Planning and installing a deck washdown system

By Frank Lanier
Chesapeake Magazine (2005)
Latitudes and Attitudes (2005 )

I come from a long line of seafaring procrastinators – stoic, red bearded men and women of the Lanier clan who throughout the ages have clung stubbornly to the old ways (no matter how labor intensive) while casting a jaundiced eye towards every newfangled idea to come down the pipe.

So it was with me and deck washdown systems.  The time honored bucket-on-a-rope method of hauling water to clean anchor, chain, and deck worked well enough for me in the past.  Some muck and debris invariably made its way on deck despite my diligent brushing and sluicing while raising anchor, but not in sufficient quantities to make cleaning up afterwards unbearable – until I discovered Chesapeake Bay mud.  After just one anchoring experience with an all chain rode (and the thousand or so buckets of water required during the exorcism afterwards) I vowed my first anchoring experience in the Bay without a pressurized deck washdown system would be my last.

In hindsight I can’t understand why boat manufacturers don’t include a washdown system as standard equipment – fish blood, seagull poop, and yes, the calling card of those suffering from mal de mar – are all easier to remove sooner rather than later back at the dock when dried to a concrete-like consistency.  In addition to overall cleanliness, installing a washdown system makes sense for a number of other reasons.  Walking about the deck with sand or grit underfoot is murder on gelcoat and painted finishes alike, while cleaning anchor chain prior to storage not only reduces corrosion (particularly in the case of fresh water washdowns) but also keeps the un-hygienic smell of Davy Jones’ gym locker from permeating the entire boat as a result of an ooze-filled chain locker.

From a safety standpoint, slimy decks are a slip-hazard and muddy rodes can introduce bilge pump-clogging goo and debris (particularly where chain lockers drain directly into the bilge) and plug drains for lockers with overboard discharges.  A deck washdown system allows you to hose off all that muck and ooze before it gets onboard!

          Installation of a washdown system is a fairly straightforward affair, however as with any project if you have questions or run into problems, seek professional assistance.  It’s also a good idea to thoroughly plan out the install (hose runs, pump location, power supply, etc) prior to grabbing that drill or hole saw.  As for components, a typical pressurized system install will include the following:

  1. 12 volt DC washdown pump (marine grade with pressure switch)
  2. Hose (garden hose will work OK above deck, but reinforced hose should be used for all runs below decks)
  3. Corrosion proof through deck fitting
  4. Appropriately sized circuit breaker or fuse
  5. Marine grade wire and connectors
  6. Stainless steel hose clamps (enough to double clamp each hose transition point)
  7. Intake filter
  8. Y or T connector
  9. Water source

Probably the first decision when installing a washdown system will be the water source.  Most are plumbed to draw directly from the water you’re sailing in (be it fresh or salt) in which case the amount of water available for use is limited only by your ability to avoid shoal water.  The only problem with using a raw water system in saltwater is the salty residue left behind, although a salty boat is better than a nasty one in my opinion.

A second option is feeding the system from the boat’s freshwater tank.  This will typically limit the amount of water you can use, but does have the advantage of reducing the effects of corrosion on metal components via freshwater washdowns.

          A third option is plumbing your system to both, giving you an unlimited supply of raw water (ensuring you have enough to get the job) and the option of that final freshwater rinse with minimal drain on your potable water supply.  Freshwater washdowns are plumbed into the freshwater system at some convenient point (possibly near the tank), while systems supplying raw water require either a dedicated through-hull or connection via a “T” fitting into an existing raw water system hose (a head intake for example).  If tapping into an existing through-hull, make sure the ability to meet its original function doesn’t suffer, such as providing cooling water to the engine for example.

Using an existing through hull is the most common route, as most boaters shy away from cutting additional holes below the waterline.  It also has the added benefit of allowing you to complete the installation with the boat in the water (simply shut the seacock of the raw water system you’re tapping into off prior to installing the T fitting).  Once again, use properly reinforced hose during the install (particularly on the pump’s suction side to prevent the hose from collapsing) and ensure all hose transition points are double clamped with marine grade stainless steel clamps where possible.

          Pump selection is probably the most critical aspect of the system in terms of performance.  Nothing can make or break your overall satisfaction more than pressure (or lack thereof), particularly when dealing with stubborn mud.  Believe me, you want to be able to blast it off with authority, rather than trying to coax it off with a wimpy steam of water.

The trick is finding a moderately priced pump that not only provides adequate pressure with minimal power draw, but can also stand up to the marine environment (pumps tend to be installed in the bowels of a vessel and promptly forgotten until they fail and washdown pumps are certainly no exception).  Output for high-pressure pumps suitable for use aboard small to mid-sized boats can range between 3 to 12 GPM (gallons per minute) with prices from less than $100 to over $1,300.  After reading various reviews, I purchased a Johnson Aqua Jet 5.0 pump (5 GPM) off the Internet for around $150 as a kit, which included pump, filter, and a quick-disconnect nozzle.  Consider the pump’s warranty as well when shopping around – most manufacturers typically offer a one to three warranty (longer being better, of course).

          As for mounting, washdown pumps should be located in an accessible area well above the normal accumulation of bilge water between water supply and deck outlet, ideally as close as possible to its power source (to simplify wiring runs).  Pumps push water better than they pull it, so it should also be as close as possible to the supply through hull or fresh water tank.  Be sure the pump installation itself is in accordance with the manufacturer’s instructions and that it includes an intake filter between pump and the water supply to prevent pump damage due to debris.

Pumps vary in their ability to self-prime or lift water vertically in order to start pumping.  Some are rated at 8 or 9 feet, while others may only be able to overcome two feet of “head” when pumping.  Make sure the location you’ve chosen doesn’t exceed the pump’s self-priming ability – it’s also a good idea to choose pumps with a “continuous duty rating” so you hopefully won’t have to worry about burning out seals or bearings.

Finally, if installing a freshwater only washdown system, don’t be tempted to simply cut into the system and use your existing freshwater pump.  You can do it, but don’t expect too much from such an install – pumps used in freshwater systems weren’t designed to move large amounts of water quickly and typically can’t provide the pressure a good washdown pump can.

When planning your install you’ll also need to figure out where to locate the deck outlet.  Most folks simply mount it on the foredeck (close to the anchor) as cleaning ground tackle is often viewed as it’s primary job, however there’s no rule saying you have to be put it there.  I installed my outlet in the coach roof above the head.  It made for a shorter internal hose run (I used the head intake to supply saltwater) and allows me to wash the entire boat using a 25 ft hose instead of the 45 foot one I’d need if it was located on the foredeck.

Regardless of where you decide to install the outlet, make sure you have enough space beneath the deck to accommodate the hose and associated fittings AND that you won’t be drilling into anything unexpected (wiring, cables, etc) while cutting the mounting hole.  Seal the edges of the hole with thickened epoxy when cutting through cored decks (balsa, plywood, etc) to prevent water intrusion into the core and the possibility of rot later on – bedding the fitting with a suitable marine caulking will help in this regard as well.

          Installation of a pressurized washdown system is an excellent return for a relatively small investment of time and money.  Cleanups after raising the anchor will be a cinch, and you’ll find so many other uses for the system (hosing off the dog, rinsing the dingy, giving the kids a bath) you’ll wonder how you ever did without it.  I know my ancestors would approve, however if not I can always use it to fill up the bucket…