Integrated Diesel Tanks

[Tayana42]

Cardinal283, what kind of Tayana 42 do you have? My aft cockpit 1989 model has two independent steel tanks running parallel to the centerline of the boat out at the edges of the hull, up out of the bilge but out near the turn of the hull. I have no u shaped tank?

[Tayana42]

You may also want to consult with the builders TaYang Shipyards.

tayangco@ms15.hinet.net

Mr. Wilson Chang has been very helpful to me several times.

[Bowdrie]

The bad rap that stainless got for diesel fuel comes from the old days when diesel had high levels of Sulphur in it.
The stainless itself was resistant, the problem was the typical/normal methods of TIG welding that's commonly used to weld-up tanks for boats.
When stainless is welded the metal in the weld changes properties.
Any condensation/water, (settling in the tank,) would react with the Sulphur and create Sulfuric Acid, and that would attack the welds, causing leaks.
Anyway, tanks using plywood/epoxy can be done quite well, but many build in a "backwards" construction method.
The key is making the tank with an "exoskeletal" construction, where cleats are external to the outside surfaces, glued on with epoxy, this gives large bonding surfaces, and creates easy to use places for mounting.
The other key is this; Don't fiddle around trying to get a good interior glass job on a tank that's already assembled.
Lay-out the individual parts that are already cut to size, Top/Bottom/Sides and glass them first, allowing the glass to drape over the edges a bit.
When you've got your laminate finished, you can trim the edges, and then when the tank is assembled you only need to fillet/cove/glass the joints with fiberglass tape of suitable width, (can buy it in rolls, or by the ft), and then do your final interior coating(s).
The clean-outs and fittings can be installed on the top before the top goes on the "box",
The Centek Co, makes all kinds of filament-wound tubes/angles, etc that can be used for fills/vents, etc.
Water tanks are easier, fills/vents/supply fittings can be nylon thru-hulls installed from inside-out to connect the various hoses.
If paying for labor a welded aluminum tank may be cheaper.

[jt11791]

Building a FRP tank could work well, but it's a big job, and when you are done you have the same issue if there is ever a leak or other problem. I would strongly consider installing multiple pre-made tanks of your choice material. A little extra plumbing is required, installing a fuel manifold, but there are benefits in having multiple tanks. For example, if one gets contaminated it isn't your total fuel supply. You can also use them to trim your boat using fuel weight. Unless you are really short on tank capacity, I don't see a benefit in having a single tank.

[sailingunity]

Originally Posted by jt11791

Building a FRP tank could work well, but it's a big job, and when you are done you have the same issue if there is ever a leak or other problem.

We have a fiberglass tank that is going on 47 years old and no leaks yet. If it does leak, fiberglass is easy to patch up. I like the custom route, a U shaped tank would get you more capacity. It doesn't really have to be that big of a job since it doesn't have to be pretty.

[Cardinal283]

Originally Posted by ksuderman

I have no meaningful input other than you may want to join the Tayana Owners Group. I joined the list when I was looking at Tayanas and they are quite active. I would not be surprised if there are other V42 owners that have already gone through the same process.

Unfortunately I have not seen any posts on the TOG that discuss this.

[Cardinal283]

Originally Posted by Tayana42

Cardinal283, what kind of Tayana 42 do you have? My aft cockpit 1989 model has two independent steel tanks running parallel to the centerline of the boat out at the edges of the hull, up out of the bilge but out near the turn of the hull. I have no u shaped tank?

I have the center cockpit version. I have 3 diesel tanks total. The large U shaped tank in the bilge - Approximately 60 gallons. And two smaller tanks above the cabin sole under the port and starboard settees - approximately 30-40 gallons each. They are not identical.

Both of the smaller tanks have been removed, cleaned inside, sanded, and are getting prepped for paint. I will reuse them.

I couldn’t find a welder that was willing to repair the tank while it was inside the boat. The large U shaped tank has been cut up into smaller pieces and removed from the boat. It had a 1/2” hole that rusted through on the bottom near the tabbing. This had been filled with copious amounts of goo/epoxy by the previous owner. This “repair” had failed. I also found a JB Weld type repair on the forward edge of the tank that seemed to be holding. At this point the large tank is getting replaced with a fiberglass tank that I will make.

There are no “floors” in the boat ie stringers. I find this very odd and when the boat is in the water with the rig on, the bilge boards stick and must be pried out, and some of the doors don’t close. After the rig was taken off and she was hauled out, all of those problems went away. I’m thinking there was some significant flex in the hull. At Bob Perry’s suggestion, I’m planning on adding a few floors near the base of the compression post to help deal with this. Conveniently, they will form the forward and aft sides the tank, plus a baffle in the center of the tank.

Interestingly, this all started because of an issue with the compression post. There was a low spot in the deck at the mast step. Low enough to pool water. I’ve found the culprit(s). 1. Tayana didn’t use solid glass under the compression post step/on top of the cast iron ballast. There’s actually a gap and the glass is unsupported 2. They also used a wooden shim under the base of the post that rotted away. 3. The base of the compression post was encased in fiberglass so the stainless steel started to rust away when a little water got under the glass and starved the stainless of oxygen. All of these issues will be addressed by redesigning this area of the bilge.

[Cardinal283]

Does anyone have any suggestions for paint/coatings for the inside of the tank?

[gonesail]

the caliber people did it with their long range cruisers. they built a 35' boat that could hold 100 gallons of diesel. the 40' would hold 200 gallons and had a range of almost 1500 miles. all integral tanks. probably epoxy coating on the inside of the tanks.