Delamination

I know a lot has been written in the forum about this subject but I have a quick question. There is some delamination on my Hobie 16. It is on top of the hull and is about 12-15" long and about 6" wide. What is the rule of thumb in determining how much Git Rot to use to fix the delamination

Buy more than you think you need (I do double). You can always return the unopened boxes. It is very hard to run to the store and buy extra when you are in the middle of the repair.

_________________
Nick

Current Boat
In the market
Previous boats owned
'74 Pearson 30
'84 H16
'82 H18 Magnum
St. Louis, MO

One pack should do it... but like HE said... buy extra.

The delamination is a thin area (like the area between pages in a book). You can pump in a bunch of resin and force the layers apart, but the structure will want to return to it's normal shape and squeeze the excess resin back out... as it should. Less material is actually better that too much. You don't really want a thick layer of resin between the glass and foam.

_________________
Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)

I tried something that I had not seen anyone post about, and it seems to have worked great.

I have been working on my '77 Hobie 16, that had delamination on the decks in front of pylons. I had already decided to install hull inspection ports fore and aft, in order to repair some other hull damage from the trailer rollers on the keel.

So having cut the holes in the deck, I decided to try injecting the Gorilla Glue using a basting needle from inside the hull. I would just stick the needle through the inside fiberglass, and into the foam. I did not need to drill holes, the needle went through the fiberglass matt inside very easily, and I would just squeeze the shringe full of glue into the various soft spots I could feel on the outside. Then when the glue foamed it was inside the hull, and my Gell coat was undamaged. The hulls are now rock hard!

Has anyone else tried this, and should I expect it to hold? The Gorilla glue is 100% waterproof polyurethane, and available at Lowe's and Home Depot. Suppose to be real tough stuff. I figured the glue when it foamed should be as strong as the original foam and adhered to the fiberglass inside and outside layers. Thanks, TnT

I tried the Gorilla Glue using the standard "drill holes in the deck" method and I didn't like the results. When it foamed it just spooged out onto the deck and I spent a LONG time sitting there wiping it off as it came out; but I STILL have sanding to do to get the rest of the foamed glue off the decks. Your method sounds like it might work okay; but didn't you get any glue where you didn't want it? Did you put some newspaper down on the inside of the hull to catch drippings or what?

Anyway, glad it worked for YOU.

_________________
Warm regards,

Jim

HobieDude,

Whatever you do, make sure you have enough epoxy to finish the job. If the epoxy even partially cures because you have to go to the store to get some more, you may end up with a less-than-adequate fix. The cured epoxy then reduces your access to the remaining delamination.

Also, because your delamination area is relatively small, if you can complete the job without having to drill holes in the textured (non-skid) portion of the hulls this would be best. Cosmetically speaking, it will be nearly impossible to patch over and hide holes there, as opposed to the smooth areas of the gelcoat.


Dave

The other holes that you do not inject the epoxy into are there to let air escape. You will get a more complete fill of the delam area if you drill these holes. I drilled them very tiny so they are barley perceptible in teh textured area of the gelcoat.

I also like the thinner epoxy mix because it flows much more redily into the delam area. Git Rot is a great pre packaged system for this repair. My concern with the Gorilla glue is the foaming. This may push the layers apart and weaken the fiberglas laminate.

_________________
Nick

Current Boat
In the market
Previous boats owned
'74 Pearson 30
'84 H16
'82 H18 Magnum
St. Louis, MO

Jim, I found that the glue did come out inside the hull, but it wasn't hurting anything inside there. The inside is sort of rough and unfinished. I figure to be able to store drybags inside the hull, and maybe other stuff like lunch and water, repair parts and tools. The ports, will also help dry out the hull, but nothing that the glue will hurt. Also if there is subsequent delamination, it will be easy to reach in and add more glue, with out having to do any refinish on the outside. Seemed like a good technique all the way around.

