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2 part foam for delam repair
http://www.hobie.com/au/en/forums/viewtopic.php?f=14&t=3799		 Page 1 of 2
Author:  pappastratos [ Wed Jun 07, 2006 7:37 pm ]
Post subject:  2 part foam for delam repair
My H16 has large delam, looked at it all, epoxy, gorilla glue, Great stuff, even saw where someone used liquid nails. How about this, using 2 part 4 lb. expanding foam, mixed in very small amounts, poured into syringe, injected into delam areas. I have only 20 seconds of work time,(20 sec. to mix, 20-25 sec to inject), it has the consistency of very thin syrup. This should allow it to flow & soak a little into bad foam before it starts to expand. Then it dries very solid and hard, & is waterproof. I would need several larger syringes without needles. Done in small amounts & evenly spaced, will prevent deformation, it looks for the least path of resistance, so deformation will not happen. What do you think ?
Author:  Hobie Dude [ Wed Jun 07, 2006 10:48 pm ]
Post subject: 
I'd be worried about it causing more harm as it expands. I'm just picturing this foam working its way inbetween the fiberglass sandwich and then expanding. Also on a previous forum there is a big difference between open cell and closed cell foam. If it's open cell it will absorb water, and now you have water held where you already have delam issues.

Do a search about that stuff. Personally I think I'd opt for the tried and true delam repair.

Just my two cents,

Adam
Author:  pappastratos [ Thu Jun 08, 2006 4:24 am ]
Post subject: 
I have thought about that, but expanding is spreading out, if you poured this into a cup, it would expand out the top, not split the cup open. Also it does not have vertical force when not contained in a tube, if it did, recovery crews would pour it under over turned 18 wheelers to right them. People use this stuff all the time in molds, & it does not split or deform the molds. I will use in small amounts to allow for expansion.
Author:  Hobie Nick [ Thu Jun 08, 2006 8:58 am ]
Post subject: 
I know there have been lots of posts recently about what to use other than Git Rot, a West Systems (or similar) epoxy. I understand your point about looking for the path of least resistance and how it will not cause further delam. Taking a step back for a moment let's look at what you are trying to do.

You have a large delam area. You don't want to buy another boat or hull, you want to try and fix it in the most cost effective way. The factory has reccommended a time tested solution to your problem (Git Rot). Other people have tried it and verified that it works (I am one of them). You have found this solution to be too expensive. You have found what you think are other viable options for much less money.

Now, you have a decision to make. Do you use the proven method knowing the repair will be sucessful or do you use your boat for research purposes and hope this alternative solution will work without causing more damage or future problems?

If you decide on the research option, you might want to take a batch of this glue and simulate the repair before you sacrafice your boat. There are many variables that you do not know. It may be wise to speak to the manufacturer of this glue and see what they say about the application. you may also want to contain the glue and see what the expansion does. another factor to consider is the limited working time you will have. Is 20 sec enough to completly bond the three different layers? Will you get enough glue where it needs to be in that time? If it works, how long will it hold up? Can it handle the flexing of the hulls? What is it's shear strength compared to Git Rot? Can it penetrate the foam layer?

I would weigh the cost of replacing the hull against using the more expensive, proven method of repair. Please let us know what you decide and what the results are.

Good Luck!
Author:  mmiller [ Thu Jun 08, 2006 10:58 am ]
Post subject:  Foam
Foam is not a good solution.

Delaminations are splits between foam or foam and glass which are paper thin. That is why the penetrating ability of the Git Rot is perfect. Expanding foam will force the glass structure apart and damage it.

Another thing about Git Rot is the softer cure. It can handle flexing abuse better than many resins. It is proven... it works.

