Hey all,
Just need some advice on a crack in one of my hulls. The littlest of my boys and his friend managed to somehow???!!!!! put a brick into the hull. As you can see its the same size as my thumb and is about 2mm deep.


It does look like it has torn the fibreglass at the right to a length of 6mm. Any ideas? I have some advice to put some marine knead it epoxy in there yet just wanting second opinions. Hate to see it crack further.

If the boat is polyester do not use epoxy - unless you want to paint it with polyurethane.

Get inside and look at the damage from inside. Also chip away at the gelcoat and remove any flaking areas. Sand the edges back. If the glass is damaged you may be fine if the laminate is thick. If not then a light piece of glass will do in the gap.

Probably you will be fine with sanding back the edges and removing the loose stuff and then putting FLOWCOAT into the gap. This is the same as gelcoat but it can cure in air. It is thick and let it stand proud. Then sand down and polish.

If your boat is a foam sandwich beach cat things are trickier.

Good as new

Phil

Yes it's a beach cat. H16.

Okay - now check if there is foam under the fibreglass. If so the repair is different from solid glass

Not mine but shows how they are constructed. Skin over foam over inside skin.
My hole is about half way up on the outside skin, on the tramp side of the hull.
Thinking because of its location there will be some flex which is why i am worried about further cracking

I am not an expert in light laminate foam core hulls. I would still dig away at the gelcoat. If the glass is okay then just flowcoat and polish. If the glass is cracked I would get a small grinder or dremmel and feather the edges of the glass back to nice areas. Then lie in some strong glass, nice close weave cloth, and wet it out and pack it down nicely. Grind the edges of the glass back and go over with flowcoat - sand with a block and then polish.

So got the grinder out. Just looking at the photos seems I might need to chase the crack up in the top right. Just eating lunch so will update after the motogp finishes.

Found this video. Its a patch it job thats kinda similar.

Thinking i can well the area by grinding back a bit and then fill it back up again. Sound right? Or would I need to cut the colour changed patches out?

Call me silly but that looks like carbon to me

Is the hole over the laminated area or near the bottom where the hull is solid glass ?

If its in the laminated area you need to fix the delamination as well as patch the hole.
I'd use West system 105 with 206 hardener and if possible get the damaged area horizontal to make it easier to wet it and build the layers of cloth . Depending on how deep you ground the area around the crack cut a few pieces of 100-200gsm fibreglass cloth starting with a small one the size of the damaged white area and increasing in size until they are as large as the area you removed the gelcoat from. Then pour 10 ml of epoxy mix over it so it wets the area and sinks into the crack to fix the delamination. If you can get your hands on a teaspoon of West System 403 mix a bit with epoxy and force it into the crack otherwise you can get away without it. Then brush some epoxy over the repair area and begin covering the hole with the glass cloth you cut earlier starting with he smallest one and wetting the cloth in between layers until is level with the surrounding area. Once the repair is cured sand it just BELOW the surrounding area finishing with some 60 grit wet sanding. The last art is to clean the epoxy blush from the surface and to prepare it to take the matching color polyester gel which goes slightly higher then surrounding area. Once the gel coat is cured sand and polish to your liking.

If you have the time I suggest that you watch the repair being done step by step by professionals , just do a search for the BoatworksToday videos on youtube. Worth your time if you want to do the job properly.

Harb is right if you are fine with painting the area afterwards. I use epoxy exclusively and it adheres very well to cured surfaces. You just won't be able to use polyester products like flowcoat over it. You could do everything Harb says and substitute poly if you want to flowcoat it. Poly is cheaper and faster to cure but not as strong or good at bonding.

I might try to grind out the white looking glass only just a little bit more but you are doing a good job. You might try going to the chemist and getting a syringe. Then you can squeeze in some thickened resing behind the crack.

Don't worry too much. Get some resin into the crack and then put a couple of fine layers of glass on top. A little silica or microballons (only a very small amount - say honey consistency) will help the very first layer of glass lie properly over the crack.

And no she isn't carbon - the foam is a grey foam that gives the glass a dark colour. Carbon is so thin it is a pain to work with in light laminates.

Cheers

Phil

sorry to but in, but if you are using cloth start with bigger pieces and work down to smaller bit,s as this will bond all the layers together ,if you put smaller bits first you will have multiple joints in the glass.try to make your first bit up to the were the gel coat starts ,also you can use flow coat over epoxy it just needs the epoxy sanded,look up boatworks he has a video testing it. i have done a 1 meter square patch on the side of a boat with good results using epoxy to repair and flow coat to finish ,you could not find the area easy after it was done.also make sure it tapers well the better the taper the better bond

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grich62 said..
sorry to but in, but if you are using cloth start with bigger pieces and work down to smaller bit,s as this will bond all the layers together ,if you put smaller bits first you will have multiple joints in the glass

But wouldn't doing it that way leave the whole build up of layers only laminated to one piece of cloth.,, meaning that if the first layer you put on some how de laminates, the whole chunk you built up will come away with it.

