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Weight bag to induce list for bridge clearance

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rrick
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USA
261 Posts

Initially Posted - 11/18/2012 : 23:21:17

I need to list my C25 tall mast about 30 degrees from vertical to clear a 30' bridge... cos(30°)*35' mast = 30' clearance.
I have a #250 scuba lift air bag that can double as a #250 water weight bag (doubled checked with the manufacturer). Could I just hang this weight from the spinnaker swivel and call it good? Or do you think I need to form something stronger at the masthead like a fore and aft attachment triangle I can lash to the main shroud when not in use?

Molly Brown: 1967 Grand Banks 32-#34. Bronze, mahogany, teak, oak, with 120hp diesel to push all 10 tons. Currently an abuser of the bilge pump. Also... The Tall Rig Spirit: 1978, #973, Cast Fe Fin Keel on a Trailer

Edited by - rrick on 11/18/2012 23:25:12

Ape-X
Admiral

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USA
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Response Posted - 11/19/2012 : 04:59:23

why not just drop the mast? There are a lot of articles on site

Edited by - on

John Russell
Master Marine Consultant

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Response Posted - 11/19/2012 : 06:43:05

You mean like [url="http://www.youtube.com/watch?v=CInYj5P4evA&feature=rellist&playnext=1&list=PL0AC885BCF5A364DF"]this[/url]?

Edited by - on

dlucier
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Virgin Islands (United Kingdom)
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Response Posted - 11/19/2012 : 07:30:48

[url="http://www.youtube.com/watch?v=SNjI0aB1AgQ&feature=relmfu"]Audi Under Bridge[/url]

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cshaw
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USA
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Response Posted - 11/19/2012 : 08:15:41

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by rrick
 I need to list my C25 tall mast about 30 degrees from vertical to clear a 30' bridge... cos(30°)*35' mast = 30' clearance.
I have a #250 scuba lift air bag that can double as a #250 water weight bag (doubled checked with the manufacturer). Could I just hang this weight from the spinnaker swivel and call it good? Or do you think I need to form something stronger at the masthead like a fore and aft attachment triangle I can lash to the main shroud when not in use?
<hr height="1" noshade id="quote"></blockquote id="quote">

Hi rrick! When I said I should probably start a thread on this in my other note, I did not realize you had already done it! Great! The ideas I have slowly been putting together were spurred on by the photos I saw a long while back of that same boat clearing that bridge.

I am planning on using my main halyard since its on a single sheeve in the center of the main truck so is very strong. Then I am planning on using my boom as a gin pole and run a line through a cheek block on the boom and then to the halyard. That gets the weight outboard as far as possible to reduce the weight that is needed and also minimizes any "pendulum" action.

The weight is the part I am still pondering. Right now I am thinking it would be some type of waterproof canvas bucket inside a cargo net (for strength) with spreader bars and a bridle for hoisting via the main halyard. Attach enough weight on the bottom of the bag to make it sink (and fill with water) and a line attached to the bottom of the bag to retrieve the bag upside down so it empties. If the angle of heel needs to be enough that the weight does not clear the water when hanging off the boom, I would first raise the boom up via the topping lift (there is no "weight" on the topping lift other than the boom and mainsail), and then secure it also with the boom vang rigged out to the rail as a preventer to keep the boom out.

I found the secret to what the guy on the Okeechobee uses to make sure there is enough clearance. He has a line that goes up to the masthead via another halyard with a weight and a float on the end. The line is the right length so that when the float touches the water, the hardware at the masthead (antenna, lights, etc.) is at whatever clearance you want. For tidal water, markers in the line let you change the clearance shown to whatever it needs to be.

What I have not been able to settle on is what to make the bag/spreader bars out of that folds up nice and compactly for stowage but is strong enough to hold the the weight. I have a big plastic barrel I am going to use to see how much weight (how much water) will be needed.

The whole idea on this is to make the setup, use and stowage as simple and quick as possible.

