Water tank placement

[SiteSurfer]

On from my previous thread about the triangular water tank in the bows of my boat I started looking at options this weekend and came to the conclusion that I could fit a pillow style water tank each side of the hull underneath the lift out lockers. However I then started to wonder if the removal of the weight of the tank from the bows would have an adverse effect on the boat.

Was/is it normal for boat designers to factor in the weight of tanks when designing boats? Or doesn't it make that much difference for the cruiser?

Obviously I could use the empty space in the bows as quite a substantial storage space then, which could possibly bring some weight back forwards.

 

[pmagowan]

Is the water tank an original part of the design? Certainly tankage is often taken into account, mostly to make sure it does not adversly affect the trim. In general weight should be kept low and close to the mast as a rule of thumb. It will depend on things such as the size of the boat and the relative size of the tank.

 

[vyv_cox]

My 100 gallon water tank is beneath the starboard seat/berth in the saloon. There is perhaps a 5 degree difference in the list of the boat depending if it is empty or full. I keep beer in the port side one and try to balance them

 

[Chanquete]

In general weight should be kept low and close to the mast as a rule of thumb.
Weight should be kept in the vicinity of the CENTER of gravity of the boat minimizing eventual increases of the inertia moments. The reason is to allow rapid variation in pitching so that the boat passes above oncoming waves avoiding passing through the waves
Saludos
Chanquete

 

[pmagowan]

In general weight should be kept low and close to the mast as a rule of thumb.
Weight should be kept in the vicinity of the CENTER of gravity of the boat minimizing eventual increases of the inertia moments. The reason is to allow rapid variation in pitching so that the boat passes above oncoming waves avoiding passing through the waves
Saludos
Chanquete

The centre of gravity of your boat is not, as a rule of thumb, generally marked by a big yellow ball with a black cross in it like in the CAD diagrams. The mast generally suffices 'as a rule of thumb' although it is normally aft of this.
Cheers
p

 

[prv]

Weight in the ends of a boat is bad for sailing performance. I learned this first-hand in a boat with an oversized engine, an additional diesel tank right aft in the counter stern, and a cast lead block plus excessive ground tackle in the bow in order to balance out all the weight aft. She trimmed level when at rest, but in a Solent chop would sometimes end up hobby-horsing up and down in the same hole, going nowhere.

Designers, particularly with smaller boats, often end up putting tanks etc in the ends anyway as a necessary compromise, but if you can bring it aft then that's a good thing, not a bad one. Try to resist stuffing lots of heavy stuff in the space vacated. Ariam's bow is quite fine and I have a large anchor, so I really need to minimise any further weight; I use the bow locker for a voluminous but lightweight cruising chute and the bulk storage of kitchen paper towel

Pete

 

[SiteSurfer]

ok.. I was just a bit concerned as the vast majority of the weight in the boat appears to be aft, with the galley, engine, cockpit (where peeps sit), fuel tank and whopping great lockers chocca stuff. In front of the mast theres quite literally a toilet, 2 bunks and the water tank.

Its looking more like me splitting to 100 litre tanks either side won't realy affect the boat at all.

 

[Tranona]

You will only find out by trying. Some boats need the weight up front, others don't. While it is logical to keep weight central the forward locker is often used for water simply because you can get good volume in a part of the boat that usually has poor access compared with the lockers under the saloon seats.

BTW I still have a new (still in package) Plastimo tank for a forward locker if you change your mind - not that it influences my explanation!

 

[blackbeard]

I have been a bit bothered about water tanks in my little 25' boat. The obvious solution is a big flexi tank in the forepeak but that would be equivalent to about 2 people standing on the foredeck and would certainly affect trim (not so much a problem, perhaps, in a larger boat).
I have used a tank in a locker in the saloon, but the locker wasn't really big enough and, besides, I needed the locker space for Stuff.
Going for a space just in front of the mast (which is what the designer intended, but the flexi tank originally installed wasn't ideal (long story) so am shoe-horning a rigid tank in).
There's an ideal size for water tanks, as with fuel tanks. Too small you obviously don't want, but too big leads to stale water (or fuel) or worse. I suspect that some boats at the close of the year are carrying some of the same water that they started the year with, and the tea tastes funny.