Tall mast low bridge
- Thread starter John T1594
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Yeah, I've seen the video before. It's pretty cool. The trick would be to know the geometry before you swung out the bags. Note the tag line, probably wrapped around a winch. He knows that at 47 degrees the bags will touch the water and the tag line would be taunt. Simple high school geometry but I think the weight of the bags would have to be calculated.
Or you could just go for it......
https://picasaweb.google.com/lh/photo/i9CB148158m2_PmtICqCs9MTjNZETYmyPJy0liipFm0
https://picasaweb.google.com/lh/photo/i9CB148158m2_PmtICqCs9MTjNZETYmyPJy0liipFm0
We did something similar on the Okechobee Waterway. We had to get under a low railroad bridge at Port Myakka, so a crew from the local marina came out to us and strapped some water barrels on our side deck. They ran a line up the mast with the main halyard. The line was a measured length and had a weight on the end. Using a gas-powered pump on their launch, they filled the water barrels with water, the boat heeled, and the line swung out to the side. When the weight touched the water, they gave me the go-ahead, and I motored under the bridge.
Does anyone know where you can get water bags like the boat in the video? I have put 5 gallon buckets on my boom to get 18" of clearance, but like the idea of the water bags.
Water bags are used for load testing cranes (the industry I work in), but they're not cheap. Maybe the ones that sailer was using are less costly, and they certainly are small in comparison.
http://www.canflexinc.com/crane_test_bags_en.cfm
http://www.waterweightsinc.com/en/lifting-equipment-testing.html
http://www.canflexinc.com/crane_test_bags_en.cfm
http://www.waterweightsinc.com/en/lifting-equipment-testing.html
Thinking outside the box. Would this work?
http://www.scuba.com/scuba-gear-245/Miscellaneous-Lift-Bags.html
Something to note on this sailor is first he is a very experienced sailor and two he was also in the salvage business so may have access to something the average person may not. Sadly this gentleman, David, passed away a couple years ago. For reference the boat, Aratinga, is an Alden 58 with an 80 ft mast and the bags are made to old 1 ton each so 2 tons total.John T1594 said:
Before you try something like this make sure to try it in open water and check the result is what you want. I've also seen 55 gallon drums used.
SC
I was pretty sure they were crane testing bags, but I haven't seen any advertised that were as small as he had. I have calculated it should take about 700 lbs to get my 356 over enough to get down the Tenn-Tom without removing the mast. Many of the "52" high" bridges down the Tenn-Tom are arch bridges and are much higher in the center. Some of the Railroad ones are flat and are real close to 52 feet.
I'm not sure about the scuba bags because they need to hold water rather than air. The attachment points should be strong enough.
If I ever see any reasoably priced bags, I am going to try this technique. May never use it, but it is an interesting idea.
I'm not sure about the scuba bags because they need to hold water rather than air. The attachment points should be strong enough.
If I ever see any reasoably priced bags, I am going to try this technique. May never use it, but it is an interesting idea.
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