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Old 08-04-2008, 13:20   #76
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How do you define "high vacuum"?

You can use around 80% vacuum (200 mbar abs) to suck it in, but need to drop it to around 60% when it starts going off, otherwise it starts "boiling" and will create bubbles.
This is what I have seen when they infuse wind turbine blades, up to 60 metres long for 5 MW windturbines.

Big cat, is the use of antimony allowed, I know its pretty poisonous stuff, and not allowed in many applications? I would be very cautious of using it for water tanks without thorough checking.

Regards

Alan
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Old 08-04-2008, 13:24   #77
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Originally Posted by BigCat View Post
"epoxy makes our cats 20 % stronger and 30 % lighter than any other resin. We also build power cats where weight is not so much an issue so these are build with Vinylester, the next best thing to epoxy. If we where to build our FastCats in Vinylester we would still be very competative and for sure cheaper but we would loose 20 % of our speed"

Gideon, if I wanted to say that you are wrong to use epoxy, I wouldn't beat around the bush-I would just say so. I am saying that some things you say just don't add up--and you have just written more things that don't add up. I am not much for jumping to conclusions, but I am relentless at pursuing conflicting information until the contradictions are resolved. If I didn't respect you, I wouldn't bother to reconcile the things you say, I would just dismiss you as unreliable.

If your cats are 30% lighter because you use epoxy instead of vinylester
The cats are not just 30 % lighter because of the resin used but the hull deck and bulkheads are resin infused and that saves around 20 % in weight
, would you lose 30% of your payload if you used vinylester? Why would you lose only 20% if that were the case?

You say that you can't infuse vinylester at high vacuums-are you saying that your power cats aren't infused at high vacuums? How much vacuum are you using on your power cats? What vinylester are you using? What are its properties?
The power cats are hand laminated, the bulkheads and floors are infused with around 50 % vacuum, A vinylester from Scott Bader

What makes you sure that your vinylester is the best available for infusion, and what makes you sure that the limitations you believe exist in resin infusing vinylester haven't been overcome by others? You say that high-vacuum resin infusion with vinylester and polyester is impossible, but others say they do it all the time. Are they liars? It is not possible to infuse polyester or vinylkester with 100 % vacuum because of the styrene that starts boiling with around 65 % vacuum and therefore the laminate is more resin rich, draw you own conclusion about the liars

My sense is that either you didn't try it, or alternatively, maybe you tried and failed, and assumed that it was impossible, instead of trying to find out what you did wrong-
I do not know of anybody trying so hard to use materials in the right way or does so much testing as we do in our facility , it is the only way to get ahead.

Greetings

Gideon
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Old 08-04-2008, 15:17   #78
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Resin infusion and vinylester resin

[quote=Nordic cat;150844]How do you define "high vacuum"?

"You can use around 80% vacuum (200 mbar abs) to suck it in, but need to drop it to around 60% when it starts going off, otherwise it starts "boiling" and will create bubbles.
This is what I have seen when they infuse wind turbine blades, up to 60 metres long for 5 MW windturbines.

Big cat, is the use of antimony allowed, I know its pretty poisonous stuff, and not allowed in many applications? I would be very cautious of using it for water tanks without thorough checking.

Regards, Alan"

Hi, Alan-Thanks for the info, especially about the toxicity of antimony. I don't know if it's allowed, but I'll keep it out of my water tanks, due to your advice.

Here is a link in which 29 inches of vacuum (almost 97% vacuum) is used with vinlyester resin in a production setting:

AOC Resins*::*News and Information*::*News Releases

It occurs to me that due to constantly improving air quality standards, there is less and less styrene in polyester and vinylester-perhaps this has something to do with the question of styrene 'boiling.' Here is a link where reducing styrene content is discussed: Defense Tech Briefs - Less-Polluting Resins for Molding Composite Structures

Infusion Flow Reinforcements has a detailed discussion of this issue-to quote that site: "While the resin chemistries were thought to be similar, remarkably one system volatilized to the point of boiling at 24 Hg gauge vacuum (HgV), whereas the other did so at 27 HgV at room temperature." The 24 inches of mercury boiling point is the one that you have mentioned, (80% vacuum = 24 Hg,) but obviously, it is possible to find vinylester resins that tolerate higher vacuums without boiling.

Clearly, the devil is in the details, and getting feedback about vacuum levels from the resin manufacturer has got to be a necessity. Also, it seems that if they don't like 29 Hg, then one should seek out another manufacturer of resin.
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Old 08-04-2008, 15:30   #79
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Vinylester infusion and boiling styrene-my conclusion

Hi, Gideon

As you can see, you and Alan have stimulated me to do research on the boiling styrene issue, and it seems that your information about boiling styrene is indeed out of date, or at any rate, true only of some vinylesters--and you can find vinylesters that are low viscosity that don't boil at 96% vacuum that are suitable for resin infusion. I don't know if you have heard of Hatteras yachts, but they have been in business for a long time (almost 40 years,) and are highly respected. (They are infusing vinylester at 96% vacuum.)

