The sponsoon sleeves, part two, and the pockets

After the banana shaped PVC I have to make the nylon parts. I make the nylon straight in stead of curved, the flexibility will allow the nylon to follow the curves.
Using permanent marker I set the distances between the lines I have to draw. I use a long and straight piece of wood as a ruler. It does not matter if it is slightly curved as long as you use the same part of the ruler for all lines. Main advantage of making straight nylon parts is that it is much less work when drawing.
I draw lines to cut the nylon, and lines to sew on. Make sure you draw the lines clearly so that they shine through the fabric, it is very practical when you are able to see the lines on both sides of the fabric.
The nylon I used was shorter than the sleeves, so I had to join two pieces:

After that I use pins to fix the nylon on the PVC. Start out with the two central lines, and after that the edges. When you start with the edges you have a problem with the centrelines: you wil not be able to check underneath the fabric if it is exactly in position. When pinning the edges, work from the middle towards the ends. Here the centreline and one edge are pinned.
I sew everything on my old and battered Vendomatic machine. My mother gave it to me years ago when she bought a shiny new one. But actually, for heavy type of work without fancy stitches this one is much better. It is very heavy, but cast iron stays forever. It is as old as I am (41), but still going strong.

The fabric I use is 64 gr/m2 Ripstop nylon for tents from ESVO, and the yarn is their polyester-cotton tent yarn. If you can get it, use a light colour for the nylon as it is easier to see the markes lines. Make sure you have sufficient yarn, I used a complete 125 meter bobbin only for he sleeves.

Sewing the sleeves done, it is now time to make the pockets for the ends of the side stringers. On the nylon the pockets can not be glued on, so I thought of a different solution.
First I stitch on an oversized rectangular piece of PVC near the end of the sleeves.
Then I cut this pattern:
Here the glue is on already, that causes the edges to come up. Now I put a piece of aluminium of 20 mm diameter on the PVC. I fold the lower flap over the aluminium, then two of the three little pieces around the end, then the big upper flap down and finally the last two small pieces. When you do this correctly you end up with this:
And seen from the backside:
No photograph of the completes sleeves yet, "Card full" said the camera.....

I put pockets on both bow and stern ends of the sleeves. Doing this I hope I can go without the straps that Tom uses on his boats. The staps are difficult to make as they have to be sewn onto the nylon.

The gluing of the pockets was the first real glueing I did. Before that I made a few test pieces. I use Helaplast glue, as I could not get HH-66 in the Netherlands. I tried various amounts of thinning and found out that with thinning the bond is better, probably because the layer of glue is thinner.
On flat surfaces it works very well to use a clothes iron in stead of a heat gun. The iron allows you to apply heat and pressure at the same moment.

The sponsoon sleeves, part one

I decided to use the new method of making sponsoon sleeves that Tom has developed for his new double. With this method the sleeves are for 1/3 made out of PVC, and for 2/3 out of ripstop nylon.
The method is lighter and might result in less wrinkles. Tom is ethousiastic about it, but his wife Rita does the sewing. As I am quite handy with the sewing machine I decided to give it a try.

Today I started out making the banana-shaped PVC parts for the sleeves. Here I use a different PVC, a quite supple grey version of about 500 gr/m2. Main advantage above the black stuff is that it is easy to mark. For sewing I need proper and clear lines to make the sleeves exactly the right dimensions.

The marked skin is put on table with the grey stuff on top of it. I tape both skin and grey PVC to the table to prevent any movement.
Then I carelfully roll back the grey PVC and put small marks at the locations of the tape markings on the skin. This way I copy both gunwhale and chine lines onto the grey PVC.

I add markings for the cutting and sewing lines.
Again the kids help, this time to connect the small marks with long black lines. Both want to help, and that usually results in conflicts or disaster. So I let them help in turns, and let the other one take photographs. Lots of them...


After cutting the banana looks like this:

A really nice fit.
Luckily the banashape proves to fit both left and right on the skin (or should I say port and star?). So I can use the first one as a template for the second one.
Some more drawing and cutting yield two nice antisymmetric sleeve bananas:


Ready for sewing. But first I have to make the nylon parts.

Starting the skin: the bottom part

A large roll of back PVC has been looking at me for weeks. Now it was time to unroll it.
Working with PVC requires a large flat table. And a large flat table requires a lot of space. So some serious ordening was necessary in the shed. All bicycles that are not used on a daily basis have been moved upstairs or hung from a wall. Four sawhorses together with two old hobby tables from our former house make a table of 0.8 x 4.3 meter. Five meter would have been better, but this should be OK.

First action is cutting a blank of approximately 5x1 meter, and marking the centerline with tape on both sides.
A disadvantage of the black material is that is is difficult to mark. The paper tape works nice, and a white pensil from the kids works somewhat. On light colours you can use permanent markers, on the black you hardly see those.

The blank is put onto the skinning frame, and clamped at bow and stern.

Using paper tape the gunwhales, chines, bow and stern are marked on the blank. Also the trim line is marked, 50 mm below the gunwhale.

Back on table the blank is trimmed to size.

For cutting I use Black and Decker elektrical scissors. That may seem lazy, but that is not the point. The elektrical scissors give you the possibility to cut the material hardly lifting it from the table and without any movement, so you can cut very precise. I started using these with carbon fibre, and for that it is a godsend as it prevents tearing out fibres. For PVC it works like a charm as well.

The final result.

The bottom tube

The bottom tube needs two bend an the ends. So I started looking for a half decent tube bender for 19 mm tubing. It proved nowhere to find. 15 mm was abtainable, for 40 euro's. And a 22 mm version for 100. Way to expensive to try.

So I dedided on a different approach. I delved into my scrap metal box and found a metal ring of about 100mm diameter. Using this and some wood I made a crude bending rig for use on the milling table.

It proved perfect on the first try. No kinking of the tube at all.

After that I had to turn down the inserts, as the tube sizes I work with do not have a sliding fit. I use 22x19mm, 19x16mm and 16x13mm for the frame. At the middle sleeve the 19 mm has to be turned down to about 18.7mm, and the inserts are turned from 16 mm to 15.7.
An insert.
Turning down the 19 mm tubing.
The middel connection, still without the sleeve.
The frame ready for skinning.

The skinning frame

Now I have got all materials the building really starts.
First the stations are drawn and sawed.Then the correct locations on the strongback get a block of pine.

The stations are screwed onto these blocks using small square pieces of wood. A piece of string and a buble level are used to align al stations correctly. I planned on using a laser, but the string was simpler.


Stringers (18x27 mm) are connected to obtain sufficient length. Gettings proper wood is difficult. The first wood I looked at was not nearly straight. The stringers I used now are straight, but two snapped wen bending the stringers.

Is stead of using HDPE snaps for the bottom tube I just changed the stations a little bit. I hope this will work OK.
Also I made the stations in such a way that the stringers fit in at the edges, this makes positioning of the stringers much easier, especially when working alone.