Replacing dodger plastic windows & PTFE thread info

[Seaworthy Lass]

I have been putting off replacing our dodger windows for nearly a year now, as I was a little daunted by the process.

I took the bull by the horns yesterday and thought I would share the procedure I used, as it went extremely well and was not difficult, as the old windows were not removed until the new ones were in place.

METHOD:

• If the existing windows have two rows of stitching then unpick the outer row. If not, skip the first three steps.

• Trim the existing plastic close to the inner row of stitches, cutting away a thin strip of old window around the entire perimeter.

• Remove all the old loose threads.

• Lay the dodger down so that the window being replaced is flat.

• Cut a piece of new window very roughly to size (no need to be accurate, just give a reasonable overlap)

• Stick down some 8mm wide double sided sailmakers sticky tape on the inner side of the Sunbrella close to the remaining row of stitching, but not overlapping the old window.

• Lay the new window over the old on the inside. Starting from one side peel back the covering on the tape a few cm. The covering will then stick out from between the flattened old and new windows and can slowly be pulled, revealing the outer sticky side. Keeping the new window smooth and flat, stick the edge down as you slowly peel back the tape in small portions.
Don't attempt to peel back the protective seal on all the tape in one hit, as it will be very difficult to stick the new window down smoothly.

• Sew through the new window and canvas just beyond the sticky tape. If you sew on the sticky tape, it is likely dirt will then eventually creep in a stick to it, creating an unsightly black line.
I used Tenara for its longevity with UV exposure (and I stitched over the rest of the old stitching on the dodger at the same time). Otherwise use heavy duty polyester eg V-138.

• Unpick the old inner row of stitching and the old window will fall out.

• Remove all the old loose threads.

• Stitch through the Sunbrella and new window along the line of old inner stitching.

• Trim the new window neatly a few mm from the outer row of stitching

Repeat for the rest of the windows.

It is a fairly foolproof, easy method .

SWL

[Jd1]

Did you have to take a portion of the dodger apart in order to get the material to lie flat? That is my biggest fear. I tried to have my dodger glass commercially replaced but was told that taking the dodger apart was a lot of work to do (and cost) considering the age of the dodger (guessing close to 10 years)
Thanks for your post !

[Sailor647]

Wow! Excellent job, well done! The finished product looks great!

To keep the new "glass" from turning yellow and cracking, we use IMar Strataglass Protective Cleaner. Cleaner and sunscreen in one. So far, so good.

[CS Cruiser]

Great job! Will put on the to do list.

[Jim Cate]

Nice one, SWL. Wish we had had your input 30 years ago when we did a similar job... 'cause we took out the old clears first. Big, big mistake!! A real learning process, it was!

Jim

[donradcliffe]

The key is leaving the old plastic in place so that the cloth keeps the proper spacing. I did things a little differently--sewed the new plastic over the old and then cut out the old plastic close to the stitching--I also did not use tape. It worked well and looked good, but next time I'll try SL's method.

[Seaworthy Lass]

Originally Posted by Jd1

Did you have to take a portion of the dodger apart in order to get the material to lie flat? That is my biggest fear. I tried to have my dodger glass commercially replaced but was told that taking the dodger apart was a lot of work to do (and cost) considering the age of the dodger (guessing close to 10 years)
Thanks for your post !

No, no need to take anything apart. The rest of the dodger will be all bunched up around the window you lay flat, but that doesn't matter.

If you can't get the whole window flat in one lot, then it wouldn't be a problem really either. As above, just tape the sticky all the way around, but don't peel the backing off. Then flatten out however much old window you can and stick the new bit down over the perimeter of this portion, peeling back the tape very slowly (again, as above). Then flatten down the rest of the old window and repeat.

The plastic is reasonably stiff and has no stretch, so the whole window doesnt need to be stuck down in one hit. Just each portion you are working with needs to be flattened.

If your dodger is 10 years old, then while you have it off, run over all the old stitching, as the old thread will be very weak by now and it is much easier doing this before it has disintegrated enough for the stitching to part. A dodger seam will split very rapidly once a few stitches fail, as it is under reasonable tension when stretched out.

SWL

[Seaworthy Lass]

Originally Posted by Sailor647

Wow! Excellent job, well done! The finished product looks great!

To keep the new "glass" from turning yellow and cracking, we use IMar Strataglass Protective Cleaner. Cleaner and sunscreen in one. So far, so good.

Thanks for the tip. I think our plastic deteriorated quicker than it should have due to my enthusiastic cleaning with houeshold products . Apart from cleanng sprays potentially damaging the plastic itself, they strip the impregnated UV protection.

I used only water and a soft cloth more recently, but it was too late .

SWL

[Seaworthy Lass]

Originally Posted by donradcliffe

The key is leaving the old plastic in place so that the cloth keeps the proper spacing. I did things a little differently--sewed the new plastic over the old and then cut out the old plastic close to the stitching--I also did not use tape. It worked well and looked good, but next time I'll try SL's method.

