Fiberglassing over seacock flange

[syjos]

In the past, wood was used for seacock backing plates. The purpose for the backing plate was to distribute the load and add thickness.

A secondary function of a wood backing plate was to stop leaks. The theory was that in the event of a leak, water would swell the wood backing plate and stop the leak.

I've witnessed leaking seacocks stop leaking after an hour or so after splashing because of the wood blocks swelling.

Modern sealants and caulk probably mitigate the seacock leak but I still use wood backing blocks. I have installed the Groco plates on client's boat when requested without issue.

 

[DDW]

Personally I would replace them with the Forespar plastic OEM ones. They do not corrode ever, do not require bonding, are less likely to evaporate in a lightening strike, and exceed the ABYC and CG required strengths. I would not trust the alloy in a 'bronze' one, even stamped Groco, unless each and every fitting was shot with an XRF gun.

 

[angus99]

In the past, wood was used for seacock backing plates. The purpose for the backing plate was to distribute the load and add thickness.

A secondary function of a wood backing plate was to stop leaks. The theory was that in the event of a leak, water would swell the wood backing plate and stop the leak.

I've witnessed leaking seacocks stop leaking after an hour or so after splashing because of the wood blocks swelling.

Modern sealants and caulk probably mitigate the seacock leak but I still use wood backing blocks. I have installed the Groco plates on client's boat when requested without issue.

In my case, some of the wooden backing plates were pulpy or poorly adhering to the fiberglass. I could peel some off easily by hand. The original Groco rubber plugged Seacocks (excellent in their day, but parts are no longer available) were not bolted to anything! They were simply held in place by whatever thread connection they could achieve with the through hull mushroom (using dissimilar threads) and some weak mastic. I couldn’t get them out of the boat fast enough and replaced all 13 (below the waterline) with Groco flanged adapters — thereby enabling Parks’ early retirement .

 

[HopCar]

In my case, some of the wooden backing plates were pulpy or poorly adhering to the fiberglass. I could peel some off easily by hand. The original Groco rubber plugged Seacocks (excellent in their day, but parts are no longer available) were not bolted to anything! They were simply held in place by whatever thread connection they could achieve with the through hull mushroom (using dissimilar threads) and some weak mastic. I couldn’t get them out of the boat fast enough and replaced all 13 (below the waterline) with Groco flanged adapters — thereby enabling Parks’ early retirement .

I did love shipping that order!