Even if you choose not to use these vinylesters that you seem not to have been aware of in your sailing cats, you may find the information useful in the production of your power cats.

TD
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Old 08-04-2008, 15:55   #80
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A better vinylester resin-

Thanks to this discussion, I have been stimulated to look at more resins-here is a low viscosity, very strong, low styrene content, fire resistant vinylester resin that requires no antimony trioxide to be very fire resistant:

http://datasheets.corrosionresins.co..._ID=EvdrQLY%3D
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Old 08-04-2008, 16:44   #81
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http://www.nordbaelt.com/Construction_philosophy.asp says:


"The Nordbaelt 46 is built from a complex matrix of materials harnessing the benefits of unidirectional E glass fibres with the most excellent elongation, and water resistant characteristics of Vinylester resins.

Due to stress cycling and water penetration it is estimated that a hull constructed wholly from Epoxy resins will be at 98% of its year 1 strength after 10 years, a hull built of Vinylester resins will be at 96%, a hull built from Isopthalic Polyester will be at 94% whilst the use of traditional Ortho - Polyester might provide values as low as 50%."

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Old 08-04-2008, 16:55   #82
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Vinylester and blisters

Blister & Laminate Hydrolysis in Fiberglass Boat Hulls
says:

"We have used vinylester for barrier coasts exclusively now for over seven years."

"Vinylester: A modified epoxy resin in a ester linking system. High physical properties and outstanding corrosion resis-tance. To our knowledge, there has never been a blister in a boat built with vinylester resin."
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Old 08-04-2008, 16:57   #83
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[quote=BigCat;150900]
Quote:
Originally Posted by Nordic cat View Post

: "While the resin chemistries were thought to be similar, remarkably one system volatilized to the point of boiling at 24 Hg gauge vacuum (HgV), whereas the other did so at 27 HgV at room temperature."
Who's room?
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Old 09-04-2008, 00:49   #84
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Different formulations will have different boiling points at room temperature. When it starts "going off" the temeprature increases, this will lower the boiling point.

As stated in the example I gave, they drop the vacuum towards the end of the infusion.

There will be a difference in how you use this stuff when looking at vacuum bagging compared to infusion. The infusion process is alot more sensitive to changes in viscosity as this will affect the flow characteristics.

At the end of the day, you can make a great boat in any of these materials, but when selling a new boat, the perception of epoxy being superior will allow the vendor to charge more for the product.
Your average boat buyer (also the rich ones) has the perception that epoxy is best (which it is) as he will use it to prime his hull before anti-fouling it.

If your research leads you to using vinylester as that gives you best value for money, then go for it. It's not easy to define the dollars/additional knot of boat speed at the design stage.

When it comes to selling the new boats, planes etc. then the customer rules!

Regards

Alan
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Old 09-04-2008, 01:13   #85
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Quote:
Originally Posted by BigCat View Post
Hi, Gideon

As you can see, you and Alan have stimulated me to do research on the boiling styrene issue, and it seems that your information about boiling styrene is indeed out of date, or at any rate, true only of some vinylesters--and you can find vinylesters that are low viscosity that don't boil at 96% vacuum that are suitable for resin infusion. I don't know if you have heard of Hatteras yachts, but they have been in business for a long time (almost 40 years,) and are highly respected. (They are infusing vinylester at 96% vacuum.)

Even if you choose not to use these vinylesters that you seem not to have been aware of in your sailing cats, you may find the information useful in the production of your power cats.

TD
Hallo Big Cat

even Hatteras lowers the vacuum level to around 60 % to prevent boiling
and so do all the other boat builders , we have tried out at least 7 different vinylesters made by as many companies and all had the same problem
Boiling at vacuum levels over 60 %.
We are producing at an altitude of 440 meters or 1400 feet and the temperatures here in Durban are around the 90 degree F. level and that has effect
Our testing has shown that epoxy is stronger than any other resin and that means weight savings at the end of the day.
For the same reason we use these exotic materials like carbon kevlar,Basalt and E glass and yes these unfortunately cost much more than r glass and Vinylester.
I am glad we have all these choices to make . It gives all of us with another perspective a different look at these things and it gives nice conversations with you for instance.
Again I wish you well and nice talking to you

