Holding Tanks and other matters

[oceandiamond]

morning all

I am attached at the hip to Ocean Diamond, a lovely SO 40 from 2000. She is currently on the hard and have a couple of questions if I may

1. Holding Tanks. Is there anything I should do to the holding tanks while on the hard in regards to cleaning etc.?
2. Should I add anything to the diesel to protect against fungal growth while she is on the hard ?

Thanks all

[rxc]

I don't know how your holding tanks are plumbed, but do you have any freezing issues where you are located? If so, then you might want to make sure that your holding tank plumbing is winterized. Cracks in waste systems can be extraordinarily unpleasant.

Regarding the diesel tank, the general wisdom is to keep the tank close to full but not quite, to minimize condensation and water accumulation, and add some biocide to prevent the water that does collect from breeding algae.

[so40gtb]

OD, my SO40 is the same year as yours. Before hauling the boat in late October, we pumped out the tank and ran 3 bowls of water into the tank and pumped out, twice. Once on the hard, I put 4 liters of pink anti-freeze into the tank via the bowl, but that which lurked in the hose came out when the hose and joker valve were disconnected from the bowl (a yearly ritual).

I removed the holding tank last weekend, draining the anti-freeze out the sea discharge first. Here on the Great Lakes, regulations prohibit drainage offshore, so the small size of the tank (the label says 50 liters but my measurments indicate 40 liters) is an issue, especially with the Admiral. And it is difficult to see inside a stainless steel tank to determine how full it is! I'm going to fabricate a mock-up of a larger tank using wood and cardboard, then ensure that it will go into the "tank locker", trimming its size as necessary to ensure that it can be placed without too much difficulty. Once I have perfected the dimensions, I am going to take it to a tank manufacturer to obtain pricing on a new tank of larger size, probably plastic so that we can see the level of the contents, which will please the Admiral greatly.

As for the diesel tank, I put a routine semi-annual dose of biocide in at haulout and then ran my polishing pump for 24 hours to clean the fuel and circulate the biocide throughout the tank. I installed dual Racor primary filters last summer, one of which can be valved through a Racor piezoelectric low-speed polishing pump back into the fuel return port of the tank. This pulls fuel from the front bottom of the tank and returns it to the upper rear. I have a 2 micron filter in the second filter position and use it for polishing every few months. I'll run the polishing cycle again just before launch in April. If I have any concerns about sludging the primary filter, I can put a 30 micron can in the second position and then have redundant filters, selected by 3-way valves. I do intend to write up this project when I have the time.