View Full Version : Location for washdown pump on pontoon houseboat
10-26-2012, 09:35 AM
I have decided to include in my winter upgrades the addition of a washdown pump to hose off my front deck on my 60' Destination Yachts pontoon boat. I am thinking that when the boat is anchored with its nose on a beach, where it is 90 percent of the time I use it, clean water from the rear of the boat will be more useful than muddy water from nearer the front of the boat. But my understanding of fluid dynamics tells me that I will get better pressure and flow if I draw water form a pickup tube nearer the front of the boat. As a compromise, I have an open midship spot where my existing lakewater draw enters the boat. As you might imagine, I need some help here with a couple of questions:
First, does anyone have experience with the pros and cons of clean water traveling a long distance vs. close but less clean water?
Second, does anyone have thoughts on a good pump to buy? One thought would be to buy a 4 gph flow jet like the one that supplies my house water; that way I would always have the ability to rob the washdown pump if the more-important house pump went out in the middle of a trip. But I don't feel strongly enough about that long-shot possibility to use an inferior pump for washdown purposes.
10-26-2012, 03:31 PM
A larger-diameter hose/pipe will have less resistance and should compensate to some extent for the long run.
I'd hook it up temporarily at the stern with the suction hose hanging over the side. If it's satisfactory, make it permanent. If not, try it midships (temporarily), and go with what you like best.
For washdown you might want more capacity than your FW service pump, but you could still adapt it in an emergency.
(You knew all that already, didn't you?)
10-28-2012, 07:21 AM
IMHO it isn't the actual length of a run that matters in this case. Once water is pressurized as long as the run is level you can pretty much push it as far as you'd like. It's the rise or elevation and the actual weight of the water when forcing it uphill that overburdens the pumps ability to create any volume or pressure at the other end. A given pump may supply good or reasonable pressure from the back to the front deck, it's more or less level. But if you were to throw the same hose topside to hose down the upper deck it very well may fall flat on it's face as far any real usable pressure. Simply stated the more lift that's required the larger the pump needed to push the weight and supply pressure.
11-06-2012, 01:23 PM
I agree with Bamby. We have a masterfab pontoon hull. Our washdown pump is located in the engine pod where it draws from deeper, cleaner lake water. The biggest considerations IMO are how much length of hose the pump can prime and then how much head pressure. As Bamby said, once the water gets through the pump it can run horizontally with very little pressure drop assuming the hose/pipe is run smoothly with minimal turns, etc. We run from the pump to two hose bibb locations, one at the stern and one at the bow. Pressure differential at either end is hardly noticable.
11-11-2012, 03:46 PM
Assuming you have typical M-brackets (or similar), how about running a length of 3/4" or even 1" ABS along the top of one log from back to front to act as your main water line. That should keep any flow losses to a bare minimum, and ABS is cheap too.
As for a pump, don't cheap out or you may regret it. Our Chaparral has a typical 2.8 gpm pump for the hot/cold washdown, the hose is all 1/4" stuff and the flow is pathetic. In the basement of our SkipperLiner when we bought it was a Johnson washdown pump, like 55 psi and 5.5 gpm, it was a great pump! I say "was" because I used it as our main water pump for 2 years, but the pressure switch wasn't designed for 'always on' use, and I burnt it up. Still need to fix it...