Thoughts?

Chuck

Edited by - on

PZell
Admiral

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USA
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Response Posted - 11/19/2012 : 08:31:58

Seems to me it would be much simpler and more controlled to just use the boom and mainsheet as a gin pole, remove lower aft shrouds at deck, loosen the others a tad, string an adjustable bridle to the end of the boom to forward on rail near where lower shroud goes to deck and just lower the mast forward a bit. You do not need to drop it very far. Once passed under bridge haul on mainsheet and tighten the shrouds.

Edited by - on

rrick
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USA
261 Posts

Response Posted - 11/19/2012 : 08:36:48

Carter Lift Bag of Enumclaw, WA ok'ed use of their bags in reverse operation. Serious well made American goods

I was planning to dip the bag and haul up to list, then drop the bag and collect, so I need the swivel provided by the spinnaker block. I know my block is sundrenched, so I may just take this opportunity to get a 650# block.

Edited by - on

cshaw
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Response Posted - 11/19/2012 : 08:49:05

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by PZell
 Seems to me it would be much simpler and more controlled to just use the boom and mainsheet as a gin pole, remove lower aft shrouds at deck, loosen the others a tad, string an adjustable bridle to the end of the boom to forward on rail near where lower shroud goes to deck and just lower the mast forward a bit. You do not need to drop it very far. Once passed under bridge haul on mainsheet and tighten the shrouds.
<hr height="1" noshade id="quote"></blockquote id="quote">
Hi PZell!

I have lowered the mast on Confetti while away from the dock just like you described. The problem I had with that approach is you have to maintain the tension in the uppers to avoid side to side swaying of the mast if there is "any" roll by the boat. And to do that you have to have a pivot point for the uppers in the same plane as the mast pivots on. I saw an Oday that had triangular plates in its uppera to provide that pivot (the 3rd point was anchored aft to the aft lowers chainplates) and have seen lots of european boats with a good tabernacle rigged like that also. Then you also have to re-tension the lowers to the same tuning you had before.

So, this time I am going to try a different approach and see how it goes. Them I can compare......

Edited by - on

cshaw
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Response Posted - 11/19/2012 : 08:54:25

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by rrick
 Carter Lift Bag of Enumclaw, WA ok'ed use of their bags in reverse operation. Serious well made American goods
I was planning to dip the bag and haul up to list, then drop the bag and collect, so I need the swivel provided by the spinnaker block. I know my block is sundrenched, so I may just take this opportunity to get a 650# block.

<hr height="1" noshade id="quote"></blockquote id="quote">

Nice looking bag! I may have to look into that since you say its rated to be used full of water!

The only concern I have with using my spinnaker halyard is the leverage the weight would have on "twisting" the main truck up at the masthead. Thats why I am thinking of using the main halyard since it pulls closer to centerline. I thought about chafe on the main halyard, but it would not be out any further than the halyard experiences when sailing off the wind with the main all the way out?

Chuck

Edited by - cshaw on 11/19/2012 08:55:03

Dave5041
Former Mainsheet Editor

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Response Posted - 11/19/2012 : 09:14:48

For what its worth, my 200 pounds at the masthead didn't come anywhere close to 30 degrees of heel, and you should probably be thinking 45º for clearance. 30 feet listed on a bridge doesn't always mean 30 is always available at the point of maximum clearance. Good Luck, but dropping the mast forward is pretty simple. The mast is pretty stable above 45º, and re-tensioning shrouds is just counting turns.

Edited by - on

cshaw
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Response Posted - 11/19/2012 : 14:01:37

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Dave5041
 
For what its worth, my 200 pounds at the masthead didn't come anywhere close to 30 degrees of heel, and you should probably be thinking 45º for clearance. 30 feet listed on a bridge doesn't always mean 30 is always available at the point of maximum clearance. Good Luck, but dropping the mast forward is pretty simple. The mast is pretty stable above 45º, and re-tensioning shrouds is just counting turns.
<hr height="1" noshade id="quote"></blockquote id="quote">

Hi Dave,

Yep my 230 at the masthead did not pull Confetti over either, and if you watch the start of the video with the large boat and yellow bags, there was not much heel induced on it either while the weight is over the deck. But when she turned and slung the weights out so there was some leverage, you see what happened....

