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Re: pitchpoling capricorns? [Re: Jake] #85925
10/09/06 03:40 PM
10/09/06 03:40 PM
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California
mmiller Offline
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Quote
fall into two basic categories. Hand Laid or Vacuum Bagged.


Actually, vacuum bagging is not related to the process of the glass being hand laid or not. You can hand lay (simple to understand) the glass, or you can shoot it in with a chopper gun. I would call resin infusion "hand laid" as it requires careful positioning of the glass layers by hand.

Vacuum bagging is a process that holds the glass in place as the resin cures. You can use a hand squeegee to work the glass and resin till it sets up or you can put the mold in a bag and turn on a vacuum. The squeegee can be good at removing more excess resin, but the vacuum bagging is less labor. The vacuum bagging is required on our foam core layup as it forces the foam to adhere to a concave surface.

Our glass process is:

- Gel coat sprayed into the mold.
- 1 st layup is hand layed glass and resin worked with a squeegee. Cured.
- Foam core is laminated in place and vacuum bagged till cured.
- 2 nd layup (hulls inner layer) is hand laid and worked with squeegee.

We do not use the vacuum bagging on the second layup because it can shift the glass and cause wrinkles. Not good for the structure.


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Matt Miller
Hobie Cat Company
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Re: pitchpoling capricorns? [Re: mmiller] #85926
10/09/06 05:06 PM
10/09/06 05:06 PM
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Posts: 12,310
South Carolina
Jake Offline
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However you decide to classify them, vacuum bagged fiberglass laminates have a much higher fiber to resin ratio than a hand wetted ambient pressure cured layup. Vacuuming the layup does more than just hold the glass in place in that it also compresses the fibers together and reduces the resin volume (much more than you can accomplish with a squeegie). You can control the amount of compression and fiber/resin ratio by simply adjusting the amount of vacuum applied. For you doubters out there, next time you are near a vacuum bagged hull, tap on it with a knuckle and then tap on the hull of an ambient pressure cured boat. The vacuum bagged boat will sound like a steel drum - the other will make a dull thud.


Jake Kohl
Re: pitchpoling capricorns? [Re: Jake] #85927
10/09/06 06:28 PM
10/09/06 06:28 PM
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California
mmiller Offline
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I don't know. Maybe with much higher vacuum. We quit doing it on the 2 nd layup for weight and consistency issues. The boats are lighter now and look much nicer on the inside because we hand work the glass and squeegee out the excess resins.


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Matt Miller
Hobie Cat Company
Re: pitchpoling capricorns? [Re: Jake] #85928
10/09/06 08:40 PM
10/09/06 08:40 PM
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Jimbo Offline
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Jake,

The cure time of the resin can be configured for infusion, especially so with epoxies. There are epoxy curatives that will give you 5 days or more work time at room temp. There is one that gives you 6 months(!) But with only modest heating (120-180*F) full cure in a few hours.

With polyester, the Sunrez system is always an option. The Sunrez system will never cure until exposed to a strong ultraviolet light source.

Then there are the 'static' mix tubes.

http://www.chreed.com/tah_mixers.htm

The resin and catalyst are stored seperately and only metered, combined and thoroughly mixed at the moment of infusion into the layup using static mix tubes, greatly reducing the chance of a mishap with gel time vs infusion time.

I saw and participated in a buildup at After IBEX a couple of years ago that used mixers like these. We built a ~12' dinghy in about 45 minutes from empty mold to finished boat (with plenty of guidance from our instructor <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" /> )

So keep in mind that there are basically two types of composite boat manufacturer in 2006: Those using some form of resin infusion and those who are going to use some sort of resin infusion soon. If Nacra or anyone else making boats has begun using infusion, then they still are. No way they would go back. Better to work out the bugs (if there are any). This is how boats will be built from now on.

Jimbo

Re: pitchpoling capricorns? [Re: Jimbo] #85929
10/09/06 09:04 PM
10/09/06 09:04 PM

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Quote

Those using some form of resin infusion and those who are going to use some sort of resin infusion soon. If Nacra or anyone else making boats has begun using infusion, then they still are. No way they would go back. Better to work out the bugs (if there are any). This is how boats will be built from now on.


