duckbill replacement, generator location and hose replacement

[rjr]

I was getting ready to post a question about duckbills until I saw Viper's list of questions. So here are my answers:
Yes, the pumps run. (2 heads).
Yes, pumps shut off.
Pumps run 30 to 40 seconds before shut off - could be a little less.
Hardly ever cycle on their own.
Yes, water will remain.
Yes, full evacuation.
Duckbills were replaced approximately 5 years ago.
Duckbills on Admiral's head are making a "weet weet weet" noise just before shutoff. So I figured it was time to replace. Then I figured might as well do both. Is it time?

I'm going to replace some of the hoses with hard plastic. Friend of mine told me I should wait till boat is in water so system can be thoroughly flushed. What does everyone think?

Question: Do anyone know where vacuum generator for forward head is located? Are generators located next to each other on starboard side of engine room near aft head holding tank? I have a waste & water schematic - if anybody wants one shoot me a PM with your email.

[Viper]

Sounds to me like your system is operating as it should. And 30-40 seconds to build the proper vacuum is excellent. You only really need to worry if it's over 90 seconds if I remember correctly. I'd be proactive though with 5 year old valves and replace them for the upcoming season.

Can't help you on the vac gen locations, can't quite remember the 440 layout. What hoses are you planning on converting to rigid? Usually, unless it was a poor install/routing, or inefficient system operation, the hoses on the vaccum side should take much longer to permeate as nothing stays in them. They should remain empty between flushes and only have waste in them during the process of transferring the waste from the bowl to the vac gen after you push the pedal. The waste is only in contact with those hoses for like a second. When the cycle is complete, those hoses should be completely empty, hence permeation takes much longer on that side of the circuit. The hoses that permeate quickly are hoses in the routing from the vac gen to the tank as waste can be sitting in those hoses depending on the routing and hardware location. Ideally, if everything runs downhill from the vac gen to the waste tank, nothing would be left in those hoses either but that's usually not the case and is where rigid lines are preferable where possible.

[rjr]

Well the boat is 25 years old. The hose that runs from the rear head to the tank is first on the list. It looks to be a straight run from the head to the tank. Haven't measured it yet but maybe 10' - 12'.