New Seacocks
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One of the few things I
don’t like about these boats is the lack of real seacocks. Scanmar installed
flangeless valves which were simply screwed into through hulls. This isn’t a very strong installation, and it
is not unheard of to snap off the thin through-hull nipple when applying
force to close a stubborn old valve. I
don’t know of this happening on a Scanmar, but it
could. This
shortcoming is not unique to Scanmar, and in fact
many if not most older boats have this problem. A true seacock has a flange cast into the
base which allows you to throughbolt the valve onto
the hull; the flange takes the strain when applying pressure to the valve to
close it, not the thin-walled through-hull.
You can see the difference between the old and new valves below. |
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Original 1-1/2” sea
valve |
New Conbraco seacocks |
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I decided on ball valves
rather than the traditional plug-type seacocks
shown below. I chose to use Conbraco
“Apollo” bronze valves for several reasons: they have chrome-plated bronze balls and Teflon seats, which help
prevent sticking, corrosion, and marine growth; the triangular bases take up
less space than square ones; they have stainless steel handles; they have a
great reputation in industry; they are rebuildable;
and they are reasonably priced. Groco also makes
ball valves, but some of these (the FBV series) have chrome-plated brass
balls, the worst possible combination in a saltwater environment. Brass
should be avoided for applications below the waterline, as it is too prone to
galvanic corrosion. Also, the
lower-priced Groco valves such as the FBV series
cannot be rebuilt. Groco does make an all-bronze, rebuildable seacock, but it is nearly twice the cost of
an Apollo. I think the reason the Conbraco valves
are priced better is because Conbraco sells mostly
to a very broad industrial customer base, while Groco
has the niche marine market. That’s my theory anyway. I bought the seacocks
and fittings at Defender, whose prices
are hard to beat. |
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The Spartan traditional, plug-type seacocks seen here are built like tanks and will probably
last forever; I had Spartan seacocks on my old |
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To avoid potential
galvanic corrosion which could occur between stainless steel bolts and the bronze
valve, I decided to use only bronze hardware, shown here. Appropriately sized
bronze bolts, nuts and washers are available from Jamestown Distributors. |
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Another concern of mine
about the original Scanmar 35 sea valves was the
cockpit drain valve. Unlike most boats, the Scanmar
35 has one big centrally-located cockpit drain, necessary because below most
of the cockpit is the huge aft cabin. The designer didn’t want to have piping
or hoses running through the cabin, and instead there is a big 2” drain
passing through the engine room and out the bottom of the hull. As this valve must remain open at all
times, it is essential that this valve be easily closed in case of an
emergency. Unfortunately, my Scanmar had a gate valve, the worst possible kind, at
this key location. A ball valve needs only a ¼ turn to close,
and a great deal of pressure and leverage can be applied to it. With a gate
valve, you will need to rotate the valve several turns to close it, and if it
gets stuck it will be very difficult to close. My own valve was always difficult to
close, and was finally impossible
to close. It had to go! I replaced it
with a bronze 2” Conbraco seacock. |
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Groco sells what they term “full-flow” components as
well as “standard” ones; Conbraco also markets
standard and full-flow valves. The
difference is that the inside diameter (I.D.) of full-flow valves and
components remains constant at the rated I.D.
Thus a 1” I.D. seacock presents a 1” I.D. to the liquid at all points,
and a 1” elbow (90°) tailpiece has a 1” inside diameter all throughout the
fitting. This is especially noticeable in a 90° full-flow tailpiece: you can
see that the full-flow model has a gentler curve, whereas the standard one
has a right angle bend. I decided to
use Groco full-flow fittings on the Conbraco full-flow valves. I figured it would be best not to restrict
the passage of water if possible. |
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I decided to farm most
of this work out to the marina. The boat mechanic I hired had several other
advantages over me for this work: he is a shade over 5’ tall and weighs about
100 lbs, two traits we don’t share.
His diminutive size would come in handy, since several of the seacocks and related hoses were nearly impossible to
reach, notably the three in the head.
Worst of all was the hose run to the waste (holding) tank, which is in
the engine room but lies up against the starboard hull (the tank in the
background in this photo). One has to crawl into this space and then lie atop
the fuel tank and whatever is in there to reach the tank. |
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On some Scanmar 35s the Y-valve, which switches the head’s output
from holding tank to direct overboard discharge, is also against the
starboard side of the hull. I planned to mount my Y-valve in the cabinet
under the sink in the head instead. This is what Scanmar installed in my boat instead of a Y-valve: a
series of 3 ball valves; this takes up a lot of space and is a pain to use. A
Whale Y-valve will be installed in this area under the sink in place of this
jumble. |
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I told the mechanic to
change out all the old hoses with new while he was at it. As you can see from these photos, some of
the hoses were ready to go. One hose
had a rusty wire reinforcement, which means water was leaking into the wire
core. |
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Another hose was torn in
the space between the two hose clamps and could have given way at any time.
This is the main reason you must shut all seacocks
(except the cockpit drain) when leaving the boat unattended! Notice also how
the hose here was cut by the clamp’s sharp edges, and weakened by being
squeezed by the clamp’s perforations. |
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I bought
several boxes of AWAB Swedish-made hose clamps; although expensive if bought
singly, a boxful brings the price way down.
Besides, a hoseclamp, even if they cost $6
each, is very cheap insurance when compared to sinking your boat! The AWAB clamps are made of 316 Stainless
chrome nickel steel throughout, including the screw, and have a
non-perforated band with rolled up/rounded edges which is gentle on the hose
and reduces the risk of leakage. These
were also ordered from Jamestown
Distributors. West Marine also carries them if buying singly. |
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After taking on the job,
the mechanic called me and said that he could not replace the suction line
(the “Waste” fitting on deck) because “there was no room”. When I drove down to the boat and got a
look at it, I discovered that the big, beautiful stainless steel holding tank
bolted onto the engine room deck was a dummy- the waste fitting on deck
opened into the engine room- no hose at all!
There was no connection between the waste deck fitting and the tank;
that meant that any waste in the tank was there to stay! The mechanic said it was
impossible to fit a hose between the waste fitting and tank now, because
there was only 4” between the underside of the deck and the top of the
tank. So we bit the bullet and cut out
the old (virgin!) tank and replaced it with a polyethylene tank mounted
amidships in the engine room. I’ll
add a picture of the finished installation here as soon as I get one. |
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I specified that the
flanges should be through-bolted into the hull and epoxy-coated plywood backing
blocks be used under each seacock. The mechanic fought me on the backing
blocks and through bolting and felt it was overkill, but I felt that the
blocks would help match the concave hull to the flat flange, and
through-bolting would add strength. His
method of installation was to simply screw the “mushroom” (through-hull) into
the seacock and call it finished. In
the end, we used backing blocks and through-bolted each with
three silicon bronze bolts which were countersunk into the hull.
Here’s how we installed each seacock: |
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And here is the result:
this is the new seacock installation under the galley sink. The small (3/4”)
seacock is for the saltwater faucet, while the 1-1/4” valve is for the sink
drain. The white object in the
lower left is the Whale galley foot pump.
The new, larger refrigerator box will fill this space up to the seacocks. The old hoses shown were replaced. Originally, the water pump and accumulator
tank were also stuffed into this space, but I moved both of these to the
head. |
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