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Discussion Starter · #1 · (Edited)
Hi, All... quick question....

My '72 P26 came w/ a disgusting flexible bladder holding "tank", a non-working Wilcox-Crittendon HeadMate, a deck pumpout fitting, and no vent. I've ripped all of that out except for the deck pumpout and replaced it with a Thetford 550P MSD porta-potty with pumpout and vent fittings, but have yet to install the vent. Can anyone advise me as to where specifically I should locate the vent thru-hull? This'll be my first time making a hole in my boat, and I'm a little nervous about it.. is there a "standard" place for the vent on the P26?

I want it in the right place the first time!

Thanks in advance.. I'm hoping to do this ASAP. Anyone?

Best to you,

Barry
 

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Tartan 27' owner
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Having read Peggy Hall's book(let) on "Eliminating boat odors"...
There are a few things to consider.

Ideally your vent line will be as straight and short as possible. This can be difficult on many boats where the head is near mid ship, or beam.
Typically a holding tank vent is located on the hull just below the hull/deck joint. If the vent is located at the beam then it will be underwater while tacking up wind at some point.
I have seen a 50' Beneteau rigged with the vents routed to hollow stanchions for the lifelines but that is a little fussy and you could smell the vent if someone used it below.
Best to make your vent hole more towards the bow or stern than directly on the beam which may mean a longer vent hose with more bends.
When we replaced the holding tank on our boat we added a second vent line as suggested by Peggy Hall (provides some "cross ventilation", if you will). Our holding tank is located under the port lazarette seat in our cockpit so our vent lines are routed towards the stern, just under the toe rail.
Good luck Barry!
 

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Discussion Starter · #3 ·
Thanks for taking the time to help out, Caleb.. much appreciated as usual. I've got Peggy's book, and she was even kind enough to spend an hour or two on the phone with me last year when I was trying to figure out the best way to install a rigid tank instead of the bladder that was on my boat when I purchased it. At that time, she suggested I forget about the tank entirely and put in the 550P MSD instead. Much simpler, gains interior storage space... great solution.

The 550 has a 5/8" vent. She suggested increasing that to at least 3/4, or even 1". The fitting is built into a cap along with the 1.5" pumpout fitting, and there's precious little real estate there to enlarge the hole, so I'm going to try it as is for now. Given that the vent is smaller than she recommends, I'm trying to get the most out of it by following the rest of the advice the she and you have given as much as possible.

The head is directly aft of the v-berth, so it's slightly forward of the widest part of the boat. The recommendations to have the shortest run possible, to keep the line as horizontal as possible, and to keep the vent as far fore or aft as possible don't intersect so well. The shortest possible run would be slightly over three feet, but it'd be pretty much vertical. I could get it up closer to the bow over a much more horizontal run, but then the run would be about 10 feet with a bend or two. Is there a priority hierarchy with the three desires; horizontal, short, and to the fore? I don't think there's a solution that meets all three.

Thanks again... :)

Barry
 
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