How Tall is Your Mast?

[Hudson Force]

Originally Posted by thomm225

Most folks just go to sailboatdata.com and get that info. It gives the I, J, P, and E for just about every sailboat you can think of:

Sailboatdata.com is the worlds largest sailboat database. You can figure clearance from that.

Sail Measurement Assistance

Total vertical clearance for my boat is not shown on these sites. Data like I, J, P & E are not calculated from the waterline or the top of the masthead. I would think that people using these numbers could be led to hitting bridges!

Ah, but I see that you say, "you can figure your clearance from that." I sometimes pass under bridges when I know my VHF antennae will be rubbing the underside of the bridge. People should be able to get an accurate number by direct measurement and not guess what remains above the head of the sail or from the foot to the waterline.

Thanks, Thomm225, for a reminder of this data site, but all you passing under bridges better obtain the full numbers!

[colemj]

Originally Posted by markpierce

Are you sure? Think of the thousands who didn't respond to my inquiry.

Actually, close to 6 billion people did not respond to your inquiry, so you are correct - nobody knows the height of the mast of their boat except for the very few who have posted here, and they are an anomaly in this regard.

Superb logic and reasoning!

Mark

[thomm225]

Originally Posted by CaptForce

Total vertical clearance for my boat is not shown on these sites. Data like I, J, P & E are not calculated from the waterline or the top of the masthead. I would think that people using these numbers could be led to hitting bridges!

Ah, but I see that you say, "you can figure your clearance from that." I sometimes pass under bridges when I know my VHF antennae will be rubbing the underside of the bridge. People should be able to get an accurate number by direct measurement and not guess what remains above the head of the sail or from the foot to the waterline.

Thanks, Thomm225, for a reminder of this data site, but all you passing under bridges better obtain the full numbers!

Well I guess I was giving folks too much credit.

I figured a person could look at the diagrams provided and measure from the waterline to deck and add to the I measurement. (and possibly add in a little fudge facter.

I guess math really is a problem here in the United States.

[Jim Cate]

Originally Posted by thomm225

Well I guess I was giving folks too much credit.

I figured a person could look at the diagrams provided and measure from the waterline to deck and add to the I measurement. (and possibly add in a little fudge facter.

I guess math really is a problem here in the United States.

Yes, that method will work... if you are SURE that you own a totally original production boat, and that the figures posted are really correct. I've found that boats, especially older ones, often are not quite the same as when they left the builder's yard, and that there are even variations within a production run. And there are still non-production boats in use (like Mark's).

Apparently many of the responders in this thread go under bridges where their clearance is measured in inches. If I was one of them, I would want to do the physical measurement. Twice!

It isn't all that hard to do, so why not?

Jim

[Hudson Force]

Yeah, it's that "fudge factor" instead of the direct measurement that I would consider the math deficiency. I want the direct measurement to the top of the lens on my masthead anchor light while I'm in the bosun's chair. I've seen different numbers in print for the dimensions of my 1973 ketch.

[thomm225]

Originally Posted by CaptForce

Yeah, it's that "fudge factor" instead of the direct measurement that I would consider the math deficiency. I want the direct measurement to the top of the lens on my masthead anchor light while I'm in the bosun's chair. I've seen different numbers in print for the dimensions of my 1973 ketch.

Ok, understood.

I went under a 40' bridge recently. The I measurement on my boat is 30'5' and my freeboard is maybe 3-4' but I still inched up to that bridge very slowly...............then went under. My VHF antenna cleared it also but it seemed close.

[Hudson Force]

Originally Posted by thomm225

...............then went under. My VHF antenna cleared it also but it seemed close.

I remember a time years ago on another boat when Nancie dropped me off at the bridge fender so I could climb up to the catwalk under the span while she backed our boat through. We wanted to move under in reverse for an easy abort. The fixed bridge was charted at 45'MHW and we were 46'6" and at mid-tide. I noticed that, of the four steel I-beams under the bridge, the third one was at an angle that made the lowpoint. With a bit of a chop on the water surface it was hard to tell wether we would clear the third I-beam, but I waved her through and we did not touch. I made careful notes of the fender boards at that time. I knew I needed to have the two higher port fender boards out of the water when southbound and the center of the bolt head on the second starboard fender board at the water line when northbound. With the binoculars ready we either stopped for tide or proceeded at this bridge for years. Knowing your limits is freedom!

BTW, that's the Shands Bridge on the south side of Green Cove Springs, Florida. I can't go south of there now on the boat I've had since 1985. There are some beautiful places down there with clear springs and alligators laying on the banks. I miss them!

[Safari38LH]

I noticed a lot of replies have the word "about" in them. How many know the exact height above water of their mast? Personally, that's something I want to know. There are places like the Cape May canal at 55ft that can save you tons of time if you can fit under.' My mast us supposed to be 56' 6". That's what the specs from the past buyer said. Can I fit under the Cape May bridge at low tide? Do I trust the specs that came with the boat - fourth owner. I would not and did not try it without knowing the exact height first. I'm also not so sure running a tape up a halyard and to the water will give you an exact measurement.

[Hudson Force]

I'm somewhat angered by the lack of clearance cards on both sides of the two Cape May Canal bridges. I have waited at anchor in the Cape May Canal and then later passed with my VHF antennae scraping the underside of the bridge. All this, and my mast height is lower than the stated MHW clearance of the bridges!

[Scott Berg]

Mine is 74' to the top of the mast and lights, 78' to the top of the antenna; not that hard to measure. Pull up a halyard to the masthead block (spinnaker halyard is easiest); measure to deck...
Then measure deck to waterline when tanks are half full...

Add the two...
Add the height of anything on top of your mast...

Total is height above water.

[colemj]

Originally Posted by Safari38LH

I noticed a lot of replies have the word "about" in them. How many know the exact height above water of their mast? Personally, that's something I want to know. There are places like the Cape May canal at 55ft that can save you tons of time if you can fit under.' My mast us supposed to be 56' 6". That's what the specs from the past buyer said. Can I fit under the Cape May bridge at low tide? Do I trust the specs that came with the boat - fourth owner. I would not and did not try it without knowing the exact height first. I'm also not so sure running a tape up a halyard and to the water will give you an exact measurement.

If you need to know the height of your mast to enable you to clear a bridge, the best way is to post a random picture of your boat here and let us guess at its height.

Mark

[markpierce]

I measured the boat today. From waterline to top of mast with lightning rod is 31'6". I'll use 32' to be on the safe side.

In the early 1960s my father sailed his Columbia Defender sloop under the Oakland end of the Bay Bridge. The wind vane fell into the cockpit. It had hit the bottom of the bridge. Good thing we weren't further east where the bridge is even lower.

Cleared it (GG Bridge):

[colemj]

Originally Posted by markpierce

I measured the boat today. From waterline to top of mast with lightning rod is 31'6". I'll use 32' to be on the safe side.

In the early 1960s my father sailed his Columbia Defender sloop under the Oakland end of the Bay Bridge. The wind vane fell into the cockpit. It had hit the bottom of the bridge. Good thing we weren't further east where the bridge is even lower.

Cleared it (GG Bridge):

And that is a beautiful picture - looks like you just squeaked by...

Mark

[Suijin]

Originally Posted by CaptForce

My mast is 57'6" high, but my vertical clearance above the water is 54'6".

So the foot of your mast is 3' below the waterline...and your mast is 57'6" long?

Just checking. I've never tried going under the Cape May bridge, with a air draft of 55' plus antenna. Maybe I can try it with a spring neap tide. Going around those shoals adds a couple of hours :\

[44'cruisingcat]

60' with VHF antenna.