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Old 07-01-2016, 20:11   #46
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Join Date: Feb 2010
Location: El Ciudad del Mission San Diego de Alcalá en Alta California, Virreinato de Nueva España
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Re: Calculating ACTUAL bridge clearance

Originally Posted by OrangeCrush View Post
So can I ask everyone's opinion on the following question?

Would you consider buying your "dream boat" if it had a 55' mast and you needed to pass under this 55' bridge every time you went out sailing? Assume you have confirmed the height of the mast down to the inch and you have confirmed the accuracy of the tide boards at the base of the bridge. 95% of the time the bridge clearance will be fine. If it is one of those infrequent moments with less than the posted clearance you can time it so that you pass at a lower tide or give the drawbridge operator 8 hours of notice so they can lift the bridge if it's a weekend.

I'm a bit tortured by this because I'm realizing some of the boats on my short list will not fit under the bridge at all times.

Corbin 39 (56 feet of air draft, probably gotta rule this one out)
Tayana 37 (55 feet of air draft, hate to say it but prob a no-go as well)
Valiant Esprit (54 feet of air draft)
Alajuela 38 (54 feet of air draft)
Baba 35 (53 feet of air draft)

These are among my favorite options and I hate ruling any of them out, but I'm also not sure it's worth the stress of having to think about clearing the bridge every time I go out for a day sail. Obviously it will not be much of a factor on longer cruises, but I will no doubt be doing both...

Any opinions?
To start someone figured out that MHW is when the tidal height is 5.2' above datum.

Next you need to figure out actual air draft.

Does the air draft include antennae, or is that just the truck height?
How tall is the antennae?
Is it a metal whip or fiberglass?

If it is a metal whip you can strike the bridge with the tip, I would keep my speed down and try to avoid any hanging lights and wouldn't want to hit the bottom 12-18" because it might permanently kink the whip. With fiberglass no striking at all.

Let's assume the air draft includes antennae and you don't want to hit at all but you are comfortable with zero clearance to the antennae. Assuming the previous math someone did was correct and the tides are the same for your bridge and the station I found at Norton Head (2016 Tide Table for Norton Point (Head Of Bay), New York for fishing <º(((><), that means MHW is 5.2' above datum and with the Corbin you need 4.2 or less to clear. For today's tides you would not have been able to pass under from 0430 to about 0800 or so. The PM high is such that you can get thru with maybe a touch of scraping the top of the antennae.

Looking ahead the situation gets worse for a while before getting better. Probably the Corbin and Tayana are out.

Something to consider is when will you be coming and going? If you are retired and mostly day sailing, you will be leaving AM and returning PM. If you never sail on Sunday mornings take that into account.

Pick a max height and look ahead at the times you will be restrained. At 53' you will be restrained by an hour or so a couple, four times per month going one way only. At 52' almost never.

By looking ahead I mean look ahead about 3 months so you know you are not looking just at a single abnormal month.

Being restrained an hour or 2 several times monthly would not bother me at all. Restrained by 3-4 hours for half the month would not bother me at all.

A house is but a boat so poorly built and so firmly run aground no one would think to try and refloat it.
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Old 08-01-2016, 06:05   #47
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Re: Calculating ACTUAL bridge clearance

Thanks, Adelie. That was definitely the kind of breakdown and opinion I was looking for with my first post. I agree with your analysis.

Reed, I agree with you and I would definitely not approach a broker with a pushy attitude. I would treat him as a professional unless I had a strong reason to do otherwise. But as someone without a lot of negotiating experience, I do think the distinction between "low-balling" a dealer (which you disdain) and offering half the asking price (which you recommend in some cases) is a subtle distinction, to say the least. I'm guessing that being forthright and friendly and at no times misleading or rude is the real difference. I'll guess I have to see how it goes. I love the business card idea and I'm definitely going to hit the marinas this spring, even though I probably won't actually buy anything until 2017.

Nemo, I don't think I'll have a problem with fuel turnover. Even though I mainly go out on afternoons and weekends during the school year (I'm a middle school teacher), I use July and August for much longer distance cruising. Maine and Nova Scotia will be my first destinations. I managed to put over ten thousand sea miles on my Pearson 26 in 7 years, and I'm planning to do much more in my new boat. If I was just day sailing I wouldn't have sold the Pearson. And even from Mill Basin I was sailing within minutes, it was just a long upwind leg out of Jamaica Bay and it took a while before things opened up. The SBYC dues are $2700 for the season, which breaks down to around $70 a foot for the boats I'm thinking of. It does seem a bit much for a mooring, and you have to provide your own mooring gear as well. I have time to decide if it's worth it.

Paul, I know there is a spec used to indicate how much additional weight it would take to lower the boat in the water by one inch. I can't remember what it is called, but that would be useful here. Then again, when you consider the possibility of a random wake lifting the boat up at exactly the worst time, perhaps it is not worth getting that exact after all. And as for thread drift, I take responsibility as the OP. I've been encouraging the parallel conversations, but it's exactly what I needed!

Thanks, all.

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