Pivoting spreaders on wooden mast (good or evil)

[jary]

Hi all

After reading and re-reading Brian's book several times I finally got up the nerve to drop my mast and re-rig my 25' double ended cutter 'Gemini'.

I'm now trying with some limited success to get the tuning correct.

The mast is a wooden spar with double wooden spreaders. The upper spreaders are taking a backward angle to the mast. The spreaders are on single pivot bolts allowing them to move. The angle of the spreaders seems to be increasing the mast bend .. I have been informed and since found a reference to the single pivot bolt on spreaders allowing them free for/aft movement being a bad idea (and dangerous to the mast). The reason given is the mast can keep bending forward and the spreaders moving back ending with a broken mast.

The upper spreaders have aft led intermediates which as far as I can understand (which is not always that far) should stop this forward pumping of the mast.

Can anyone in the group tell me if this is the case? I've seen several wooden masts with this single bolt set up. Should I set them in place with a bracket or second bolt to keep them strait and stiffen the mast or could this result in broken spreaders and a mast over the side?


Jary Nemo (Gemini)
Melb Australia

[Ian McColgin]

Ahoy there.

You need a good engineering consult with a competant rigger. I've had pivoting and non-pivoting spreaders on a variety of boats and there is definatly, especially in the older traditional boat, an important place for pivoting spreaders. There are plenty of places where a rigid spreader will actually fail at the spreader/mast connection due to fatigue.

And it is absolutely the case that a rigid spreader/mast connection will not prevent mast bend or pumping with any safety, though it may put both off pending catastrophic failure.

So, cure or control the bend first. For example, I cured a yawl with a wicked wierd upper mast bend when I figured out from filled in holes on the face of the mast that she'd had jumpers to oppose the staysail. Running backs alone did not quite do it. This example may have nothing to do with your situation. Don't let it mislead you into looking for a wrong cause. Just start with: Why the bend?

G'luck

Ian

[jary]

Thanks Ian

Sound advice.

I'll have another go at that bend. I tried for four strait days. Had to take it for a sail in the end to remind myself why the hell I was doing it.

Cheers Jary

[Brion Toss]

Hello,
I've seen rigs in which the upper shrouds go over the upper spreaders, but lead just aft of the lower ones. But intermediates? Odd. Are you sure everything is going to the right chainplate? Raking spreaders aft should be done intentionally, to control/induce mast bend and/or stay tension. On traditional boats, the pivot allows the leeward spreader to get out of the way of the main'sl off the wind. If your system has no such logic to it, it isn't really a system.
Fair leads,
Brion Toss

[jary]

Its more likely to be my odd explanation rather than the rig being that odd.

The rig is pretty close to the 'Lyle Hess Cutter' described in The Riggers Apprentice (p127-128). But the upper spreaders have two pairs of intermediates that are attached to the mast at the upper spreader mast fitting.

The first set of intermediates follow the upper shroud over the lower spreader to the deck.

The second set lead directly to a chain plate several inches back from the aft lowers and help support the inner forestay. I believe these are called aft lead intermediates?
There's also a set of running backstays.

Hopefully that makes more sense.

I've taken the previous advice and got a professional rigger coming down in the next few days for a look. So hopefully he will be able to see what's going on.

Cheers Jary Nemo

[Brion Toss]

HI again,
First, lose the aft-led intermediates, making them runners instead. Next, I wonder why people so often refer to riggers as "professional riggers". You never hear about professional doctors, professional CEO's or professional plumbers. Is there a vast army of amateur riggers out there, that we need to distinguish ourselves from? Or is it that there is something unlikely about someone actually getting paid to do rigging?
This matter has bothered me for many years. At the end of the most recent article I did for Sail Magazine, the editors described me as a professional rigger in the bio. Like there was a question? Like maybe people would otherwise assume that I was an independently wealthy philanthropist who merely dabbled in rigging? Get back to me on this, will you?
Fair leads,
Brion Toss

[jary]

Never thought about it before. I actually wrote 'rigger' and then changed it to 'professional rigger' because it didn't look right. Feel you are standing in front of a great wave of clique with this one.

I have the opposite problem. I have been working as a "Professional" web developer since 1995 and a software developer for 20 years. There IS a vast army of armatures out there and often when quoting for jobs I'm told the client has a cousin who walked past a computer in a store window once and they can do it for free.

Oh well we all have our cross trees to bare ;-)

Jary

[AaronS]

I splice a few halyards and do some work on friends boats, and they call me a rigger. Believe me, I would never call me that - I'm just a hobbyist who loves messing about in boats. Riggers have to make a living and push stuff out the door. I'm too slow for that, and I'm fortunate to have a decent job. Brion, I would refer to you as the "Consumate Professional" due to your honesty and your contributions to this art that makes if fun for hobbyists like us to tag along. I wouldn't take offense to 'Professional' moniker if I were you, I think they are just trying to distinguish your work from a myriad of work that has been done out there, with less than professional results. I'm sure you've seen your share of it. My two pennies,

Aaron