I am thinking using the boom as a simple gin pole will provide a lot of leverage.

Since I always lower Confetti's mast the way you described, I am very familiar with doing it that way. I just do not want to mess with the rig if at all possible. I'll let you know how well it works and how much weight is required.....

Good point to remember that the clearance is usually the mid-span clearance. For me, I am looking at a 35ft clearance, so I want to be no higher than 33ft, and that requires a 29 deg angle of heel from vertical to get my 37.5 height to the tip of the radio antenna to the 33ft. A 45 deg heel angle would result in a 26.5 height, so I don't think I need to go over that far. Now RRick may need to go that far since his bridge is only 30 ft and he has tides that may reduce that 30 ft even more.....

Chuck

Edited by - on

GaryB
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Response Posted - 11/19/2012 : 18:42:21

How are you going to power the boat under the bridge with it leaning that far over? If you lean the boat one way te motor would be close to get submerged if there any waves at all and lean it the other way and the lower unit may be out of the water?

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awetmore
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Response Posted - 11/19/2012 : 18:53:38

Is your antenna only 1' high? Most are 3' or 1 meter (39") high and on a tall mast boat that means about 39' clearance, not 37.5'.

alex (who sailed under a little bit low bridge once with a lot of heel and knows he'll never try that again...but nothing went wrong)

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cshaw
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Response Posted - 11/19/2012 : 18:59:00

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by GaryB
 How are you going to power the boat under the bridge with it leaning that far over? If you lean the boat one way te motor would be close to get submerged if there any waves at all and lean it the other way and the lower unit may be out of the water?
<hr height="1" noshade id="quote"></blockquote id="quote">
Hi Gary!

Excellent points. I put the motor down all the way a while back when it was blowing pretty hard to see how close the powerhead comes to the water and then sheeted in and put her on her ear. It got pretty close, but seemed to be fine. We were moving prety good however, and there was a quarter wave that helped keep the water away.

I have in my plan to dry run this in the slip to see how things work, and will take pictures and post them as I learn. For example, if it simply takes too much weight to get 30 deg of heel, then I may have to look at the rigging changes it would take to put stabilizer rings on the uppers and guy wires from the rings to the forward and aft lowers. Then I would also have to add a quicker way to release the lowers and the backstay and to re-attach them. Un-screwing turn buckles and then re-attaching them would work, but I prefer not to.....

Lots to learn and experiment with!!!

Cheers!

Chuck

Edited by - on

GaryB
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Response Posted - 11/19/2012 : 19:13:04

Coming into the Kemah Boardwalk one blustery afternoon I was motoring at a good clip trying to beat a 60' or so motor yacht kicking up about a 4' wake to the entrance of the Kemah Channel. With the stern squatting due to the speed I took a big wave over the top of the motor in the worst possible spot just before the entrance.

That little Suzuki choked, gagged, spit, spewed, and almost died but she finally came around and got me out of a situation that very well could have gotten ugly very quickly if she died. Everything under the cowling was soaking wet and I have no idea how it kept running after gulping a fair amount of saltwater.

It's a wave that's going to get you, probably not the angle, so be careful.

Edited by - on

rrick
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Response Posted - 11/19/2012 : 19:20:12

yeah, my motor mounted starboard, and the storage position for this Suzuki 4-stroke is lay on its left side. Possible I could starve it of oil because I don't know if it's wet or dry sump.

Chuck, I also asked the bag people if I could store the bag rolled up wet and told me not necessary to baby it.

