another gelcoat question - how thick ding before filler?

[fstarocka]

i spoke to a pro who does all the local insurance work and we spent 90% of the time talking about gc vs paint as a final - he suggested a filler though. Im not new to fibre glass work, the whole damaged area is 4" long (incl spider cracks) -

I appreciate the info but I dont think the severity warrants that much "digging" into the hull - it was a light bump that cracked the gc - there isnt even a resemblance of a dent. Had there been yes I would delve deeper.


Dave thanks for the vid - so in short die gring the cracks / apply marine filler / sand 180 grit to leave a key for the gc / gc with factory kit / buff in 3 stages and final wax

The rest of the surrounding areas just looks real good so ill be working very carefully :/

fyi I have done about 8 years body work and a fair amount of fg work on inflatables and fishing boats..

anyway tx for all the replies -

this kind of answered my original question:

https://youtu.be/Flj8vapM5mU?t=256

[ramblinrod]

Originally Posted by fstarocka

i spoke to a pro who does all the local insurance work and we spent 90% of the time talking about gc vs paint as a final - he suggested a filler though. Im not new to fibre glass work, the whole damaged area is 4" long (incl spider cracks) -

I appreciate the info but I dont think the severity warrants that much "digging" into the hull - it was a light bump that cracked the gc - there isnt even a resemblance of a dent. Had there been yes I would delve deeper.


Dave thanks for the vid - so in short die gring the cracks / apply marine filler / sand 180 grit to leave a key for the gc / gc with factory kit / buff in 3 stages and final wax

The rest of the surrounding areas just looks real good so ill be working very carefully :/

fyi I have done about 8 years body work and a fair amount of fg work on inflatables and fishing boats..

anyway tx for all the replies -

this kind of answered my original question:

https://youtu.be/Flj8vapM5mU?t=256

Boat works today prepares great videos,but I fear you are only listening to the answers that support your predisposition.

If you watch the other videos in that series, you will realize that for the damage shown i that photo, yup need to do a lot of grinding and glossing before the filler is touched.

Neither filler nor gelcoat fixes fractures.

For fractures you need glass.

[ramblinrod]

For what it is worth, in the hope that I can prevent an improper repair from being performed, and more future complaints about "I hired a professional with 8 years experience and they only used filler".

Originally Posted by fstarocka

i spoke to a pro who does all the local insurance work and we spent 90% of the time talking about gc vs paint as a final -

The other 10% should have been spent talking about the glass repair before the filler is applied.

Curiosity, with all of your prior experience, after speaking to a pro at length, why turn to forum of boaters with unknown qualifications, asking such a rudimentary question?

he suggested a filler though.

I concur that filler will be required to fair the repair after the old damaged glass is ground out and new glass laid in. Filler is only used in a thin layer to fair a sound surface. On its own, filler has little strength, gelcoat even less.

Im not new to fibre glass work, the whole damaged area is 4" long (incl spider cracks) -

Then you should know how to determine the extent of the fracture, and that the repair area will end up being at least 12" long by 8" wide, if 1/4" glass is fractured all the way through.

I appreciate the info but I dont think the severity warrants that much "digging" into the hull - it was a light bump that cracked the gc - there isnt even a resemblance of a dent. Had there been yes I would delve deeper.

The point is you can't "think" about how deep the fracture is, you have to "know". Grind it out, a bit at a time, wiping with highly thinned lacquer to show the crack, and keep grinding until there is none, or you are one layer of glass from going all the way through. Then feather a 12:1 ratio (to depth) beyond the damaged area. Then lay in new glass to .080 below the original surface, fill to 0.40 below, and gelcoat to 0.20 above. Then progressive sand and polish to fair.

If possible, work from the backside so the least amount of good side needs to be final finished.

Fibreglass does not dent. On impact it deflects and springs back. If the deflection exceeds the tensile strength of the substrate, it fractures, but it still springs back.

[David M]

Originally Posted by fstarocka

Yes I have the original gelcoat from manufactoring company. But it's arriving in over a week. Was just curious if I could patch up the groove with filler so boat can go out and finish off with gelcoat.. Yes will grind cracks etc.. Or tape it with clear 3m since it's way high up and only gc it..

Wait until you get the original color gel coat. You don't want to risk your wrong color filler showing through your final application of gel coat.

[ramblinrod]

Here are some photos of a proper crack repair (this one not accessible from the back side).

Typical "gelcoat spider crack"...



Actual repair required (original photo 3rd repair aft from front)...



Final result...



Normally, I recommend gelcoat final finish (more durable and easily repaired, as seen on decks and coachroof) but the hull is Awlgrip (as my wife wanted our personal boat to be "Flag Blue").