Folding Kayaks Forum

This thread started as part of the "Homebuilt kayak durabilty and seaworthiness" thread, but as this
is now about building a new Sonnet inflatable / folder, I've decided to start a new thread.

viewtopic.php?f=27&t=2946 - "Homebuilt kayak durabilty and seaworthiness". Scroll down at the link to find the Sonnet skinning frame pics / text.

The Sonnet 16 in the "Inflatable Kayak Builders Manual" differs in a number of ways from the new Sonnet Combi. Most notable is the use of 3
sponsons per side vs 2 sponsons per side on the Sonnet 16, and nylon sponson sleeves vs glued PVC sleeves, This change necessitates
the use of 2 stringers per side on the Sonnet Combi vs 1 stringer per side on the Sonnet 16. The stringers are inserted lengthwise between
the sponsons and work in conjunction with the sponsons to provide shape and rigidity to the structure. Like the Sonnet 16, the side
stringers are free standing with no connection points to the stems for ease of assembly. I hesitate to call them chines as the sponsons are
the chines, as well as the gunwales.

..... The following is a description of making nylon sponson sleeves for the Sonnet Combi.

The sleeves are lightweight rip-stop nylon with a top and bottom section sewn together to create a D-shape for each 15' Folbot sponson.
The bottom section contains 3ea X 3.5" sections that are sewn to a top that has 3ea X 8" sections for a total individual sleeve circumference
of 11.5" to accommodate the 11" circumference sponsons. Between each individual sleeve are 3/4" wide flat sections that isolate the 3/4"
aluminum tubes. I made 4 ea X 93" sleeve sections for ease of sewing. 2 sections per side will hold the 15ft sponsons.
Sewn to the bottom sections are full length 6" wide 10oz PVC strips for glueing the sleeve to the inside of the hull .

Sonnet Combi "Sponson Sleeve" Pics ......

The yellow nylon bottom and red nylon top are sewn together along the lines draw on each section. This forms a "D" shape and allows the
bottom to lay flat against the inside of the hull. Before starting, I immersed sample 12" nylon squares repeatedly in water and measured
them again after drying each time. The coated yellow nylon ( Seattle Fabrics) showed no shrinkage, and the red ripstop nylon ( JoAnn Fabrics)
showed just a very slight amount. I oversized the sleeves slightly ( 1/2") to compensate for any shrinkage while in use.
.

Rita sews the sponson sleeves on her Pfaff. It took her about 12 hours to sew the sleeves, Some of that spent finding the right dimensions via sample sleeves.


The top of the 93" sleeve . A second sleeve (folded) is on the next table.


The bottom of the sleeve showing the 6" wide PVC glue strip (10oz). If not glued to the inside of the hull, it would be very difficult to position
the sponsons and aluminum tubes during assembly.


Sponsons inflated with 2ea X 93" sections butted together to form one full length sleeve.


Inflated full length sponson and sleeve. 186" sleeve and 180" sponson. The sleeves may be shortened if needed when attaching to the skin.
I haven't decided yet whether or not to sew the sleeve ends shut.


Inflated sponson showing bottom of sleeve / PVC glue strip.


2ea... 3/4" 6063-T832 aluminum stringers inserted between the sponsons. These, the 1" keel , and 3 cross brace tubes are the only hard
structure in the frame. There are no cross sections like those found in most folding kayak frames. During assembly, the inflated sponsons will
trap the side tubes (stringers) and they will not be visible.


This is a prototype , so there likely will be changes to the above as construction progresses. Building a prototype is very different than
following plans for a boat already developed from tried and tested materials and processes. The sponson sleeves are the sticking point for
this type construction. From here on in, it's all down hill

The aluminum Sonnet frame is much easier to build than the standard "Feathercraft style" frame on my other folders.

Next Time... Gluing in the sponsons and skinning the hull and stems.

Regards, Tom

Thanks for keeping us up to date. I'll be watching for more.

>

You must have some questions.... so go ahead and ask. Otherwise I'm talking only to myself ... and I do enough of that already

After the shop warms up, I may get started on the hull skin later today since it's too cold and snowy for a motorcycle ride.

I'm using a one sided PVC... meaning that although the vinyl coatings are on both sides of the woven polyester core, the majority is on the outside for greater protection. I've never used this type before. I've had it for several years, so I may as well give it a go.

Tom

Well, since you opened the door...

At first glance it appears that the red nylon top is being sewn to a yellow PVC coated bottom, and that would seem to be a logical way to go - although the weight might be ever so slightly more (but maybe not) there would be less work (one less layer to sew), material savings (the yellow ripstop), and I'll bet that sewing 2 layers of the ripstop together is challenging. It's loose and slippery and it seems like the PVC coated fabric would give the whole assembly stability and be easier to sew.

What thread was sued to sew ripstop to ripstop? Ripstop to PVC coated fabric?



I'll be in Miami in early Nov and will visit the TriVantage distribution center close to the airport (they are nationwide). They are reputed to have a large selection of fabrics at good prices and I expect to be buying for my own boat. The weave of the PVC coated fabric you use shows clearly in your photos. That somehow looks like it would be more vulnerable to flexion and abrasion wear over time than a smoother surface with more coating and finer weave substrate. I have some smooth surfaced scraps on hand that I used for awnings that lasted for many years in topical sun. Testing them, it is just barely possible to puncture with scissors a wide piece held tightly between two strong hands. No idea what oz weight it might be, but it's substantially lighter than truck traps - bought it in a marine supply store. Another sample on hand - even lighter - is a fabric used for gym/athletics mat covers, also fine weave substrate and very strong in the puncture test. Both are very good in abrasion tests - rubbing tightly stretched surface with scissor point. So, the question is, what do you suggest I look for in optimum fabric choice, other than the obvious?