Expense? It takes very little resin to fix a delam. You use more if you are sloppy or pump too much in. One of the small bottles is plenty for most deck delamination issues.
Author:  pappastratos [ Thu Jun 08, 2006 11:00 am ]
Post subject: 
You said 'flexing' ? that is what we want to avoid, my experience with epoxy is that it cracks with flexing, as in boat gel coat. If it will hold up; boat makers have used this stuff for years, adhisive quality; I do some boat repair and this foam is very hard to remove from under the cap, & it still leaves a layer on boat, so it sticks to things, deforming the hull; done in very small amounts (30cc per time) should avoid this problem. If boat had a "foam" core, why not put foam back in it. I bet some surf boards are made of this,,,I like being controversial ,,,,
Author:  Hobie Nick [ Thu Jun 08, 2006 11:28 am ]
Post subject: 
You can lead a horse to water... :lol:
Author:  MBounds [ Thu Jun 08, 2006 1:11 pm ]
Post subject: 
Quote:
epoxy is that it cracks with flexing, as in boat gel coat


Gel coat is not epoxy. It is polyester resin. Very, very different. Git-Rot hardens to a semi-flexible consistency. It will not crack under moderate flexing.

There is nothing "wrong" with the existing foam core. It's the bond between the foam core and the fiberglass skins that has broken down. Epoxy is an adhesive resin that will form a chemical bond with nearly anything. It's the ideal replacement for that failed bond.

If you didn't intend on listening to our advice, then why did you ask for it? :roll:

Go ahead, knock yourself out and do it your way. Report back and let us know how it went.
Author:  mmiller [ Thu Jun 08, 2006 5:00 pm ]
Post subject:  Foam?
Once again, Foam...bad idea for this repair.

Now...looking back into old posts, I see you are the same user that proposed this foam idea before.

Git Rot is epoxy. Has great bonding strength. Will not crack when flexed. Some resins will crack. Some amount of flex is expected in the decks. I have used it personally and have an example done in 1984 than was heavily used and is still good today.

We have other threads on the issue that showed the foam core.

Image

http://www.hobiecat.com/community/viewtopic.php?t=1156

Here is an old cut up Hobie 14 that shows a delamination in the upper edge of the shot.

Image

If you expand the original structure with foam, you will weaken the structure. We are talking about filling a paper thin void with resin and rebonding as near to original structure as possible.

I think your 20 second work time is a huge limitation as well. The stuff will not penetrate and you will end up ratcheting the layers apart with the many seperate injections that would be needed. Each will fill the expand a bit more. You will end up with a bunch of small circles of bonded material.
Author:  pappastratos [ Thu Jun 08, 2006 7:08 pm ]
Post subject: 
well Mbounds, are we being ugly ? "[color=red]If you didn't intend on listening to our [/color][color=red]advice, then why did you ask for it?" [/color]Who said I will not listen ? I was asking for a opinion, sometimes its good to think outside of the box, if not we would be still rowing our boats made of hollowed out logs or sailing square riggers !!
Author:  pappastratos [ Thu Jun 08, 2006 7:17 pm ]
Post subject: 
You said a "paper thin void ?" pressing down on the hull its about 1/4" + .
Would epoxy work on that ?
Author:  MBounds [ Thu Jun 08, 2006 8:04 pm ]
Post subject: 
I'm not being ugly - I don't give a rat's a$$ how you fix your boat. It's your boat. Do what you want.
Author:  [FIN]Sailor [ Thu Jun 08, 2006 10:44 pm ]
Post subject: 
pappastratos wrote:
You said a "paper thin void ?" pressing down on the hull its about 1/4" + .
Would epoxy work on that ?


I'd bet the void is paper thin but when you push on the delam area, both layers of the deck flex and you feel like it's a huge void. At least with my boat it was so...
Author:  nevillemwiles [ Fri Jun 09, 2006 4:43 am ]
Post subject: 
We use 2 part foam at the hospital I work at to make cradels for patients to lay in. About a month ago a tech. shook up a batch and didn't get the cap off fast enough (about 20 secounds)..... it exploded and we now have foam all over the room.. Everyone here is correct, it is a bad Idea...
Author:  Coral Reefer [ Fri Jun 09, 2006 5:36 am ]
Post subject: 
And you thought I took some heat. Still sailing hard and will never have soft spots again. Pour them tips solid...
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