I'm new to sailing...have a Nacra 5.2 witha 25ft mast...got a 24.5 foot clearance bridge. Is there any way to safely lower the mast partially to get under a bridge ?

Rake it way back.



Fly a hull under it.



Or, beach near it and capsize to boat on the shore intentionally. Walk it under, right the boat, and away you go!

ohhhh, that's a good one!!!



I like todd's "fly a hull" suggestion.... it means you're actively sailing the boat under, as opposed to limping along under modified rig, or dragging the capsized boat, etc.. besides, it'll give good "wild thing" boat balancing practice!



it begs the question: how deep (wide) is this bridge? the wider it is, the longer you'll need to maintain this delicate balancing act, AND the wider it is, the more it will wreak havoc on the air currents up near the underside of the deck, which will make that balancing act more difficult.



typical wave conditions would also be a concern.



of course, I'm talking out of my butt. any way you do this, it's a shaky proposition. you're bound to incur some mainsail damage in the learning process.



A more stable solution might be to rig some sort of extendable headstay (aussie-halyard style?) that would allow you to temporarily rake the mast way way back, and then re-erect it once on the other side. I'm thinking that you'll want to go 30 degrees or so in order to give yourself a cushion. of course, this means that the shrouds are no longer taut, and the mast will likely swing wildly out to one side, so someone will need to steady it. it also means that you probably can't sail the boat like that, so you'll need some other means of propulsion to get under the bridge.



damned interesting problem! be sure to post your solution once you get it figured out!!

Unless you've cut down your mast or replaced it with something else, it should be 28.5 feet long instead of 24 feet.

- and then you've probably got the base of the mast about 1.5 feet above the water line. You would need roughtly 30' clearance to make it through in flat seas.

Agree with Jake's rough estimate- To measure more precisely use a long tape rule (or long line you can measure later), put boat in water and hoist tape/line using main halyard and measure to water- Add ~3" for the masthead casting and thimble on the halyard.

Point is- You will need a "lot"- So mast rake won't work, loosening forestay could be "iffy" (How old is your 5.2?? If it does NOT have the "captive ball" loosening your forestay this much could be disastrous!). Only reasonable options I see are using your trapeze lines tied snugly at the front beam to limit side "sway", use boom (as a "gin pole") with halyard connected to rear of boom (or mainsail up- but probably not best idea due to possible wind issues during this process) and mainsheet (may have to take some "purchase" out of the system to get enough "travel") to lower mast forward (will have to take side shrouds loose- boom connected via halyard to top of mast and to rear beam via mainsheet will control forward "tilt" of mast- Once you figure the distance out you could mark your mainsheet. Once under bridge just sheet in, reconnect side stays, raise sails, untie trap lines and off you go! Reverse process to return-

Other viable option is just lay boat over on side and walk it beneath- Make sure rudders are up, tiller is secured (bunjied or stuck under hiking strap, boards (and everything else loose) are tied to boat or secured (or take them under separately) and have one person at tip of mast and other at bow/stern-



Kirt

How about a "Heifeld Lever" or Rig-Tensioner (see Murray's catalog, PN 02-1060). This will allow you to safely loosen one side of your rig for a "simulated" flying a hull.

Shrouds extender, same as on Catapult. Doubles as a bulletproof righting system

See attachment

When i was a young sprout I ran a truck into the Burger King drive up window. The truck was jammed into the overhang by a foot. The solution? We let the air out of 4 tires in order to back out. Seems crazy,but you could flood your plontoons,but then no steerage. Hmm best find an alternative route.

If you are looking at a chart for your bridge height, remember that bridge clearances are listed at high water... or high tide. Water depths are listed at low water.

Okay, this is swatting a fly with an intellectual sledgehammer, but I got to thinking

See, the mast ball actually RISES when you go up on one hull. Since the masthead's motion in the early stages of heel is mostly sideways even without a rising ball, I wondered how far you'd have to heel to actually shorten your boat's overall height.



Then I wondered, "Can I still cudgel my aging gray matter to actually figger this out?"



So naturally, I just had to try....



