I’ve been working on my industrial switching route and one source of traffic will be via a carfloat operation. I was toying with buying a couple of the discontinued Walthers car barge and floatbridge kits, but the price of them on eBay has pushed me into scartchbulding one myself.
I’ve decided that I want to build a pontoo-style bridge becuase 1. it seems more prototypical for a lower-traffic interchange that would only use it a few times a week and would want to build it cheaply and 2. it seems easier for me to scratchbuild. Based on the images I’ve seen here (http://trainweb.org/AbandonedLIRR/nych2/nych555.jpg) and here (http://hbs.railfan.net/hbs21.jpg) it seems like it basically a steel girder bridge with a pontoon under it.
But this leads to my question: can someone give me an idea of where to find pictures of what the pontoon itself should look like? The Cross Harbor railroad site (a great resource for anyone who has interest in the “ugly” side of railroading like I do) mentions they are basically steel tanks of air, but I didn’t know if I could just use a spare storage tank under the bridge or if someone had an idea of what the tank should look like.
Any assistance through ideas, images, descriptions, etc. I’d be very greatful.
I just posted on the propane thread about using the CO2 cylinders for paint/pellet guns/soda bottles. They are about 3/4" daimeter by 2 1/2" long. If you place the rounded end on the visable end of the float it should look OK (use/empty the cylinder first!!) I’ve seen 55 gal steel drums used as floats also - filled wirh foam they are “unsinkable”!
I doubt that there was any standard design for a pontoon-borne apron. Flotation tanks could have been anything with enough displacement to support the car float end of the apron at or slightly above deck height when unloaded. Such a rig would depend on the float to take the load of cars being moved aboard, and the whole operation would have to be handled with great respect for weight distribution.
Were I to put on my motheaten old Naval Architect’s hat, I would probably seek out something like an old tank car tank, or several 1000 gallon oil storage tanks. 55 gallon drums are tempting, but can only support about 400 pounds per each, not much when looking at a structure that has to take the weight of railroad equipment. The apron should be able to ride along tracks sloping into the water to allow for changing water levels (tidal or seasonal) and should be heavy enough at the shore end not to float away if the shoreside mooring came adrift.
