Bilge hose - important difference!

[Fr. Frank]

A friend and I did a test last night on the difference between corrugated plastic bilge hose, and smooth-wall hose. The results were surprising to me.

Using a 600 gallon steel stock tank, and a 325 gallon clear sprayer tank with exterior volume markings, we measured the output and amperage draw of two bilge pumps using the different hoses. We placed the pumps in the bottom of the stock tank, and then hooked the pumps up to a battery for 15 minutes.

My friend then had a beer (one during each test). I had a diet Dr. Pepper. (one for all 4 tests)

The first pump used was a new Attwood 500gph automatic bilge pump from WalMart. Using a 6' long piece of straight wall 3/4" garden hose, after 15 minutes the measured output was approximately 180 gallons, or about 620 gallons per hour. The amperage draw throughout was about 1.9-2.0 amps.

Repeating the process with 5' of corrugated 3/4" bilge hose gave us an output of approximately 95 gallons, or 380 gallons per hour, with an amperage draw of 2.2 amps.

The next pump we used was a 2 yr. old Rule 1250 manually switched pump, with a 1 1/8" output. Using 5' of fiber-reinforced straight-wall bilge hose, we got an output after 15 minutes of about 320 gallons, or 1280 gallons per hour, at 2.7 amps

Using 5' of corrugated bilge hose from West Marine, we got an output of only 240 gallons, or 960 gph, at 2.9 amps.

People, the difference may be between sinking and floating. These pumps are obviously rated for using straight-wall hose, NOT corrugated hose. Using corrugated hose provides less output while using more electricity.

While I expected a slight difference, I didn't expect so dramatic a difference. And I have corrugated hose hooked up to all three of my pumps in my bilge.

(Yes, I have THREE bilge pumps in a 20' Seafari, all 1200 gph rated. Two at the transom, and one in the bow under the cabin. I discovered the hard way that with 5 persons on board, and three of them sunning on the cabin deck, a Seafari will begin to sink bow-first when the drain plug is left in the engine well instead of being stuck in the little hole in the transom)