IIRC the way US laws are going at present with respect to emissions and staff exposure to chemicals and fumes, in a few years you won't have any choice but to infuse if you want to build composite boats in the US.

Re: pitchpoling capricorns? [Re: ] #85930
10/09/06 09:36 PM
10/09/06 09:36 PM
Joined: Jun 2001
Posts: 12,310
South Carolina
Jake Offline
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Jake  Offline
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Quote
Quote

Those using some form of resin infusion and those who are going to use some sort of resin infusion soon. If Nacra or anyone else making boats has begun using infusion, then they still are. No way they would go back. Better to work out the bugs (if there are any). This is how boats will be built from now on.


IIRC the way US laws are going at present with respect to emissions and staff exposure to chemicals and fumes, in a few years you won't have any choice but to infuse if you want to build composite boats in the US.


I understand that a large part of the reasoning behind the proposed law (I think they put a guidline year date in the law) is environment and worker health....this is likely a stupid question, but where do the fumes go if you are resin infusing?


Jake Kohl
Re: pitchpoling capricorns? [Re: Jake] #85931
10/09/06 10:40 PM
10/09/06 10:40 PM
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Jimbo Offline
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Jake,
'Fumes' are the result of the volatile reactive solvent styrene (aka vinyl benzene) coming into contact with air and evaporating. If you have a closed can of styrene, you don't have any air contact, no 'outgassing', hence no fumes (duh <img src="http://www.catsailor.com/forums/images/graemlins/tongue.gif" alt="" /> ). Resin infusion is a 'closed' process. It's like building a boat without taking the caps off of the cans of resin.

Jimbo

Re: pitchpoling capricorns? [Re: Jimbo] #85932
10/10/06 10:53 AM
10/10/06 10:53 AM
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California
mmiller Offline
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...and the vacuum exhaust? Back into the can? I would think that is still going to be an issue. How do you dispense of the fumes in the vacuum exhaust?


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Matt Miller
Hobie Cat Company
Re: pitchpoling capricorns? [Re: mmiller] #85933
10/10/06 11:13 AM
10/10/06 11:13 AM
Joined: May 2003
Posts: 4,451
West coast of Norway
Rolf_Nilsen Offline
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In the case of infusion, you only have vacuum exhaust and outgassing while pulling the resin into the layers of fibers. This is done in a short time, from then on you only maintain the vacuum, and the amount of outgassing is very, very, small as long as you have a good airseal. A very tight vacumbag is a necessity when using infusion, otherwise you get faults in the laminate. It is therefore standard procedure to check the vacumbags integrity before you pull the resin in.

On the topic of laminating by hand.. A skilled worker can achieve about the same resin/fiber ratios as a wet layup with vacuum, but he uses more time and is exposed to the fumes and chemicals for a longer time. I am not certain infusion results in stronger/lighter parts when compared to wet layup with vacuum. I think infusion uses more resin to fill all voids in the foam surface, but have not had the opportunity to compare weights.

Re: pitchpoling capricorns? [Re: Rolf_Nilsen] #85934
10/10/06 12:45 PM
10/10/06 12:45 PM
Joined: Jun 2001
Posts: 12,310
South Carolina
Jake Offline
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I have done a lot of both - but I confess to not previously using rollers to laydown a hand layup...Having vacuum bagged 8 layers of 11oz fiberglass into a laminate less than 3/16" thick, I would find it astonishing that this can be accomplished without a vacuum. Secondly, if you do some research into building a foam core laminate, doing so under vacuum and filling the rough surface of the foam creates an extremely superior bond and increases the strength of the structure 10 times or more. If I get some time, I'll try to locate that article.

I have done side by side hand laminations and vacuum bagging and achieved substantially different results (but admitedly was not using the beaded rollers at the time for hand laminations).

Even if you vacuum bag without infusing, you still get a much better bond to foam cores. The infusion process allows you to place all your reinforcments before having to deal with cure times and reduces some of the materials needed for production.


