Author Topic: Spider cracks in cockpit hatches  (Read 4031 times)

MagicalArmchair

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Spider cracks in cockpit hatches
« on: October 30 2019, 17:58 »
Hello, thanks for all your help. Glad to see the boats have such an active community.

The cockpit hatches clearly have been slammed by a previous owner leading to spider cracks through the gelcoat. What colour is this gelcoat (is it off white? pure white?) and what is the best method for patching up?

This stuff (oyster white) looks too good to be true... https://www.amazon.com/MagicEzy-Hairline-Fix-Navy-Blue/dp/B00J1Y6PFU?th=1


Yngmar

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Re: Spider cracks in cockpit hatches
« Reply #1 on: October 30 2019, 19:30 »
Dirty white, by the looks of it! ;-)

Forget the MagicEzy stuff, it's for much smaller (hairline) cracks, and even then it didn't work particularly well when I tried.

These looks quite severe, you should check if the fibreglass below is still intact.

If it is and it really is just the gelcoat that needs repair, use a Dremel or similar to cut a groove out along each of the cracks, clean up with acetone, then mask (optional, but great trick to reduce sanding later), apply some gelcoat filler (the plastic padding stuff seems to match our 2001 Bavaria fine, but be very careful to get the mixing ratio right or it will yellow later) into the grooves. Let it cure through (24h depending on temperature), then sand smooth, wet-sand with increasingly finer sandpaper and finally polish. Should blend in perfectly if your gelcoat wasn't discoloured (it's quite hard to tell in this photo if it's just dirty or discoloured).

I do suspect you might need to do some fibreglassing first though, it really looks like the length of it has flexed (perhaps someone tried to force it close while something was wedged in between once).
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Baddox

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Re: Spider cracks in cockpit hatches
« Reply #2 on: October 30 2019, 20:48 »
I've tried the hair-line crack repair MagicEzy filler and wouldn't buy it again.  Despite following instructions to clean the crack with a pin it still didn't fill very well and the finish it gives is soft and not at all durable.

If it were my locker lid, I'd unscrew the hinges and take the lid somewhere warm to work on.  Clean if first with soapy water and no polish as that will have oils and wax which can affect bonding strength.
The cracks can be gouged out a tiny bit, to clean and give access to deeper parts before repairing with epoxy.  Warm the lid and epoxy to thin it and help if flow and creep into the crack.  Once the epoxy takes care of the structure, I’d fair it to a slight concave and add a colour matched gelcoat before polishing.

Salty

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Re: Spider cracks in cockpit hatches
« Reply #3 on: October 31 2019, 04:53 »
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The cracks can be gouged out a tiny bit, to clean and give access to deeper parts before repairing with epoxy.  Warm the lid and epoxy to thin it and help if flow and creep into the crack.  Once the epoxy takes care of the structure, I’d fair it to a slight concave and add a colour matched gelcoat before polishing.

Last I heard, while epoxy will stick to cured polyester resins such as glass fibre or gelcoat,  gelcoat would not stick to epoxy. At the time (seven years ago) epoxy would bleed some kind of resin, even after curing. That bleed would prevent polyester gel coats from sticking successfully. Maybe things have changed since then, but I’d want to check it out first before using epoxy.

Yngmar

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Re: Spider cracks in cockpit hatches
« Reply #4 on: October 31 2019, 09:43 »
Last I heard, while epoxy will stick to cured polyester resins such as glass fibre or gelcoat,  gelcoat would not stick to epoxy.

That is false and/or incomplete information. Gelcoat will adhere just fine to correctly prepared epoxy.

The "bleed" you mention is amine blush, which does form on the surface of some epoxy types during curing, but this is well known and treated by either washing it off (hot soapy water) or sanding off, as always, followed by a wipe with acetone to get any grease (usually from un-gloved fingers) off. With this preparation, there are no issues with adhesion of following layers, including gelcoat/flowcoat.

The only thing that has changed over time is the introduction of peel ply, a thin layer of woven nylon that is laminated on top of the epoxy and then ripped off after curing, taking the amine blush with it and leaving a nice smooth surface, therefore making the extra steps of washing (and sometimes even sanding) unnecessary if peel ply is used. But on small area repairs, sanding is still the go-to tool.
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Symphony

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Re: Spider cracks in cockpit hatches
« Reply #5 on: October 31 2019, 10:07 »
Agree that the underside needs investigation as they are more than the usual gel coat spider cracks. Actual repair method will depend on what is found after the crack have been opened out and any reinforcement applied underneath. If the cracks only go through the gel coat then the Gel coat filler is probably the best option rather than just gel coat. If they go deeper into the laminate then using epoxy first to seal the exposed laminate maybe worthwhile. The standard Plastic Padding filler seems to blend in well with original gel coat.

