Union in my head...

[Ben Coombs]

I am fitting a 9 gallon holding tank for the head in my 25. The space is tight to say the least. I am thinking about making the pumpout line a straight shot--from the deck fill to the tank with no elbows. A hard fitting would be easiest, but would require a union to install the tank.

So from the deck fill down it would involve a close nipple, a union, a second nipple and then the tank. I could then install the tank in space, and snug it's platform up underneath so there would be no play in the fittings. I am quite certain I can make it solid enough that the motion of the boat would not add wiggle room to the fittings (all thread clamps). But, is there another reason for not doing this method of install? I know don Casey argues against hard fittings, but if the motion could be elimanated....

Also, this is a pump out only system--no discharge.

Thoughts? Eulogies?

Thanks.

[Steve Laume]

The fewer fittings the better. Can you set everything up and then make the final connection by inserting the deck fitting and then bedding it down?

You would hate to have the union come lose or start leaking. Murphy dictates that this will only happen when the tank is full and the seas are rough, Steve.

[Ben Coombs]

That's an interesting angle... Bolting the deck fill in last.

I am in agreement that fewer fittings are a better route. Are marelon nipples available? I'd prefer not to put a bronze thread into the tank. And would also think LDPE nipples don't want to be in the deck fill.

Hmmm.

[moctrams]

Have you thought about using Saniflex hose?
http://www.defender.com/product.jsp?pat ... id=2052128

[M. R. Bober]

My $0.02. Something has to yield to vibration, flexing, temperature change, or there is likely to be a bad outcome.

Let us know what you decide.
Mitchell Bober
Lancaster, (Where the reeds bend with the wind, as do sailboats.) VA

[rtbates]

I know don Casey argues against hard fittings, but if the motion could be elimanated....

Thoughts? Eulogies?

Thanks.

That's the issue. Motion can not be 100% eliminated. It can be highly reduced sure, but over time even a small amount of movement against hard mounted fitting results in stress cracks. Something in the system should provide the give between deck fitting and tank. A simply run of waste grade (smooth not flex) hose provides all the flex needed.

good luck with your project

[Ben Coombs]

Thanks for the replies. I guess I was hoping for someone to say "sure that'll work". Even though I know I should put a hose in there. I have found hose barbs short enough to use in the space allowed. Now, onto the vent location.... Topsides under toe rail, deck, or cabin top "wall" (a convenient spot, but I fear my ankles would smack it all the time).

No hard fittings here. Thanks.

[sharkbait]

You might want to lift a stanchion and install the vent to come up inside the stanchion. Out of sight - out of mind but well protected against mud dobbers.

[M. R. Bober]

You might want to lift a stanchion and install the vent to come up inside the stanchion. Out of sight - out of mind but well protected against mud dobbers.

CD stanchions are hollow, BUT they have a plastic sleeve where the life lines pass through them. If you want to use a stanchion as a vent, you will need to remove the sleeve & drill through the base. Doing so would allow water a means of entering the cabin. IMHO: Find another alternative.

Mitchell Bober
Sunny Lancaster, (The fumes? They vent thataway.) VA

[satu]

I would second M.R.Bober's opinion. Specifically that something has to give. Mounting the tank in a firm but flexible bed that allows thermal expansion as well as flexing would likely provide a long happy life to your installation.

Craig Urquhart
1984 CD27 No.272
S/V Satu
Brunswick, Maine

[Ben Coombs]

Definitely going with hoses, and no union.

Also not using a stanchion for the vent. Peggie Hall the "head mistress" (her own moniker, not mine) says that a topside mounted vent will have sufficient back pressure to stop any sudden inflow of water in heavy seas. So I am tempted to locate the vent up near the toe rail. My CD doesn't like to sail with the rail under water (its just a better handling boat at less heel than that), so I don't imagine that would force too much water in either.

Tho other location I have in mind is in between the shroud plates on deck...

Any other ideas. My other thought was to run a second, long vent tube to the transom. The topside vent that faces forward would allow air to be forced in, and the longer aft facing vent would give the old air a place to escape.

Maybe.