Taking down to fiberglass

[Scot McPherson]

If you wanted to take your finish all the way down to the fiberglass to do some patching and add another layer of cloth to your hull, which tool would you pick to remove material the fastest?

A belt sander
An angle grinder

Or something else?

I have a hull that was cracked on the rocks, and I want to take a large swath of material down clear to the glass so I can reinforce and patch where it's cracked, then lay another layer or two of 9oz glass over the entire section.

If you had t pick one, which would you prefer and why?

Thanks,
Scot


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[2hullvenus]

When you're in sort of a hurry, you use a variable speed buffer/polisher with approximately 34 grit paper on it. A foam backed pad if you want any sort of fairness or taper to it.

When you REALLY want to remove a chunk quickly, use an angle grinder and cut it right out. No fairness or taper that way but fast AF.

Belt sanders are mostly useless, but have moments, such as flats or using the round part to get into a cove.

For your job, I'd consider a power long board, air file or the variable speed buffer.

You'll need an absolutely smooth surface to lay the glass properly and might as well keep it as close to fair as possible to avoid time consuming finish work.

[Scot McPherson]

Searches on power long boards results in skate board designs


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[2hullvenus]

Exact plan of attack:

1) Identify all cracks

2) Take foam backed, low grit # pad on variable speed polisher and grind out a sort of "dishpan", concave shape tapering out about 3-6" from the cracks, depending on deepness of cracks and thickness of hull. Grind cracks all the way out. Leave as smooth of a surface as possible with no sharpness.

3) Cut glass in increasingly larger widths from 1" to full width of the repair. Glass them in to the dishpan/taper starting with the 1" and working your way up, or start large and work to 1". Jury is out on which is better. Lots of room for debate.

4) Crack repairs should stand slightly proud of the hull when complete. Take the foam backed pad on the sander/polisher and make everything prett smooth and fair with the curve of the hull.

5) inevitably, you'll have lows. Fill these with thickened epoxy, making them proud so you only need to do it once.

6) Use a hand longboard or power long board or air file to fair everything and get rid of all the "shiny." (cured, non sanded epoxy)

7) now lay up the sheets of the larger glass pieces you wanted to add to the hull to prevent future cracks.

8) add some thickened epoxy with microballoons over the laminate now. while it's still a little tacky, to save a sanding step. Lay it as perfectly as possible.

9) Fair the fairing compound with a hand long board.

10) repeat #8/#9 until happy or crying. it'llbe one or the other!

11) prime/paint

[2hullvenus]

Originally Posted by Scot McPherson

Searches on power long boards results in skate board designs


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Sorry. We called them that and they were custom built by us.

Air file is the word, but they arent ideal fairing tools.

When it comes to the final fairing, nothing but a hand longboard will do.


Hutchins brand are top of the line. Harbor Freight carries ones that may last half the project.

[Freemind]

Originally Posted by 2hullvenus

Sorry. We called them that and they were custom built by us.

Air file is the word, but they arent ideal fairing tools.

When it comes to the final fairing, nothing but a hand longboard will do.


Hutchins brand are top of the line. Harbor Freight carries ones that may last half the project.

So a hand "long board" is a large file then?

[Hard Rock Candy]

In my experience a hand longboard Is a flat board with sand paper on it so that you can only sand outside curves and flats with it. I've used one to flatten out mud on drywall.
This is something that might help for someone that is new to fiberglass work. Polyester resin is good when you are doing layup on a new hull. BUT IT is not good to patch a hull or to attach to a hull made out of Polyester. for any repairs you should always use Epoxy resin. It sticks to almost everything. If anyone knows why I may be wrong, speak up. I have been wrong many times before, but we all use the knowledge we have at the moment and anything to the contrary we reject until we have pretty good evidence to the new information. Mac

[skipgundlach]

Originally Posted by Hard Rock Candy

In my experience a hand longboard Is a flat board with sand paper on it so that you can only sand outside curves and flats with it. I've used one to flatten out mud on drywall.
This is something that might help for someone that is new to fiberglass work. Polyester resin is good when you are doing layup on a new hull. BUT IT is not good to patch a hull or to attach to a hull made out of Polyester. for any repairs you should always use Epoxy resin. It sticks to almost everything. If anyone knows why I may be wrong, speak up. I have been wrong many times before, but we all use the knowledge we have at the moment and anything to the contrary we reject until we have pretty good evidence to the new information. Mac

Agreed on Epoxy repair; secondary bond of epoxy to poly is the same as prime bond poly.

Longboards are that when you have 4 hefty guys who can do it with you. Otherwise, they are relatively flexible, firm rubber foam 2.5" wide, various length (we used 24" and 30") which do inside just as well as outside curves if the radius isn't insanely small.

You can see more than you'll ever want to do about hand-repairing/refurbishing a bottom in your lifetime here:
Pictures: Flying Pig Refit 2011-2012/Bottom Job

HTH

L8R

Skip

[Cheechako]

A large angle grinder, aggressive grit. A belt sander wont work well, except on flat ish surfaces.

[minaret]

Originally Posted by Scot McPherson

If you wanted to take your finish all the way down to the fiberglass to do some patching and add another layer of cloth to your hull, which tool would you pick to remove material the fastest?

A pro laminator. With a peeler.

[Scot McPherson]

Hey cheechako, yeah that's what I was thinking really, most of what I want to strip is flat-ish, at least in the sense that i am stripping a large portion of the hull. But the angle grinder I can use for other tasks as well if I am careful with the stripping. It doesn't need to be perfectly fair because I am going to build up again anyway and that build up will need to be faired some anyway. I am resheathing most of the hull below the water line to bulk up the hull a little and cover everything instead of finding out later than I _missed a spot_.


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[Scot McPherson]

Specifically I need to cut out the chain plate backing and replace it with new lumber. The chain plate blocks are fiber glasses in and in a tight space so I'll need an angle grinder to get in there to cut.


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[Cadence]

Originally Posted by Scot McPherson

If you wanted to take your finish all the way down to the fiberglass to do some patching and add another layer of cloth to your hull, which tool would you pick to remove material the fastest?

A belt sander
An angle grinder

Or something else?

I have a hull that was cracked on the rocks, and I want to take a large swath of material down clear to the glass so I can reinforce and patch where it's cracked, then lay another layer or two of 9oz glass over the entire section.

If you had t pick one, which would you prefer and why?

Thanks,
Scot


Sent from my iPhone using Tapatalk

Use and angle sander with 40grit. You can go lower if you are brave. Just make sure to keep moving it so you aren't digging out areas.

[Hartleycruiser]

Scot
I have seen a boat peeled with a tool like this GelPlane Gelcoat Peeler Osmosis Treatment, Gelcoat, Gel Plane, Gel-Plane, strips, peels gelcoat, stripper

[Sailing55]

Originally Posted by Scot McPherson

If you wanted to take your finish all the way down to the fiberglass to do some patching and add another layer of cloth to your hull, which tool would you pick to remove material the fastest?

A belt sander
An angle grinder

Or something else?

I have a hull that was cracked on the rocks, and I want to take a large swath of material down clear to the glass so I can reinforce and patch where it's cracked, then lay another layer or two of 9oz glass over the entire section.

If you had t pick one, which would you prefer and why?

Thanks,
Scot


Sent from my iPhone using Tapatalk

See if there is anyone in your area that specializes in "Peeling" glass hulls to eliminate osmotic blistering.
It is a tool similar to a electric hand plane and it removes glass in the same way a plane removes wood. Consistent and to any depth you need.
Very noisy, but fast and extremely efficient.