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Old 28-08-2023, 07:31   #376
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

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Exactly. Also see how I rounded to the safe side, i.e. the wire to 25,000lbs instead of 21,400 to create extra room and also make the math easier (I was going for 20% instead of 15% pre-tension at the time, before we saw that Selden owner say 15% is better for a cat).

There’s more: the math/analysis you did doesn’t work well for multihulls. In the past when they did this, there were rig failures (they don’t do the rounding I do but go for the absolute minimum required because of lowering cost).
The solution was to take it as a starting point, go up to the next size wire because of the failures and test to see if it is durable enough. This all came from dynamic loading, not the static heeling force. A monohull absorbs most of the peaks by heeling while the multihull resists that, increasing the forces on the rig. This is why multihulls have much beefier rigging

I learned all this from reading but don’t remember exactly which book. Probably Dashew’s encyclopedia because he started with multihulls so has that design experience.


Yes, this was bothering me as well. Dynamic loading.

Even with the perfect righting moment/forestay/shroud angle force calculation, there is a different and higher dynamic load.

As an extreme example:

Picture a catamaran launching off a wave while flying the starboard hull just a little. The port hull initial displacement would be the static displacement of the entire boat, but the wave action as the port hull sinks down into the water upon landing (via gravitational potential energy) greatly increases the displacement figures for the static calculation momentarily.

You can actually feel these forces all the time on a catamaran when in chop, to a lesser extent, but they are quite obvious when you’re at the helm.
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Old 28-08-2023, 15:17   #377
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

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Yes, this was bothering me as well. Dynamic loading.

Even with the perfect righting moment/forestay/shroud angle force calculation, there is a different and higher dynamic load.

As an extreme example:

Picture a catamaran launching off a wave while flying the starboard hull just a little. The port hull initial displacement would be the static displacement of the entire boat, but the wave action as the port hull sinks down into the water upon landing (via gravitational potential energy) greatly increases the displacement figures for the static calculation momentarily.

You can actually feel these forces all the time on a catamaran when in chop, to a lesser extent, but they are quite obvious when youíre at the helm.

Original wire rigging is correctly sized for the boat (rather, the rigís original boat) so you donít need to do anything fancy. See the SS wireís breaking strength and work forwards from that - it already should be capturing the required factor for dynamic loading (if originally on a cat). For static load it should be 20-33% of breaking strength.

So for Dyneema rig you use the SS wire 50% breaking strength number and you make that your Dyneema 10% breaking strength number. That should eliminate creep and elastic stretch with static rig loads and provides you way more strength than the wire you replace to handle dynamic loads and losses due to splicing and UV.

With a tight rig (possible on your boat and mine, but not on the usual charter type cats) you should plan on 200% of static load for. the dynamic loads. Wire stays will get close to breaking strength, but Dyneema will be very happy.
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Old 29-08-2023, 06:07   #378
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

Agreed, Fxykty.

Crane appointment secured for this week!!!

Exciting times !!
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Old 29-08-2023, 18:23   #379
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

Attachment of lights/instruments to mast:

Stainless screws with lock washers and tef-gel?

Tap and die set?

Should be all I really need, right?

No need to rivet anything is there? I have not really done any of that before.
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Old 29-08-2023, 19:16   #380
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

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Attachment of lights/instruments to mast:

Stainless screws with lock washers and tef-gel?

Tap and die set?

Should be all I really need, right?

No need to rivet anything is there? I have not really done any of that before.

Tap into the mast and use SS screws (with tef-gel) to affix lights and wind instrument base is fine. For antennas you may need to go with heavier duty attachments such as rivets.
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Old 29-08-2023, 20:04   #381
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

I like rivets so much that I just bought the Milwaukee M12 rivet gun to save my hands

But drill and tap is great.
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Old 29-08-2023, 20:42   #382
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

Lets assume that you really mean a machine screw like a #10x32 or a #12x28, not a type A, B or F self tapping screw.

