Wednesday, March 18, 2015

Improving Deck Drains

--Blogpost written by Bob

On the C&C Landfall 38 there are four deck drains, two at midship and two a few feet forward of the stern.  Originally, all the deck drains had plastic deck fittings that connected to 1/2-inch hoses.  The two aft deck drains were routed to a single tee mounted on a small thru hull fitting (about 3/4-inch) that was slightly above the waterline at the stern just to port of the boat's centerline.  The two midship deck drains were directed into the bilge--so, when it rained, the bilge accumulated a lot of rainwater unless the bilge pump transferred it overboard.  In my opinion, this was a design flaw by C&C.  In the event of a failure of an automatic bilge pump (which were not supplied as original equipment), a heavy rain could cause internal water damage to the vessel.

In addition to this design flaw, during the early years of my love affair with s/v Rainy Days (there's no other way to describe it!) I noticed that the deck drains would regularly become blocked.  Most of the time it was due to a collection of (helicopter) seeds from nearby maple trees--these seeds were just the right size to block a 1/2-inch deck drain.

These "helicopter" seeds falling from maple trees carry a fair distance
in the wind and collect on the boat's deck and cockpit in the late-summer
and early-fall.  The seed structure (called a double samara) is common
in the eastern United States and Canada.

The solution I developed for my boat was made incrementally over several years of trying things and then making modifications.  I ended up with a system that no longer experiences blockage and all the rainwater drains overboard the way it should.  This system has been in place on my boat for the past 15 years and I'm posting it here so that other Landfall 38 owners can benefit from my experience.

Enlarged Deck Fittings

First, I enlarged the deck drain fittings as large as I could--I was restricted by the size of the troughs that were built into the deck.  I increased the midship deck drain fittings to 3/4-inch and the aft deck drain fittings to 1-inch.  (Long after the increase in sizes, I changed all the deck fittings from plastic to stainless steel.)

Enlarged Hoses & Rerouting

I ran a 3/4-inch hose from the midship drain fitting to the plastic tee that is about 12 inches below the 1-inch diameter aft deck drain fitting.  This resulted in a 125 percent (for the midship drains) and a 300 percent (for the aft drains) increase in flow area compared to the original 1/2-inch diameter hoses used on both drains.  It is surprising how such small increases in hose diameter can make such huge increases in flow area.

This image is looking upward from the ice box.  Because of space constraints, I had to form 
a small loop in the drain hose where it is connected to the midship drain--this loop 
causes a little bit of flow restriction.  The drain hose is the clear vinyl hose with 
the red and white tracers.  It exits to the left of the image into the quarter 
berth ceiling area  The black hose in the corner is the old drain 
hose that drained to the bilge.

The aft deck drain fitting ties into a 1-1/4-inch plastic tee where the drain hose size increases to 1-1/4-inch diameter.  Hose barb adaptor fittings are used to adapt to the three different sizes of hoses that come together at this tee.

The black 1-inch diameter hose in the center of the image is coming from the aft deck drain.
The white plastic tee allows the water coming from midship drain (to the right of the
image) to combine with the water from the aft deck drain and go toward
the discharge in the stern

The 1-1/4-inch hoses from each side of the boat join together in a bronze tee that is mounted to a new 1-1/2-inch bronze thru hull fitting that is located just above the waterline just to starboard of the centerline of the boat.  (I'm using the original 3/4-inch thru hull fitting intended for the deck drains for discharging warmed water from my air conditioner.)  All the hoses run at a generous and uniform slope to promote good drainage toward the dedicated hull fitting at the stern.  All hoses and fittings in this system are above the boat's waterline.

The two 1-1/4-inch hoses from the deck drains on each side of the boat join at a
1-1/2-inch bronze tee and discharge through a 1-1/2-inch thru hull that is above
the waterline.  This is located aft of the propane storage locker.

The four deck drains are connected with increasingly larger hoses as the drained
water moves aft and the ultimately drain through a 1-1/2-inch thru hull in the stern


The largest expense associated with this project was having a new 1-1/2-inch bronze thru hull installed at the stern--this had to be done during a haulout.  (Another option to having a dedicated 1-1/2-inch thru hull is to tie the deck drains into the 1-1/2-inch cockpit drain hoses.)  The hoses and fittings were relatively inexpensive until I changed all the deck drain fittings to stainless steel.  This system has proved advantageous during the winter when rainwater in the bilge would freeze and prevent the bilge pump from doing its job.

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Next up will be my do-over for the spaghetti wires...

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