SPIDER CRACKS IN GELCOAT

[Bimmerguy]

Hello and thank you for reading..
I have a few spider cracks in my blue hulled gelcoat, there are also a few scratches, I'm getting ready to do my yearly prep work to get the boat in the water and would love to get rid of the scratches, I've read that 600 grit wet works then rubbing compound but I sure would like input before I do anything I may not be able to repair... Thanks in advance for any replies.

[Divecoz]

Ive rubbed out a lot of Custom paint jobs in my lifetime.. Water is the key.... use lots of water with that 600.. Go easy as well with the rubbing compound.. I have BIG Heavy Professional buffers.. I Very Seldom Use Them ANY More.... I have 2 cheap plastic ones from some Big Box Store.. 1 is 9" 1 is 6" both are Orbital and much easier to use ( lighter less violent!).. I have found for myself that Meguires ( SP) Polishing Liquid Does a Beautiful Finish Buff.. I DONT USE Dish Soap.. I Do Use Automotive ( Car) soap..and I wash and rinse 3 times.. I just did the wife's car Monday.. 2006 Ford Taurus.. I washed it 3 times Buffed it with the Meguires and then gave it 2 coats of Nu Finish.. Nu Finish is not a real wax so it might well be absorbed into the gel coat.. Who cares?? Those who think someday they will spend either THOUSANDS! of Dollars!!! having their boat entirely painted or spend a couple months doing it themselves..
1 member on this board , did just that .. I envy him but NOT enough to spend a month or more doing it..
FR Many Years I was a Die Hard Blue Coral Wax guy.. Over The Years I have com to realize.. Its not worth it EXCEPT ! For the bragging rights..
I no longer hang out with the Custom Car and Bike Crowds, but when I see them I always as what they are using and NONE waste his time on Old Fashion Waxes.. 1/10 the time and more luster and greater depth is accomplished with numerous new products..

[DaveB]

All depends on how deep the scratches are. Mac. is known for thin gelcoat, a good gelcoat is 20 mils thick. If your scratches are deeper than the gelcoat or close to it you will need pro to do the job. If it's minor than use a small wood block and wrap between 400 and 800 wet sand paper, only sand until you barely see the crack. Than go to 1200 than 1500. Than wax.
If you are talking about structual/facial cracks and not rubing scratches than you need to V shape the crack and best left to a pro.
Good to thing to remember is if you scratched the hull, easy fix but if stress at that hull point be left to a Pro.
Dave

Hello and thank you for reading..
I have a few spider cracks in my blue hulled gelcoat, there are also a few scratches, I'm getting ready to do my yearly prep work to get the boat in the water and would love to get rid of the scratches, I've read that 600 grit wet works then rubbing compound but I sure would like input before I do anything I may not be able to repair... Thanks in advance for any replies.

[Ixneigh]

My boat came from the factory with spider cracks. I thought they were just part of the Mac mystique.

[Steve K]

Bimmerguy,

If they are, indeed, cracks in the gel-coat, they go completely through it, to the raw fiberglass.

Sometimes there will be a patterning in the oxidation, that looks very much like cracks. This will buff out.

The outer layer of the boat hull (or first lay-up) just under the gel-coat is fiberglass mat. This is a compressed sheet of randomly facing fiberglass strands that are around an inch or two long. This mat provides strength in all directions and also helps hide the weave pattern in later layers of cloth and roving.

Don't ask me why, 'cause I don't know the science behind it, but the gel-coat will sometimes have an oxidation pattern that follows these fiberglass strands, producing what looks like little, whitish cracking in multiple directions.

I wouldn't use #600 grit for this. I would start with much finer (perhaps #1000 to start), then buff. I use a hard rubber block, or a stiff sponge block, depending on the couture of the area being worked on (hard rubber for flat areas, sponge for curved or rounded. Be VERY careful sanding convex curves!!!!!!! or outside corners. A little bit of dish soap or car wash soap in the water keeps the paper from dragging.

I like most Meguiar's products. Try "#49 Heavy Duty Oxidation Remover" or "#67 Marine One-Step Compound" followed by one of their fine polishes like "#45 Boat/RV Polish & Gloss Enhancer", then wax.
Heck, just buy the kit:
http://www.meguiars.com/en/marine/produ ... moval-kit/

Anyway, my two cents.