Gideon
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Old 09-04-2008, 01:14   #86
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Thank You all for the discussion. It seems that quality vinyester has come a long way and with low styrene and fire resistance, all that one needs to worry about is the nasty catylysts. It has made me think seriously about using fire resistant vinylester I was planning to vaccuum bag rather than infuse as I plan to use polyprophoneycomb and the bonded scrim and any holes in the honeycomb can take up a fair bit of resin, thus negating any weight advantage in infusing, so 60% vacuum is quite OK for me. There are different grades of epoxy and some are less allergenic than others. I have already had lots of children, so sterilisation from styrene is not a concern for me.
The extra cost is marginal in the total cost of the boat
Robert
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Old 09-04-2008, 01:39   #87
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Originally Posted by Robertcateran View Post
Thank You all for the discussion. It seems that quality vinyester has come a long way and with low styrene and fire resistance, all that one needs to worry about is the nasty catylysts. It has made me think seriously about using fire resistant vinylester I was planning to vaccuum bag rather than infuse as I plan to use polyprophoneycomb and the bonded scrim and any holes in the honeycomb can take up a fair bit of resin, thus negating any weight advantage in infusing, so 60% vacuum is quite OK for me. There are different grades of epoxy and some are less allergenic than others. I have already had lots of children, so sterilisation from styrene is not a concern for me.
The extra cost is marginal in the total cost of the boat
Robert
Hallo Robert impotence is not only about sterilization , it is mostly about getting it up and that might be an issue to you

Greetings

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Old 09-04-2008, 01:44   #88
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Hallo Robert impotence is not only about sterilization , it is mostly about getting it up and that might be an issue to you

Greetings

Gideon

The price of those small blue pills also needs to be factored in to the cost/benefit analysis. There is a joke going around at the moment that the nursing homes have started giving them to the old men. 1 at night to prevent the rolling out of bed, and in the morning so they can improve their "aim" when taking a leak.
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Old 09-04-2008, 13:15   #89
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The price of those small blue pills also needs to be factored in to the cost/benefit analysis. There is a joke going around at the moment that the nursing homes have started giving them to the old men. 1 at night to prevent the rolling out of bed, and in the morning so they can improve their "aim" when taking a leak.
Nice one keep the humor going, thanks

Gideon
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Old 09-04-2008, 13:15   #90
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Vinylester vs. Epoxy, round 11 zillion and four

"Different formulations will have different boiling points at room temperature. When it starts "going off" the temeprature increases, this will lower the boiling point."

Hi, Alan

I am doing more research on this. Apparently, if you use CHP instead of MEKP as a catalyst you can keep the temperature down. This has to approved by the resin manufacturer, of course.

There is no problem with viscosity and vinylester, as it is offered in the mid-200s CPS by various manufacturers.

I don't know the specifics, but some manufacturers are starting to thin resins with fatty acids, and are reducing the styrene levels. There are vinylesters with no more than 25% styrene available now (1/2 of the styrene common a few years ago)-less styrene and lower temperatures = less shrinkage, further chipping away at epoxy's last remaining advantage.

There are many more stock boats being made with vinylester than epoxy, so I would say that when it comes to stock boats, only the largest and most expensive multihulls or racers would be likely to succeed with epoxy. As far as catering to prejudices goes, that leads to making boring boats that cater to people's prejudices in all ways. This holds no interest for me. My main interest is in making my own boat, and discussing new ideas with those open to them. To me, selling plans is a minor, secondary interest, and I have no interest in making stock boats at all.

I have seen the process whereby a slight advantage becomes exaggerated to an absolute-the fact that marconi rigs can point 10 degrees higher than flat sail junk rigs becomes 'junk rigs can't go to windward,' would be an example. Then ear flaps close when new developments make obsolete these 'facts' that were never true to begin with. Junk rigs now usually have camber, and can tack through 90 degrees. Try telling that to the typical prejudice-bound yachtie, however, and he chants 'I can't hear you, junk rigs can't sail to windward,' with his fingers stuck in his ears.

I also challenge those who say that epoxy resin is stronger than vinylester-false-and that epoxy resin is more elastic-also false- when speaking of those epoxy resins and vinylester resins actually in use in boat building. Watching those with a vested interest in epoxy exploit this prejudice to market their wares is pretty annoying to me, because I have looked closely at the facts, and know better.

Gideon, I agree that your temperature and altitude would make epoxy easier to work with, and while it may well be that epoxy can result in laminates slightly superior to those made with vinylester, I am interested in quantifying this issue. I myself am near sea level in a cool climate, and can obtain better properties with vinylester than you can with your temperatures and altitude.

As far as dropping the vacuum pressure once the resin has distributed, I have read that people do this in order to not starve the laminate of resin, but haven't heard infusers worry about vacuum causing boiling if they don't.

I do assume that VectorPly has some good reason for believing that you can get 70% glass by infusing with vinylester. They do make marine reinforcements for a living, including carbon fiber and kevlar. I know that they do in house testing, because I have exchanged e-mails with their testing engineer.

I have never heard of r-glass. E-glass is used by everybody here in the US, and the higher grade S-glass is very rarely used, with people seeking higher properties preferring kevlar and carbon fiber. I think the basalt cloth is fascinating, and my thanks to you for mentioning it.

Robertcateran, I have never heard the assertion that some epoxies are less allergenic than others. Do you have a reference to post? Here's one from me on the subject, from a website about resin infusion boatbuilding:
Epoxy Sensitivity

Tim Dunn, aka BigCat
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