Jake Kohl
Re: pitchpoling capricorns? [Re: Jake] #85935
10/10/06 02:38 PM
10/10/06 02:38 PM
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Jimbo Offline
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Jake,
I've never been one to use those little rollers either. I got into composites from the aerospace side and learned the 'Rutan Method' which uses plastic bondo squeegees or the rubber screen process squeegees to both spread resin and remove excess. Very fast and effective. No brushing at all. You might be able to find one of Rutan's videos where he lays up a whole foam core wing in about, oh, 15 minutes or so. Amazing!

Jimbo

jimbo

Re: pitchpoling capricorns? [Re: Jimbo] #85936
10/10/06 03:11 PM
10/10/06 03:11 PM
Joined: May 2003
Posts: 4,451
West coast of Norway
Rolf_Nilsen Offline
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Jake,

I always put on a layer of epoxy thickened with collodial silica on the foam first, to fill all gaps. Then I put on the glass and wet it out. I hope I save some weight that way and still have a good bond..

I have used a rigded alu roller, but found it to be too messy. For thick laminates it can be nice, but most parts on cats are so delicate that I prefer a squeege. Squeege and vacuum is my preferred method.

Re: pitchpoling capricorns? [Re: Rolf_Nilsen] #85937
10/11/06 02:32 AM
10/11/06 02:32 AM
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North-West Europe
Wouter Offline
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Rolf wrote :

Quote

I am not certain infusion results in stronger/lighter parts when compared to wet layup with vacuum. I think infusion uses more resin to fill all voids in the foam surface, but have not had the opportunity to compare weights.



I think I wrote earlier that several other builders found that the old method resulted in better quality boats and have disgarted infusion as a result. Infusion did not result in lighter hulls. It had increased the risk of warranty issues because of insufficient wetting out of the laminate in remote area's. These builders tend to make a very large portions of quality lightweight hulls. Maybe they didn't try hard enough to make it work, that is possible. But rumour has it in the A-cat cirquit that also Nacra has reverted back to the old technology for their A2 catamaran. For very much the same reasons. However the last claim is a single source claim so I categorize it as less dependent.

It seems that infusion is mainly advantageous in the way of cleaning up your production line and satisfying more strickt environmental regulations. In the way of quality of the laminate it doesn't seem to be better then the old vacuum bag techniques. It certainly doesn't appear to be better at all autoclave techniques with manual layup.

Wouter

Last edited by Wouter; 10/11/06 02:34 AM.

Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
The Netherlands
Re: pitchpoling capricorns? [Re: Wouter] #85938
10/11/06 02:43 AM
10/11/06 02:43 AM
Joined: May 2003
Posts: 4,451
West coast of Norway
Rolf_Nilsen Offline
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A good strategy for where to have the resin inlets and vacum ports is necessary for proper wetting out of all fibers. There are flow-simulation software available to do this for you, which might be smart to invest in if you are going to do production parts. A fellow countryman of you has written extensively about his experiences with infusion while building a F-39 trimaran: http://www.fram.nl/

Re: pitchpoling capricorns? [Re: Wouter] #85939
10/12/06 09:21 PM
10/12/06 09:21 PM
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Fiber fractions in the 55% range are consistently echievable with RI methods. That's certainly good enough. Autoclave is not really applicable to the construction of most beach cats since they use foam cores. Autoclaves are only used when you want compaction pressure greater than one atmosphere. The lower density cores do not do well with ths type of pressure, especially at elvated temperatures. Autoclave copaction/curing is the territory of the Nomex honeycomb cored boats, which is to say, the high-end boats. I have managed to crush some of the lower density PVC foams with only a good vacuum at room temperature.

One small problem with RI is that it may tend to oversaturate certain areas of the dry stack-up, like the edges of scrim & score foam, or corners where foam pieces meet together. In hand layup, these would be hollow voids, which is OK since it is in the core anyway. But with RI it winds up being solid resin. Stronger? probably, though not in any meaningful way. But certainly heavier by as much as a few pounds per hull. There is usually a simple solution in changing certain details of the core to avoid these resin pockets.