I have plenty more questions about the Combi, but those are obviously premature so I'll give you a break. Thanks again for opening yourself to questions.

All sewing was done with Dabond Polyester thread V-69.
That seems to be your only real question

Tom

Tom, would the inside-out skin assembly work for any of the Sonnet models? How are the esthetics of the skin joints at the stems on the outside after making them only looking at the inside?

Hi Sean,

If I understand your question correctly, you are referring to this statement from the earlier Link....

"This time around however, the hull skin will first be placed wrong-side out on the skinning frame, and the sleeves attached before the skin
is turned right-side out for final trimming and gluing up of the stems.... In theory anyway."

Only the sponson / sleeves are attached with the skin inside out. Then it's turned right side out for gluing the stems as before.
I've not attached the sleeves this way before, but it seems like it might be a bit easier than on earlier Sonnets... This should work the same on any of the Sonnet's.

Tom

Hi Tom.
This way of connecting the sleeves crossed my mind many time when I worked on the Sonnet.
I use the Sonnet at open sea. It behave very well. From my Pintail I found that the over hang
of the stems is not an advantage. So I Shorted the stem (fore and aft). This gives a better speed
and better direction on following seas. To get good tension along the keel, I glued a pvc 3" pipes to the
top of the stems. The keel is connected with the insert to the pipes. Also the kayak is drained by the
pipes.

best regards.

how is the loading cap of the different sonnets???

Do you have photos you would be willing to post to show us the details of your boat?

The only downside to nylon sleeves is that a sewing machine is required, and someone skilled at
operating it.... One more variable to complicate matters. All glue and no sewing makes these boats
possible for more builders, and that's the bottom line. However, the nylon sleeves sure are lighter
and less bulky....

I like your caps idea. And since it's proven, I think I'll try that myself on the new Sonnet. Thanks.

Tom

Sonnet 14 - 175lbs

Sonnet 16 - 200lbs

Sonnet 17.5 - 260lbs

Sonnet Combi - 450+ lbs ... I hope

I like your caps idea. And since it's proven, I think I'll try that myself on the new Sonnet.

If you make pipes with outer threads for the cap, it will damage quit soon the threads
when you drain the water.
If you make an inner thread for a plug, it will last longer, but not too long.
Then you will go for a bottle of wine cork, but then the inner thread will not help.
The solution is to go direct for the cork and leave the pipe blank.

I've been busy all week cutting , splitting, and stacking firewood for this winter so Sonnet Combi progress
has suffered as a result. I did find time to cut most frame tubes, and rivet inserts.... so here's some pics
of the process. Tomorrow morning I'll be skinning the hull......


6ft X 3/4" 6063-T832 stringer tubes are marked at 36" for cutting. 4ea X 15ft stringers (60 ft) are required.


Cutting 7/8" X 7" sleeves. Tube cutters..... You get what you pay for !


Marking 3/4" stringers and 5/8" X 6" inserts for drilling and riveting


Drilling with a 1/8" bit for rivets.


1/8" diameter / Medium length aluminum rivets for attaching 5/8" inserts to 3/4" stringers


Keel tubes.... 1" keel with 7/8" X 8" inserts, 7/8" tapering to 3/4" stems, and 1 1/8" X 8" center sleeve


Side stringers ( 4ea. )....... 3/4" X 36" stringers. 5/8" X 6" inserts , and 7/8" X 7" center sleeves


Break time

Today I attached the sponson sleeves to the inside of the hull. Unlike earlier Sonnet's, this time I turned the skin inside out and placed it on the skinning frame and glued
the sleeves in place. Tomorrow, I'll turn the skin right side out, and glue the stems before removing the skin from the skinning frame, inserting the stringers, and adding the deck.

The outside temp was 22F this AM, so heating the shop to approximatly 75F for gluing required firing up the Jøtul. A cappuccino is a welcome addition on a cold morning
Once the skin is ready from prep and gluing, the stove is shut off, and all coals disposed of before proceeding due to the highly combustible nature of MEK and vinyl cement
if exposed to open fire or flame. An electric heater helps maintain the desired temperature.


The skin is trimmed 4" below the gunwales ( frame is upside down ). Tape is placed along the keel to maintain visual alignment while working.
The outline of the 6" wide PVC glue strips on the sponson sleeves is drawn on the hull ( skin is inside out). This section is centered exactly
between the chine and gunwale.


Prep the PVC glue strip and the hull with MEK. Allow to dry completely.


Brush on 2 coats of HH-66 vinyl cement to the PVC glue area on the hull and on the sleeves. I applied the glue to 1.5" at the top and 1.5" at the bottom on the 6" wide strip.
Allow the first coat to dry completely before applying the second coat.


Once the HH-66 is completely dry, lay the PVC strip of the sponson sleeves along the hull area marked for gluing. Use a heat gun to reactivate the glue
and apply hand pressure ( wear a glove) along the exposed black PVC strip.


Follow the same procedure along the bottom of the PVC strip. Both top and bottom are now glued in place. Repeat this for all four 7.5' sleeve sections.


This pic shows the openings for the sleeves. When the skin is turned right side out, sponsons inserted and inflated, the sponsons will fill the area between the gunwale
to the chine ( 11" ). Note the weave in the 18oz PVC skin (inside). The outside of the skin is quite smooth due to a greater concentration of PVC coating..... Tom