Replacing Stanchion Vent

womble

.
Jan 13, 2015
41
Catalina 30 Middle River
The existing vent is vertically mounted under the stanchion. A new mushroom vent would be horizontally mounted beneath the rub rail, so a 90 degree turn for the hose. Using both would mean installing a T-connector to connect the two vents right below deck, then attaching the vent hose to this connector. More work for marginal added vent space. Easier to fill the stanchion vent (or cut it off and fill the deck hole) and connect only to the mushroom vent out the side.
I'm simply proposing adding a new bigger vent and not touching the existing one.
 
Jul 27, 2017
44
Catalina 30 5167 Texas
My existing vent was a pretty bad source of foul odor with the 30 year old hoses and theoretically an ingress point for water.
 

womble

.
Jan 13, 2015
41
Catalina 30 Middle River
Hi Peggie,
Are we totally confident in the Uniseal?
I'd hate to drill a hole in my holding tank and have it leak!!!
 
Feb 26, 2004
22,759
Catalina 34 224 Maple Bay, BC, Canada
Hi Peggie,
Are we totally confident in the Uniseal?
I'd hate to drill a hole in my holding tank and have it leak!!!
If Peggie says it works, seems counter-intuitive to ask again, doesn't it?
 
Jul 27, 2017
44
Catalina 30 5167 Texas
I agree fully... Peggy is correct, the Uniseal does not leak. My pipe is even at a tiny bit of an angle and stays bone dry. Just make sure you install it correctly.
 
Dec 2, 1997
8,708
- - LIttle Rock
Hi Peggie,
Are we totally confident in the Uniseal? I'd hate to drill a hole in my holding tank and have it leak!!!
I have total confidence in the Uniseal as long as it's sized and installed correctly, not just "close enough." It will not leak unless a hose pulls to one side hard enough to break the seal...and that can only happen if a straight hose fitting is used where a 45 or 90 is needed. There's only one place I wouldn't use a Uniseal: a discharge fitting at the bottom of a tank...and that's only out of an abundance of caution.
--Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein
 

Ward H

.
Nov 7, 2011
3,645
Catalina 30 Mk II Barnegat, NJ
I used a 45 degree fitting to connect the 1" hose into the Uniseal.
My old vent was barely clear. The hole in the stanchion is less than a 1/4". The hole in the stanchion the hose connects to looks to be about 1/4". Like Smunkey reports, my hose was a source of odors so I removed it. I don't think it was worth the effort to replace the hose and clean the clogged stanchion vent.

After I put the new vent in and before I put the plug in the hole where the old vent nipple had been, I filled the holding tank with water and some bleach. I then went sailing in 15 to 20 winds for the afternoon. On the way back to the marina I stopped by the pump out station.
Back at the slip I looked around the Uniseal to see if there was any leakage. It was completely dry.
I'm sold.
 

Ward H

.
Nov 7, 2011
3,645
Catalina 30 Mk II Barnegat, NJ
I'm simply proposing adding a new bigger vent and not touching the existing one.
I don't see any issue doing so. There is no requirement to remove the old vent. Your boat, your choice.
 
Oct 29, 2012
346
Catalina 30 TRBS MkII Milwaukee
I just did this project last week on my 88 TR. I drilled from the outside in, because I was worried about coming out in the raised section below the rub rail and going outside in assured that I wouldn’t. It wasn't very hard to figure out the horizontal position by just eyeballing it and measuring a little just to make sure.

I used Trident 101 as suggested. Found some 1-inch ID on eBay at a good price. I bought 5 feet, but the guy only sent me 55 inches. This is ok though because it still fit. Seems like anything between 50 and 60 would have done the job.

I used a Uniseal and a 45 degree PVC elbow, with about 1.5 inches sticking out either side. I used two hose clamps on either end in opposite directions.

Since I was not sure how it would all fit together, I bought a pack of 1" Uniseals and a pack of 3/4" Uniseals. Then one of each size PVC pipe and elbow. I also had two hole saws, 1-3/4" and 1-1/4". My thru hull was a 1-inch Forespar marelon mushroom head from West Marine.

The hose fit the thru hull no problem, but the hose would not go onto a 1" PVC pipe, so for the tank end, I had to use the smaller Uniseal, elbow, and pipe.

I used a 3/4" PVC plug in the tank where the old vent connected. I then used a 1/2" PVC plug in the end of the old vent hose, with the intention of shortening the hose later and moving the plug closer to the stanchion, rather than trying to remove the stanchion and plug it.

For the gap between the hull and the liner, I did nothing. I debated using thickened epoxy but voted in favor of butyl tape on each side. I can always add epoxy later if necessary.

I had to drill 3 holes. One through the boat, one through the bottom of the shelf, and one through the storage compartment behind the port side settee back cushion.

I also added a SCAD solo tank monitor, which seems pretty handy.

I will attach a few pictures. I didn't really have any issues other than the temperature being 95 degrees in the boat at the time, but I am kind of used to that now, plus cerveza makes it 72 degrees in my head. I can also say with 100% certainty that it has helped with odor so far.

