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Description
The Groco BB Series Backing Block provides a stronger, more reliable foundation for flanged seacock installations. Designed to press-thread into the hull, it creates a secure, flush connection while its flexible yet rigid construction conforms to minor hull curves. Durable, moisture-resistant, and built for marine reliability.
Groco BB Series Backing Block Item # 867606
Description
Groco's BB-Series Backing Blocks improve the installation of a flanged seacock by creating a more secure connection through press Insert Threads and a flexible design that conforms to minor hull curvature.
Features:
- Flanged seacock installation is improved with the use of a backing block between the valve flange and the hull
- Includes insert threads that press into the hull side of each block
- 1/2" thickness is rigid enough for a secure installation but flexible enough to conform to minor hull curvature
- Will not swell or absorb moisture
4.29" (BB-1) Specifications:
- Fits Seacock Sizes: 750 and 1000
- Insert Threads: 5/16"-18
- Diameter: 4.29"
5.38" (BB-2) Specifications:
- Fits Seacock Sizes: 1250 and 1500
- Insert Threads: 5/16"-18
- Diameter: 5.38"
7.13" (BB-3) Specifications:
- Fits Seacock Sizes: 2000 and 2500
- Insert Threads: 3/8"-16
- Diameter: 7.13"
9.5" (BB-4) Specifications:
- Fits Seacock Size: 3000
- Insert Threads: 3/8"-16
- Diameter: 9.5"
Notes: Seacock sold separately. Backing block includes brass inserts; stainless steel bolts are recommended.
Part Numbers for Groco BB Series Backing Block
Reviews
Questions
Can 5200 be used to secure backing plate to fiberglass hull? Thanks
Absolutely. It's also held in place by the inner and outer fittings once threaded together
Date published: 2025-05-10
2 questions really can the blocks be glasses to the hull? Second question it says stainless steel bolts are recommended and the threaded inserts are brass that doesn't create a problem area for galvanic corrosion shouldn't bronze bolts be used?
Yes, the backing block adheres very well to a fiberglass hull using epoxy. Make sure the hull is prepared well and clean.
You can use a good quality stainless steel bolt with the bronze inserts. Both metals are very close on the galvanic scale (potential) so the risk of corrosion is low, especially around the bilge where any water should be mostly fresh. If you have a concern you can use bronze bolts but they won't be as strong.
Date published: 2024-03-28
Is this made from epoxy resin and fiberglass?
no to composite or epoxy.
The backing block appears to be a relatively dense PVC foam material of similar.
light weight and somewhat pliable, but easy to shape in order to better follow hull contours
Date published: 2025-12-02
Will these backing plates fit the BV-series Groco seacocks?
This backing block was installed on this unit item #503591FBV0750 Groco FBV Series Full-Flow Flanged Ball Type Seacock - 3/4"
Date published: 2024-03-28