looking for another P42 owner who has taken their P42 under the bridge. bridge height is stated to be 66’
Would really like to go through but ......
Would really like to go through but ......
P42 and the Kent Narrows Bridge on the Chesapeake.
- Thread starter Puesta del sol
- Start date
I keep my boat just north of there and go through on a regular basis. The fixed bridge is 65 feet above the water and my 1993 H42 is 61 feet plus the antennas, wind instruments, etc. I am nervous if the tide is more that 3 feet above normal (as determined at my home dock). I don't even look up anymore when I go under, as it always looks like I am going to hit (never have yet).
Terry, I thought the bridge heights are normally published based on Mean High Water (MHW) rather than 0 tide state. I'm not sure exactly what 0 tide state is? Just want clarity on this since my published clearance at the design water line is 63' 3" before anything on the top of the mast 
Thank you for details... always love oking for other P42 owners on the bay. If you see give me a call on the VHF
You might be right here. I would still recommend transiting at zero tide state, which would be the tide table low water time of transit before changing to a flood.
Agree. It’s a pretty narrow channel and the current is a challenge. Also the depth at either end can be an issue. So going between tides seems best.
Keeping wanting to go through as it would cut hours off a trip to St. Michaels
According to the tide tables, the tidal range at the Kent Narrows Bridge is only about 1 to 1 1/2 foot total range between low tide and high tide (its quite variable). Low tide varies from 0.3 above datum to 1.9 or so above datum. (I don't see any 0 tide levels so I assume when you say 0 tide level you mean low tide) There is not much help there from the tide. Of course there are other considerations such as the current, the narrow channels and shallow depths. Pick your poison.
It is important to know your actual air clearance and its also a matter of your tolerance of the "pucker factor" of going under a bridge with only the barest of clearance. Is there a height board at the bridge (from one or both sides, both I hope)? If so do you have any reason to doubt them? An inch is as good as a mile. I have gone under numerous bridges on the icw with height boards showing 65 feet on the boards and have made it through all of them although it does make you question your sanity now and then. I do try and not go through with there is any idiot power boater throwing a wake when I'm going under the bridges since they can "bounce" the boat some. Might to hard to control at Kent Narrows.
I have been told that the height board reflects the measured height at the lowest point of clearance of the bridge and it may be higher at center but I don't know that for a fact. (The operative word is MAY).
It is important to know your actual air clearance and its also a matter of your tolerance of the "pucker factor" of going under a bridge with only the barest of clearance. Is there a height board at the bridge (from one or both sides, both I hope)? If so do you have any reason to doubt them? An inch is as good as a mile. I have gone under numerous bridges on the icw with height boards showing 65 feet on the boards and have made it through all of them although it does make you question your sanity now and then. I do try and not go through with there is any idiot power boater throwing a wake when I'm going under the bridges since they can "bounce" the boat some. Might to hard to control at Kent Narrows.
I have been told that the height board reflects the measured height at the lowest point of clearance of the bridge and it may be higher at center but I don't know that for a fact. (The operative word is MAY).
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By the way, my charts show the published height of the Kent Narrows bridge to be 65 feet. Where are you seeing the 66 feet?
Also, the specs for a Passage 42 here on SBO show a mast height of 60'3" Even with some pretty tall stuff on the top of your masthead I doubt it is even near 65 feet? You should check your owner's manual and with other Passage 42 owners about their total air clearance. The VHF whip antenna will flex as long as you're not right at the attachment point and the wind instruments probably don't extend much more than a foot above the masthead. HOWEVER, you need to confirm your air clearance.
My 40.5 Owners manual lists a mast height of 63'3" I have a VHF whip that extends above the masthead and I use 65 as my air clearance and have never scraped my vhf whip on a bridge marked as 65 feet on the boards but the pucker factor is always there. HOWEVER, I have never gone under the Kent Narrows Bridge.
Also, the specs for a Passage 42 here on SBO show a mast height of 60'3" Even with some pretty tall stuff on the top of your masthead I doubt it is even near 65 feet? You should check your owner's manual and with other Passage 42 owners about their total air clearance. The VHF whip antenna will flex as long as you're not right at the attachment point and the wind instruments probably don't extend much more than a foot above the masthead. HOWEVER, you need to confirm your air clearance.
My 40.5 Owners manual lists a mast height of 63'3" I have a VHF whip that extends above the masthead and I use 65 as my air clearance and have never scraped my vhf whip on a bridge marked as 65 feet on the boards but the pucker factor is always there
. HOWEVER, I have never gone under the Kent Narrows Bridge.
Official bridge clearance numbers are posted at MHW (MEAN HIGH WATER). official depths are posted at MLW.
