According to our bridge commission, the air draft of the two bridges crossing Halifax Harbour can very several feet depending on ambient temperature. I assume that temperature has influence on most bridges to some extent.
Lots of variables to consider if clearances get tight. Rich Knowles INDIGO - LF38 Halifax, NS From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Dennis C. Sent: November 5, 2012 14:20 To: cnc-list@cnc-list.com Subject: Re: Stus-List Bridge clearance issues Caution! Charted bridge clearances are often "design" clearances. Many older bridges have subsided. Two notable examples in my area are the East Pass Bridge at Destin, FL and the Navarre Beach Bridge. Most locals believe the actual clearances are a foot or so less than that stated on the charts. Also watch for wires and cables hanging under bridges. Another idea for the stout of heart, don't pass through the charted channel clearance. Pass under 1 or 2 spans on one side of the channel passage. Because of its wider horizontal clearance, the channel passage will usually have a larger girder supporting the span. To the left or right, the shorter spans will have smaller girders or concrete "Tees". Often there is more vertical clearance in these spans than the channel passage. Of course, there may not be enough depth or width for passage. I don't recommend this unless you really, really know what you're doing. Years ago, there were a couple of tall racing sloops in New Orleans. To pass under the I-10 bridge at Slidell, LA, they routinely passed one span from the channel clearance. Look at this picture of the Navarre Beach Bridge: <http://www.google.com/imgres?q=navarre+beach+bridge <http://www.google.com/imgres?q=navarre+beach+bridge&num=10&hl=en&biw=1366&b ih=596&tbm=isch&tbnid=AH5vUSygQ54BEM:&imgrefurl=http://www.wunderground.com/ wximage/jennjeff1/4429%3Fgallery%3D&docid=9lCQM_FWA4qVvM&imgurl=http://icons -ak.wunderground.com/data/wximagenew/j/jennjeff1/4429-800.jpg&w=800&h=464&ei =7feXUIXXEoj1ygGGqoDoBA&zoom=1&iact=hc&vpx=551&vpy=312&dur=78&hovh=171&hovw= 295&tx=133&ty=129&sig=113816113435251940368&page=5&tbnh=135&tbnw=224&start=8 8&ndsp=24&ved=1t:429,r:70,s:20,i:345> &num=10&hl=en&biw=1366&bih=596&tbm=isch&tbnid=AH5vUSygQ54BEM:&imgrefurl=http ://www.wunderground.com/wximage/jennjeff1/4429%3Fgallery%3D&docid=9lCQM_FWA4 qVvM&imgurl=http://icons-ak.wunderground.com/data/wximagenew/j/jennjeff1/442 9-800.jpg&w=800&h=464&ei=7feXUIXXEoj1ygGGqoDoBA&zoom=1&iact=hc&vpx=551&vpy=3 12&dur=78&hovh=171&hovw=295&tx=133&ty=129&sig=113816113435251940368&page=5&t bnh=135&tbnw=224&start=88&ndsp=24&ved=1t:429,r:70,s:20,i:345> The charted clearance is 50 feet. The best I've seen on the clearance board is 49'2" at low tide. However, according to one local sailor, there is 51 feet of clearance two spans to the south of the channel (see the first reply here: http://forums.hunter.sailboatowners.com/showthread.php?t=45201). That would be the first span closest at the end of the blue girder support. Not for the faint hearted!! The admiral has threatened me with grievous bodily harm should I attempt it!! Dennis C. Touche' 35-1 #83 Mandeville, LA _____ From: Andrew Burton <a.burton.sai...@gmail.com> To: cnc-list@cnc-list.com Sent: Monday, November 5, 2012 11:10 AM Subject: Re: Stus-List Bridge clearance issues Another thing to take into account: how wide does the boat get when you heel her over 25 degrees? Check the horizontal clearance on the bridge. It should be on the chart. Joel, bridge height is measured from mean high water. Cheers Andy On Mon, Nov 5, 2012 at 12:04 PM, Richard N. Bush <bushma...@aol.com> wrote: Joel; you're correct about the mast height, (50 ft, plus a three foot antenna, I added a foot or so for the sphincter factor); the bridges I am looking at are rivers, so there's no tide as such; they do have a "mean low water mark" which is typically summer pool stage; thanks Richard 1987 33-II Richard N. Bush Law Offices 235 South Fifth Street, Fourth Floor Louisville, Kentucky 40202 502-584-7255 -----Original Message----- From: Joel Aronson <joel.aron...@gmail.com> To: cnc-list <cnc-list@cnc-list.com> Sent: Mon, Nov 5, 2012 11:54 am Subject: Re: Stus-List Bridge clearance issues Richard, You must have a large antenna. My 35/3 has a mast height of 50.5 feet according to sailboatdata.com <http://sailboatdata.com/> . (No dimension for your boat). Your mast looks to be about 2 feet shorter than mine. Aren't the readings at Mean Low tide? Have you factored that in? Can you rig a temporary adjustable forestay? 24 degrees is a lot of heel! Maybe 10 large friends on the rail? On Mon, Nov 5, 2012 at 11:40 AM, Richard N. Bush <bushma...@aol.com> wrote: Hi all; I am planning for a trip (next summer) I will have to pass under a bridge with a 50 ft clearance; I calculate that the mast is 55 ft from water including all antennae, etc; I have come up with a chart showing that I will have to heel the boat 24.4 degrees to clear a 50 ft span; and 35.9 degrees to clear a 45 ft span; (I had to have help from an engineer friend!); now, what is the best way to get the boat to 24.4 degrees and keep it there long enough to get under the bridge? Richard 1987 33-II Richard N. Bush Law Offices 235 South Fifth Street, Fourth Floor Louisville, Kentucky 40202 502-584-7255 _______________________________________________ This List is provided by the C&C Photo Album http://www.cncphotoalbum.com/ CnC-List@cnc-list.com -- Joel 301 541 8551 _______________________________________________ This List is provided by the C&C Photo Album http://www.cncphotoalbum.com <http://www.cncphotoalbum.com/> CnC-List@cnc-list.com _______________________________________________ This List is provided by the C&C Photo Album http://www.cncphotoalbum.com <http://www.cncphotoalbum.com/> CnC-List@cnc-list.com -- Andrew Burton 61 W Narragansett Ave Newport, RI USA 02840 http://sites.google.com/site/andrewburtonyachtservices/ phone +401 965 5260 _______________________________________________ This List is provided by the C&C Photo Album http://www.cncphotoalbum.com <http://www.cncphotoalbum.com/> CnC-List@cnc-list.com
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