For cracks, read my article on repairing gelcoat in the features/ articles tab above. I've meant to update in for some years now, but it will still help you get the job done. I just don't know how the guys with blue gelcoat, will ever be able to match it perfectly

Best Breezes,
Steve K.
Mac 26D "Three Sheets"

[kmclemore]

The only way to properly repair spider cracks is to grind out the material to the ends of the cracks, repair the underlying fiberglass, and then restore the gel coat with new. You also need to determine what internal or external stress caused the crack in the first place and eliminate it so that the crack does not reappear. It's a heck of a lot of work when done properly. Trust me, I used to do this for a living.

However, your average smaller spider cracks are rarely a serious problem, and my choice - if the gel is not greatly separated or deeply cracked - is to lightly sand them down with some fine paper (1000) and then buff them out and apply a good wax. Yeah, the crack will still be there, but I like to think of them as if they were the tiny wrinkles that form at the corners of my wife's eyes... they show age, but you only get them by virtue of smiling (or in the boat's case, through use, and smiling whilst doing so).

[Divecoz]

I am with Kevin.. Glamour cracks / Crazing... could make you crazy trying to fix everyone every time .. But keep an eye on them.. Ive got them most if not all boat owners have them.. Structural should be pretty obvious..

The only way to properly repair spider cracks is to grind out the material to the ends of the cracks, repair the underlying fiberglass, and then restore the gel coat with new. You also need to determine what internal or external stress caused the crack in the first place and eliminate it so that the crack does not reappear. It's a heck of a lot of work when done properly. Trust me, I used to do this for a living.

However, your average smaller spider cracks are rarely a serious problem, and my choice - if the gel is not greatly separated or deeply cracked - is to lightly sand them down with some fine paper (1000) and then buff them out and apply a good wax. Yeah, the crack will still be there, but I like to think of them as if they were the tiny wrinkles that form at the corners of my wife's eyes... they show age, but you only get them by virtue of smiling (or in the boat's case, through use, and smiling whilst doing so).

[Québec 1]

I restored my blue hull a number of years ago and maintain it quite well. This is my story

http://www.macgregorsailors.com/forum/v ... =8&t=17929

http://www.macgregorsailors.com/forum/v ... =8&t=13273

Q1

[Bimmerguy]

Thank you all very much so far, my cracks and scratches are relatively small so a light wet sanding in area sounds like the trick..

P.S. Merci beau-coup Mr. Quebec..Excelent photo

[Québec 1]

De rien Mr. Ontario Guy
Q1

[Ixneigh]

What if one sanded and recoated the hull with new gel coat? I am sure even west marine brand gelcoat is better the Rogers factory gelcoat.
I plan to paint the top part of the hull a light blue because I think a two color (blue above white below) will look sharp and make the boat appear longer. I've not decided what coating to use yet.

Ixneigh

[DaveB]

Re Gelcoating is best left to a pro. I just compleated a 6 slide 45Ft.x 30 ft. at Sunsplash Water Park. It was 20 years old and required major sanding and prep. along with restructure weak areas.
You need High Tec. equipment and knowledge to do this. 90% is prepareing the surface.
Dave

What if one sanded and recoated the hull with new gel coat? I am sure even west marine brand gelcoat is better the Rogers factory gelcoat.
I plan to paint the top part of the hull a light blue because I think a two color (blue above white below) will look sharp and make the boat appear longer. I've not decided what coating to use yet.

Ixneigh

[kmclemore]

What DaveB said.

Plus, most gelcoat cannot be just applied and left open to the air. It must be covered after you apply it - saran wrap works well. If you don't, it will become 'gummy' on the surface and never properly harden.

[Divecoz]

I agree with DaveB.. That's a HUGE project! If you going to be painting the the top I would suggest ? Repairing small issues and painting the bottom as well..
OMG you could easily end up with a real mess trying to Fair the entire hull as a first time effort.. That said , at least no one would ever see it again

What if one sanded and recoated the hull with new gel coat? I am sure even west marine brand gelcoat is better the Rogers factory gelcoat.
I plan to paint the top part of the hull a light blue because I think a two color (blue above white below) will look sharp and make the boat appear longer. I've not decided what coating to use yet.

Ixneigh