Groco Backing plates

We are manufacturing in house 1/2 inch thick Extren 525 fiberglass seacock backing plates. We have stock available for Marlon, Groco, Trudesign and Buck Algonquin valve and thruhulls.  Buck Algonquin and Groco valves use the same size and bolt pattern backing plates. We cut and drill these on a cnc router.

Extren 525, see Strongwell.com is water proof, fire proof, mass produced structural polyester fiberglass sheet. Epoxy, Polyester and Vinyl ester resins will bond to it. 30.000 PSI compression and tensile strength.

The Seacocks and thruhulls can be purchased from West Marine and Defender.com and many others.
We do have the 5/16"-18, 1" long Bronze bolts available.

These backing plates have the same bolt patterns as the Groco BB1, BB2 and BB3 backing plates without the inserts as they are drilled and tapped. The inside diameter of the hole is specific for each thru hull size but by having 6 bolt holes and not 3 you can use the 1" for the 0.75" thru hull and the 1.5" for the 1.25" thru hulls if needed.

We believe that Groco backing plates are made from injection molded pvc which does not bond well with epoxy and also they use brass, not bronze inserts which can corrode.

Our prices are much cheaper than Groco backing plates as we only sell direct.

Just install the Groco valve or Buck Algonquinwith bronze bolts directly to the backing plate. After adjusting valve to desired position and cutting off any of the bolts if they protrude through the backing plate insert the thru hull a couple of threads. Smear some thickened epoxy between hull and plate and tighten the thru hull. This prevents any epoxy getting into the fitting. Thickened epoxy will also fill any slight hull curvature.

Install as a dry fit first. If the backing plate needs to be sanded to fit the curvature of the hull, orientate the valve correctly first and mark off the correct section to sand with very course sand paper or file. A belt sander works well.

Order here or call us to order at 304 723-4553

Just install with silicon bronze bolts as studs seem to be a lot more expensive.
We do have bronze bolts available separately.

Welcome to MeriMarine custom boat parts including the Capt. Don Boom Brakes, Dolphin Cleats, custom made sheaves and anchor rollers, custom cut fiberglass sheet and other items since 2012.

Contact us to order.

Thank you
Capt. Don & Sharon

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