Wednesday, August 31, 2016
Burmese Long Tails
In our last post we looked at Paul Wilson's photos of Philippine bancas. This time we'll view Paul's images of longboats from Myanmar. (I've always heard such boats referred to as "long-tails," but it appears that both terms are in common use.)
Here's Paul's description:
I agree. This leg rowing is fascinating stuff.
In contrast, Thai longtails mount the engine right on the transom, atop a pivot. This is mechanically simpler, in that it eliminates the universal joint for the driveshaft. It has a substantial downside, though: placing the weight of the engine entirely on the transom must make the boat very stern-heavy. It also orients the prop shaft at a downward angle, which reduces propulsion efficiency. To minimize this problem, the shaft is very long (making the angle shallower), but this "solution" compounds the problem of a long, awkward extension behind the stern. The Burmese arrangement, with its horizontal prop shaft, is shorter and inherently more efficient.
Thanks again to Paul Wilson for the Myanmar photos.
Here's Paul's description:
The Myanmar (Burma) photos were pre-digital scans of some photos I took while working/touring there in 1999 or 2000. The photos are of longboats in Inle Lake in central Burma. I was interested in the articulated drive mechanism. Unlike the longboats in Thailand, the engine is stationary with a universal joint at the transom. The pipe in the wash from the prop is for water cooling to the engine. Very simple and effective. I loved these boats and their chug, chug, chug with their big Chinese diesels. The long bow allows them to extend out over the shore for easy loading and unloading at the market.
Much more here: http://en.wikipedia.org/wiki/Inle_Lake
I don't have any photos of them but the leg rowers of Inle Lake are fascinating so give them a google if you haven't seen them before.
http://www.youtube.com/watch?v=dmSYpWIzidYhttp://www.youtube.com/watch?v=gpScZKmDkLo
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| It's plank-on-frame construction, but I'd bet money that it's shell-first. Substantial ceiling or floorboards allow cargo to remain dry and possibly protects the planking from damage. Interesting to see a shiny new engine in a boat type that probably dates back centuries. (Click any image to enlarge.) |
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| A rubber hose connects to the front of the water intake pipe and curves over the massive transom. By pushing down on the tiller, the driveshaft and prop can be raised. The gunwales extend far beyond the transom: I'd like to know the reason for this. |
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| Steering combines the forces of directed thrust (i.e. changing the angle of the prop, as on a sterndrive) and the rudder just ahead of the prop. These steering systems don't look cobbled together: someone is clearly manufacturing them to a standard pattern. |
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| With numbers like this, it's clearly an economically practical design that suits the needs of the society. |
In contrast, Thai longtails mount the engine right on the transom, atop a pivot. This is mechanically simpler, in that it eliminates the universal joint for the driveshaft. It has a substantial downside, though: placing the weight of the engine entirely on the transom must make the boat very stern-heavy. It also orients the prop shaft at a downward angle, which reduces propulsion efficiency. To minimize this problem, the shaft is very long (making the angle shallower), but this "solution" compounds the problem of a long, awkward extension behind the stern. The Burmese arrangement, with its horizontal prop shaft, is shorter and inherently more efficient.
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| Thai longtail. (Source: Kellerna, via Wikipedia) |
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