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Discussion Starter #1
What bent the boom vang?

Last October we had our Catalina 36 hauled. We winterized her and put on the winter canvas.

When we removed the canvas this spring the boom vang was seriously bent. There appears to be no damage to other parts of the boat nor to the winter canvas.

Had the vang been damaged when being hauled/blocked, we would have seen the damage when we put the winter canvas over the boom.

There are no trees near the boat.

There is not enough room between our boat and the boat we were parked next to for the marina's travel lift to pass through.

There were reported gusts of 50 mph during the winter, not enough, I would have thought, to bend the vang without disturbing the winter cover.

Partly, I'm curious as to how this might have happened. More importantly, if it is something that I did or didn't do, I'd like to see that this doesn't happen again next winter. I would say that the sheet for the vang and the mainsheet were snug, not hanked down and not flopping.

One last thing. I figure if there was enough force to bend the vang so badly, that force must have been transferred to other places, but there is no apparent damage to the boom or the fitting at the base of the mast. The screws that fastened the vang to the boom were in place and undamaged.

Thanks for any insight you may have.
 

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Learning the HARD way...
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I will hazard my guess; that the weight of snow loading on that winter cover pushed the boom down (is there any other support for the boom?). In the future, disconnect the rigid vang and use a topping lift to hold the boom up over the winter.

Where are you located? The winter in the northeastern US was not that bad this year. Certainly not enough to cause that.

Contact Garhauer directly. Show them the pictures, and speak with Guido if you can. Guido can probably provide you with only the parts that you need, and NOT at a ridiculous price.
 

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So I'm assuming there was no topping lift attached, yeah?

I'd at least stick a 2x4 support at the aft end of the boom rather than cantilevering it all winter.

Also canvas shrinks A LOT when it gets wet. Its really hard to unzip my winter cover when its raining. Could be a contributing factor?? Doubt it though.
 

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Was the boom noticeably lower than you left it? IIRC the garhauer is spring loaded so why didn't the spring just give a little?
 

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I will hazard my guess; that the weight of snow loading on that winter cover pushed the boom down (is there any other support for the boom?). In the future, disconnect the rigid vang and use a topping lift to hold the boom up over the winter.
Agree
Most probable that a heavy load (snow, ice on the boat cover) exerted a significant down force on the boom which caused the rigid vang to 'buckle'.
Buckling failures are caused by a relatively small compressional load acting along the long axis of a very slender support member, once the support member (vang) 'deflects'/ bends under the applied load it doesn't take much further load to bend such in 'buckling' failure.

Its the same reason that you don't do handstands, etc. on top of a thin, but easily bendable, wooden 'yardstick' held end to end between you and the ground, as once the midspan of the yardstick becomes 'offset' or deflected from the centerline - buckling takes over and requires very little compressional force to complete the failure, even though there is sufficient material to bear the compressional load along the long axis of the 'yardstick'.
 

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Discussion Starter #7
I had not thought of snow being the culprit. (I'm reminded of an old Alfred Hitchcock episode where the victim was shot with an ice bullet, leaving no evidence.) We did have a blizzard w/ maybe 20 inches but it was dry.

We did have the topping lift, as well as the main halyard, attached to the boom. There would have been some stretch, I guess.

I don't recall that the boom was lower this spring than when we left it.

The boat is on the hard on the Maryland side of the Potomac some 30+ miles from the Chesapeake Bay.

In the picture, we had not finished attaching sand bags to hold down the canvas.
 

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Over Hill Sailing Club
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+1 on snow theory. Having kept my boat for years in the Northeast, I can verify that snow loads on canvas are significant and certainly enough to bend a long, unsupported length of aluminum. The heaviest loads usually come from the water that melts and freezes in puddled areas on the canvas. A regular boat job in the winter should be clearing snow off any cover.
 

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I use a 2x4 support for my mast as I don't want to rely on the topping lift. As noted, if water can collect on the cover, weight loads can be substantial.
 

