Announcements
New Discussions
Great Texas 300
by cyberspeed. 06/15/18 11:12 AM
Great Lakes Cat Racing!
by TiberiusGV. 06/12/18 12:49 PM
do you carry one of these?
by Setwill. 06/12/18 04:01 AM
Rudder Slop
by rehmbo. 06/11/18 05:55 AM
Nacra17 rating for upcoming regatta
by rehmbo. 05/28/18 07:45 PM
CAT FIGHT VII
by TiberiusGV. 05/25/18 01:39 PM
Catamaran charter in BVI
by mickaelc. 05/25/18 11:44 AM
Previous Thread
Next Thread
Print Thread
Rate Thread
Hop To
New Nacra Infusion MKIII - Epoxy F18 #288658
02/23/18 02:59 PM
02/23/18 02:59 PM
Joined: Dec 2002
Posts: 267
Memphis, Tennessee
Damon Linkous Offline OP

enthusiast
Damon Linkous  Offline OP

enthusiast
Joined: Dec 2002
Posts: 267
Memphis, Tennessee
Calling on the F18 guys to comment on the new Nacra F18 Infusion MKIII and the changes to the F18 class rules allowing all epoxy hulls.

Nacra mentions the following changes:

What is changed:
  • New daggerboard position: more to the front.
  • New daggerboard case: will fit straight and curved. The case is ready for full foiling.
  • New progrip
  • Option for a decksweeper
  • Hulls are made from Epoxy, allowed by the class by October 2018.

more pics from Nacra
https://www.thebeachcats.com/pictures?g2_itemId=129603

What do you think this means to the class?

Attached Files
Last edited by Damon Linkous; 02/23/18 03:02 PM.
-- Have You Seen This? --
Re: New Nacra Infusion MKIII - Epoxy F18 [Re: Damon Linkous] #288659
02/25/18 08:50 AM
02/25/18 08:50 AM
Joined: Mar 2017
Posts: 109
fl
M
Mn3Again Offline
member
Mn3Again  Offline
member
M
Joined: Mar 2017
Posts: 109
fl
what is progrip? is that deck padding?

also - what is the advantage to just epoxy?

Last edited by Mn3Again; 02/25/18 08:55 AM.

Mn3
Re: New Nacra Infusion MKIII - Epoxy F18 [Re: Damon Linkous] #288660
02/25/18 04:22 PM
02/25/18 04:22 PM
Joined: Mar 2009
Posts: 901
Solomon's Island, MD
S
samc99us Offline
old hand
samc99us  Offline
old hand
S
Joined: Mar 2009
Posts: 901
Solomon's Island, MD
The new Mk. 3 from Nacra looks like a nice evolution and retains the very proven Infusion Mk. 2 hull shape in a potentially stiffer package.

As to epoxy, that's a complicated issue. I spent some time looking at the difference in material properties. Vinylester is actually stiffer than epoxy, but some epoxies have the advantage of higher elongation before failure and a slightly better fatigue life, but that also depends on what materials it is used with. For example, an S-glass Vinylester boat will be stiffer and have a higher fatigue life than a pure E-glass/epoxy build. One could even build an S-glass pre-preg vinylester boat and have a product on par with the Marstrom Tornado (which is an S-glass pre-preg nomex hull) due to the allowable weight margin.

The real gains on an F18 are made in the fabrication process and choice of paint over gelcoat. I don't know if Nacra have chosen a painted or gelcoated hull.
Paint alone can save 16+ lbs out of a pair of hulls, which is good for an extra layer of glass plus local reinforcements. Phantom were the first to realize this (and win a World Champion in 2012), Exploder followed suit with the Scoprion. Cirrus build a quality boat in France, they don't employ this trick but they make up for it in the fitout details and extremely beefy beam sections. Edge are similar in this regard as are Falcon.

Where does all that leave Nacra? They have switched Infusion production to the same facility that is building the N17 Mk. 2 so I expect the build quality to be on par with the other top builders and the fit out of the beams to be nicely done. The convertible trunks are a smart move with an eye towards the future. The new board position is also super proven on other F18's. I'm not sure what the new Pro-Grip looks like but the Pro grip on my Mk. 2 is of a high quality and very durable so I expect that to continue. Nacra probably have the best parts and support network in the U.S.

Hopefully this launch combined with the decksweeper generates some renewed interest in the F18 class here in the U.S as we look towards hosting the World Championship this fall in Sarasota.


