Thought it would be interesting to go back to some boat system details (Now I know some of you are yawning, but I like this stuff!). So here goes with a look at the raw water system.
First a few comments about below the water line hull penetrations. In short, it amounts to taking a very good hull and poking holes in it – not a good thing, so less is better then more. Further, where there are below waterline penetrations, they should be in locations that are easily accessed with appropriate means to shut them off. On some of the boats I have owned over the years, it was almost impossible get to some of the seacocks that isolate these penetrations. I remember one in particular where I had to crawl into a locker barely large enough to get my shoulders in, remove an access panel at the back and reach as far as I could to get to the seacock – needless to say that seacock didn’t get exercised very often.
Well the FPB 64 has exactly four below the water line penetrations. There are two in the forepeak – one for a salt water wash down and one for the forward blackwater tank discharge. Both have readily accessible quarter turn Marelon seacocks (very little risk of seizing) with nice big red handles. Remember – the forepeak is isolated from the rest of the boat by a water tight bulkhead as well.
The other two penetrations are in the engine room. One is for the aft backwater tank.
You can see the tank sitting to the right and behind the genset. The thru hull shut off is to the right of the tank.
The second is a sea chest which serves all the other salt water consumers in the engine room.
The sea chest is basically a pipe welded to an open hole in the bottom of the boat. It then extends up above the waterline and comes up adjacent to the workbench in the engine room. Note the clear plastic top so a quick look down confirms whether or not there is any debris in the pipe. Further note the small plug in the top. If we suck up a plastic bag in to the intake pipe and lose our raw water flow, it is a simple matter to remove the plug (as it is above the waterline) and run a broom handle down thru the hole to eject said bag from the intake pipe. Much better then having to dive the boat (which I have had to do in the middle of the Gulf Stream on one of my boats – fortunately it was a calm day).
From the sea chest, there are two pipes leading off horizontally to two massive intake strainers under the engine room floor boards.
Note the shut off valves before and after each one so they can be serviced while underway. There is so much capacity that we have never really had any plugging issues although I check them about once every week or two – it just takes a few minutes as the floor boards simply lift up out of the way.
From the strainers, the piping leads to a manifold which feeds all the raw water consumers – again under the engine room floor boards.
Note the the two clean out ports (caps) on top of the manifold. Can’t imagine that I will ever really need them but they are sure nice to have if I do.
Leading aft from the manifold you can see four ports with shut off valves and hose leading from there. One leads to the genset, one leads to water maker, one leads to the aft saltwater wash down and one under the manifold (which is not visible) leads to the engine. If you look carefully, you can see two little red wires above one of the manifold clean out ports – these are for a raw water flow sensor for the main engine which warns us of a water flow failure on the Maretron system at the helm station and flybridge. On many boats, there would also be a requirement for raw water cooling for the air-conditioning system but we use thru the hull cooling on Iron Lady – no salt water required. So the port labeled “Air Con” is actually a spare.
As in the forepeak, the engine room is isolated from the rest of the boat by a water tight bulkhead.
That about does it for the below the waterline penetrations. Should something really serious go wrong in this department (VERY hard to imagine), we also have a high capacity hydraulically driven crash pump in addition to our bilge pumps.
More about that in another post.
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