Captain Dave, I would restate, that I did not have to drill any small holes in the deck, I just reached inside the hull, and injected the glue through the inner glass mat. I can also add more of the glue in the future, so that I am not restricted by having all the epoxy resin to start with. I did some last weekend, and plan to do a little more this coming Sat. That way I don't have to worry about repairing the gel coat at all or the textured part of the deck now or in any future repairs.

Hobie Nick, I was also curious about the foaming of the glue, but the inside glass is porous enough that the excess glue does not build up pressure and distort the hull, but instead just bled through the glass matt inside, and dripped down a little inside the hull. I expect that the same technique could be used with the Git Rot, but the Gorilla Glue is a lot less expensive. Also the foam readhered to the existing glass, and stabilized the original foam structure. The epoxy resin and Git Rot, would have adhered to the glass fine, but the contact with the existing foam would be no stronger than the Gorilla Glue, and subject to the same delamination.

I examined the hull material that I cut out inorder to install the hull inspection ports, and found that the foam had separated in three area. The first was at the division between the foam and the outer glass, second, the foam and the inner glass, and third, in some cases the foam had split apart. The glue had to be able to readhere to both glass layers, and also the foam itself.

So I saw no gain by using the resin, unless you removed all the existing foam, and filled the entire layer with the resin. Otherwise any new layers would still be based on the strength of the foam itself, and the strengtn of the other layers, ie. the resin would be compromised by the contact with the foam.

The foam removal could be done only by removing the entire outer shell of the deck which would then allow you to reinforce the whole area with resin, but that would be a lot of work, with questionable results.

So though the glue does not have the strength of the resin, it is just as strong and probably stronger than the original foam. It seems to have re glued all three areas of delamination, and the hulls that I have done are now rock hard. TnT

_________________
Life is about each moment of breath,
Living, about each breathless moment!

Tinkerntom, aka TnT

and now a friendlier, "RkyMtnHootOwl"


2 WW kayaks,
'73 Folbot Super,
pre '60 AEII
77 Hobie Cat 16

Tinkerntom,

Your fix is an interesting one. When I made the comment about trying not to drill through the non-skid gelcoat, it was meant for Hobiedude and not in reference to the work you have done.

As for your fix - it does sound clever. However, when I read your emphasis that your repair job DID NOT require you to "drill any small holes in the deck" - I confess I made a little chuckle to myself - because your fix only works if you cut a GIANT hole in your deck. To me this is not very appealing. But, if your goal was to install the hull ports anyway, then your tactics definitely have merit and your fix is a viable option.

Regarding Gorilla Glue, I have never used it myself. I have no problem with the fact that it is a polyurethane per say, but, I would worry a bit about the low viscosity and expanding qualities of that adhesive for a job like this. Matt said it best when he desribed delamination as being similar to the space between the pages of a book. In that sense, the traditional epoxy fix is designed to thoroughly wick into the smallest space and and re-bond the core to the glass - uniformly and without really occupying voids to any significant degree - there shouldn`t be any real voids. An expanding polyurethane glue is specifically designed to FILL VOIDS. It has no wicking ability in this form, and will expand in a way that may actually separate, to some degree, the core from the glass. It will then try to occupy SOME of the voids left behind - which the glue itself created.

This repair may hold, but it may also create future problems. Such as; slight architectural distortions and more likely , renewed delamination because of poor wicking and the resulting incomplete bond between the two surfaces. In this case, unfilled voids or poorly bonded areas continue to flex slightly and then break the bonds of adjacent areas, and so forth....delamination all over again. This is why professional repairs of this kind are synonymous with low viscosity, slow cure epoxies which do not behave in this fashion.