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Water/ice has a density of ~65.4 lb. per cubic foot.

Snow, the light 'fluffy dry' stuff can have a density of about ~7 lb. per cubic foot; but, could be much more due to moisture content.
So, assuming a 10 ft. length boom and a beam of 9 ft. at the cockpit, & 20" of 'dry' snow:
10 ft. X 9ft. X 20"/12" ft. X 7 lb./ft^3 = 1050 pounds snow load on the 'tarp'
Assuming 1/2 of the load is born by the 'tarp' at the coaming, etc.: 525 lb. hanging on the boom.
............. or 'Quarter Ton or more' hanging on that boom from 'just' 20" of 'light fluffy' snow.

:-(
 

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Discussion Starter #13
A dry snow, regardless of its accumulation on the ground, wouldn't pile up on a steeply sloped winter cover. I live on the Virginia side of the Potomac. I'll check with the marina people to see if their weather was different from what we experienced over here.

So from "crowd sourcing" we hypothesize that a hyper-extended boom (with topping lift) vang, deflected by gale winds, was bent due to the accumulated downward force of heavy wet canvas, sand bags, ice and snow.

The FIX? Further suggestions?
a) no winter cover next year
b) detach the boom vang
c) support the boom at a spot close to where the vang is attached.

You all are great. This has been very helpful.

mrmac
 

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Hindsight, of course, and I wouldn't have thought it necessary... but disconnecting the vang at the boom and laying it on deck would have avoided this issue - or created and even deeper mystery ;)
 

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how is the boom attached to the mast?
on mine the gooseneck is free to move up or down, if that is the case on yours that could be the weak point that caused the vang to buckle
 

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We got a 32 inch snowfall with gale winds about 50 miles north of you

I am betting that's the incident which bent it
 
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When I put my boat away at the slip, the main halyard is used as a topping lift, even though I have Hall spring-loaded vang that will support the boom by itself. Then, to minimize the swinging of the boom in the wind, I haul down on my boom-end main sheet. The stretch of the main halyard (synthetic with less stretch than Dacron) is noticeable--maybe 5 or 6 inches.

Also, it appears that the winter cover is supported from the boom, without any intermediate support between the boom and toe rail. A fellow with a sister ship here in CT had snow damage with a boom-supported winter cover, so it is entirely possible that snow--with or without wind loading could pull the boom down--especially if there was subsequent rain to add weight to the snow.

It doesn't look like your cover is treated cotton canvas, which I have and really does shrink when wet. However, it doesn't shrink enough to pull your boom down significantly, IMHO.

A simple solution would be to disconnect the vang for the winter, as the gooseneck and topping lift ought to handle the load.
 

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Discussion Starter #19
Topping lift and main halyard were in place. Will take advice about disconnecting vang. Thanks.
 

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A dry snow, regardless of its accumulation on the ground, wouldn't pile up on a steeply sloped winter cover. I live on the Virginia side of the Potomac. I'll check with the marina people to see if their weather was different from what we experienced over here.

So from "crowd sourcing" we hypothesize that a hyper-extended boom (with topping lift) vang, deflected by gale winds, was bent due to the accumulated downward force of heavy wet canvas, sand bags, ice and snow.

The FIX? Further suggestions?
a) no winter cover next year
b) detach the boom vang
c) support the boom at a spot close to where the vang is attached.

You all are great. This has been very helpful.

mrmac
Around the shores of Lake Champlain, I've seen a lot of different solutions to snow and ice build-up. Some build elaborate, STEEP framework, others go with no cover. I have always used a regular blue/brown type cheap tarp but have also put wood supports under the mast every 5' or so. It's really important to make sure that water cannot form huge pools where the tarp is tied off underneath. I've seen at least 100 gallon bags, frozen solid, at times on poorly thought out tarp jobs. I go over after every significant snowfall and shovel her off. Ice will accumulate in sagging spots. During thaws, I remove any ice that has accumulated. I don't think there is any way to avoid some winter maintenance. Hope that helps.
 
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