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Jolene said..

grich62 said..
sorry to but in, but if you are using cloth start with bigger pieces and work down to smaller bit,s as this will bond all the layers together ,if you put smaller bits first you will have multiple joints in the glass

But wouldn't doing it that way leave the whole build up of layers only laminated to one piece of cloth.,, meaning that if the first layer you put on some how de laminates, the whole chunk you built up will come away with it.

Exactly ! A little research will reveal that small to start with following the contour of the ground out "hole", over build slightly, sand back fair and refinish. Poly is perfect for this job.
Cheers.

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Jolene said..

grich62 said..
sorry to but in, but if you are using cloth start with bigger pieces and work down to smaller bit,s as this will bond all the layers together ,if you put smaller bits first you will have multiple joints in the glass

But wouldn't doing it that way leave the whole build up of layers only laminated to one piece of cloth.,, meaning that if the first layer you put on some how de laminates, the whole chunk you built up will come away with it.

you are looking to have a good bond , so it will not mater how you put the glass in if it de laminates you have not prepared it right the idea of laying the big piece in first is to stop fibers butting up there layer which lines all the breaks up and is weaker .look at smmrr video and you will see he started with the big piece and finish with the small .also if you check out west systems they will show you the correct way to lay down the glass for filling holes using there product



uncle bob
i have researched this and it is on several sites by starting small you are lining up end fibers and relying on the glue if you want to test this get some glass and sand a 12 in 1 taper in it. but the glass up to each layer and resin then do it over lapping the big down the fibers have got more contact and are stronger because no ends line up.
this page has very good help and you can read how they lay glass.it is in section 4 of the download.
http://www.westsystem.com.au/files/fibreglass_boat_repair__maintenance/rm_fiberglass_boat_repair_and_maintenance.pdf
not looking to start a fight about this but i think it important info ,cheers

The correct method for what is essentially a cosmetic repair on a used Hobie cat is as follows:

-roughly remove any flakes of gel coat.
-fill the indentation with a tight screed of car bog.
- affix a 'Hobie... it's a way of life' sticker over the top.

An alternative is to affix an 'I love my Hobie' sticker over the ding.

Anything above this is overkill for a cosmetic repair in a noncritical area on an overengineered used Hobie cat.

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AshleyM said..
The correct method for what is essentially a cosmetic repair on a used Hobie cat is as follows:

-roughly remove any flakes of gel coat.
-fill the indentation with a tight screed of car bog.
- affix a 'Hobie... it's a way of life' sticker over the top.

An alternative is to affix an 'I love my Hobie' sticker over the ding.

Anything above this is overkill for a cosmetic repair in a noncritical area on an overengineered used Hobie cat.

love your work ashely ,whats wrong with just gafa tape ,to hard to find stickers

Geez feeling a bit burnt by all this. Emotional rollercoaster. Carbon fibre h16 to stickered up diving pontoon. Lol.

Thanks for all the help everyone. Really appreciate the advice so far.

I'm really glad no one has chipped in with the knead it putty as it re-affirms to me that I needed to do a proper job. This boat while a little old was in top condition and it took me a while to find. So it means a lot to me. Even without all the good times hanging off the side blasting around.

It will take me a couple of weeks to finish this as I'm at the pointy end of university for the semester. Plan is to chip away so its ready for the summer.

Simmrr, if you like tinkering around on boats then do what you feel compelled to do. But your initial ding was cosmetic in nature. I didn't think of the Sellys Knead-It putty, but that would have been sufficient. Given that you've now ground the daylights out of your boat, I think you are committed on a path that will no doubt bring you much potential satisfaction.

As an aside, is your Hobie foam cored? I'm pretty sure the early Hobies were solid glass.

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grich62 said..

Jolene said..

grich62 said..
sorry to but in, but if you are using cloth start with bigger pieces and work down to smaller bit,s as this will bond all the layers together ,if you put smaller bits first you will have multiple joints in the glass

But wouldn't doing it that way leave the whole build up of layers only laminated to one piece of cloth.,, meaning that if the first layer you put on some how de laminates, the whole chunk you built up will come away with it.

you are looking to have a good bond , so it will not mater how you put the glass in if it de laminates you have not prepared it right the idea of laying the big piece in first is to stop fibers butting up there layer which lines all the breaks up and is weaker .look at smmrr video and you will see he started with the big piece and finish with the small .also if you check out west systems they will show you the correct way to lay down the glass for filling holes using there product



uncle bob
i have researched this and it is on several sites by starting small you are lining up end fibers and relying on the glue if you want to test this get some glass and sand a 12 in 1 taper in it. but the glass up to each layer and resin then do it over lapping the big down the fibers have got more contact and are stronger because no ends line up.
this page has very good help and you can read how they lay glass.it is in section 4 of the download.
http://www.westsystem.com.au/files/fibreglass_boat_repair__maintenance/rm_fiberglass_boat_repair_and_maintenance.pdf
not looking to start a fight about this but i think it important info ,cheers

Starting with small pieces and working out with larger pieces is an attempt to repair each of the layers of glass in the original laminate.
Starting with a big piece and working out to smaller pieces is nothing more than a plug. You might aswell lay one piece of cloth and fill with bog.

