Shower sump syphons on my 45f5

[Leakie Marine]

I just discovered a worrying design issue with my 1992 45f5 (hull number 94). When the filter on the forward shower sump pump got partially blocked it allows the line to be primed. The outlet is below the waterline so when the pump is turned off a syphon starts and would sink the boat!
In the past when the filter was clean air sucked into the line when the sump emptied so the syphon was broken.
My thoughts on rectifying this are:

1. Turn the seacock of every time (a pain, but safest)
2. Find/invent an electric seacock that fails to closed (violates the KISS principle)
3. Keep the filter clean (not good enough solution for a sinking risk)
4. Re-route line to above the waterline with a anti-syphon vented loop (relies on vent not blocking)
5. move skin fitting to above the waterline. (a lot of work and not a good look)

Has anyone else had this problem? What are your thoughts?

 

[TimFromLI]

I never noticed that on mine. I'll have to take a look at it, maybe install a loop with a siphon break but I'll keep the thru hull closed for now.

 

[TimFromLI]

I'm a new owner to the 45f5 ... great to find another owner. Absolutely love it so far!

 

[Leakie Marine]

I got mine in November, so happy as well
I had raced on her with the PO 2 handed as well as fully crewed, she is a great performer as well as being very comfortable. I am still finishing off my old boat to get her on the market, once done I can do a couple of 5 minute jobs on Magique and then head off cruising!
I would be interested to see if you have the same plumbing setup in the fwd head.
Do you have a boarding ladder on the swim platform? I don't and am scratching my head on how to mount one. I have not been able to find even a photo of the design that would work.

 

[TimFromLI]

My setup is the same, I'll have to see if the pump drains or if it creates a siphon. I removed the holding tank from under the forward berth and am installing a new one in the sail locker. The old tank smelled up the whole cabin. All the head hoses were 25 years old too. The PO left the tank half full while the boat was laid up for 2 years. I do have a swim ladder but the swim platform is in the shop getting some fiberglass work done. I'll PM some photos when I get it back. Ironically, one of the repairs to the platform are chips caused by the swim ladder.