That’s not saying they are always accurate.
That’s not saying they are always accurate.
My two sources of tide datum come from our local tide book and my chart plotter. Both are pretty close to each other. Zero tide as described in these two sources is at the point between whether water is at a minus tide state (below zero) or a plus state (above zero). What all that means matters little to me. All that I know is our marina has insufficient water for our boat to leave (our boat has a draft of five feet) when the tide state is below a plus one foot. So, when making a sail plan, I make sure I have at least a plus one foot of tide state before leaving (usually at the beginning of an ebb) /entering our slip (usually at the beginning of a flood).
Low tide is variable here depending upon the period and can range from a minus three plus feet to a plus some feet. To me a zero tide state is at that point between a minus and a plus tide state, again according to our published tide tables.
66’ was from memory, the listed height is as you noted 65’By the way, my charts show the published height of the Kent Narrows bridge to be 65 feet. Where are you seeing the 66 feet?
Also, the specs for a Passage 42 here on SBO show a mast height of 60'3" Even with some pretty tall stuff on the top of your masthead I doubt it is even near 65 feet? You should check your owner's manual and with other Passage 42 owners about their total air clearance. The VHF whip antenna will flex as long as you're not right at the attachment point and the wind instruments probably don't extend much more than a foot above the masthead. HOWEVER, you need to confirm your air clearance.
My 40.5 Owners manual lists a mast height of 63'3" I have a VHF whip that extends above the masthead and I use 65 as my air clearance and have never scraped my vhf whip on a bridge marked as 65 feet on the boards but the pucker factor is always there
Terry, I thought you were referring to the tide tables at the Kent Narrows Bridge. They seldom, if ever get to a "0 tide state" at that location. Each Tide Station is "unique" based on the datum used. Some station never get to 0. (Current gets to 0 but not the water level above datum). If the PO wanted to go under at "0 tide level" he would never go under the bridge. I now understand what you mean. I do much the same
What's important in transiting bridges where you are concerned about air clearance is knowing your air clearance your boat has and understanding what bridge clearance actually is and the latter is a real challenge in some places. To understand the bridge clearance you need to know that datum on which it is based and what the variability of Mean High Water (MHW) is for that location along with the charted bridge Vertical Clearance. Lacking that, you probably have to have a little "faith" in the Height Boards, if you're lucky enough to have them at the particular bridge. The charted bridge Vertical Clearance is easy to find. Without the Height Boards, finding the actual height of MHW can be a real chore in a place where there is a large variability of high tide level like here in Beaufort, SC. Its compounded by the fact that we have NO TIDE BOARDs at the McTeer Bridge. There is "local knowledge" that says its 65' 5" at the top of the 5th board showing but many of the high tides here are well above the top of the 5th board and some as high as the top of the7th board. I am guessing that the local knowledge is very conservative but I don't want to be the one to test that theory.
What's important in transiting bridges where you are concerned about air clearance is knowing your air clearance your boat has and understanding what bridge clearance actually is and the latter is a real challenge in some places. To understand the bridge clearance you need to know that datum on which it is based and what the variability of Mean High Water (MHW) is for that location along with the charted bridge Vertical Clearance. Lacking that, you probably have to have a little "faith" in the Height Boards, if you're lucky enough to have them at the particular bridge. The charted bridge Vertical Clearance is easy to find. Without the Height Boards, finding the actual height of MHW can be a real chore in a place where there is a large variability of high tide level like here in Beaufort, SC. Its compounded by the fact that we have NO TIDE BOARDs
at the McTeer Bridge. There is "local knowledge" that says its 65' 5" at the top of the 5th board showing but many of the high tides here are well above the top of the 5th board and some as high as the top of the7th board. I am guessing that the local knowledge is very conservative but I don't want to be the one to test that theory.
We sail our Hunter 340 in the Barnegat Bay region of New Jersey (NOAA Chart 12324). There are two fixed span bridges that limit travel at each end of the bay and Intracoastal Waterway. To the south, there is a fixed span bridge at Manahawkin Bay, carrying Route 72 East from the Jersey mainland to the barrier island. The bridge is charted at 60 feet of vertical clearance at mean high water. My mast stands 56 feet off the water and normally I would not worry about passing under this bridge on a low or falling tide. The tide boards at the bridge, however, indicate that the vertical clearance ranges between 56 - 58 feet depending upon the state of the tide. On our first trip under and with a clearance of 57 feet showing on the tide boards we stood off and debated for some time before venturing slowly and carefully through. Perhaps I should have turned back but we made it through with the VHF antenna intact but don't really know what the true clearance is at that location.