Holding Tank Design

We already have a holding tank fitted to the forward heads but with us planning to spend a lot of time in various idyllic anchorages we have decided that we need to fit a holding tank to the aft heads as well.  The photograph to the left is of a mock-up of the tank made from hardboard.  It has been very worthwhile making the mock-up as I have been able to check that it fits through all of the doorways and hatches as it is wiggled into position.  It has taken 3 modifications to get it right so I think the time was well spent

checking and double checking the dimensions.  It has also allowed me to properly visualise the pipe runs.  The sanitation pipes are quite thick with an outside diameter of 45mm so don't bend around corners very well.  Getting the tank made is going to be expensive so hopefully this work will mean that the tank will be constructed exactly right first time with all of the connections in the right place so that the pipes will run neatly.

It's not just the tank that needed careful thought.  The holding tank needs to be able to be pumped out when we are at sea or from a shore

facility, plus it needs to be vented properly and a carbon filter installed to remove any nasty smells.  The photograph on the left shows the carbon filter housing and the new vent pipe running back through the bulkhead.  The run continues aft and the pipe is vented through a fitting on the transom.  The photograph above shows the  new manual pump which will allow us to pump the holding tank out when we are a suitable distance offshore.  With the pump in position I'm making a few modifications to the wooden cover which will hide the pump adding holes for the pipes and the pump handle.  With that complete we will be ready to fit the tank.  The tank will be ordered next week and I'll use the time it takes to be made to 'psych' myself up for pulling apart the old sanitation pipes.  It doesn't matter how much we flush them through, pulling apart and replacing the old 'pooh-pipes' is not going to be a great job!  We've decided to replace all of the pipes that take effluent with high spec butyl rubber and hopefully that will ensure many years of aroma free sailing.

The last job I stared this week was fitting a cooling vent to the enclosed locker that houses the HF radio.  The radio is made up of 3 boxes with just a control facia at the chart table.  That has allowed the main radio box to be tucked away out of sight.  However, the box will get warm in use and the locker needs a vent to allow the hot air out.  The photograph on the right shows how far I have got cutting the hole.  By my next blog entry the job should be done and the wooden vent cover fitted in position.  That will be after a lot of careful trimming to make it a precise fit plus some time spent varnishing the exposed end grain to seal it.

This week I have also managed to book a crane at the end of May to lift BV out onto the hard for a week and to take down the mast.  A marine engineer will change the cutlass bearings for us and we'll change the anode bolts, the anode, polish the prop and touch up the coppercoat antifouling in a couple of places.  The mast will also be taken down so that we can fit the new cap shrouds and intermediates.  That will finish the re-rig as well as  allowing us to more easily let in a sheave for the new storm jib halyard and to attach the track for the storm trysail.  I'm also expecting to spend many frustrating hours replacing the VHF coaxial cables in the mast.  How long that takes will dictate how much time I have left to polish to topsides.

Hopefully in and around all of this industry we'll get the chance to spend a few days sailing as well.