If so, then you will also need the right size of drill bit, which for the above size of machine screws are respectively a #21 and #15 bit, provided you can live with a thread depth of about 75%, which is common. Use a fractional inch sized bit at your peril.

If it was me, I would try a series of bits going in the smaller direction (a higher number) to acheive greater thread engagement. Practice on a scrap piece of Alum. first to see what works best.
I would also use a thread cutting fluid or paste as it will help form proper threads and possibly save you from breaking a tap. Clean up (acetone or Dawn) would also be required. You only want to do this once, right.

Well formed threads in an Alum. plated about twice as thick as the root diameter of the fastener should result in the fastener failing, not the threads.

With respect to the rivets contemplated for the antenna whip, how are you going to pull or set them? I'd use multiple machine screws instead.
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Old 30-08-2023, 06:22   #383
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

For drilling and tapping, I recommend to buy a kit that includes the correct drill bits. I have this one and am very happy with it: https://www.amazon.com/gp/product/B00SG6C4A4

For cutting fluid, in case of aluminum wd40 actually works as good as any specialized aluminum cutting fluid. For stainless steel I use a foaming cutting fluid from CRC but Iím told there are better ones. Never had a problem though.

For riveting, you need the exact right rivet for every connection. Easily sourced on Amazon. Before I got my new tool, I used the $40 hand tool with gloves to protect my hands/fingers from the snap but itís still very hard to do more than a dozen. I have done jobs using more than 500 rivetsÖ. with the hand tool
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Old 30-08-2023, 06:22   #384
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

Marvel Mystery Oil also makes a decent cutting oil in my experience. And it's fairly cheap and easily available, like WD-40. Plus it smells nice (like wintergreen).
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Old 01-09-2023, 08:19   #385
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

The mast isÖ. OFF!!! Yay!

I can start attaching things and running halyards and stuff now.

Then in bit, i will be a sailing vessel!! (With no running rigging lol)


No treadmill required today! This is since dawn:
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Old 01-09-2023, 11:03   #386
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

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The mast isÖ. OFF!!! Yay!

I can start attaching things and running halyards and stuff now.

Then in bit, i will be a sailing vessel!! (With no running rigging lol)


No treadmill required today! This is since dawn:
We need a massive amount of pictures Chotu
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Old 01-09-2023, 11:18   #387
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

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We need a massive amount of pictures Chotu

The thread has a lot. But I will do a lot more of the Mast and all of the attachments and halyards and everything. I promised them in the title and I will deliver!
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Old 01-09-2023, 11:20   #388
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

I guess I can only keep 1 furler, right? Having 2 is too heavy? It’s free though.

I have the new Harken and the old Facnor.

Can’t run a code zero or something off the old one?

Although I think I just answered my own question here. That would require a metal stay for the code zero. That becomes very heavy at that point
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Old 01-09-2023, 11:22   #389
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

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I guess I can only keep 1 furler, right? Having 2 is too heavy? Itís free though.

I have the new Harken and the old Facnor.

Canít run a code zero or something off the old one?

Although I think I just answered my own question here. That would require a metal stay for the code zero. That becomes very heavy at that point
If you wanted to set up for a Solent rig and accept the extra weight and windage you could use both. I don't think those would work for a code zero though. With something like a Solent rig vs a single forestay and furler, it becomes a game of "technically better" vs what you'll get better use out of.
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Old 01-09-2023, 11:27   #390
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Re: Chotuís Advanced Standing Rigging Thread (lots of pics)

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If you wanted to set up for a Solent rig and accept the extra weight and windage you could use both. I don't think those would work for a code zero though. With something like a Solent rig vs a single forestay and furler, it becomes a game of "technically better" vs what you'll get better use out of.
True.

That settles it right there actually. There is no space for a solent because I have a self tacking (100%) jib.

Better get into the classified section and sell the Facnor. It works just fine. There was never anything wrong with it. That Rigger just made me buy the new one (Harken dealer).

Phase 2 of the rigging (after sailing it) will add a code zero on a bow sprit.
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