F18 Infusion
Re: New Nacra Infusion MKIII - Epoxy F18 [Re: samc99us] #288661
02/25/18 04:31 PM
02/25/18 04:31 PM
Joined: Dec 2002
Posts: 267
Memphis, Tennessee
Damon Linkous Offline OP

enthusiast
Damon Linkous  Offline OP

enthusiast
Joined: Dec 2002
Posts: 267
Memphis, Tennessee
Originally Posted by samc99us
The new Mk. 3 from Nacra looks like a nice evolution and retains the very proven Infusion Mk. 2 hull shape in a potentially stiffer package...


Thanks samc99us! Nice info.

Last edited by Damon Linkous; 02/25/18 04:31 PM.
Re: New Nacra Infusion MKIII - Epoxy F18 [Re: samc99us] #288662
02/26/18 02:53 PM
02/26/18 02:53 PM
Joined: Jun 2001
Posts: 12,303
South Carolina
Jake Offline
Carpal Tunnel
Jake  Offline
Carpal Tunnel
Joined: Jun 2001
Posts: 12,303
South Carolina
Originally Posted by samc99us

...

Where does all that leave Nacra? They have switched Infusion production to the same facility that is building the N17 Mk. 2 so I expect the build quality to be on par with the other top builders and the fit out of the beams to be nicely done. The convertible trunks are a smart move with an eye towards the future. The new board position is also super proven on other F18's. I'm not sure what the new Pro-Grip looks like but the Pro grip on my Mk. 2 is of a high quality and very durable so I expect that to continue. Nacra probably have the best parts and support network in the U.S.

...




Interesting - where is the new production facility?

Convertible trunks are definitely interesting but I wonder about the compromise in the boards more forward position (presumably) for foiling on a relatively heavy boat. I would think the rearward position (where everything evolved to) is better for tacking and a more forward position would be a bit of a compromise for foiling or partially lifting foils.
If it does sacrifice some tacking speed, I would question the performance loss. However, this change would make more sense if they were anticipating a future rule tweak in F18 to allow some "out of vertical hull plane" angle or shape out of the boards. Is there any rumor of something like that in the works?


Jake Kohl
Re: New Nacra Infusion MKIII - Epoxy F18 [Re: samc99us] #288663
02/26/18 10:24 PM
02/26/18 10:24 PM
Joined: Apr 2017
Posts: 4
Madison WI
M
MadmanAcrossTheWater Offline
stranger
MadmanAcrossTheWater  Offline
stranger
M
Joined: Apr 2017
Posts: 4
Madison WI
Sam, can you elaborate on the vinylester vs epoxy details that you mentioned? I am not an engineer but have read and worked with... I would say more than the average sailor regarding composites and materials science.

Beside cost, I have never really heard of any benefit of vinylester resin over epoxy resin in virtually any application. My understanding has always been that epoxy resins have greater adhesive properties, greater strength and stiffness properties, greater fatigue resistance over time due to the nature of the cure (vinylester cure seeing ~5-10% 'shrinkage'), greater resistance to water incursion, greater chemical and UV stability, etc. Of course, this all in addition to epoxy being easier to work with, having a longer shelf life, less volatility, less harmful to human life, etc.

Not trying to pick a fight over technical details insomuch as trying to learn more about a subject that maybe I didn't have as good of a grasp on as I thought I did.

Re: New Nacra Infusion MKIII - Epoxy F18 [Re: Damon Linkous] #288666
02/28/18 11:44 AM
02/28/18 11:44 AM
Joined: Mar 2009
Posts: 901
Solomon's Island, MD
S
samc99us Offline
old hand
samc99us  Offline
old hand
S
Joined: Mar 2009
Posts: 901
Solomon's Island, MD
Jake,

I won't speak to details on the new production facility, that is for Nacra to share. No rumor regarding change in board cant or board type for the class. In terms of board position, the choice Nacra went with on the Nacra Mk. 3 isn't so much an innovation as one may think, nor is it a deviation from what has evolved in the class. The Phantom F18 (World Champ 2012) and Scorpion F18 (World Champ 2017) have the boards forward of the shrouds, close to where the current A-Cat board position is relative to the beam. This is the position Nacra are using from what I can tell (or close to it):

http://www.catsailingnews.com/2017/04/f18-worlds-2017-denmark-mitch-booth.html
http://www.catamag.fr/wp-content/uploads/Page-10-V3_3.jpg

If this was slower in a tack for World Champion level sailors at the Worlds, well it didn't seem to impact the results. There are interviews with Martin Fischer and Alex Udin explaining the choice on the Phantom, and they did try further forward than this which did have a negative impact on tacking speed and no additional benefit in a straight line.

With foils, one can go further forward as the extra lift generated by the foil through the tack helps negate the additional moment required as the pivot point shifts forward of the sail plans center of pressure.


