Your under-settee water tank ideas

[Cyrus Safdari]

I am considering building integral water tanks under the settees. (I can't use a bilge space since I have a centerboard) so I'd appreciate any photos/suggestions.

Right now the house lead acid battery lives under the stb settee. I will be going to lithiums, in another location

I prefer to use the clear reinforced vinyl hose so I can see any clogs/bubbles

The boat's hull will be the bottom/side of the tanks. All I'd need to do is glass-in a top and the other sides.

It would be nice to be able to use the space for storage when the tanks aren't being used to store water> I was even considering somehow putting a bladder tank inside the integral tanks for this reason. Then if the bladder tanks leak then the water will be contained too

I am going to use the water as ballast when I can and have a pump to shift water between the tanks.

I figure I can store about 30 gal on each side. More than enough for my purposes.

Thanks

[psk125]

If a pint’s a pound, 30 gallons of water is going to weigh about 240 pounds - roughly the weight of a big guy. Putting in two tanks and pumping the water to the windward one would be like having this big guy move from one settee to the other. On a Pearson 35, which weighs about 13,000 pounds, shifting this little weight so close to the centerline will not help flatten the boat much. Even having a heavy crew lean out on the windward rail on this boat is only getting 5’ (half of the 10’beam) of leverage. Unless you’re racing, weight on the rail is not going to improve performance much; you’d want five guys up there to make a difference. Pumping water uphill is a lot of work, whether you’re doing it by hand or draining your batteries to make it happen. Pumping 30 gallons could also take a while.
Using clear tubing so you can see clogs and bubbles sounds like fun. One of the reasons people don’t use clear tubing is because it promotes bacteria growth - which causes clogs that burn out pumps. Bacteria in the tubing or tanks might also sicken the crew or make the water look or taste bad.
Do you need more water supply? There’s supposed to be a 78 gallon tank somewhere on board already. That’s about twice the tankage on our boat, and we manage to cruise for a week or more before needing to refill ours.

[Cyrus Safdari]

Thanks for the feedback. Clear hose does indeed allow things - algae mainly - to grow but only if exposed to light. None of the hose runs on any boats I know are exposed to sunlight and clear hose has been used for generations on boats.

340 lbs is still 340 lbs. (Actually it would be partially filled tank) and better have it to windward than lee if you can, which is why we here all also pretty uniformly put our 5 gal jugs of diesel on the rail on either side. Power wise it really doest take a lot of juice since you don't rally pump it all uphill,, you first heel the boat and let gravity do its thing. The pump isnt really just for ballast, I'd have a pump between the tanks just to have the ability to shift water content from one tank to another for all sorts of other reasons that can arise ie to empty one leaky tank into the other, etc. Add some y vavles and the same pump can be used for house water.

The boat had a water tank in the bow, it wasn't 78 gals and in any case it was way too much weight up front so that's gone and is now a watertight crash compartment under the vberth with extra storage access. So much so I'm thinking of putting a small 19 gal spare diesel tank there. Diesel is more precious than water.