250# might not be enough? Well with all the bullion I'm salvaging 250# at a time, it could be time for an upgrade, ha ha.

Edited by - on

rrick
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Response Posted - 11/19/2012 : 19:35:01

34.5' ?

Edited by - rrick on 11/19/2012 19:52:13

cshaw
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Response Posted - 11/19/2012 : 19:39:52

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by awetmore
 Is your antenna only 1' high? Most are 3' or 1 meter (39") high and on a tall mast boat that means about 39' clearance, not 37.5'.

alex (who sailed under a little bit low bridge once with a lot of heel and knows he'll never try that again...but nothing went wrong)
<hr height="1" noshade id="quote"></blockquote id="quote">

Hi Alex!

Mine is just the more or less standard VHF masthead antenna. Looks to be around 2 to 3 ft (never really measured it by itself). Its attached to the side of the mast with the top of the loaded coil actually a bit below the end of the extrusion, so it probably adds slightly more than 2ft to the extrusion height?

I measured the height with a pig stick marked off in 6" increments that was attached to the jib halyard, and the bottom of the pig stick had the steel tape secured to it. The result was a steel tape that gave me the distance to the bottom of the pig stick, and the stick itself was a vertical (when the halyard was tensioned) spar that extended about a foot above the top of the antenna. Then I used binocs to get a good reading on the pig stick marks vs the height of the masthead light, windex, and tip of the antenna.

That gave me the distance from the base of the mast to the tip of the antenna as 33ft 2" (The I measurement for a tall rig is 31ft, so the 33ft 2 inches seems consistant with a 31 ft extrusion plus something more than 2ft of antenna sticking above the extrusion.

I used an 8ft long 2x4 with a 6ft long level on it sitting on the cabin top, and with the 2x4 level, I measured from the bottom of the level (i.e. the cabin top at the base of the mast) to the water and it was 4ft 4".

33'2" + 4'4" = 37'6" = 37.5 ft

I certainly could have made some dumb mistake when doing all this, but there were two of us doing it, and we were checking what each other measured, and there was no wind, so I think its pretty close.

Edited by - on

cshaw
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Response Posted - 11/19/2012 : 19:47:10

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by GaryB
 Coming into the Kemah Boardwalk one blustery afternoon I was motoring at a good clip trying to beat a 60' or so motor yacht kicking up about a 4' wake to the entrance of the Kemah Channel. With the stern squatting due to the speed I took a big wave over the top of the motor in the worst possible spot just before the entrance.

That little Suzuki choked, gagged, spit, spewed, and almost died but she finally came around and got me out of a situation that very well could have gotten ugly very quickly if she died. Everything under the cowling was soaking wet and I have no idea how it kept running after gulping a fair amount of saltwater.

It's a wave that's going to get you, probably not the angle, so be careful.
<hr height="1" noshade id="quote"></blockquote id="quote">

Ahhh, that brings back a LOT of similar memories coming in that very channel for the 30 years we were in Houston!! If its not boat wakes, its current against the wind there making it like a washing machine!

Fortunatley, the two bridges I am looking at passing under are in relatively sheltered water, and even when its blowing pretty hard (which would mean I would not be doing this anyway!), its never as choppy as the Clear Creek channel entrance to Galveston Bay......

You are quite right about drowning the motor being a big risk, and I am quite paranoid of dunking the motor!

Chuck

PS: Is the "Boardwalk Beast" still making runs from the dock there by Landry's?

Edited by - on

awetmore
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Response Posted - 11/19/2012 : 20:27:49

I had bad measurements memorized. I had looked up the mast height here:
http://catalina-capri-25s.org/tech/c25spec.asp

It is 35', but for some reason I had always remembered that as 36'. My VHF antenna had a 3' whip and was mounted with the whip starting just above the masthead, which gets you just over 39'. I then would round to 40' to be safe.

37.5' seems plausible with a 3' antenna mounted a bit below the masthead.

Sorry for the confusion.