Rampage

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Re: Spider cracks in cockpit hatches
« Reply #6 on: October 31 2019, 17:36 »
I’ve used this https://www.ecfibreglasssupplies.co.uk/product/gelcoat-repair-kit-super-white kit repairing gel coat dings and cracks.  It’s a good deal thinner than the Plastic Padding and other repair kits (think none drip paint) so it’s not as easy to work with but it give first class results.
Open put the cracking with a Dermel, clean and then apply the repair so it is at the level of the surrounding surface.  Apply peel film over the top and allow to go off.  Remove the film and that may be it.  However, it’s difficult to get the surface level with first coat, so you may need to build it up a bit before sanding back.
I’ve found that using the putty type repair kits the colour match goes over time, whereas the East Coast stuff doesn’t loose its colour at all.  It’s also easier to make sure that there are no little bubbles in the repair which are difficult to see when you complete the repair but they fill with dirt over time and the repair becomes obvious.

Salty

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Re: Spider cracks in cockpit hatches
« Reply #7 on: October 31 2019, 20:44 »
Last I heard, while epoxy will stick to cured polyester resins such as glass fibre or gelcoat,  gelcoat would not stick to epoxy.

That is false and/or incomplete information. Gelcoat will adhere just fine to correctly prepared epoxy.

Thanks Yngmar, that’s interesting to know.

Back in 2011 my boat was used for charter, but during the middle of that year a group of sixteen persons chartered two boats from the hire firm. One of the boats was mine while the other was a larger Bavaria. They went offshore and had a collision in which the bow of my boat was holed above the waterline. The chain locker remained reasonably intact, but the damage extended back as far as the aft bulkhead of the chain locker. The damage was repaired at the boatyard by a glass fibre “specialist” called in by the yard to carry out that repair. Initially I had been advised they would make a mould and lay up a new bow in the conventional manner, but that didn’t happen. Instead they made a repair using epoxy resins, and were unable to get a gel coat to stick, and I was advised of the different procedure only after the repair had been completed. The surveyor employed by the yard to oversee the repair gave me an assurance that it was a good repair, an assurance which I paid for separately, but who went on to tell me that they had been unable to get the gel coat to stick. Going online at the time of the actual repair in early 2012, the various reports I read confirmed that one would be unlikely to get a polyester gelcoat to adhere adequately to an epoxy resin repair, and more recently I have spoken to a different GRP specialist and he has not been forthcoming to suggest anything different from that of the original repairer. In consequence the bow was painted following the repair, but although time has gone by, there is still a noticeable difference in colour between the repaired area and the adjacent gel coated areas. I would love to have the bow matched in to the rest of the hull, but I don’t want to pay for having gel coat applied if it is only going to fall off after a year or two.
As for the strength of the repair, well I’d say it falls into the category of the proverbial brick built outhouse which may sound good, but with my seafaring background I am very conscious of the fact that ships years ago used to have tremendously strong bows, but after a head on collision they were written off because so much damage was transferred further aft as to make repairs financially not worthwhile. Since then ships have been built with crumple zones, much like cars.
If anyone has some definitive information on successfully applying gelcoat to an epoxy substrata, I’d appreciate seeing it.
The photos below show before and after the repair.

Yngmar

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Re: Spider cracks in cockpit hatches
« Reply #8 on: October 31 2019, 21:47 »
Video by Andy from BoatworksToday showing epoxy/gelcoat (polyester) bonding: https://www.youtube.com/watch?v=kHAbyglpp3M
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Salty

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Re: Spider cracks in cockpit hatches
« Reply #9 on: November 01 2019, 04:07 »
Thanks Yngmar, that looks pretty convincing.

My repairs after seven years should be fully cured by now, and hopefully the paint should come off with sanding and/or paint remover treatment followed up sanding.

One last thing, does anyone know how long the West 206 and 207 systems have been around?

fjoe

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Re: Spider cracks in cockpit hatches
« Reply #10 on: November 01 2019, 10:52 »

MagicalArmchair

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Re: Spider cracks in cockpit hatches
« Reply #11 on: November 01 2019, 13:41 »
Or a new one? https://www.svb.de/de/bavaria-gfk-deckel.html

Regards
Frank

Thanks, I'll look at that kit from EC fibreglass. I have used EC many times in the past for other GRP stuff I've done, so I'll give that a go. I'll look at the structure underneath to see if it needs any reinforcing as just repairing the cracks without repairing the cause of the cracks won't move me much forwards!

Yikes Salty, that looks like quite a ding - the repair looks more like a feature than a mis match mind you, which is something at least.

What Dremel attachment would you suggest for opening those cracks up with? Something like the one on the far left of the below?

https://www.amazon.co.uk/dp/B07PVFCGGL/ref=cm_sw_r_cp_tai_zxdVDbYYB4MAX

Rampage

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Re: Spider cracks in cockpit hatches
« Reply #12 on: November 02 2019, 22:14 »
Something like that will be fine.  I inherited a job lot of dental drill burrs (from my father in law, who was a railway modeller) which fit nicely into a Dremel.  Those off The Amazon link look surprisingly like the ones I have.