Flushing the head while cruising

[S Scott]

Has anyone else had problems with flushing the head while under way? On our last couple trips, if we flush the head while at cruising speed it seems the system seems to get an air bubble in the lines and will not draw in any water even once we stop. I was able to "burp" the air at the strainer and it started working again. I assume it's just sucking in air. Any thoughts?

 

[venajeff]

That is a common problem with thru-hulls when the boat is traveling at high speeds. I am assuming you are cruising at 20+ MPH. The intakes on my last boat had a specific design to be able to work while moving fast. They looked like this:

With our R27 I slow down to 6 MPH or so if someone needs to use the head.

 

[Bsmith]

Not to high jack the thread but does the same caution for avoiding an air entrainment in the toilet water supply (slow down!) also apply to use of the AC while underway? Is the design of the through hull for the AC such that water flow is normal even if up on plane? I have a 2023 R27OB LE.

 

[venajeff]

Our boat doesn't have AC so I don't have first hand knowledge. It's possible that the AC condenser system can handle air in the line.

 

[Cutwater28GG]

I think you will find there is also more suction from the engine than the toilet pump can overcome.

When I look at the seastrainer when the engine is running at high cruise, the vortexes in the strainer are so significant that it cavitates and produces bubbles. I struggle to see how the toilet pump would be able to compete!

 

[Submariner]

We use the head doing 25knots and haven't had a problem. It's flat water though (relatively flat, anyway).