Sailboats and bridges

[Andrew Hamilton]

This is a question for any naval architects out there. I found a great source for crane weight testing bags to carry on my SV in case I encounter a questionable bridge on my trip from providence RI to Chattanooga. My challenge is how can I determine the righting momentum of my Island Trader 41. How much weight would I need to heel my boat ? degrees? 1,000 lbs. or 2,000lbs.? Just enough to gain 5 to 10 ft off of 58 ft height.

[slug]

Well....I haven’t heeled boats under a bridge since I was a kid

One detail I remember was the plumb bob.

Cut to the exact clearance needed...Hung from masthead

When it touched the water ..you were clear

For weight we used 169 liter barrels hung from the boom, perpendicular to boat ..barrels empty..the barrel was then filled with sea water from a pump

Can’t remember the righting moment..these were 35 to 40 ft 1970s race boats

Go under the bridge in reverse..current on your stern

[Andrew Hamilton]

Excellent idea with the plum Bob. I am about to purchase these 1,000 lbs. Water weight bags, I am wondering one or two bags.

[slug]

And another detail I have used is a “tickler”. Normally an old fishing rod that is lashed to the spinnaker halyard , hoist to the max ....so that the tickler, fishing rod, extends above youR tallest masthead ant.

Go dead slow....If the tickler touches , back off and try again

Nothing more embarrassing than passing under a bridge successfully ..but Snapping off your ant

Be aware the dead center of a bridge can be dangerous...light and electrical cable

Have a good look for these dangers before passing under

[Andrew Hamilton]

Thanks for that tip
I will bring my Island Trader 41 around from R.I. to Chattanooga this summer. Homeport there while my sons finish highschool. To the top of the mast is approx.58ft not counting alot of expensive equip. I will start by keeping one weight bag on board 1,000lb (for any contingency). I plan on taking the Tom-Bigbee if I can and the trip will all be upstream. The supplier is easily helpful. Maybe I can keep notes for other inland sailors. Looper guides are pretty vague about important stuff to boats with sticks.
Andy

[Montanan]

A reference:

https://www.sam.usace.army.mil/Porta...av/bridges.pdf

Be sure to confirm the clearances and to tilt over with room to spare, including rocking due to wake effects. Not sure if this is complete and current data and note that it is for normal pool.


Have fun ducking under.

[BugzyCan]

This just sounds like a Darwin moment.. halfway under the bridge the weight falls off or mast buckles. lol
Found a youtube vid showing it though. Bold move.

https://www.youtube.com/watch?v=kiv0fxFcV3I

[Andrew Hamilton]

Yup. That's the move. My sticks are not nearly as high. The weight bags are insurance. And yes I am aware of engine water intake and exhaust
I just feel pulling the sticks can be traumatic for the girl

[Andrew Hamilton]

Thank you for the info. Lived by a TVA lake for years. Winter, Summer, Flood draw down is dramatic.