Gas Tank leak on my 25

They look to be plastic and the four of them are what the tank rested on. Probably about 1/2" of space between the tank and the floor.
The new tank will rest on fiberglass stringers that will be glassed onto the bottom of the boat. The tank will be about 1 1/2" up from the floor. Also the new tank will be coated with epoxy. Looks like the tank capacity will be just under 100 gallons from the measurements that have been taken.

BTW the old tank's bottom, which only could be seen after cutting the tank out, looked like swiss cheese from salt water corrosion. So just patching the two bad spots would have been a total waste of time.
 
With your experience, it suggests that other boats will experience this problem--especially when kept i salt water. Agree with your plan. Probably coal tar epoxy is the best way to go.
 
The new tank has been delivered and completely epoxied.
New_90_gal_tank.sized.jpg

Two new 1 1/2" spacers have been glassed to the floor of the boat. The patching in between was to repair the small cuts into the fiberglass when they cut out the tank.
New_Spacers3.sized.jpg

New_Spacers2.sized.jpg
 
I had a similar problem with my Cape Cruiser. If you look in my album you'll see some pictures of my gas tank problems. There was a strip of raised floor that was rounded and about 3/4 inch wide and 3/8 inch tall to support the tank. Corrosion occurred along this raised strip of fiberglass where the tank touched it. My solution was to grind off the raised strip on the deck and epoxy 1/2" X 1/2" strips of starboard to the bottom of the tank running fore to aft to provide an airspace between the tank and the bottom of the boat. No moisture can get between the tank and the starboard as the sides and top of the starboard are encapsulated. My concern on your fix is that, if the epoxy coating on your tank should wear off from vibration, you will have a situation similar to what corroded my tank. My concern my be misplaced however. As long as the epoxy coat holds up, you should never have a problem.
 
forrest":2hq8i8ew said:
My solution was to grind off the raised strip on the deck and epoxy 1/2" X 1/2" strips of starboard to the bottom of the tank running fore to aft to provide an airspace between the tank and the bottom of the boat. No moisture can get between the tank and the starboard as the sides and top of the starboard are encapsulated.
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I think that was a good idea. I've done similar although using strips or angles made of fiberglass instead of Starboard (because I was concerned with Starboard's possible creeping under load, and also that it does not really "like" adhesives - both of which made me wonder if the bond might break - although that may not be a real concern, I don't know). Another way I've seen it done is to have metal "legs" welded to the tank and then using them to fasten to the boat (if there is room). Of course that's another weld.
 
Bash me, I'm sorry but that original construction is just total trash. I can't believe a boat builder would choose such a poor method of mounting a fuel tank.

Jake
 
Jake,
I agree that this is not an ideal way to put in a tank--but it is better than most of the boat builders (Grady, Rinker, Proline, Pursuit, Hydrosport, Sea Ray etc) do. Many of them foam the tanks in, and that guarantees salt water held against the entire tank.

C Dory got it half right--The tanks should be epoxied, the Aluminum should be the correct series, the spacer strips should have been higher, and 5200 should have adhered the strips to the bottom of the tank. (Not HDPE--plastic or fiberglass strips).
 
Sorry, have to admit I'm not familiar with how other builders do it, but still... gotta be a better way. The more I read about all kinds and makes of boats the more I sense it's a "as long as it works when it leaves the shop" that's good enough. Think if your car, which is much less expensive in most cases, was built in this manner.
 
Besides the gas tank(s), there are a lot of poor compromises in equipment placement that are necessitated by the raised cockpit deck in boats like the CD-25.

It would be much simpler to have everything exposed and accessible, such as in a smaller boat like the CD-22 and similar, smaller boats.

The raised cockpit deck (and similar structures inside the cabin) make for a situation that forces a designer to make use of the space under the floor, which makes accessibility, service, and replacement of components very difficult.

It's really pretty ridiculous to put gas tanks, maceator pumps, black water storage tanks, water tanks, pumps, hot water heaters, plumbing,or anything, really, that requires observation, service, and replacement under a shallow floor, often sealed up without access ports.

Similar problems occur with catamarans with their shallow floors and long twin hulls which contain considerable space, but which must remain sealed while the space within must be utilized.

This part of the naval architect's job is no picnic!

Joe. :teeth :thup
 
One of the more successful new Catamarans is the Ameracat--there the fuel tank is standard under the console. Same for my Caracal. This avoids the problems with tanks in the bilge.

All boats have compromises. Cars are built on a massive scale. If your chevy was built so that there were only 20 built a year, it would be far more expensive than any small boat.

