Friday, 9 September 2011

Re-thinking the Water Storage Capacity

It’s come a somewhat of a shock to realise the water storage capacity on Waiouru is likely to be insufficient for our constant cruising plans.  The plan was to have almost to same duration in water and sewage.  Hence the large underfloor blackwater tank.

The current boat design uses the bow area for a water storage compartment.  Now we are in the UK and physically on and around boats I’ve been able to do some rough measurements of bows and realise this area has a capacity of approximately 68 gallons.  Kelly-Louise has a capacity of 78 gallons and the water lasted 3 days.  We can be more frugal with the water, but I suspect the water on KL won’t stretch more than 6 days!

Paul, from nb Piston Broke, left a comment on our blog informing us his tank capacity was 250 gallons and lasts 10-14 days.

250 gallons is approximately 40 cubic feet.  So if I am to get anywhere near the same capacity I need to find an area to store an additional 180 gallons of potable water.  One option is to change from pump-out to cassette toilet systems and use the area for the pump-out tank as a second potable water tank.  That would give us another 137 gallons.  However Jan isn’t keen on a cassette toilet. 

For every problem there is a solution……..  I just need to look for it!


Peter and Margaret said...

My opinion only, as there are many on the subject of types of toilet system, but if you opt for cassette, you will be exchanging 3 - 4 days supply of fresh water for the need to empty cassette tanks over the same time. Personally, I would prefer the convenience (excuse the pun) of the large pumpout tank. There are plenty of available water points throughout the system for use in summer cruising. It is winter, where a problem might arise, but many constant cruisers arrange a marina stay, for example, during the coldest months.

Peter and Margaret said...
This comment has been removed by the author.
nb Chance said...

Hi Tom Our tank lasts us 2 weeks as well, and we shower every day! perhaps you may need to be more careful with your consumption, definately agree with Jan and stick to the pump out, as trying to find an elsan every 3 days would be more trouble if you are moored up!

Tom and Jan said...

We are going to stay with the pump-out system. However I do need to consider how we can increase the potable water storage capacity.

Andy, the builder, believes the bow will hold approximately 250 gallons but I have reservations. I'm going back to my school maths to add some science to the issue!

nb piston broke said...

Tom My tank is under the gas locker and comes back three quarters of the cratch area I cant remember the dims but the calculation worked out at just over 253 gals 6.25 gals = 1.0034 cu/ft hope this is some help Paul

Tom and Jan said...

I've just finished calculating the volume (in gallons) of the bow compartment and my estimate is 84 gallons. If I then calculate the area under the foredeck (cratch)I have another 147 gallons. This would give a combined capacity of approximately 234 gallons. It would mean giving up our storage area under the foredeck.
Another option is to have a large but shallow tank under the floor. We could consider this as there is no requirement for ballast with the 20mm baseplate.

nb piston broke said...

the other way is to have side tanks this is where the cheeks are double skined only problem is one cannot get inside to give them a coating unless you whent for the plastic bag option Paul