I am a sucker for authenticity. It’s not for everyone, I know. But, my goal with restoration is to be faithful to the original methods. Does it improve the performance of the boat? No. Does it mean the restored items will need less attention over time? Not necessarily. But, the restoration does serve as a pretty darn faithful example of how these boats were made back in the day. To my eye, if parts are reproduced with an eye towards visual and functional accuracy, they should be very difficult to discern from the originals.
One of the things I have always favored is the look of the original galvanized, rolled and soldered fuel tanks. Most held up well for 50+ years—and that was with typical use, stored out in the elements, etc. A new tank, built with those methods, especially with a boat seeing less use, and pampered in a garage will last a long, long time.
I needed to replace old tank on several boats. I can go into more of the “why,” but these old tanks were always much worse off then meets the eye. When I set a goal to build a faithful reproduction tank, the first thing I needed was the bronze fittings—scavenged off of a donor tank, purchased off of eBay, or whatever. The tank fittings themselves have gotten harder and harder to find.
Pre war tanks used by Chris-Craft and Gar Wood were largely the same construction, ie: rolled galvanized sheet metal with a top seam (I think this is referred to as a flat lock seam). The ends were also sheet metal, with flanges that were then wrapped over the ends of the tank, and then peened tight. All of the seams were then flowed with solder. The tanks for each manufacturer were so similar that they may have been sourced from the same vendor.
Pre war fittings were generally cast bronze flanges of various sizes, that were affixed to the tanks with rivets, with their mating surfaces also flowed with solder. ) Post was tanks were a different animal). The big flange received a threaded copper pipe with a large jam nut for the fuel fill. Tank vents, (if the era dictated that) were typically NPT fittings—standard plumbing fittings of the day. The fuel pickups were another matter. Most tanks had a hexagonal fitting that threaded into a flange for the fuel pickup. Very early tanks were actually bottom (gravity) feed fittings on the tank bottom. These fell out of favor when Coast Guard regulations said so. The fuel feed fittings were move to top mount, which meant there had to be a fuel pickup tube that extended to the bottom of the tanks. What looks like a simple hex fitting at the top of the tank is actually an assembly—the hex fitting itself, which has a reduced diameter neck that accepts a straight copper pickup that is soldered in place. The length of that pickup varied depending on the tank diameter. There is also an important fitting at the top of the fuel pickup, which was an anti-siphon feature. There is another hole in the neck that is drilled and tapped to accept a carb jet with a given orifice size.
Out of all of these components you are doing well if you have a good donor tank. The tanks are worthless. The flanges are worth keeping track of.
In my case, I had some, but not all of what I needed. I watched eBay for years, and never really case arose the right fittings. So I proceeded with making them.
Unlike my previous posts which utilize 3D printing, casting etc, I decided to go a different route and have these machined on a CNC controlled mill. By using this method, I was able to get all of the geometry exactly right including the I.D. diameters, and the thread pitch. in this case all of the threads were machined.
The issue with machining these is they just did not have a cast look—which is important for them to not look like computer machined reproductions. All this took was some time with a pneumatic needle scaler. I pounded the heck out of them with the scaler, giving them an authenticate sand cast look. All of this work got painted a Gar Wood green-gray color, but even under the paint you can spot the stuff that looks too new.
The net result is a brand new fuel tank built exactly like they were in 1936. Again, this is not for every one, but it pleases me!
Original Tank
Machined Brass Fuel Pickup With Soldered Pickup Tube and Anti-Siphon Fitting
Closeup of Fuel Pickup Hex Fitting And Machined Flange (Made to Look Cast)
Detail of End of Sheetmetal Tank. The Recessed Bead is to Support the End of the Tank While the Craftsman Rolled and Peened the End Caps in Place
All in Place and Ready for Cleaning and Paint
