Help me understand secondary bonds?

[Levi]

So I get that in orders of strength epoxy is the strongest vinylester is second strongest and polyester is the weakest of the three but in terms of secondary bonds what makes epoxy stick so much better ? what occurs when vinylester is applied to existing fiberglass vs. when epoxy is applied to existing fiberglass?
I ask all this because I think I've found some Prisma hull beams that will work for my stringers and I'm thinking about laying a layer of 5 oz. Kevlar over them for added strength its probably overkill but  it shouldn't add much weight if I bag it and should add a ton of stiffness.
Does the vinylester effectively "melt" the surface of the existing fiberglass in the secondary bond?
Does epoxy do the same?
In terms of usable strength could I use poly for the hull beams and then use the vinylester for the Kevlar layer or would  doing everything in vinylester be best?
the beams come with 36oz quadraxial glass stitched over 2lb foam. Is this enough glass or will a layer of Kevlar help add significant strength? has anyone used these before? my original stringers were taken out AT LEAST two rebuilds ago and replaced with wood so I either have to build them out of glass and foam, or make a form to lay glass into or use something similar to the prisma beams cost wise looks like I can do the #40100 beams for about $375 shipped plus resin through Jamestown but I was wondering if there was somewhere I could get these locally at about the same or a better price?
Building a melamine mold would be my second choice but by the time I add foam fiberglass and resin I'll have put some serious coin into this method.
I have yet to find 4lb. foam in 2" 4'X8' sheets locally and shipping cost is why I put this option as a last choice but maybe you guys can direct me where I can get them?

Also I'm black and forth  on my transom material between 3/4" lightweight PVC and Gulfstream's CarbonFoam board? do I have to do solid inserts for this like you do  with Coosa? which would be a better option?

[RickK]

Sounds like we need Joel here.

[Levi]

Yea I like asking the tough questions lol.

[Callyb]

It is the molecular structure the determines the secondary bonding strength. Epoxy's structure allows it to "dig" deeper into the imperfections of other surfaces.

I used to have a .pdf that had really good illustrations... I will see if I can find it and I'll upload it to the gallery.

Edit: try this link...
https://www.slideshare.net/mobile/biswajitmaity5895/epoxy-resin-presented-by-biswajit-maity-39419288

[dirtwheelsfl]

It was put to me simply a long time ago.   Use epoxy if you want things to stick together, the others belong on an assembly line...

Im no chemist, but it has to do with the strength of the molecular chains yadayadayada

To get the most out of Kevlar epoxy should really be used...

The preforms are sweet, but then you've gotta find a way to support the sole because the preform is a fixed height. Itll follow the hull and wont have a flat top for the sole to sit on. You want that to create a giant I-beam pretty much. As far as coin, youll have about as much in resin to wet out those preforms as it would to just lay em up with biax, so that's a wash... 

Im not a fan of the pvc board for a transom, its not as stiff as the other options...

[Levi]

On the flatbacks the bottom of the hull where the stringers should be is mostly flat until the last three forward feet of the hull that part I would do in either foam and glass or plascore and glass either way that part would be cut to the shape of the forward portion of the hull and glassed down.
Do I need all the strength epoxy affords in conjunction with kevlar? I mean this will be a mostly inshore boat and I'll probably NEVER run it hard enough to launch of waves or catch air and the only days she'll break the inlet would be those summertime slick as glass  days otherwise I've got an offshore boat for everything else.
I'm also concerned about where I may end up with epoxy at because I plan on gelcoating the inside and outside of the boat and this wouldn't be a problem with vinylester but I DEFINITELY couldn't put epoxy on the transom where I will eventually be gelcoating but also would have to tie the stringers into the transom and the knees. Seems like at some point the new components and materials you epoxy in
far exceed the strength of the hull itself doesn't it? I mean if vinylester is double the strength of polyester that should be good enough right?
 Those 40100 preforms are 10 7/8" tall which puts the deck well above any previous waterline I can see on the exterior of the hull. wouldn't that be high enough to rest the deck on?
Chris I know you and Rick have done SEVERAL of these boats each and I REALLY respect you guys sharing your knowledge with me.
Would the single layer of 3610 triaxle glass be enough reenforcement or would you guys go another layer of 1708 or something?

[RickK]

Levi, if you spend some time looking through my rebuild you'll see I did everything below the sole in epoxy and everything above in poly.  I did the entire inside of the hull in a new layer or two in epoxy and 1708.
After that you need to get creative on hiding where epoxy is and where you need it to be poly. I have a full liner in  my boat so that made it easy. I made a liner out of poly for the transom so I would have poly on the inside of the boat and I epoxied that to the transom.
If you want the strength of epoxy where you need it, you'll need to get creative.

If you are building a bay boat why bother with Kevlar, a couple layers of 1708 is enough.  BTW, I'm not sure where you are located but we have bays here that are large enough to get quite nasty in a storm.