Jimbo

Re: pitchpoling capricorns? [Re: new2sailin2] #85940
10/18/07 09:04 AM
10/18/07 09:04 AM
Joined: Aug 2006
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Okay, my 2 cents having looked at both boats, with a serious purchase pending. You can dump any of these boats at a gybe, but (all other things equal mass, mast position relative to center of effort, sail area) I find that how aggressively you can bear off, coupled with, foredeck hull volume, and hydrodynamic drag, and mast postion relative to center of effort can be pretty boat-specific. First, both the Cap and the Nacra are really nice boats. All this about masts snapping is baloney. Unless you raise a phone-pole on your F18, any mast will snap with a spin if not appropriately rigged for the conditions. Learn how to set your rig tension and read and repeat: big breeze, no mainsheet tension or incorrect diamond-wire setting, with any spinny= *SNAP*. If you think, with thousands of pounds of wind force pushing on it, that mast strength is solely a function of the flimsy aluminum and not the assisting stay settings and mainsheet tension, I can recommend a physics class. (Don’t be so dumb.) Having souped up the 5.5sl (and sailed most other F18’s), I can say that there is, a critical moment at the gybe when the kite goes up that is extremely boat-specific. When the kite goes up, the top of your boat wants to scoot forward, but its, draggy hulls (they are in water, a much more dense a fluid than air) are slower to accelerate and hold it back. This acceleration causes the center of effort to move very far forward until such a time as the hulls can catch up a bit and get back under the rig. Once sufficient speed is achieved on a catamaran with a spin, the leeward hull begins planing, the hull slips forward under the mast, and the center of effort moves aft again, and the process is facilitated by the lift provided by the spinnaker on the front of the boat, re-directing air both downward and aft. However, on each, hull design governs acceleration and is quite different. Based on my experience, hull design and water chop largely govern a propensity spectacular catamaran gymnastics at the gybe. At the downwind gybe, nose diving is a function of lesser volume fore, and less leeward, outward side hull curvature, and how much water is on top of the hull as the top of the boat (mast, sails) tries to go fast and the bottom (hulls) drag behind. Narrow sleek hulls and far forward CE design elements provide greater ease in the hull hunting for the bottom of the ocean in a big breeze as the CE tips fore on the boat at the gybe, with hulls pointing to the bottom of the ocean for a bit of time until planing begins. At the same time, the sleek hull features providing less overall resistance in the water (hulls more slippery) and better acceleration. Having souped up a (spinned) a nacra 5.5sl and sailed it as F18 (Second ! on day one in a big breeze, and...umm, oh yeah, dead last on day 2 in a light breeze)... the low volume hull 5.5sl (spi) with the F18 class in force 4 winds was very, very fast downwind in heavy air, especially after it got rolling, presumably because of the small hulls. Once planing, the old boat actually felt very stable. However, watching the 5.5’s low volume hulls torpedo until the boat started to plane at the gybe is a pretty “exhilarating” experience. This acceleration is not necessarily bad (I have lots of experience with the my skinny, low volume 5.5 hulls!), but does influence how hard you can (should) push the boat immediately off a gybe-I go a little deeper and more s l o w w l y). Reduced hull volume can make for a startlingly fast acceleration but managing the boat during this point, requires a bit of care, until the hulls begin planing (if it is breezy enough). Just looking at the cross-sections-one would then expect the Cap to provide better acceleration, is probably quicker to plane, but maybe a bit more likelihood of a stuffed hull during a reckless, hard gybe’. The big volume on the Nacra hulls may provide a bit more overall stability at this point, at some expense of overall acceleration. It’s a trade off. Once planing, though, the boats are about the same. As for quality, I think AHCP (Cap) makes a really nice, solid boat, but then again, it costs more than the Nacra Infusion. Bottom line? Learn your boat, avoid generalizations-all F-18’s are pretty fast.


Nacra F18 #856
Re: pitchpoling capricorns? [Re: ] #85941
10/18/07 07:27 PM
10/18/07 07:27 PM
Joined: Jun 2001
Posts: 1,911
South Florida & the Keys
arbo06 Offline
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Lost me at "multiple inlets".

