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Old 07-12-2020, 17:45   #1
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Silicone VS PVC Dorade Vent Cowling

I need to replace an old PCV Vent Cowling that has gotten sticky and can no longer be cleaned. I see several brands offering Silicone cowlings and am wondering if these are better or worse than the PVC ones. Any comments would be welcome.
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Old 07-12-2020, 18:21   #2
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Re: Silicone VS PVC Dorade Vent Cowling

My dorade vents are stainless steel, never get sticky, and are easy to clean. In a bad blow, I bet if I passed a chain through several of them, and had a long enough rode, they might work marginally well as an emergency anchor.
Probably could rig up a pretty wicked weapon with them to repel unwanted boarders too.
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Old 07-12-2020, 18:24   #3
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Re: Silicone VS PVC Dorade Vent Cowling

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Originally Posted by richardhc View Post
I need to replace an old PCV Vent Cowling that has gotten sticky and can no longer be cleaned. I see several brands offering Silicone cowlings and am wondering if these are better or worse than the PVC ones. Any comments would be welcome.
I replaced the sticky uncleanable pvc ones with chinesium stainless, all good years later.
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Old 07-12-2020, 18:42   #4
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Re: Silicone VS PVC Dorade Vent Cowling

The stainless vents do look nice but come with three problems:
1. the cost (Yipes!)
2. sharp edges should someone happen to fall or blunder into it during nasty weather at night.
3. if a sheetline accidentally captured the stainless one it would rip the dorade box right off the deck. Unless I added a stainless rope guard over it.

My other two PVC vents are still OK after 45 years but the one that went bad was a replacement from the original vent and has only lasted about 10 years.

I was just wondering about PVC vs Silicone constantly exposed to harsh tropical sunlight. I don't suppose the Silicone has been used in these conditions very long so probably there really isn't good comparison information.
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Old 08-12-2020, 09:39   #5
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Re: Silicone VS PVC Dorade Vent Cowling

I sourced a pair of SS low-profile cowl vents directly from China about two years ago. The workmanship, etc. is flawless. That's in a freshwater environment. I think my total costs, including shipping (which took less than two weeks), was under $C200 for both, including deck fittings and screw-in plates when the vents are removed. They were literally a drop-in replacement for my original PVC cowls. Feel free to contact me at kenpole2aticloud.com.
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Old 08-12-2020, 10:09   #6
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Re: Silicone VS PVC Dorade Vent Cowling

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Originally Posted by richardhc View Post
The stainless vents do look nice but come with three problems:
1. the cost (Yipes!)
2. sharp edges should someone happen to fall or blunder into it during nasty weather at night.
3. if a sheetline accidentally captured the stainless one it would rip the dorade box right off the deck. Unless I added a stainless rope guard over it.

My other two PVC vents are still OK after 45 years but the one that went bad was a replacement from the original vent and has only lasted about 10 years.

I was just wondering about PVC vs Silicone constantly exposed to harsh tropical sunlight. I don't suppose the Silicone has been used in these conditions very long so probably there really isn't good comparison information.
My SS dorade vents have generously rolled edges - nothing sharp to cut lines. I have had staysail sheets get fouled around them - albeit in light air - with no ill effects except some ozone charged air from cursing under my breath as I have to go forward to clear the sheet.
My original comment was intended to be facetious. The Chinesium replacement suggestion I will keep track of in case I get hit by a thermo-nuclear bomb. That might scratch my SS cowls.
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Old 08-12-2020, 11:32   #7
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Re: Silicone VS PVC Dorade Vent Cowling

Having worked for a company that makes silicones I declare my bias upfront.
Frankly I have not heard of a silicone vent so if you have a link please send it. As a sailor I have only seen PVC, with some ABS and also metal of course. To address your question, silicone has a much higher resistance to heat ( and cold) and will not degrade like PVC. Itís chemical resistance is very good. Typically it would be more flexible than a PVC vent unless it is some sort of silicone blend. I would expect it to be more expensive than PVC and cheaper than SS.
Hope this helps a little.
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Old 08-12-2020, 12:22   #8
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Re: Silicone VS PVC Dorade Vent Cowling

We replaced the 30year old Vetus PVC ones on our Swan with Vetus Silicone ones. They’re a bit softer but after 3 years in look like new, and fitted the existing mountings so it was a tool free operation. The Vetus silicone ones are very much cheaper than the PVC but unlike the PVC is fabricated with a visible mould seam. I’m very happy with them.
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Old 08-12-2020, 13:07   #9
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Re: Silicone VS PVC Dorade Vent Cowling

Cripes, we installed new Vetus dorades and PVC cowls 2 years ago and they look like crap. Very UV deteriorated. They were in the Caribbean sun all this time so maybe that did it.

If the silicone works as well and does not degrade like the PVC I am in.

Edit to add:

Never knew they were available in silicone.
For Vetus 4” vents using tbox dorade..
TOM is SS cowl
TOM2 is PVC cowl
CHINOOK is SILICONE cowl

I think! Vetus confuses me.

Looks like silicone is all Defender sells.
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Old 08-12-2020, 15:55   #10
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Re: Silicone VS PVC Dorade Vent Cowling

I just painted mine with a standard acrylic paint....my choice of colour too!
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Old 08-12-2020, 17:04   #11
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Re: Silicone VS PVC Dorade Vent Cowling

[QUOTE=hpeer;3292067]Cripes, we installed new Vetus dorades and PVC cowls 2 years ago and they look like crap. Very UV deteriorated. They were in the Caribbean sun all this time so maybe that did it.

Not the sun. We've used Nicro and Sea Dog PVC and they both lasted about 2 years here in BC. We tried waxing them every 6 months and it helped slow the deterioration a little.
I don't see any silicon replacements for standard Nicro cowels so I think we will paint them with plastic paint.
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Old 08-12-2020, 18:01   #12
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Re: Silicone VS PVC Dorade Vent Cowling

Or, if you have a classic boat, use bronze cowls. Mine are solid cast bronze and are indestructible, though not for lightweight boats. My dorades are sturdy teak construction and I have never worried about them either. Cowls of sheet (spun?) bronze are also available but not nearly as strong.

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Old 08-12-2020, 18:09   #13
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Re: Silicone VS PVC Dorade Vent Cowling

Pvc formulations changed in response to significant environmental and health problems with the older formulations.
Some chose to exit that business rather than make short lived products.
There may be formulations that survive better. I suspect the silicone cowls are part of that evolution.
If I were buying now I would buy stainless or bronze. But my boat is already a tank.
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Old 08-12-2020, 19:42   #14
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Re: Silicone VS PVC Dorade Vent Cowling

Your old cowl vents can easily be restored to as-new condition with some light sanding to key the surface and this https://www.duplicolor.com/product/v...abric-coating/
The results will amaze you and youíve only spent a little time and a few bucks.
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Old 09-12-2020, 06:39   #15
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Re: Silicone VS PVC Dorade Vent Cowling

Vetus Silicone Cowl Vents ➥ https://www.vetus.com/en/ventilation...ntilators.html
https://www.marineoutfitters.ca/inde...=8717372363535
https://www.marineoutfitters.ca/inde...=8717372363856
https://www.fisheriessupply.com/vetu...wl-ventilators
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