Lessee.....granted, the lee hull sinks slighlty, so let's picture the boat as simplistically as to limit the impact of the things we ignore to a couple of inches, for the moment, then pick 'em up later...



So call your angle of heel angle A. The change in ball height (no puns please) is one side of a right triangle, with angle A opposite it, and a 4.25 foot other leg. The total vertical height of the mast alone, measured from the ball, is the long leg of another right triangle, with angle A adjacent, and mast length "M" as the hypotenuse. (let's refrain from advertising how long the leg next to our balls is/are!)



Thus



H(b) = change in ball height as you heel. (Ever have your Balls "heeled" or even "healed"?)

H(m) = vertical height of the leaning mast, measured from the ball up. (Don't go there.)

Then H(t) is the total, overall height of your boat, if you ad a foot and a half for the original height of the ball off the water.



So:

H(t) = H(b) + H(m) + 1



Trig tells us how to figger the terms above:

H(b)= sine of A X 4.25 (the other leg, half a tramp's width, is 4.25) (no jokes about the tramp's balls!)

H(m)= cosine of A x M (where "M" is the actual length of the mast) (no jokes about the tramp's mast!)





I can't solve equations for lowest f(x) anymore, but I plugged all this into a spreadsheet and used "goal seek" for A and both Figures for the mast length. (To check my work, I plugged in 90 for heel and got 4.5 feet, the hight of the ball when the boat's perfectly on it's side, mast precisely parallel to the wet stuff. When I specified 0 degrees of heel I got 30 feet, which is the sum of our mast length plus our starting ball height.





and the results are:



With a 28.5 mast, you have to heel 45.5 degrees to be exactly 24.5 feet tall. If you want a foot for wave clearance, you need to heel 48.7 degrees.





Wow. Almost 50 degrees of heel. Anybody know the "point of no return?" That would vary with sailor weight, wind strength, tramp fabric etc but there's gotta be a rough guideline out there....



At the 48.7 degree heel, your windward hull will be over six and a quarter feet in the air, your (6 foot tall sailer's) head will be almost 4 feet higher, making his hat a total of 10 feet up, darn near halfway to the bridge!



If your mast is in fact 25 feet in length, ball to head (Give it a rest already.), you will only need to heel 39 degrees to leave one foot clearance under your bridge in flat water at mean high tide, smack in the middle, when the moon is in either the first or last quarter and barometric perssure isn't unusually high or low and you have neither an onshore nor offshore high wind condition. Actual mileage may vary, actual california highway mileage will probably be significantly lower. This product is not intended to cure or diagnose any illness. Product is sold by weight, not volume. Contents may settle during shipment. Intermediate markdowns may have been taken. Dealer contribution may affect final price. Not to be taken internally, or seriously, either.



Keep one hull (very high) up!



Ed Norris

Ed,



I've tested the point of no return for a Nacra 5.2 and I can tell you that, depending on crew quickness, and the skipper's neck strength, a healing angle of 90 degrees can be brought back. The skipper needs the neck strength because he's hiking out on the top hull while the crew has his leg around his neck hiking (rather dangling) out further. The drawback here is that when the sail finally inverts and lifts the boat back upright (whew), you quickly find yourself on the wrong side of the boat after an inadvertant tack and now you're blowing bubbles laughing in the water....point returned but a bit too far (and no balls involved).

The Santa Cruz Harbor in California has an area on the upstream side of a low overpass. Last time I passed by it I noticed lots of large monohulls with masts much taller than the bridge. Obviously, they've figured out the nuts and bolts of how to deal with the issue. (At least for monohulls with backstays.) And they probably don't use Ed's equations, since they can't fly a hull.



The folks at Santa Cruz Harbor may know the definitive answer to this mariner's mystery...Tried to call them earlier--closed for the day. I'd suggest contacting them through their web site: www.santacruzharbor.org.



And by the way, it's also a great place to sail....if you can tack out the narrow harbor entrance through the breaking surf, since it is often in need of dredging.

"(and no balls involved). "



????!!!!!!!!



Heeling a 5.2 to 90 degrees in my humble opinion, involves at least a modest quantity of the aforemention speroids.





-Ed