— The website of the Sailing Vessel Beatrix, Kelly-Peterson 44 #276 (1980).

There I was at the bi-annual Fisheries Supply swap meet, facing a used Groco Paragon Senior Pump for a mere $150.00.  Now this is a pump that usually costs almost $1000 -- I couldn't resist.  So after the $350 factory rebuild that was necessary I now have a terrific washdown pump at only about twice the cost of a new one (albeit not a new Groco, a company that makes really robust, old-fashioned and ridiculously expensive equipment).  The following is from a posting to the KP44 group in answer to a member's questions on washdown pumps.

Q.  Do we think it is a good thing?  

A.  You bet.  Being able to hose off your anchor chain is a wonderful convenience.  Secondarily you can wash your deck of mud and garbage.  

Q.  What would be the best location to install a washdown pump, and the outlet faucet?

Anywhere that is convenient.  You can run hose to one or more deck outlets, and that is easy to do.  I would MINIMIZE the hose run from the through hull to the pump.  On Beatrix we have used the "spare" through-hull that is located below the galley floorboard (see photo below).  It's a good location for the pump, too, as it is not used for anything else and is easily accessible for inspection and strainer cleaning, and close to the electrical supply.  Two pieces of teak for pump mounts were glued to the hull with epoxy and epoxy cloth tabs provide additional attachment to hold them firmly to the hull.  

The best setup for a washdown system is identical to a fresh water pressurized system, i.e. it has a high/low pressure switchl,  so when the pump is energized it pumps until the water line is at pressure and then automatically shuts off.   When the pressure drops, the pump goes back on.  If it's a heavy draw pump a solenoid may also be required  in the circuit.  A pump can draw a lot of power.  The Paragon Sr. draws 50 amps! The  kind of pump you have:  vane, impeller, displacement, or centrifugal, has a bearing on where you place the pump.  Ours is a "twin chamber self-priming rotary pump".  It can be run dry periodically and could have been located above the waterline if desired.   Many pumps are not self-priming and have to be below the waterline as they can't be run dry for long, if at all.

Here is how the entire seawater washdown pump system is organized:


  1. Intake hose: It's below the waterline -- use the heaviest "Shields" type hose for your intake and double clamp with AWAB (smooth) hose clamps or T-bolt clamps.  The through-hull is valved of course.
  2. The check valve and high/low pressure switch may be built in to your pump.  If not they can be purchased at Grainger's or any pump store.
  3. The outlet hose needs to be strong and flexible.  There are lots of options here, but I don't like that white plastic stuff, so I used engine heater hose, which is reinforced with fabric internally.  I.e. I would use a good rubber fabric reinforced hose rated for the pressure you expect.  Our pump uses 1 inch input and output hose and operates at about 40 PSI.  It's flow rating is 11 GPM.
  4. Check valve.  Very important for an automatic pressure system.   
  5. The accumulator is a 1-gallon pressurized steel water tank with a rubber lining.  It keeps the pump from cycling on and off too fast.  The GROCO PST-1 is an example, but there are cheaper and/or better models from plastic to stainless.  The accumulator tank can be installed anywhere on the downstream side of the check valve.  Mine is in the anchor locker above the door.
  6. The pressure switch is often integral to washdown pumps, as is the check valve.  Larger pumps will be energized by a high amperage high/low pressure switch or a smaller ampacity pressure switch plus a DC solenoid.  I bought mine from Grainger's, but a marine supplier or a pump store should have the equipment.  They should be adjustable to set the ON pressure and the differential between ON and OFF.  Tune the switch so the pump does not cycle (i.e. is always running) when the hose is full on.
  7. Deck fitting.  Don't use a faucet, they are a pain to mount.  The only deckwash I've found that I really love is the Washdown Valve from Newfound metals (see photo at right below).  It is a purpose-built through-deck washdown fitting.  It's features are: flush mount, special bayonet connector with a standard  hose thread, automatic valve that closes when the hose is disconnected, and O-ring seals. 
  8. If  you want more than one deck fitting you can tee off anywhere.  We have one near the cockpit and one at the bow.  A short (7') hose with a trigger nozzle is used for anchor and chain washdown.

Q. Do I have to cut another through-hull for this or can I plumb it from some existing source?  If so, which one would be best?   A.  It's not a good idea to share through-hulls for pumps, but with use of check valves it can be done.  The through-hull and intake has to be big enough to allow for the pump's rated flow.  The strong flow can suck backwards on a shared intake, but a check valve solves that problem.

Q.  My initial thoughts were to install the pump in the chain locker or under the forward cabin bunk, put the faucet forward of either the port or starboard bow cleat outboard of the anchor rollers, and run the intake from the throu-hull feeds the forward head fixture (either by installing a T or getting a manifold through-hull).

 As I wrote above, my advice is to locate the pump close to the through-hull you choose for an intake.  Running output hose in the bilge is safe and easy so consider minimizing electrical runs and intake hose length.  With the flush-mounted Newfound Metals valve you can install the fitting where convenient as you don't have a toe-stubber faucet to trip over.    

Another good idea is to also plumb for freshwater deck washdown.  With large tanks and a watermaker it becomes feasible to rinse off chain, sails, and gear with fresh water, thus massively extending their life.  I'm planning a freshwater deck valve that goes direct to the pressurized freshwater system (with a shutoff at the tee that leads off the main freshwater system).  It will have less pressure and flow (which is good -- don't want to empty the tanks too fast) than the seawater washdown.  I originally thought about having a 3-way valve to the seawater washdown pump intake but decided I didn't want to mix the systems. 


The contents of this page are an example of a refitting job performed on a single vessel by its owner.  Just because I put it here for your interest and information does not guarantee it will work on your boat, or work at all. Fair winds & smooth sailing. -- Jeff Stander


Last modified: March 23 2014 03:38