Thanks for the great tutorial and pics.
Any chance of getting a picture of thru-hull on the outside of the boat? I am hoping to do this project before I splash and the boat is on the hard and temps Not in the 90's.
 

Ward H

.
Nov 7, 2011
3,645
Catalina 30 Mk II Barnegat, NJ
Here's a cropped shot of where I put my vent. Above water when heeling and inside the port cabinet.
IMG_2750.jpeg
 
Jul 12, 2011
1,165
Leopard 40 Jupiter, Florida
Here's other cropped photos, from inside and out. As you can barely see, I selected a vent spot too high, and actually had to shave off part of the mushroom head of the external through-hull to fit under the rub-rail. I excuse my over-abundance of caution due to occasionally "accidentally" burying the saloon ports, even with the stripe, on breezy days and I did not want to have seawater back filling my vent pipe. I did not want to re-route the vent line out of the head area even though it is a longer vent run due to (1) laziness and (2) could not get it high enough and still hidden behind cabinetry by going straight up above the waste tank in the saloon. I had to Dremel away a bit of interior trim, which may not have been needed if I had placed it only an inch or two lower.
Vent edit.jpg
Vent edit 2.jpg
 
  • Like
Likes: captcoho
Oct 29, 2012
346
Catalina 30 TRBS MkII Milwaukee
Thanks for your fast reply....I have been ruminating over this since seeing the post last fall. With the weather starting to warm and the boat still covered it has made it comfortable to start the project. The vent lines have been replaced, and all that is needed is to drill the hole for the mushroom thru-hull. I will still need to remove the cover to have full access to the outside location. Hopefully will uncover and polish and wax in the very near future and be able to splash in three weeks.
It is some what daunting to even consider drilling into one's hull, especially when it is of a considerable size.
I especially welcomed weekendkren's idea of starting with the small hole and inject foam to serve as a dam to apply epoxy support considering that there is little room to get a drill motor with proper hole saws on the inside to drill from both directions.
How big of a gap did you find between the hull and the cabin liner? I realize your boat is a 36 and a some years newer, but I would think the "gap' would be similar.
Thanks again for providing me, and hopefully others your insightful knowledge, and tips to solve our tank vent malaise.
 
Apr 5, 2009
2,774
Catalina '88 C30 tr/bs Oak Harbor, WA
Ward and Parson, I was in a race once when a clear-air squall came in off the bluff and the wind went from 8 to 35 with no warning. after retrieving the shrimping spinnaker due to a snapped halyard shackle we turned upwind with full main and no headsail. My foredeck crew was standing in a steady 6" of water on the low-side deck so there can be those times where that vent can go under. Granted it is not common and was not of long duration but it can happen.
As for backfilling the tank, when the vent is under water, the tank is unvented as long as your deck cap seal and joker value are good. With no way for the air to get out, you should not get much water in. Peggy, what are your thoughts on the matter?
BTW, that race was the reason I installed a very smoothly functioning single reef system. :yikes:;)
 
  • Like
Likes: Ward H

Jac123

.
Apr 19, 2019
48
Catalina 30 Forked River
As a temporary fix could the vent hole in the stantion be drilled out larger?
 
Dec 2, 1997
8,708
- - LIttle Rock
Jac... That wouldn't improve air exchange because it would be facing aft. Plus, I'm pretty sure that a 1" or even a 1/2' hole in a stanchion would seriously weaken it.

Hayden, I'm not sure how much impact pressure from the tank would have...I do know that brief dips don't put enough into a tank to notice--if any...that the vent thru-hull would have to be under water for several minutes for enough water to make it into the tank to matter. How long were your decks awash and did you see any rise in tank volume on your tank level indicator (if you don't have one, for Pete's sake install one!)?
--Peggie
 
Jul 12, 2011
1,165
Leopard 40 Jupiter, Florida
Increasing the size would improve airflow. The greatest problem is complete clogs, however. Spiders love that little hidden spot, and build arachnid condominiums in that pipe! Running a water hose in there at every pump out is an effective antidote.
 
  • Like
Likes: Jac123
Apr 5, 2009
2,774
Catalina '88 C30 tr/bs Oak Harbor, WA
Hayden, I'm not sure how much impact pressure from the tank would have...I do know that brief dips don't put enough into a tank to notice--if any...that the vent thru-hull would have to be under water for several minutes for enough water to make it into the tank to matter. How long were your decks awash and did you see any rise in tank volume on your tank level indicator (if you don't have one, for Pete's sake install one!)?
--Peggie
The deck was only awash for a minute at most (although when my foredeck crew tells the story it was HOURS! ;>)) I doubt that I got even a cup of sea water. My contention is that without venting, a submerged thru-hull will let in very little water. BTW, I do have a tank full sensor but it just lights up when you are down to 2-3 small flushes. Then it is "run to the nearest pumpout! We need better.