Large Sanitation Hose Nipple

[Thorpydo]

Long story short.. I'm perplexed why trident marine's premium sanitation hose is offered in 1.875" ID, while nipples from groco and the like are offered in 1.5", 1.75" or 2". Why didn't they make that hose a squige smaller or larger...?

I called trident and talked with a couple of their guys. They couldn't give me a good answer except that 'this is what people want'.

So I ask how you guys make this work, because I know I'm not reinventing the wheel here.

Long story long.. I'm wrapping up a gravity fed holding tank install. I've already got the 1.5" through hull/flange/ball valve assembly. I have one of groco's regular nipples for 1.5" hose. The ID of the nipple is 1.25" and I'd like to increase that if possible. Groco offers 'full flow' nipples. The full flow nipple has the same threads and will fit onto my ball valve, doesn't neck down as much and accepts 1.75" ID hose instead. Hence my search for a slightly larger sanitation hose.

Maybe I should use the regular nipple and hose and be done with it. I just really don't want a clogged drain with a holding tank full of crap. What are your thoughts?

Thanks

[peghall]

I dunno which "premium" sanitation hose you're asking about...but their top of the line 101/102 is available in THREE sizes (to accomodate metric fittings: 1", 1.5" AND 1 7/8" sizes. You can read it on their website: Trident Marine: Sanitation Hose

1" and 1.5" ARE what most people want because 99% of toilets discharge fittings, y-valves, discharge pumps, thru-hulls, and tank fittings are 1.5" or 1."

My thoughts: you have two choices...

1. flush out the holding tank and discharge line with plenty of water--which can be sea water--about once a month....or

2. use rubber engine hose or any other heavy duty hose that's available in the culvert size that will allow you to avoid doing ANY maintenance to prevent clogs.

[Thorpydo]

I was aware that it is offered in the smaller sizes as well.

That is probably what I will do then, go ahead and use 1.5" hose and be okay with the 1.25" diameter constriction at the nipple.

It's still a bit odd to me though. When I was waist deep in research, I remember reading that some recommended a 2" ID hose for discharge, from holding tank to thru hull. How they accomplished that.... I don't know. Maybe they used engine hose like you proposed.

Thanks.

[Thorpydo]

And one other quick question.

I plan on installing two vents for better cross ventilation. One port, one starboard. I was planning on making the vent thru hulls our of fiberglass tubing with a G10 donut for support. On the outside of the boat, you would see a hole and that is it.

Is there any reason to use a stainless or bronze thru hull here like you'd see closer or below the waterline? Or any reason to do it as I have proposed?

[ShipShape]

Originally Posted by Thorpydo

I plan on installing two vents for better cross ventilation. One port, one starboard. I was planning on making the vent thru hulls our of fiberglass tubing with a G10 donut for support. On the outside of the boat, you would see a hole and that is it.

Is there any reason to use a stainless or bronze thru hull here like you'd see closer or below the waterline? Or any reason to do it as I have proposed?

I used white Marelon thru-hulls with white polysulfide sealant, they took about 10 minutes each to drill the holes and install. Used an appropriate sized spade bit that fit in the thru-hull slots and held the shaft still inside with vice grips to keep the thru-hull from turning while tightening the nut. Loop your hose up and around before going down to keep water out of the vent.

[peghall]

Your tank should be high enough to let your vent line be short, straight and relatively horizontal--which, if you go with 1" ID, should eliminate the need for a second vent line.

Loop your hose up and around before going down to keep water out of the vent.

That's a good idea for fresh water and fuel tank vents, but not for waste tanks 'cuz keeping the tank aerobic requires a straight vent line. If the thru-hull has to be in a location that'll put it under water when the boat's heeled, a clamshell cover will prevent taking on any water.....but, unlike fuel and fresh water, it doesn't matter if a little sea water gets into a waste tank. Splashing won't catch enough sea water to notice.

However, you do want both the inlet fitting and the vent fitting on the tank to be next to the edge that's closest to the centerline of the boat, NOT next the edge that's closest to the hull. This prevents tank contents from spilling out the vent or running back toward the toilet when the boat is heeled.

[Thorpydo]

ShipShape, a white marelon thru hull might make a good alternative to the permanent fiberglass tubing I am proposing. Do you happen to have a picture of the thru hull from the outside?

Peghall, I plan on straight, horizontal vent lines without a loop like you suggest. The tank has a vent fitting on each side. The furthest outboard vent (on port side) will cross back to a thru hull on the starboard side. The vent closest to the centerline will exit a thru hull on the port side (holding tank is on port side). I had to put the tank up high on the bulkhead to achieve this arrangement. I'm going with 1.5" ID vent lines. Might be overkill but that's okay as long as it effectively reduces the smell.

[ShipShape]

Here is a pic of one thru-hull, both are above the max heeled waterline. Since you don't intend to install a loop in your hose the mushroom shape will be better for you as less rainwater runoff will be likely to get into your tank, but you'll still get water from wind-driven rain and rough seas. Expect any good surveyor to say something if you get an insurance survey.



To do it right, here is the loop on the inside. I think this is 5/8" hose, and even the slightest breeze can be smelled on the downwind side - there is no question that the loops don't inhibit airflow. Hoses need to be downhill with no low spots all the way to the tank.



Getting airflow through my tank has made a remarkable difference in making the smell more acceptable; this project was well worth the *effort* of opening the tank.

[peghall]

but you'll still get water from wind-driven rain and rough seas. Expect any good surveyor to say something if you get an insurance survey.

If you do, just put a clamshell on it. However, if you want to find out just how much water wind driven rain is likely to put into a tank through the vent thru-hull, lay a gallon milk jug on it's side and from a distance of 3-5' aim a garden hose with a sprayer nozzle on it at the mouth of the jug.

I think this is 5/8" hose, and even the slightest breeze can be smelled on the downwind side - there is no question that the loops don't inhibit airflow.

That's because there is no free FLOW of air in AND out, only smelly gasses forced out by incoming waste and/or pressure generated by the rocking of the boat. A straight 1"--or even 1.5" if your boat is big enough that a thru-hull that size is cosmetically acceptable--vent line and a tank product that works with nature instead of poisoning it, and the breezes on the downwind side of the boat would no longer just be "acceptable" they'd be unnoticeable.