For the advice on layering and such I'll defer to Chris, since I learned a lot from him.

[Levi]

Do you have a link Rick?

[RickK]

From the home page where you see all the active topics, mine is one of the ones on that page that you can click on.
Here is to page one http://classicaquasport.com/smf/index.php?topic=10101.0

[dirtwheelsfl]

On the flatbacks the bottom of the hull where the stringers should be is mostly flat until the last three forward feet of the hull that part I would do in either foam and glass or plascore and glass either way that part would be cut to the shape of the forward portion of the hull and glassed down.
Do I need all the strength epoxy affords in conjunction with kevlar? I mean this will be a mostly inshore boat and I'll probably NEVER run it hard enough to launch of waves or catch air and the only days she'll break the inlet would be those summertime slick as glass  days otherwise I've got an offshore boat for everything else.
I'm also concerned about where I may end up with epoxy at because I plan on gelcoating the inside and outside of the boat and this wouldn't be a problem with vinylester but I DEFINITELY couldn't put epoxy on the transom where I will eventually be gelcoating but also would have to tie the stringers into the transom and the knees. Seems like at some point the new components and materials you epoxy in
far exceed the strength of the hull itself doesn't it? I mean if vinylester is double the strength of polyester that should be good enough right?
 Those 40100 preforms are 10 7/8" tall which puts the deck well above any previous waterline I can see on the exterior of the hull. wouldn't that be high enough to rest the deck on?
Chris I know you and Rick have done SEVERAL of these boats each and I REALLY respect you guys sharing your knowledge with me.
Would the single layer of 3610 triaxle glass be enough reenforcement or would you guys go another layer of 1708 or something?

If youre gonna go the gelcoat route, id just stick with vinylester. Keep all your ducks in a row ya know...
10 7/8 is plenty tall, but the bottom of the boat isn't flat. It goes down as it goes forward from the transom before coming back up. If its sitting on the designed waterline the first third of the keel will hit aground before it does in the stern. Youll basically end up with a big dip in the stringers (probably 3 or 4"). Did some work on my stringer forms today, theres ~3" of difference between their height at transom and deepest part. And this is a 12deg hull, flatback would be worse.

Untitled by dirtwheelsfl, on Flickr

The preforms would certainly work but then youd have to figure out how to level/extend the tops for the sole to rest on (that doesn't sound like much fun! haha)   You can have these forms when im done with em if ya want. Bottom edge just need some tweaking I reckon!

O I sent ya a message too...

[Levi]

I was doing some reading up on them over the weekend and apparently as long as you wet out all the glass on the preform you can use the 4" of 3610 tabbing on either side of the preform to make up for unevenness in the bottom of the hull I would still lay  glass over that and onto the hull bottom especially if I used the majority of the tabbing but ill DEFFINITELY get the hull cradled and level before I order them to make sure the 4 inches is enough and if not I would build a shim of sorts to get a flatter surface for the preform to ride on because YES if I let the preforms follow the bottom of the hull exactly ill have a NIGHTMARE on my hands when it comes time to level the top of them so the sole has a flat surface to ride on. I wish I could buy the preform in a full 16' length because that would alleviate the problem of a sag in the middle of the stringer.

If look at the install video on Jamestown Distributors website for the preforms and youll see where they let the tabbing take up for the unevenness. I also found a thread where they used the 4' sections on a 19' mako and once again allowed the tabbing to take up the slop underneath the preform.

Chris,
Once I get the hull chocked up I'll know more and I will lay out strings for the centerlines of the stringers to access the dip in the bottom of the hull and determine if 4 " of tabbing will get it done or not and if not ill got the melamine mold route as it appears you are doing. (getting good at that after building a console and helm for my 28' offshore boat)
For now though I'm busy busy until after the 23rd due to the holiday, my wedding next week, family coming into town Saturday, and helping the soon to be wife plan our reception party thing for the 23rd.

Did I mention were closing on a house on or before the 28th in the midst of all of that?

[Shine]

It is the molecular structure the determines the secondary bonding strength. Epoxy's structure allows it to "dig" deeper into the imperfections of other surfaces.

I used to have a .pdf that had really good illustrations... I will see if I can find it and I'll upload it to the gallery.

Edit: try this link...
https://www.slideshare.net/mobile/biswajitmaity5895/epoxy-resin-presented-by-biswajit-maity-39419288

thats it in a nut shell. 

I was doing some reading up on them over the weekend and apparently as long as you wet out all the glass on the preform you can use the 4" of 3610 tabbing on either side of the preform to make up for unevenness in the bottom of the hull

I have used a number of these, and that is true to a point.  The scrim on the bottom is pretty thick and it acts like a sponge so it can go over uneven surfaces.  Downside is that is absorbs a ton of resin, I would guess as much as two layers of 1708 per equal area.