This is the method I had read about and it would be much easier, as there is no unpicking of old seams involved. It does trap a rim of old plastic under the new stitching though. In our case this had not only yellowed, but dirt had become trapped underneath, so the rim was unsightly.

Tape makes the job so much easier, as nothing is sliding around. It is magic stuff in this regard and the professional's "trick of the trade" with any canvas or sail work. I keep a few reels of different widths on board. It does not seem to deteriorate significantly with age.

SWL

[pesarsten]

Can you please tell me what materiel and thickness you used. I am going to have to follow in your footsteps soon.
Do you think I can hand sew this?

[barnakiel]

Two tricks (I imagine already mentioned):

- cut a small hole in the old plastic before you attach the new one (this helps lead scissors in later to cut the old plastic out),

- you may consider zigzagging if the old window was attached with straight stitch (this may help avoiding making to many holes too close to each other).

Another neat method is to build the first window smallish and then the next one is attached outside the perimeter over clean never stitched canvas.

Cheers,
b.

[Seaworthy Lass]

Originally Posted by pesarsten

Can you please tell me what materiel and thickness you used. I am going to have to follow in your footsteps soon.
Do you think I can hand sew this?

I used Crystal View 20 thou purchased from Kayospruce in the UK, replacing existing 0.5 mm thick vinyl. Kayospruce recommends 20 or 30 thou for sprayhoods. Crystal View is the better quality of the two rolled products they sell and only available in 20 or 80 thou. The cheaper one comes in 10, 20, 30 and 40 thou.

Our dodger folds right down, giving excellent airflow under the boom tent in summer, which limited the thickness that I could use. Anything greater than 30 thou should only be rolled.

If a dodger window is permanent or only loosely rolled, then I think Stataglass is the best product. This comes in sheets rather than on a roll and is pressed to give the best optical clarity. It apparently also has better durability and UV resistance.

Regarding hand sewing, it is not impossible, but would be a very slow arduous task. The vinyl cannot be penetrated easily by hand, so pliers and a solid palm would need to be used. You would need a LOT of time and patience. Two rows of stitching for our windows was about 16 m in total.

SWL

[Seaworthy Lass]

Originally Posted by barnakiel

Two tricks (I imagine already mentioned):

- cut a small hole in the old plastic before you attach the new one (this helps lead scissors in later to cut the old plastic out),

.....
Cheers,
b.

Hi B
The technique I used does not leave a rim of old window trapped between the new window and the Sunbrella. When the inner row of stitching is unpicked, the old window simply drops out and no cutting is required.

SWL

[Seaworthy Lass]

By the way, whatever materials you select, I suggest going for the best. It is false economy to do anything less, as the job is labour intensive. I think it took around five hours to replace the windows.

If thicker polyester thread is used (eg V-138), the thread will probably outlast the vinyl, depending on the type. Using V-92 polyester the life is probably less than or similar to the vinyl. However, the Sunbrella has a life expectancy higher than any polyester thread. It is costly and a PITA having to restitch seams that have parted or worst still have to dismantle the dodger, find a canvas worker and pay for the repair.

I suggest using Tenara for all your exterior sewing. The cost is about 5x higher than with polyester, but so little is spent on thread compared to Sunbrella and labour that it is not sensible to use an inferior thread. The middle weight Tenara that is roughly the weight of V-92 (the thinner of the two Sailrite currently sell) retails at around 7.4 cents per metre.

If you are outsourcing these jobs it is worth having some Tenara on board and asking the canvas worker to use it. I understand many do not stock it. The cost of the Tenara for our dodger window replacement was only around $3.

I struggled tremendously trying to use Tenara initially. Below are a few tips for working with Tenara (courtesy of Sailrite) that I found worked when using a Sailrite Ultrafeed. I just set up the machine and thread this way from the start now and the sewing is trouble free:

• Use a size 14 needle (16 max if needing to go through many layers) if using the V-92 equivalent weight. The Gore website suggests a size 18 needle.

• Rotate the needle about 20 degrees clockwise so that the long groove is further from you. The Sailrite booklet that comes with the machine says go clockwise, the website says anticlockwise. Just rotating the needle away from its normal position is obviously the key, unless they made an error on their website.

• Drop the needle slightly (a mm or so)

• Place the thread 2-3 metres from the machine to help avoid the thread kinking. Better still place the spool horizontally on a rod so that the thread comes off kink free. I find the latter is time consuming to set up without friction so don't bother now. When I first set up the thread I pass the thread through my fingers so that the kinks are at least removed for the first 3 metres and if the kinks are starting to appear near the machine I cut the thread and repeat this. It is a small thing to do to stop the thread constantly breaking.

One other thing, I find the top tension needs to be higher to hold the slippery thread. Sailrite say it should be looser . This bit is easy though. Before you start stitching just use a scrap bit of fabric and adjust the top tension so that the stitch tension is equal top and bottom. I have rarely had to fiddle with the bottom tension.

SWL

[OzClipper]

Neat and tidy job, what machine was used.