F18 Infusion
Re: New Nacra Infusion MKIII - Epoxy F18 [Re: MadmanAcrossTheWater] #288667
02/28/18 12:10 PM
02/28/18 12:10 PM
Joined: Mar 2009
Posts: 901
Solomon's Island, MD
S
samc99us Offline
old hand
samc99us  Offline
old hand
S
Joined: Mar 2009
Posts: 901
Solomon's Island, MD
Originally Posted by MadmanAcrossTheWater
Sam, can you elaborate on the vinylester vs epoxy details that you mentioned? I am not an engineer but have read and worked with... I would say more than the average sailor regarding composites and materials science.

Beside cost, I have never really heard of any benefit of vinylester resin over epoxy resin in virtually any application. My understanding has always been that epoxy resins have greater adhesive properties, greater strength and stiffness properties, greater fatigue resistance over time due to the nature of the cure (vinylester cure seeing ~5-10% 'shrinkage'), greater resistance to water incursion, greater chemical and UV stability, etc. Of course, this all in addition to epoxy being easier to work with, having a longer shelf life, less volatility, less harmful to human life, etc.

Not trying to pick a fight over technical details insomuch as trying to learn more about a subject that maybe I didn't have as good of a grasp on as I thought I did.


Madman,

I come from an aerospace background where we use epoxy almost exclusively for many of the reasons you mention. For home builders and DIY composites guys, or frankly for most boat yards, I wouldn't use anything else but epoxy because of the shelf life concerns and nastiness in using vinylester. For many years I was also led to believe that vinylesters have lower strength and stiffness properties than epoxies and that is why we are using epoxy in the aerospace world. I went and checked this out and the data doesn't really support this:

Interplastic Vinylester: Flexural Strength 128 Mpa, Tensile Strength 75 Mpa, Elongation at Break 7.9%
Norester 680TPA Vinylester (at least one major F18 builder is using this): Flexural Strength 149.6 Mpa, Tensile Strength 87.5 Mpa, Elongation at break 4.2%
Pro Set 125/229 (AFTER post cure at 140 deg F for 8 hours): Flexural Strength 134 Mpa, Tensile Strength 72 Mpa, Elongation at break 4.7%
MGS 285/287 (the only aviation certified room temperature cure resin system): Flexural Strength 115 Mpa, Tensile Strength 75 Mpa, Elongation at break 5-6.5%

I also have test data comparing Vinylester with Epoxy in composite coupons, including fatigue (driven by elongation at break to a great extent) and the report concluded that you can use either as long as they are properly mixed and cured. One should also keep in mind that epoxy molecules form the backbone of most vinylesters.

The bottom line is reach the same conclusion as this gentleman: http://www.multihulldesigns.com/pdf...%20are%20Preferable%20to%20Polyester.htm
"In conclusion, both epoxy and vinylester are much preferred to polyester. Structurally, epoxy and vinylester are close in properties. Epoxy however is much easier to work with, and is much more forgiving."

So, in a production environment with controlled temperature and controlled mixing of vinylester, plus you are using it at a pace that is well under the shelf life, their is no reason a vinylester part should be any different than an epoxy part.

I didn't go looking at vinylester vs. epoxy in terms of shrinkage during cure or moisture resistance, but I believe both are relatively similar with the nod going to epoxy. The biggest area that epoxy wins in is secondary bonding, with some epoxies having shear strengths exceeding 4000 psi and Vinylester more like 500-1000 psi. So it is now class legal to use epoxy to do the hull seam which is a good thing, though there may have been a loophole in the rule allowing this for a long time and exactly how that seam is done in my experience is going to make a much larger difference to the stiffness of the boat than what glue the actual panels are made from (well, as long as polyester isn't the backbone of said panels). The other driving factor in stiffness is how well the beams fit the sockets and how stiff the beams are. A bonded beam F18 would be a nice improvement over the bolted connections but it isn't enough of an improvement to warrant a change in the class rules or make it vastly more expensive to ship the boats to cool regattas like St. Barths.

Last edited by samc99us; 02/28/18 12:10 PM.

F18 Infusion

Moderated by  Damon Linkous 

Search

Who's Online Now
0 registered members (), 22 guests, and 232 spiders.
Key: Admin, Global Mod, Mod
Newest Members
Captain_Oblvious, freddie12345, PCSikpper, COOKER, racelis
7794 Registered Users
Top Posters(30 Days)
rehmbo 5
tback 2
JeffS 2
Forum Statistics
Forums26
Topics22,304
Posts266,584
Members7,794
Most Online554
May 12th, 2017
--Advertisement--
Powered by UBB.threads™ PHP Forum Software 7.6.1.1