Thursday, October 25, 2012

The Sea Chest

As would be expected when you buy a new boat, there are several things that are new to us on this one: we have refrigeration, air conditioning, a second head, room to actually swing a cat and a sea chest, to name a few.

A sea chest, despite what it's moniker might suggest, is not filled with gold and silver.  It is not intricately carved out of mahogany.  It is not, in fact, a place to store treasures.  What it is, is a box (or chest, if you will) integrated into the hull of a boat that contains water pulled from a single sea cock (ours is 1.5").  The idea is that systems that require raw water to run (in our case, the "non-essentials" like refrigeration, AC, watermaker, head...etc. our engine and generator are on their own seacocks) can be lead to the box instead of to their own respective sea cocks, thus eliminating the need for more holes in the bottom of the boat.  Instead of having a thru-hull for each system or having a bunch of systems tee'd off one another, you run each system separately off the water collected in this magical chest.

"Sea chests" are very common on large work boats, less so on cruising boats.  There are advantages and disadvantages, of course; the main advantage being that we have significantly less holes in our boat and the disadvantages being that they are famously tricky to clean and hose runs are a lot longer.  I'm sure there are more, but those are the top from either camp as far as I can tell.
Our sea chest is right below the galley floor and does not, unfortunately, hold treasure.
Scott has spent the past two days installing isolation valves on our sea chest so that we can turn off any given system if need be.  Right now, we have our watermaker, air conditioning, refrigerator, freezer, both heads, and our salt water wash down pump run to our sea chest.  If that sounds like a lot, it is.  Isolation valves (the grey pipes with the red knobs pictured above*) will allow us to turn off the water going to any given system to either service it or close it off, because running all of those at once would certainly run our sea chest dry.

Any of you out there have sea chests and care to share any tips/tricks/wisdom with us?  We'd love to hear it!

Now if only we had somewhere to store our boo-tay...

*Before you jump on us for installing plastic isolation valves, keep in mind Scott considered bronze and went back and forth about this.  Because the actual sea cock that feeds the sea chest is bronze, he decided the plastic valves would suffice (they are about $30 less a piece than their bronze brethren, fyi).  From now on, however, he'll always go bronze because of the headache the back and forth has caused him.

4 comments:

Terje Moglestue said...

I have no experience with a sea chest.

It sounds like a good idée. I got a similar issue upgrading our Grand Soleil 42. I am about to fit a water maker and air con both need sea water. I would like to have as few holes in the hull as possible. The yacht already got water intake for fridge cooling and a few other things. All units got its own intake with its own sea cock. A sea chest sounds like a very good plan.

If the sea chest runs dry you will have a problem. Why not fit two sea water intakes to the sea chest? This improves the volume of sea water you take in, less change for blockage and hopefully this reduce the change for getting dry.

Plastic or bronze? Never ending debate. The yard where I purchased our boat from replace all sea cocks with cheap sea cocks from France. Now three year later – I need to replace most of the work they did due to the simple fact they went for low cost and not high quality.

Anonymous said...

My husband (still building the boat) explained his reasoning as - bronze for all the ones with direct pressure on them and the engine ones, and the ones without direct pressure he has chosen plastic.

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