Also there is competition in the market place. The company must make a profit and yet sell boats. Some boat builders get around this, and do make the proper adjustments--such as putting Coosa board under areas where there are attachments to the deck--cleats, antennas, chocks etc. To pot every fitting in epoxy is very time consuming and expensive. Same with the hatch frames--ideally the cut out should be covered with either a layer of glass and polyester or epoxy to avoid exposing the deck core to moisture.

We built one off boats--and could do all of those things--our labor we valued at about $3.00 an hour! Don't quit the day job! When we rebuilt the Cal 46, again, we pulled all fittings, including windows and did proper potting--fuel tanks, 5200 series aluminum, epoxy and then LP coated--with proper support and abrasion resistance--20 years later the current owners say the tanks are still like new. No deck leaks, no deck rot.
 
While this would probably never work out in real life, I always thought it would be interesting if a boat builder offered two versions of their boat. They could have the one built "as usual," which was price competitive with all the other similarly built boats, and then an upgraded (and more expensive) version where they did the details properly (no exposed core, tanks situated well, etc.). I've always wondered: If the builder were able to clearly communicate the issues with "standard" construction, and educate the customer as to how they would be alleviated with the "upgraded" construction (even though it would come at a cost) - how many people would choose the "upgraded" one? And how much more would it actually cost?

I don't have answers, but I find it interesting to think about. I do suspect that a fair buyers would choose to spend more if they truly understood what they were getting (but then I may be wrong and that may just be how *I* think, having had to correct the "standard" issues time after time :amgry and seeing how much easier it would have been to do it in the first place as compared to "digging into it" on an already built boat :cry)

Sunbeam
 
Bob,
What type of material would you use as stringers under the gas tank assuming that they were to be glued to the bottom of the tank "(Not HDPE--plastic or fiberglass strips)"
 
Anna Leigh,

Any idea of the cost to epoxy the new tank? Just wondering how much that step adds to the total cost.

Jake
 
Considering all these anchoring, abrasion, and corrosion issues, it would seem prudent to keep the gas tanks 1.) up at floor height and above at the rear of the cockpit and 2.) as saddle tanks, just in order to allow them to be inspected, serviced, and replaced as needed?

Why build another "Pandora's Box" fuel tank under the skin in the boat's belly?

How about bladder tanks? Wouldn't they solve some of these problems? Good enough for airplanes, though they may be expensive………?

Joe. :teeth :thup
 
WHen the boat is not in use, you can mod old deck plates into vents
see
https://picasaweb.google.com/1006779684 ... 0181640962

1994Parker2320EC
 
Having had the 25 Cruiser and the 26 Venture side by side, I can say that buyers prefer the self bailing cockpit of the Cruiser over the Venture's lower cockpit with tanks aft.

Boat design is a series of compromises, and tanks below deck are not a bad design, as it keeps the center of gravity lower in the boat. There are different installation needs when the tank is installed below deck.

As for the idea of having a builder offer a "standard" and a "built-right" boat, it would never sell. Because the consumer would never accept the cheaper boat, and they wouldn't be sure that the "better" boat was really built any different.

Most buyers aren't that interested in the nuts and bolts of construction. They look at function, aesthetics and comfort. C-Dory buyers are different, just as the C-Dory itself is different than the vast majority of boats manufactured.
 
Agree with Matt on construction.

Forrest--I was not clear--I would use fiberglass or plastic strips--not HDPE.

The average buyer has no clue as to how the boats are built--from the materials, to layup to what makes it better. Many folks use the boat for X years and then upgrade to a larger or newer boat. C Brats are the exception.....sort of.
 
Matt Gurnsey":8imterma said:
As for the idea of having a builder offer a "standard" and a "built-right" boat, it would never sell. Because the consumer would never accept the cheaper boat, and they wouldn't be sure that the "better" boat was really built any different.

Most buyers aren't that interested in the nuts and bolts of construction. They look at function, aesthetics and comfort. C-Dory buyers are different, just as the C-Dory itself is different than the vast majority of boats manufactured.
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I agree with you, which is why it's just an idle fantasy, and I'm not starting a boat-building business. And I agree that most people just don't care - although I still wonder if educating people might encourage some (a vast minority, but some) to want to pay for "proper."

I do know a builder who builds (more expensive) boats properly, and they do sell, but it's on a commission basis, so completely different from production building (and they do spend time educating their customers as to why they build the way they do). As for being sure a boat is built the way it's claimed to be, well, with any builder it's a matter of trust as to how any of the boat is built (even C-Dory). Knowledgable folks can check, or have someone else do it, but most don't.

So yeah, that's why I only think about it "idly" from time to time, but wouldn't try to do it. I'm not that interested in convincing people why they should want things a certain way, and as you say, most probably don't care.
 
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