Decomisioning Holding tank question

[Alan Wheeler]

Sounds like you found one of the reasons why ferro boats are held in suspicion by so many folks, Wheels.

Mate! I was waiting for that :-)
Actually it is a common problem in FC and has nothing to do with hull intergrety. This is an inside plaster finish issue. The plaster mix when applied is very dry. It is not a slurry. This is so you have little to no shrinkage when the hull cures. But certain areas make the getting the plaster into, very difficult. For those that have built a few hulls, knowing those areas can exist and where thos areas are likely to be, ensure that thye either work harder at filling that area at time of plaster, or that attention is required shortly after the hull hardens. The experts even miss these areas at time of plaster. What makes them experts is to know where they will be and to fix them shortly after by introducing a slurry into the areas with a simple pump.
If I was building an FC hull today, I would be ensuring that intigral tanks are fully sealed from the inside. But then, on many boats no matter what they are made of, I constantly see dumb ideas with tanks and cables and other things. Making them totaly impossible to get at.
What I have learn't. If you are contemplating building a boat, ensure all tanks can be easily removed or have good access. Ensure all cables are run through conduits or trays. Ensure all bilge areas are easily accessed. Ensure you can get to the oil drain on the engien sump easily.

[Alan Wheeler]

I'd also think long and hard about the size of your holding tank.

Yes Bill, that will be a longer term "thought". I certainly want to cut it in half. I may make that a winter project.

[Boracay]

I found a reference in the Atlas Tanks brochure that states that according to the Australian Standard for pleasure boats breather size for holding tanks should be should be 1 1/2".

[GordMay]

Would it be impudent to paraphrase your second-last comment to mean "no integral tanks; but especially in Ferrocement boats"?
Integral tanks always present an access problem, no matter the construction. Access is almost always required to fix defficiencies in F-C tankage (because it's nearly impossible get get right the first time).
This shouldn't be understood to be a criticism of F-C hulls; so much as a criticism of integral tankage.

[Alan Wheeler]

Yes I agree Gord. I don't like the idea of integral tanks in FC. I also don't like the idea of integral in any material. I have seen a steel tank leak, it couldn't be fixed, I have seen an alloy tank leak, couldn't be fixed and I have heard of many GRP tanks with problems as well. If I was building, no matter WHAT material, I would have tanks that could be accessed and easily removed. I would have wiring that was laid in conduit and had spare lines run. I would have pipes and hoses run where every fitting and joint can be easily accessed. I would have every pump able to be accessed. Why oh why do pro built boats today not do this so obviouse excercise.

[hellosailor]

Wheels-
"Why oh why do pro built boats today not do this so obviouse excercise."
In case that's not a rhetorical question...Because buyers who don't know any better, are impressed when they get a 40' boat in a 36' package. Or a $150,000 boat for $145,000.

It's always the money, isn't it?

[Rod Headlee]

Peggy Hall is a great person and an authority on all things to do with head systems on boats. She wrote some books on boat odors:Get Rid of Boat Odors

Peggie also frequents the CSBB (cruising- sailing bulletin board) and is always happy to help out.

http://www.cs-bb.com/forums/CSBB/index.cgi?#78664


good luck

[Alan Wheeler]

Yep I have read her writings and tried all the advice and none of them worked.
Well I just got in from a lovely weekend out again. I sailed and for the first time in 3yrs, we did not have any smell on board. It was just plain wonderful. I even got rid of the big 32mm breather hose and left only the 19mm (3/4") breather. the 32 means too much gas escapes outside and you get wiffs of the smell when the breeze is blowing the wrong way. Now I smell nothing inside or out. I am one very happy chappie.

[hellosailor]

Wheels, I think Peg made the rash assumption that any big porous FC tanks with lots of gaps and leaks would be filled and sealed before her advice was tried on them.<G>

[Alan Wheeler]

Ummm, yep, I would imagine her thoughts would be along those lines as well.
I do have one issue with her advice though. Why go to all the hassle of ensuring oxygen flows in the tank are good, and the tank "life" are living in lovely surroundings when you want to pump the stuff out of the boat as soon as you can anyway. I don't see the point of having such a big breather. But then I suppose my tank is a little out of the norm. It's more like what you woudl find on a ship ;-)

[hellosailor]

Ouch, that makes my teeth grate. "Why go to all the hassle of ensuring oxygen flows in the tank are good," Reminds me of the TV Nooze talking about scuba divers and their oxygen tanks. Peg's just concerned with air flow, the oxygen is just a part of it.

For many pleasure boaters in the US, a pumpout may still happen only once a month, or once every two or three months. So maintained the right bacterial brew in the tank is more important.

Sure, we have pumpout stations. On paper. Or at resorts. But for the vast majority of boaters? It's easier to get a dentist to make a house call to the boat for root canal!

A thousand liters, hmm. Speaking of ships, just how much sewage can one crew produce per day anyway?? Even with copious flushing...Could you push more than ten liters a day? So you've got what, a hundred person-days of storage in that boat?!

[Whimsical]

1000 liters, Alan could start a part time business as a pump out barge

[Alan Wheeler]

Might be a good way to get moorings all to my self. Advertise the fact that I hold 1000ltrs of sewerage and they may never come near me.:-)

[Steve Kidson]

Originally Posted by Alan Wheeler

OK so who here thinks this is just plain and simple a bad idea. I have a 1000'ish ltr water tank">fresh water tank built integral to the hull. I also have a tank close to twice that size that is also part of thehull. This bigger tank is my holding tank.

Back to the original post......just wondering about the change in performance/sailing characteristics of the boat if you were to increase the weight of the boat by 2 tonnes by adding 2,000l of fresh water???

Thats a lot of boat showers

Fair winds

Steve

[senormechanico]

This link may have come from this board in the first place; but having lived aboard and cruised the tropics for several years, it makes a lot of sense to me.

thecoastalpassage.com/poopscoop.html