Getting a tall mast under a low bridge

[Hwyl]

I don't talk much about my work, but we had a boat with a 65' mast, circumstances forced us to take it uop the intracoastal between Beaufort NC and Norfolk VA, thereby missing Cape Hatteras.

The bridges are supposed to be 65' high, there is one that is (reliably informed by forumite HR) 64'

The authorities give you a nice gauge.


We hung fuel cans and water cans and the liferaft on the end of the boom and guyed it out (we'd already done the trigonometry (SOCAHTOA) and worked out the angle needed




This picture shows the angle nicely






We backed slowly under the bridge, many Aussies will recognise
Captain Murray Jacob



Made it

[StevenBauer]

How tall was your rig, Gareth?


These guys got 80' under a 65' bridge:

http://www.youtube.com/watch?v=epz6BBZm__0&NR=1

http://www.youtube.com/watch?v=CInYj5P4evA







Steven

[Hwyl]

Dave, Yes, but I don't particularly want to talk about that

[Hwyl]

Steven I saw that but working t out in Cosines they'd have to get to 32 degrees if those numbers are correct. It does not look like 32 degrees to me

[willmarsh3]

That's pretty cool. Just curious Gareth why you backed under the bridge instead of going forward?

[RFNK]

That's pretty cool. Just curious Gareth why you backed under the bridge instead of going forward?

When we take our Folkboat under the Tea Gardens Bridge (Port Stephens, NSW, Australia) I always reverse under if I'm not quite sure that I'll have the clearance. This is simply because, like so many yachts, it's more responsive going forward than in reverse so if I find I've miscalculated and actually hit the bridge, I can quickly go forward. As it is, each time we've gone under, we've had about 15cm clearance. I know this because the radio aerial scrapes the bridge. Rick

[Canoez]

SOHCAHTOA, the amazing Native American revelation of lengths...

[Noah]

Great work!

[Hwyl]

When we take our Folkboat under the Tea Gardens Bridge (Port Stephens, NSW, Australia) I always reverse under if I'm not quite sure that I'll have the clearance. This is simply because, like so many yachts, it's more responsive going forward than in reverse so if I find I've miscalculated and actually hit the bridge, I can quickly go forward. As it is, each time we've gone under, we've had about 15cm clearance. I know this because the radio aerial scrapes the bridge. Rick

That's the reason. A quick burst of forward is a better stopper than a quick burst of reverse.

With the parallax it's impossible to tell if you are going to hit.

[willmarsh3]

Yep. That makes perfect sense. My boats will go from backwards to forwards much more quickly then from forwards to backwards whether its diesel or electric. Thanks everyone for that little pearl of wisdom. The only downside is if the boat doesn't like to back up in a straight line. But that's obviously small potatoes compared to hitting the bridge.

[Hwyl]

SOHCAHTOA, the amazing Native American revelation of lengths...

My math teacher was a WW2 veteran and I actually leaned the mnemonic "Some officers have curly auburn hair to offer attraction" amazing what you remember.

[Raka025]

I had backed down into the bridge going from Dover to Newington, NH to get into the Great Bay Marina for a haul out to paint the bottom and topsides. The tide was flooding and I had a less than reliable Gray Marine engine. We missed the window and tagged the bridge with the backstay and powered on up, which wasn't that much faster given the current of the Piscataqua River. Certainly an adrenal moment.

[Doug Wood]

Nicely done.

[Bob Adams]

How tall was your rig, Gareth?


These guys got 80' under a 65' bridge:

http://www.youtube.com/watch?v=epz6BBZm__0&NR=1

http://www.youtube.com/watch?v=CInYj5P4evA







Steven

Talk about a huge set of Gronicles!

[rbgarr]

Here's why you want to back through a bridge if you're not sure about clearance: http://www.youtube.com/watch?v=2VMrrT4X6Qg&feature=fvw

[RFNK]

The only downside is if the boat doesn't like to back up in a straight line.

This did make me laugh. My Folkboat motoring in reverse is a wayward beast indeed! I should have added that to reverse under the bridge, I also need to leave plenty of manouvering space on each side! Rick

[paladin]

AH! Yes......there's this one bridge on the intercoastal just south of Norfolk...........

[elf]

Here's a bit of a discussion about getting the huge maxis under the Bridge at Melbourne.

http://www.victoriaweek.com.au/dockl...gle.asp?ID=224

[Ian McColgin]

Back in the '70's there was a rich fellow in Portland, Oregon, who fameously had raised a meter boat belonging to the former king of Norway (I think it was). There were times when the water level under the highway bridge over the Columbia was a nudge high. He was fameous for strapping her tight on a beam reach to heel her enough to sail under.

A thirty degree heel takes perhaps 12' off the height of a 90' mast. Forty five degrees gives you 26' of headroom.