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Tankage upgrade?

2K views 9 replies 8 participants last post by  Faster 
#1 ·
i have noticed that many solidly built boats on the used market have small fuel and water tanks. Is it easy to upgrade to a bigger tank without tearing apart the boat, say from 20 to 30 gal tank to 80 to 100 gal tank?
 
#3 ·
It would depend on the boat and how space is used now. I have a Mariner 32 ketch that I am increasing the tankage on. The way it can work for me is that I don't have a hull liner and I have the skills to open up the bilge and build some custom tanks in that area. On a boat with a hull liner and a shallow bilge (most racer/cruisers) it would be very difficult to do without putting a lot of extra weight in the ends where you don't want it. It also would usually involve major surgery on the boat and unless you have the skills it could wind up being a real mess. If there is space available it might be fairly easy to do because sometimes the small tankage is not from lack of space but from the desire to keep the weight of the boat low. It really depends on the boat, how it is constructed and the displacement as to whether of not it could handle the increased weight without huge performance losses.
 
#5 ·
dawg, Rick makes an excellent point but I think the upgrade is "only" about 500 lbs. of extra fluid, which is the same as 2-3 crew on a boat. Odds are a boat planned as a crusier will be planned for the extra displacement, including hull design, but one built as a "racer/cruiser" honestly has to optimize one way or the other, including the design water line figuring in the load. I guess part of that is just semantics, I prefer the term "express cruiser" or something similar to indicate a boat meant to cruise--but with speed.

Remember that if a 32-36' racer is going around the buoys, it may carry 4-9 people on board and that's a greater weight range than the 500# of tankage is. Take the same boat on a distance race...and you can be real sure that it has to carry still more weight because crew don't come back unless you at least carry SOME food and water for them.<G> And feeding 4-9 for a week, again, is weight.

Whether any boat has enough stowage for an extra 60-70 gallons of fluid, preferably low down someplace, is probably the bigger concern for you. And trimming it around, trying to keep it down low and centered. So I wouldn't worry as much about converting, as about the stowage needs in general. If you are not planning extended cruising full time, jerry cans stowed below can be worth using once or twice a year as and when needed. Not perfect, but something a lot of folks do.
For that matter you could even borrow an agressive trick from the racers: Plumb in a ballast tank [read: 6" PVC pipes<G>] up under each side of the deck, and use the extra weight as live ballast. Illegal in many racing groups, legal in others. And pretty much the same way that our supercarriers keep their flight decks level, although they throw thousands of gallons per minute to do that trick.<G>
 
#6 ·
It really depends on the boat.

Many boats don't have the room for that much tankage, even if you split it into multiple tanks. Bluewater cruising boats generally have more tankage than coastal cruising or daysailing boats, as they're designed to make longer passages.

IMHO, you're really better off buying a boat that was designed to have the tankage you're looking for in the original design, rather than retrofitting it into a boat that was not designed that way. Also, remember that larger tanks need to have baffles to prevent free surface effects and problems with the contents sloshing in heavy seas. Sixty gallons of water can build up some serious inertia if it has a chance to get sloshing, and can help capsize an otherwise relatively stable boat.
 
#8 ·
Surfesq said:
If the boat will structurally allow water tanks, I do not see why this would not work for you. But I think SDog is onto something by recommending that you look at a true blue water boat.
I agree. J34C and J34 are essentialy the the same boat. One has a small tank or thepther has s big one. To my understanding C&C is a solid boat, but the tank is very small, 20 to 30 Gal.

Guys, I promise that I will not buy a chevy and build into a Humvee. :D
 
#9 ·
The manufacturers of my olde EO Union 36 though it best to weld the stainless tank with electrodes that were not chrome-rich (like any old electrodes they had at the time).

Years later, the net result was a badly leaking tank. I had to cut the top off it, and clean the weld sites and use a two-part polysulphide sealant. I recovered about 30 UK gal, and that's enough for coastal work. It still leaks when heeled, but I have to live with it. I will fit a water-maker on a long trip.

Taking the tank out of there and fitting a new one would have been a nightmare, and would have meant gutting the boat.

I really would not do it.... it's too much work.
 
#10 ·
Everyone here who is cautioning against ill advised modifications and overloading is on the mark.

Locally we have an extreme example. One of the Soverel 40s "Locura" from the early 80s made its way to the West coast. Someone bought it cheap cheap and then spent about 8 years "redesigning" it. The length was extended about 6 feet, the cabin house lengthened and heightened to ludicrous proportions, the keel profile altered and a huge skeg added to the spade rudder. At the same time a new cockpit was created in the extension, and apparently the interior was reworked.

So picture this: now you have an overlength, unsightly "cruiser" atop which sits a very spindly 1-ton fractional rig that looks like it will snap in the first 20 knot gybe. The hull is sitting - no kidding- 8 - 10 inches down on her lines. I've yet to see this boat underway....

The cosmetic finish of this project is actually impressive - but what a misguided plan.

I realize this is far beyond adding a water tank, but I think it illustrates what can happen when someone loses sight of the big picture.
 
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