers. Adjustability for the other 3 foot thwarts was also another issue that was addressed.

We did not have a second face to face meeting:

With all of these issues, it may seem impossible that we did not meet again. However this is the power of Edrawings. I did the design, and I showed the team a number of Edrawing files that they could rotate around to visualize what we had accomplished in our first meeting. When they agreed that these concepts were sound, we moved on to the next step.

This is how it proceeded:

In the first meeting we agreed on what the general design concepts were. I designed these concepts into the computer model, and I explained some things about tapered tubes vs straight tubes kick and cargo, and in this case paddling capacity. We used the boat that they were familiar with (white lightning) to give a comparison to what they were accustom to and what the new design offered. I designed a cutout in the Drop stitch floor, and showed them how we would cover the bail slot to minimize foot entrapment issues. The design team was show a number of different edrawings or Jpegs that show the issues, and how we intended to deal with them, they were offered options to change things, but in fact we changed very little. We did add the tapered tube at the end for the foot thwart, and made 3 handles per side. The d ring placement may have been a small issue, but the overall look of the profile and top view and floor were accepted almost immediately.

I think it is important to note that with both raft designs the inflatable floor is removable. That means things can get under the floor. We have made it easy to clean under the floor. We also feel that having a removable floor will make maintenance easier. The inflatable floor on any self-bailing raft has usually been the first maintenance issue, and we wanted to make it easy to send this part back for repair if necessary.

System 6 Urethane:

One of our suppliers is Man of Rubber in Tennessee, and we wanted to try putting a urethane coating on the bottom of the raft to make it slicker in the water and add abrasion qualities we cannot get with PVC. We also thought that in the long run this would make the boat lighter than putting a 42 oz. double bottom on it. I talked the team into trying this out, and when put in those terms they all agreed to give it a go. Besides I had never used the product, and wanted to know how easy it would be so I could recommend it to my customers.
I found it easy to use, but did not expect to have it as thin as it first started out. The instructions were good, and I followed them carefully, and I received good results. We used a blue and red pigment to get a maroon bottom. We were shooting for purple, but I was unwilling to be too careful with the color and compromise the application. So I took the resulting color, and it was beautiful.

Now it is up to the team:

I asked the design team to be honest with me about this design. It is entirely possible that we all had some bad ideas and it will not work well, or some parts will work great while others will not. I asked the Amazons to give me good honest feedback, and I am confident that they will. Most importantly I hope they will all have fun in this competition.
Above all this is an attempt to prove that when we design something, that is what you will get, and we have a way of letting you know that is what you will get. The design technology is there for our customers to use. There may be a cost, but for some customers, that design cost may be worth it. That is what this experiment was all about. If the boat works well that is also frosting on the cake.

Images of the Design Process:
amz race boat side view with no tap comp

This first image shows the White lightning design, and the new boat “Blue Thunder” superimposed on top with a transparent feature so we can see the differences. One end is tapered only, and the other end is both tapered and not tapered to show the difference. On that end there are a lot of dimensions that explain the design with numbers.
amz race boat top view corner not tapered
This image shows a ¼ section that is not tapered so one can see the amount of space that the tapered design gives inside the front area.
amz race boat top view
This image shows the difference between White lightning, and Blue thunder so the team could get an idea of capacity from length and form taper. The Blue thunder tubes are the transparent main section only ones overlaying the solid color.
Assem1 end section
This image shows how the inflatable drop stitch floor fills the middle of the raft and actually puts pressure on the main tubes.
Assem1 long section
This image is a section view of the boat showing how the floor fits lengthwise in-between the end tapered tube sections
Assem1 show main bail holes
The floor cutaway section that exposes the middle bail holes for more rapid bailing
web spec foot thwart
The finished design with the tapered end foot thwart
compare 2
I laid the finished main tube model over the finished product to see how close I was able to get it. The camera is taking the photo from slightly above, and there is perspective in the camera shot (depth), but the accuracy of the design is there to see.
curved ds floor
Before the bottom “main” floor is installed the drop stitch floor is laid in place notice what a tight fit it really is. One can see the cutout in the drop stitch floor for enhanced bailing.
websep 3
A computer model of the ds floor in place and bail holes
web spec 4 curved ds 1
web spec 4 curved ds 2
The curved feature of the Drop Stitch floor is visible in these two images.
web specs1
Finished dimensions
on tundra em
Finished boat on top of the old tundra

Edrawings for those who would like to dive deeper: read about edrawings and how to use them at this site

Down load edrawings at this site

Then download this edrawing document to see the edrawing of the main tube superimposed on the whight lightning jpeg design.

You may also download the entire assembly of the boat by clicking to download this file.

There are interesting things you can do with the assembly file like move parts of the assembly around you can also zoom in and out and do section vies. A mouse with a scroll button is handy. These are probably computer only activities.

** Bakers Box should not be attempted by anyone but the most experienced kayakers who know what the risks are, and are in the best physical shape. JPW does not recommend it, and did not participate in any kayak trips through the box.
If there are any comments to this blog, you must email me at this email address. There is a lot of spam in blog comments and this is the way that I can keep it to a minimum.

What Cody from the Amazons says about the New Boat “blue thunder”


Blue Thunder is awesome! I took it down Browns last weekend at about 2,700 CFS and it ran great! (unfortunately I wasn’t able to take it down the Numbers or the Royal Gorge) The Amazons took it out today and again it was great!

