I just purchased a C&C 24 (1983) and would like to find out the mast height from the waterline to see if I can squeeze under a bridge that's at 34 feet during high tide. I would be eternally grateful anyone can help me.
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Easy - Attach Line to Main Halyard....
... and hoist it to the top of the mast. 2. Mark the line where it touches the water. 3. Note how far the halyard and line knot is from the top of the mast. If the halyard has a splice in the end it would probably better to attach the line a couple feet up the halyard where there is no taper. 4. Pull the line and halyard down and disconnect the line and note where the end of the line was attached to the halyard (that is, subtract the end needed to make the knot). 5. Measure the length of the line. 6. Estimate the distance from where the knot on the halyard was to the top of mast/VHF antenna/Windex or what ever and add that to the length. The angle from vertical centerline to the edge of the boat when you determine the vertical height would minimal, maybe only a couple inches difference, and the error would be on the safe side. Quick and dirty solution.
... and hoist it to the top of the mast. 2. Mark the line where it touches the water. 3. Note how far the halyard and line knot is from the top of the mast. If the halyard has a splice in the end it would probably better to attach the line a couple feet up the halyard where there is no taper. 4. Pull the line and halyard down and disconnect the line and note where the end of the line was attached to the halyard (that is, subtract the end needed to make the knot). 5. Measure the length of the line. 6. Estimate the distance from where the knot on the halyard was to the top of mast/VHF antenna/Windex or what ever and add that to the length. The angle from vertical centerline to the edge of the boat when you determine the vertical height would minimal, maybe only a couple inches difference, and the error would be on the safe side. Quick and dirty solution.
Three Ways to do it with a Barometer
You are actually wanting some real advice. Tough luck. Measure the pressure difference between the top of the mast and the water. Drop the barometer from the top of the mast and measure how long before it hits the water. Measure the length of the barometer and determine how many barometer lengths between the top of the mast and the water.
You are actually wanting some real advice. Tough luck. Measure the pressure difference between the top of the mast and the water. Drop the barometer from the top of the mast and measure how long before it hits the water. Measure the length of the barometer and determine how many barometer lengths between the top of the mast and the water.
You can use a 100 ft cloth tape measure..
and tie one end to your main halyard, hoist it up and measure. Then add the deck to waterline. Try these web sites also.
and tie one end to your main halyard, hoist it up and measure. Then add the deck to waterline. Try these web sites also.
32 - 1/2 Ft ?
According to the brochure ( http://www.cncphotoalbum.com/index1.htm ) the C&C24 had a Bridge Clearance of 32 Ft. 5 Inches.
According to the brochure ( http://www.cncphotoalbum.com/index1.htm ) the C&C24 had a Bridge Clearance of 32 Ft. 5 Inches.
Remember to include waves
You could easily lose a foot of clearance if your boat bobs up and down in the wake of a passing boat. If the clearance is really that tight, try not to go under the bridge at high tide if there's any traffic close by. Good luck. Peter H23 "Raven"
You could easily lose a foot of clearance if your boat bobs up and down in the wake of a passing boat. If the clearance is really that tight, try not to go under the bridge at high tide if there's any traffic close by. Good luck. Peter H23 "Raven"
OR........
.....simply sail under the bridge instead of motoring. If you are motoring there is no way to reduce the height of the masthead above the water. If you sail, the heeling of the boat lowers that height thereby giving you the added clearance that you need and wave action is much less of an issue.
.....simply sail under the bridge instead of motoring. If you are motoring there is no way to reduce the height of the masthead above the water. If you sail, the heeling of the boat lowers that height thereby giving you the added clearance that you need and wave action is much less of an issue.
Alan, you're close, but...