You mentioned a few times about the "strength" of the original foam not being aided by epoxy resin and that polyurethane foam is even stronger than the original foam. This may be true, but the important point here is that in a cored construction of this sort, the strength of the foam is irrelevant - within reason. The foam core serves only to keep the glass laminates (inside and out) at a constant distance from each other - thus reducing overall flexibilty. This provides the kind of superior strength, light weight and rigidity seen in the physics of a tube - as opposed to a solid rod. Tubes are lighter and stronger (pound for pound) than a solid rod of the same material. But, a tube is only like this along as its` architecture retains its shape/integrity. The same reasoning applies to boat construction. What is important, is the UNIFORMITY and COMPLETENESS of the bonding between the foam and the glass (ie.) all surface area is bonded with no voids or distortions. Even small unbonded areas can eventually lead to problems or structural weakness. Expanding polyurethanes are unlikely to prevent this as well as epoxies - too much air/gas in the expanded adhesive and too viscous. The bonds between the foam core and fiberglass don`t even have to be very strong - anyone can rip a bond from a piece of foam - regardless of the adhesive used.

This can all happen with epoxy too of course. It is just a matter of degrees. Keep your eye on it and check it often. If it starts again, nip it in the butt (so to speak).


Dave

Captain Dave, I appreciate your chuckle about no small holes, but one large hole!!!

I had to really twist my arm to convince myself that I really wanted to cut those big holes. One port was already installed in the port deck, and the port stern was where the damage was that I had to get into to repair from the inside. The SB hull was delaminated in front, with a lot of water inside, and so I decided to bite the bullet, and install hatches at all four points. I figured at least the hulls would be able to dry out, and then I also figured out that I would be able to inject the glue from inside, and that convinced me.

Anyway, when I injected the glue, I started about 6" inside the hole, and the glue flowed fine back to the edge exposed at the hole. The glue has about the viscosity of maple syrup. It does not foam up immediately, but seems to flow around, and then foam as it dries. There does not seem to be any distortions from the foam, and I will certainly be watching it for future delaminations.

Regarding the structural design strength of the foam sandwich, I understand what you are saying about the tube being stronger than a solid rod. What I found in the delamination that I found in my decks, was that the layers of fiberglass had separated from the foam and from each other. They could flex independently of each other. The glue would reform the orginal structure, which was dependent upon the strength of the internal foam layer. Obviously this was the weak point because this is where it broke. The Gorilla Glue appears to have reformed the original foam structure by reattaching the two glass layers.

I will be watching real close for any further delamination or other breakdowns in structure. Thanks for your insight. TnT

_________________
Life is about each moment of breath,
Living, about each breathless moment!

Tinkerntom, aka TnT

and now a friendlier, "RkyMtnHootOwl"


2 WW kayaks,
'73 Folbot Super,
pre '60 AEII
77 Hobie Cat 16

Hey, how is the Gorilla Glue working ??

Due to some major changes, I have sold the Hobie 16, happily it passed the buyers concern over any soft spots. The hulls sat outside all winter, and were still in great shape. So someone is going to have a great time sailing this summer! TnT

_________________
Life is about each moment of breath,
Living, about each breathless moment!

Tinkerntom, aka TnT

and now a friendlier, "RkyMtnHootOwl"


2 WW kayaks,
'73 Folbot Super,
pre '60 AEII
77 Hobie Cat 16

Boy, you took some heat about the gorilla glue, but if it works,,I have a very large area to repair too

Well I don't know that I felt the heat so bad, I realized I was suggesting doing things different than they had been done before, but it definitely seemed to work, the fore decks had been soft, and afterwards, rock hard!

If I did it again, I would take a little more time to turn the hull upside down, that way the glue would have stayed on the underside of the top deck. As it is there was some that ran down the inside of the hull, but no real problem.

Also by being able to open the inspection ports, the hulls were nice and dry. The new owner thought it was great to be able to store small things in the hulls.

So it all worked out, and the only thing I had left to do was paint the hulls, but the new owner said it was just the way he wanted it, and that way he did not have to worry about scratching the boat as he learned to sail.

He was happy, with his new boat, and I will just have to get another one some day! TnT

_________________
Life is about each moment of breath,
Living, about each breathless moment!

Tinkerntom, aka TnT

and now a friendlier, "RkyMtnHootOwl"


2 WW kayaks,
'73 Folbot Super,
pre '60 AEII
77 Hobie Cat 16