Re: pitchpoling capricorns? [Re: rexdenton] #85942
10/19/07 06:21 AM
10/19/07 06:21 AM

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Quote
Okay, my 2 cents having looked at both boats, with a serious purchase pending. You can dump any of these boats at a gybe, but (all other things equal mass, mast position relative to center of effort, sail area) I find that how aggressively you can bear off, coupled with, foredeck hull volume, and hydrodynamic drag, and mast postion relative to center of effort can be pretty boat-specific. First, both the Cap and the Nacra are really nice boats. All this about masts snapping is baloney. Unless you raise a phone-pole on your F18, any mast will snap with a spin if not appropriately rigged for the conditions. Learn how to set your rig tension and read and repeat: big breeze, no mainsheet tension or incorrect diamond-wire setting, with any spinny= *SNAP*. If you think, with thousands of pounds of wind force pushing on it, that mast strength is solely a function of the flimsy aluminum and not the assisting stay settings and mainsheet tension, I can recommend a physics class. (Don’t be so dumb.) Having souped up the 5.5sl (and sailed most other F18’s), I can say that there is, a critical moment at the gybe when the kite goes up that is extremely boat-specific. When the kite goes up, the top of your boat wants to scoot forward, but its, draggy hulls (they are in water, a much more dense a fluid than air) are slower to accelerate and hold it back. This acceleration causes the center of effort to move very far forward until such a time as the hulls can catch up a bit and get back under the rig. Once sufficient speed is achieved on a catamaran with a spin, the leeward hull begins planing, the hull slips forward under the mast, and the center of effort moves aft again, and the process is facilitated by the lift provided by the spinnaker on the front of the boat, re-directing air both downward and aft. However, on each, hull design governs acceleration and is quite different. Based on my experience, hull design and water chop largely govern a propensity spectacular catamaran gymnastics at the gybe. At the downwind gybe, nose diving is a function of lesser volume fore, and less leeward, outward side hull curvature, and how much water is on top of the hull as the top of the boat (mast, sails) tries to go fast and the bottom (hulls) drag behind. Narrow sleek hulls and far forward CE design elements provide greater ease in the hull hunting for the bottom of the ocean in a big breeze as the CE tips fore on the boat at the gybe, with hulls pointing to the bottom of the ocean for a bit of time until planing begins. At the same time, the sleek hull features providing less overall resistance in the water (hulls more slippery) and better acceleration. Having souped up a (spinned) a nacra 5.5sl and sailed it as F18 (Second ! on day one in a big breeze, and...umm, oh yeah, dead last on day 2 in a light breeze)... the low volume hull 5.5sl (spi) with the F18 class in force 4 winds was very, very fast downwind in heavy air, especially after it got rolling, presumably because of the small hulls. Once planing, the old boat actually felt very stable. However, watching the 5.5’s low volume hulls torpedo until the boat started to plane at the gybe is a pretty “exhilarating” experience. This acceleration is not necessarily bad (I have lots of experience with the my skinny, low volume 5.5 hulls!), but does influence how hard you can (should) push the boat immediately off a gybe-I go a little deeper and more s l o w w l y). Reduced hull volume can make for a startlingly fast acceleration but managing the boat during this point, requires a bit of care, until the hulls begin planing (if it is breezy enough). Just looking at the cross-sections-one would then expect the Cap to provide better acceleration, is probably quicker to plane, but maybe a bit more likelihood of a stuffed hull during a reckless, hard gybe’. The big volume on the Nacra hulls may provide a bit more overall stability at this point, at some expense of overall acceleration. It’s a trade off. Once planing, though, the boats are about the same. As for quality, I think AHCP (Cap) makes a really nice, solid boat, but then again, it costs more than the Nacra Infusion. Bottom line? Learn your boat, avoid generalizations-all F-18’s are pretty fast.


When did W change his handle?

Lost me at equal mass

Re: pitchpoling capricorns? [Re: ] #85943
10/19/07 08:25 AM
10/19/07 08:25 AM
Joined: Jan 2004
Posts: 1,884
Detroit, MI
mbounds Offline
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Looking at that makes my brain hurt.

Re: pitchpoling capricorns? [Re: mbounds] #85944
10/19/07 09:09 AM
10/19/07 09:09 AM
Joined: Jun 2001
Posts: 3,293
Long Beach, California
John Williams Offline
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John Williams  Offline
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Long Beach, California
I read it twice. The take-away was that he once had a fast 5.5. <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />


John Williams

- The harder you practice, the luckier you get -
Gary Player, pro golfer

After watching Lionel Messi play, I realize I need to sail harder.
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