Mike,
You should know from your charts before the bridge operator ask what clearance he can provide. The next piece of the puzzle is the length of the mast (I) and how you boat sits in the water. By that I mean, how high is your cabin top (mast step) above the water? Racers that continually focus on removing weight sit higher and conversely the longer you own a cruiser the lower it will ride in the water so the number varies. I know you'll get a simple answer, but miss judging a bridge or overhead cable clearance can sink your boat. We had a dramatic sinking near downtown Sacramento at the I Street Bridge. The skipper used his standard number without giving it much thought and hooked an overhead cable marked on the chart. Being caught abruptly swung him crosswise to the current and an open companionway scooped in the rushing water. Luckily he had standing rules about wearing lifejackets when on deck and everyone was on deck to see the city go by. The boat was gone in seconds and was unrecoverable. Once you have you deck height and mast length then you'll need to add for you accessories up at the mast head. That 39" VHF antenna is probably that tallest common item. So what that 5' +34' + 3' or 42' under perfectly smooth conditions with no other boating traffic in sight! Wakes, don't forget wakes. When the bridge operator asks for clearance he is asking permission not to raise the bridge to its full height, what you read on the chart. When you answer 42' you've taken on the risk that you won't get waked by cabin cruiser while you're under the bridge. Your response should always be your clearance number plus the biggest local wake/wave you can imagine. In the end you might ask for 45' or 46' of clearance. When there is no operator or when it is a swing bridge it can be more complicated. The operator's calculation for a lift bridge will adjust for tide and river level to match your request. A swing bridge operator has no need for your clearance requirements as it is either open or closed, however they are powered in the middle and that means overhead cables in many cases. The chart will be marked with a mean high water clearance but a rain swollen river may be feet higher than that in the winter. http://mw2.google.com/mw-panoramio/photos/medium/234591.jpg Phil Agur <http://www.catalina27.org/public_pages/profile270.htm> s/v Wing Tip C270 LE #184 MMSI 366901790 From: [email protected] [mailto:[email protected]] On Behalf Of Michael Sent: Monday, March 08, 2010 9:12 AM To: [email protected] Subject: [IC27A] Height of Mast Hello all, Does anyone have a ballpark figure for the height of the mast with an average weight C27 (average stocked stores, equipment etc.)? I have a couple of bridges close by and always look with mild fear as I pass under them. Invaribly, some bridge operator will ask what the height of the mast is. I would like to have the answer for him/her. Thanks, Mike (So. Cal)
