SO30i under a 14m air draft bridge

Good morning,

I’m new to this forum and hope you can help me.
I’m planning to buy a second-hand Sun Odyssey 30i (lifting keel version) but I need to pass a bridge on my way to my marina. The bridge has an air draft of 14m at the highest tide.

From the technical specs of the SO30i (app.jeanneau.com[...]3a6.pdf ) its air clearance is of 13,91m. And I guess I need to take into consideration an extra height for the wind vane and anemometer, plus the VHF aerial (let’s say this implies a total air clearance of 14,6m).

If I do not want to take risks and wait 2 hours for tide conditions each time I want to go sailing, one possibility is to lean the boat. From my calculations, I’ll need to lean it around 18 degrees.
In your opinion, do you think this will be a feasible approach? Any idea of the total weight I need to put in the top of the boom (completely opened to the side I decide to lean the boat)?

All your comments and ideas will be very welcomed

L'équipage
15 oct. 2018
16 oct. 2018
0

Giving Google translate a shot before posting in English might get you more responses on this website. Posters here often discuss finer points of language as it pertains to boating, and the language they discuss and use is French.

Sounds like you're going to buy the boat, but need to figure out how to get under the bridge. Most of the time there should be no problem, but you're right to want to err on the side of caution and over-heel the boat to make sure you're always going to clear. 18º is a good bit of heel. Is there a way to observe exactly how much clearance you have when going under the bridge with that much heel? Perhaps you can get by with less. (Our VHF antenna and instruments don't add 2' to our mast's height.) In any case, you may need more than 100 kg out at the end of the boom, and, depending upon the physics, the end of the boom may have to go under water. In that case, you won't be able to use water (in buckets, for example) as counterweights, unless you pull in the boom, which reduces your lever arm and calls for additional weight to achieve the same 18º angle. Powerboat wakes may also knock your careful calculations awry. (You know that with your hull all the way over to one side as you go to heel, they will try to blast by.) It would be a good idea to actually try several different methods before you buy the boat, to make sure one will work. There are videos of people doing what you propose as they cruise down the Intracoastal, but they're specific boats that have obviously planned it all out carefully. It might be simpler to get a tide table and work around the 2-hour window, as you suggest. Safer, too.

16 oct. 2018
0

Hello,

Thank you very much for your advice.

After I post this message, I realized the question of the language, so I translated it and post another one in French (subject: "SO30I sous un pont de 14m").

As I'm Portuguese, I'm not very good either in English or French, but sailors are nice people and try to understand each other :)

I thought that another alternative would be to reduce the mast height a little (around 0,5 to 0,7m).

For this, do you think a suitable approach would be to cut the top of the mast just above the exit of the spinnaker's halyard? In this way (with only an adjustment in the length of the backstay and with a reshape on the top of the main) I would keep all the remaining rigging intact.

Any idea if this would work?

You know what's the available length between the exit of the spinnaker's halyard and the top of the mast (in a SO30I)?

Best,
Jorge

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