A cock and bull story

Bronze v plastic? Groco v Marelon?

Is DZR ever OK? Why don’t our seacocks fit our skin fittings? What about flanges?

We went shopping in Phuket with American McGee for seacocks and other essentials. Along the way, we visited all the chandleries and stayed at another smart hotel for a knockdown-out-of-season-last-minute-price.

Liz enjoying a night in a swanky hotel…

While we were there Jamie discovered a few things about seacocks and why ours weren’t connecting properly to the skin fittings. We chatted with Ian Lok of East Marine about NPT vs BSP pipe fittings.

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Our Groco seacocks are threaded with the NPT (National Pipe Thread) system, which is used in the US and Canada. The tapered thread of the skin fitting wedges into the female seacock. The skin fitting effectively stretches the female fitting and creates a force so that the connection can hold pressure.

Jamie and a big seacock….

Because we’d cut the top off the skin fitting we lost that tapered effect and couldn’t make a seal. What further confused us was that older skin fittings and seacocks on SY Esper were BSPP (British Standard Parallel Pipe). These can be screwed onto the newly cut skin fittings, but they would not make the seal that an NPT fitting is designed to do.

After recording this video we discovered that Groco sell flange adapters to get around this problem, but East Marine did not have these in stock. Groco also sell complete seacock and flange units in one. In hindsight we should have installed these instead.

Peace and fair winds!


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