Here what we noticed:
- It handles well in big waves. Even with the low profile in the front the boat wants to punch through waves. The raised floor seems to have a trampoline affect like water bounces out and/or the work you did on the floor makes it drain very quickly. Either way it’s good!
-It handles beautifully in wind! It was windy as hell in Brown’s and the boat moved quickly downstream. FYI- I was out with a guy named NIck (who has one of your White Lightening boats) and Blue Thunder was way faster than White LIghtening even with one fewer paddler. Some of that I’m sure was me guiding versus Nick, but I definitely think the boat wants to move.
-After loading a WL and then BT, BT is so much lighter!
-We love the mini thwart in the front! LOVE LOVE LOVE! Mia thinks we are going to start a new trend.
-Today we thought Blue Thunder handled a lot more like the Culebra than a traditional raft in that it really wants to keep turning once it has started. That might have been because the floor was a little soft or maybe it’s because the floor is raised. We’ll try again with a harder floor and get back to you. I do remember thinking how well it tracks this weekend.
-We are all interested to see what the extra width affects us. It kind of feels like there’s a dance floor in the middle of the boat!

We are going out again on Monday and will do a little experimenting with thwart placement. We might try the mini thwart in the back and put the third thwart in the front to try having the front paddlers’ weight more towards the center of the boat.

We all feel so incredibly privileged to paddle your amazing boats! This is such a cool process!

Many thanks and more feedback soon,
Cody & the Amazons

    Here is a nice sequence of the boat in Gore Canyon. Mostly a survival race from what the ladies told me.


San Juan River Clean Up trip on the San Juan River in Southern Utah- April 2014

April 5, 2014, a semi-sunny Saturday, 10 people in 6 boats launched from the Mexican Hat boat ramp on barely 500 c.f.s. of water, to spend the next eight days picking up trash along the San Juan river. Immediately we started to find some big trash stashes and the random tire. We made only 4 miles that first day, camping at the bottom end of Mendenhall Loop. During the trip we basically walked most of the shoreline; not only picking up trash but walking all the regular campsites, doing casual camp site assessments, looking at plant growth along the river corridor (both native and invasive) and marveling at the wildlife and beauty of the San Juan River corridor. All of the trip participants were experienced trash pickers, some having been doing these trips twice a year for 14 years.
jerry scouring
Jerry scouring the banks. (note the invasive Ravenna Grass and dead tammies)

With all that experience there were many discussions about the evolution in the trash we’re seeing along the river corridor. There are fewer and fewer glass bottles and not as many aluminum cans, but there’s been a big spike in the numbers of individual plastic water/drink bottles and there are still uncountable pieces of Styrofoam. The number of large appliances has decreased but the amount of tires seems to be stable. We had to leave a stash of 14 tires (and a washing machine agitator) below Ross camp for pickup during higher water in order to lighten some loads and make room for more bagged trash. We still ended up with 6 more tires by takeout!

Tim, Karen, Sue, Jerry

A big change over just the last several years is the invasion of weeds, in particular camel thorn, Russian thistle and Russian knapweed throughout the river corridor. Even in the most well used campsites the encroachment of these weeds is becoming serious. On the other hand the tamarisk have taken a big hit from the beetles and the willows are coming on strong.
As the week went on the water got lower and loads got bigger. by the time we got to Government rapid the river was in the mid or low 400′s. For the first time in my 34 years of running the San Juan we lined boats through Government. Our loads were so heavy and the water so low and the wrap potential so high…
in gvt

Mark and Tim in the water, Joan at the oars, Mary fending off and everyone else on bow or stern lines.

We had multiple bighorn sheep sightings, and discovered several deceased bighorn during our shore walks. Observations and locations will be in a separate report to the BLM. There were lots of geese (many nesting) but only a few great blue heron. Several peregrine falcons, cinnamon teal, hooded mergansers, mallards and one lone seagull were also sighted.
By the time we reached Slickhorn we could hold no more trash, the river had kept dropping and we were all dreading the sandbars below Grand Gulch. The sedimentation issue below Government Rapid is getting worse. Low water with big heavy boats is a real test of one’s river reading skills.
slick horn
Slickhorn B
k daddy
Karen zig zags between the sand bars

Note from Jack: In a jpw daddy cat. Karen must be behind the load.

We left Oljeto Wash on our last morning to even less water, we had to drag most of the boats out to find a channel. Despite the low water and multiple shallow water/sand bar drags we made pretty good time. As the canyon walls dropped away and Clay Hills Crossing came into view we were feeling a bit tired but pretty good till the last quarter mile. As we got closer to the takeout the channel kept moving left but the take out is on the right; we came aground about 40 yards of mudflat short of the takeout. There we were boats piled high with trash, a NPS dump truck parked above the cut bank waiting for us and 40 yards of mud between.
40 yds of mud

Fortunately a couple of guys from another trip helped us hump trash across the flats to the waiting dump truck. When it was all portaged across we had an overflowing truck and another pile stacked up for a second truck load!!
dump truck
Kenny wondering if he can drag his boat closer now that the trash is off it, as the NPS guys marvel at the amount of trash from only 6 boats.

It was a great trip, the weather was pretty kind to us, the pickins were good, the camaraderie was second to none, we ate well and even though it was a “work” trip, it was 8 days on the river in some of God’s most beautiful country.
Trip Participants: Sue Agranoff, Karen Carver, Mary Gillam, Tim Hunter, Doug Jacober, Mark Ott, Jerry and Joan Rohwer, Kenny and Patsy Smith.

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

water and air em
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.

Please read this article about pluging the side of the sluice gates at the water facility in Detroit MI.

Thanks for reading this.

comments will be added if you email me directly 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:  (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.