G10 Question

kloudie1

kloudie1

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Nov 6, 2006
9,892
Hunter 34 Mandeville Louisiana
Phenolic is good strong stuff, but it can be brittle compared to fiberglass board.. If the surface is really flat, it'd be fine.. if the surface has some concavity to it (center of phenolic not touching when edges touch) then tightening the thru-hull nut is likely to crack the phenolic, where the fiberglass board would flex without cracking.. Very general statement, but I wouldn't use phenolic on a hull shape that required it to flex a good bit to have everything tight.
 
D

dlochner

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Jan 11, 2014
11,399
Sabre 362 113 Fair Haven, NY
A while back Practical Sailor evaluated different materials for backing plates. It would be worth reviewing their findings.
 
FastOlson

FastOlson

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Apr 8, 2010
1,950
Ericson Yachts Olson 34 28400 Portland OR
If you buy your G10 (aka "FR4") from McMaster-Carr, all the specs are spelled out their fine site.
 
Richard19068

Richard19068

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Jun 11, 2004
1,633
Oday 31 Redondo Beach
FastOlson said:
If you buy your G10 (aka "FR4") from McMaster-Carr, all the specs are spelled out their fine site.
Click to expand
Yes but it is about five times the cost so I'm just researching and wanted to find out what the difference in the material is.

Thanks

Edit: I take it back, it is only two and a half times the price so for what I need maybe that's okay. Problem is I need to buy way more material than I need.

Thank again
 
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Maine Sail

Maine Sail

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Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
Guys,

G10 (fiberglass & epoxy resin) is a NEMA/Electrical manufacturing specification for PCB materials. G10 or G10 FR-4 / FR-4 are just two different versions of the spec. FR-4 is essentially the same as standard G10 only with an added fire retardant mixed with the epoxy.

Garolite is just a trade name of G10 and I don't even know who owns it today? Lots of manufacturers make G10 or FR-4 material. These days G10/FR-4 is often less expensive because it is more popular and sees more production than regular G10. There is also GPO-3 which is the same as G10 but instead of using an epoxy resin it uses a standard fiberglass resin..

For backing blocks I usually use 1/2" thick G10..
 
Richard19068

Richard19068

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Jun 11, 2004
1,633
Oday 31 Redondo Beach
Maine Sail said:
Guys,

G10 (fiberglass & epoxy resin) is a NEMA/Electrical manufacturing specification for PCB materials. G10 or G10 FR-4 / FR-4 are just two different versions of the spec. FR-4 is essentially the same as standard G10 only with an added fire retardant mixed with the epoxy.

Garolite is just a trade name of G10 and I don't even know who owns it today? Lots of manufacturers make G10 or FR-4 material. These days G10/FR-4 is often less expensive because it is more popular and sees more production than regular G10. There is also GPO-3 which is the same as G10 but instead of using an epoxy resin it uses a standard fiberglass resin..

For backing blocks I usually use 1/2" thick G10..
Click to expand
So the fact that one is called Phenolic and the other fiberglass is irrelevant and they are interchangeable?
Thanks you for the input.
 
Maine Sail

Maine Sail

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Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
Richard19068 said:
So the fact that one is called Phenolic and the other fiberglass is irrelevant and they are interchangeable?
Thanks you for the input.
Click to expand
If it is G10 it's G10... PCB's for a long time were made of a phenolic paper thus the term has stuck around for a while. Most of what you get on eBay are scraps and they are often suitable for backing blocks so long as you can find 1/2" thick. In some cases even 3/8" or 1/4" would be fine..
 
Richard19068

Richard19068

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Jun 11, 2004
1,633
Oday 31 Redondo Beach
Maine Sail said:
If it is G10 it's G10... PCB's for a long time were made of a phenolic paper thus the term has stuck around for a while. Most of what you get on eBay are scraps and they are often suitable for backing blocks so long as you can find 1/2" thick. In some cases even 3/8" or 1/4" would be fine..
Click to expand
Thanks a bunch.
 
thinwater

thinwater

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Mar 26, 2011
3,410
Corsair F-24 MK I Deale, MD
Richard19068 said:
Is G10 Phenolic sheet the same as G10 fiberglass board?
I've looked around the net and can't quite get an answer I understand.

Phenolic sheet:
https://www.ebay.com/itm/G10-Phenol...hash=item2f1112645b:m:mQgjCIOOks-Zt7IH-eNznOA

Fiberglass board:
https://www.jamestowndistributors.com/userportal/show_product.do?pid=8758

I'm looking for Thru Hull backing material.

Thanks.
Click to expand
Obviously, it depends on what you are backing, the construction of the hull (both quality and whether it is solid or cored) and whether you will bond it to the hull. In general, good quality fiberglass board needs to be about one fastener diameter thick and extend at least 5 fastener diameters past the attachment point. It also need to have good contact; this can mean filling or bonding. G10 can be a little thinner. In both cases you still need to use a bolting washer (not a fender washer--they are too flexible).

I did a lot of testing, breaking cored layups, to get to these figures.
 
Parsons

Parsons

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Jul 12, 2011
1,165
Leopard 40 Jupiter, Florida
Gunni said:
GROCO is now selling custom fitted backing plates for their thru-hull that include threaded inserts aligned to the flange base.
Click to expand
That's what I did in replacing one of mine, because I did not want to use epoxied wood, or own another 4x4 foot sheet of 1/2 inch G10. It's much more expensive per-use, but if you're only doing one or two through hulls, it's sure more convenient to just buy it pre-made.
 
S

SFS

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Aug 18, 2015
2,070
Currently Boatless Okinawa
@thinwater - What is a bolting washer? I can find no specific reference via google searching or the Wikipedia entry on washers. I am about to put in two large (starboard) backing plates for cleats, and I want to use correct washers.
 
FastOlson

FastOlson

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Apr 8, 2010
1,950
Ericson Yachts Olson 34 28400 Portland OR
A local plastics company cuts pieces of G10 for me without extra charge. Price per square whatever is pretty reasonable. I have also bought larger pieces and angle-molded sections from McMaster-Carr.
I rough up the composite with some 60 grit, clean it with acetone, and lay it (or clamp it) into a bed of thickened epoxy. Strong!
 
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