De-lamination can occur due to mechanical forces even though the bond is at maximum strength. By laying the large piece of cloth first you create a single, smooth uninterrupted joint of different materials that runs from the outside then in, over a large area to the full depth of the laminate ( A plug). This may be fine for small holes that pose no risk to sinking your boat if the plug where to de-laminate.

I think one has to undergo serious thought as to the way this sort of repair method is undertaken when repairing below the waterline
eg: glassing over an old through hull,,,

Starting with a larger piece makes a lot of scarf joints.

Starting with smaller pieces makes a lot of butt joints.




I know which ones I consider stronger

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nebbian said..
Starting with a larger piece makes a lot of scarf joints.

Starting with smaller pieces makes a lot of butt joints.




I know which ones I consider stronger

Grinding out a damaged area at 12 to 1 and filling the resulting hole starting with the small piece layering ever increasingly larger sections will give you a series of scarf joints layed over the previous ones, essentially multiple scarfs, not a butt joint to be had. The boat was built with poly and poly properly used is a perfect repair.

If you want to view some brilliant glass work, jump over to crusiers and sailing forum and search through the posts of a member that goes by the name of Minaret.

Doesn't matter which way you lay up the patch ie small to large or vice versa, what is important is the adhesion of the new to old. Polyester resin has an adhesion of 1when applied to a cured poly surface, vinyl ester resin 4 and epoxy resin 10. therefore an epoxy patch will stick on and be stronger by an approximate factor of 10. For a small patch area gelcoat will adhere well enough to washed and sanded epoxy to complete the job, just need to add wax to the gelcoat or cover with gladwrap to aid cure.

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Kankama said..
Harb is right if you are fine with painting the area afterwards. I use epoxy exclusively and it adheres very well to cured surfaces. You just won't be able to use polyester products like flowcoat over it.

Of course you can, just have to prep the epoxy properly.
I did just that on my kayak and on the bow of the cat when I started learning to fiberglass and was experimenting with fixing the cat and the kayak. I had no adhesion issues with either the repaired patches or the test pieces which were done using gelcoat on triaxial cloth and on twill epoxied to strips of polyester sheet. The last one I gelcoated on both sides to compare the difference. Te adhesion was fine but I did ran out of tint before I could match the faded gel coats , one green the other blue, so the repairs stood out but on white hulls is easier to match color. In the end my plans changed and decided to strip the entire gelcoat from the boat , reinforced it with more cloth and fair it before painting with 2 pack.

Here is a site describing Andy Miller's tests,
www.epoxyworks.com/index.php/applying-polyester-gelcoat-over-epoxy/

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UncleBob said..

nebbian said..
Starting with a larger piece makes a lot of scarf joints.

Starting with smaller pieces makes a lot of butt joints.




I know which ones I consider stronger

Grinding out a damaged area at 12 to 1 and filling the resulting hole starting with the small piece layering ever increasingly larger sections will give you a series of scarf joints layed over the previous ones, essentially multiple scarfs, not a butt joint to be had. The boat was built with poly and poly properly used is a perfect repair.

If you want to view some brilliant glass work, jump over to crusiers and sailing forum and search through the posts of a member that goes by the name of Minaret.

Here is a link to the member that I mentioned previously.
www.cruisersforum.com/forums/showthread.php?s=5479b5d083f6a95835e162b3daaf23fb&p=2626567#post2626567

So small repair job has turned into a bit more than I thought it would be. Nothing major.

Just found another small hole stabbed in the other hull. Flipped the hulls over and noticed a couple of spots where the gel coat had chipped off the bottom. The more I sanded the more chipped off. There were small spots of some sort of bog that the gel coat just chipped off. So repaired it properly with some resin with fibre dust added.

Long story short with the holes in the hulls I went with polyester resin, added some fibre dust into it and then layed the fibreglass. Hopefully that gives the resin a bit more strength. Just put the first coat of gel coat on.

The more I look the more I see. Glad its only a small boat.

A couple of shots of the fibreglass repairs.






Pretty happy with the outcome. There are two layers of gel coat over the top of that now. Just waiting for my back to chill out before sanding again.

New discovery is this protusion abovr the rear pylon! Just happened to catch it at the right time of day and shadow to notice it.




There is some cracking at the lump and around the pylon on the top of the hull. Have asked on the hobie forum and it is possibly a loose pylon shoe? I will have to cut an inspection hole to see what has happened.

Thread resurrection from the grave.

With my back feeling better I've finally managed to flip the hulls over and cut a hole in the boat today.








So as you can see the pylon has let go of the glue. Possibly the fibreglass around the pylon has come away as well. Need to have a closer look when the rain has gone.

So going to be a bit of messing around to do this job through the hole.