Edited by - on

GaryB
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Response Posted - 11/20/2012 : 19:15:50

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by cshaw
 <blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by GaryB
 Coming into the Kemah Boardwalk one blustery afternoon I was motoring at a good clip trying to beat a 60' or so motor yacht kicking up about a 4' wake to the entrance of the Kemah Channel. With the stern squatting due to the speed I took a big wave over the top of the motor in the worst possible spot just before the entrance.

That little Suzuki choked, gagged, spit, spewed, and almost died but she finally came around and got me out of a situation that very well could have gotten ugly very quickly if she died. Everything under the cowling was soaking wet and I have no idea how it kept running after gulping a fair amount of saltwater.

It's a wave that's going to get you, probably not the angle, so be careful.
<hr height="1" noshade id="quote"></blockquote id="quote">
...PS: Is the "Boardwalk Beast" still making runs from the dock there by Landry's?
<hr height="1" noshade id="quote"></blockquote id="quote">
Yes it is. Ticks me off every time I go out because they seem to love to circle around sailboats in a large circle making a washing machine effect in the middle where I always seem to get caught.

Whenever the approach to the channel is clear they like to come right up to the end of the channel before chopping the throttles which sends some nice rollers down thru the channel.

Edited by - GaryB on 11/20/2012 19:17:14

redviking
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Response Posted - 11/20/2012 : 23:03:18

Wrong boat for this operation in my opinion... That is a bluewater vessel trick only... Drop the mast...

Sten

Edited by - on

PZell
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Response Posted - 11/21/2012 : 10:45:53

Chuck, on lowering mast forward some. Adjustable bridle on boom end keeps mast centered. Its pivot point should pass near the mast pivot point. An additional adjustable bridle from spinnaker pole ring to points outward and forward could also help dampen mast swinging side to side.

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rrick
Captain

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Response Posted - 11/21/2012 : 23:19:53

But Sten, my reinforced pop-top makes me a bluewater boat

. The hull isn't even wet yet, just collecting wintertime opinions

Both me and Chuck, the C25 pioneers of this method, have fin keels. Easier to list with a swing keel? Patents (pending) for sale.

Edited by - on

dmpilc
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Response Posted - 11/24/2012 : 06:44:48

Seems to me that it would be a lot safer to use DavyJ's method (see YouTube videos) for going under bridges. The A-frame and transom mast support are very easy to build.

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cshaw
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Response Posted - 11/24/2012 : 08:51:59

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by rrick
 But Sten, my reinforced pop-top makes me a bluewater boat

. The hull isn't even wet yet, just collecting wintertime opinions

Both me and Chuck, the C25 pioneers of this method, have fin keels. Easier to list with a swing keel? Patents (pending) for sale.
<hr height="1" noshade id="quote"></blockquote id="quote">

Gotta agree with my "podnah in crime" rrick's position... I too am surprised folks would think its unsafe to simply heel the boat around 30-35 degrees in smooth water when so many have pointed out their confidence in our boats?

Seriously, my approach to seeing if this works for me will be to rig things in the slip and practice this a bit. Needing to haul up over #250 is probably not going to be in the cards (That was my weight including tools, etc. last time I got hoisted up the mast).

I will also have a headfoil that I would need to be careful with if the mast gets lowered and I'm not sure I want it to be draped over the bow pulpit (It will always get slipped off the forestay before the mast is lowered at the dock or on the trailer to avoid any significant bends in it since its old enough to be getting a bit brittle and not too tolerant to bends).

This has to stay a very simple and quick thing to do to so I can easily go under the two 35ft bridges to my north, and so far my experiences in lowering the mast have been neither simple nor quick, especially when I did it out away from the dock..... But I have not had the rig modified and/or extra aids to provide the improved side to side stability others have pointed out either So, we shall see what we shall see! Fun to collect ideas!

Chuck

Edited by - cshaw on 11/24/2012 08:56:22

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