Reducing effective mast height by heeling the boat makes sense, but I don't know if I'd do it by sailing. IMHO and experience there are way too many things that can go wrong while sailing under a bridge to justify attempting it with limited vertical clearance. For example, the wind diection may not be favorable, wind speed and direction can change suddenly under the bridge (bridge piers are notorious for doing this), there may be a current, other traffic may limit your ability to maneuver, wind direction may force you to sail under at an angle instead of straight through and the leeway of the boat may force you close to the piers on one side or the other. Maybe listing the boat by moving as much weight below to one side and motoring through may be the way to go. Peter H23 "Raven"
Reducing effective mast height by heeling the boat makes sense, but I don't know if I'd do it by sailing. IMHO and experience there are way too many things that can go wrong while sailing under a bridge to justify attempting it with limited vertical clearance. For example, the wind diection may not be favorable, wind speed and direction can change suddenly under the bridge (bridge piers are notorious for doing this), there may be a current, other traffic may limit your ability to maneuver, wind direction may force you to sail under at an angle instead of straight through and the leeway of the boat may force you close to the piers on one side or the other. Maybe listing the boat by moving as much weight below to one side and motoring through may be the way to go. Peter H23 "Raven"
One more question for Tony
Did you get the 34 ft vertical clearance under the bridge from a tide gauge in the water, from a chart or measure it directly? It makes a difference. Most bridges down here have a stream or tide gauge in the water that shows the vertical clearance corresponding to the water level at that time. I don't know if these gauges are set precisely or if they have some "wiggle room". I assume they don't. Vertical clearance on a chart is based on mean high high water (MHHW), which is higher than the normal high tide level. In other words you should have more clearance than the chart shows. Measuring clearance under a bridge isn't easy as you have to measure relative to the underside of the bridge. You also have to know the tide level at the time you measure so you can compensate for its change. Even if you measure at high tide, high tide doesn't come up to the same level every time so you have to keep your tide tables handy. I don't mean to complicate matters but if your vertical clearance is really that tight then you need to know how much room you really have because of the possible consequences. Good luck. Peter H23 "Raven"
Did you get the 34 ft vertical clearance under the bridge from a tide gauge in the water, from a chart or measure it directly? It makes a difference. Most bridges down here have a stream or tide gauge in the water that shows the vertical clearance corresponding to the water level at that time. I don't know if these gauges are set precisely or if they have some "wiggle room". I assume they don't. Vertical clearance on a chart is based on mean high high water (MHHW), which is higher than the normal high tide level. In other words you should have more clearance than the chart shows. Measuring clearance under a bridge isn't easy as you have to measure relative to the underside of the bridge. You also have to know the tide level at the time you measure so you can compensate for its change. Even if you measure at high tide, high tide doesn't come up to the same level every time so you have to keep your tide tables handy. I don't mean to complicate matters but if your vertical clearance is really that tight then you need to know how much room you really have because of the possible consequences. Good luck. Peter H23 "Raven"
Bridge Clearance while Sailing
Las summer I observed the unfortunate and not to funny result of one sailor having sailed under the trusses of one of the spans of the Chesapeake bay bridge near the Kent Island side east of Annapolis. He made it under the southern section but must have tacked or lost his wind just as he was directly under the northern spans. As the boat came upright, he was 'boxed in' by the outer trusses of the span. When I happened along I transited several spans closer to the mid span and he already had two tow boats trying to figure out how to heel him over and hold him against the tide until his mast could clear. Meanwhile we could hear the banging of the mast head on the girders above him. I don't think he lost the mast, and I believe the tow boats eventually got him out as a rather nasty squall passed thru an hour later and I didn't see him there.
Las summer I observed the unfortunate and not to funny result of one sailor having sailed under the trusses of one of the spans of the Chesapeake bay bridge near the Kent Island side east of Annapolis. He made it under the southern section but must have tacked or lost his wind just as he was directly under the northern spans. As the boat came upright, he was 'boxed in' by the outer trusses of the span. When I happened along I transited several spans closer to the mid span and he already had two tow boats trying to figure out how to heel him over and hold him against the tide until his mast could clear. Meanwhile we could hear the banging of the mast head on the girders above him. I don't think he lost the mast, and I believe the tow boats eventually got him out as a rather nasty squall passed thru an hour later and I didn't see him there.
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