Spreaders

[ryderp]

I'm building my own spreaders for the rig. My initial thought was to use a foam core, and then wrap it with fiberglass and carbon fiber sleeves. A friend suggested that that might not be strong enough to support the compressive loads of the spreader, and with the foam core it could buckle. I bought some tapered foam cores (NACA15) from Flying foam and am trying it out. Would it be better to use a wood core with a bit more weight and a less perfect airfoil shape, or will the foam core be good enough for this application? Any thoughts?

Phil

[Chad]

I bought un-attached carbon spreaders from C-Tech, and theirs are filled with air...

Just looking at the laminate, it looks like one layer of biax (or two layers of uni at +/- 45), and then enough zero degree uni to make the top and bottom skins about 1/16" thick, (divide by .0018"/oz. = about 35 total oz./yard of fiber reinforcement). The lowers are 1" thick at the root, and the uppers are about 3/4" thick.

For a different take on airfoil spreaders, have a look at the Swift Solo rigging guide, starting about page 10.

[ryderp]

Thanks for the info. It seems that the design that I have should be pretty good. I think that I'll add another layer of uni on the top and bottom just to be sure.

[Chad]

Correction, lowers about 1.25" at the root, and uppers about 1" at the root.

Memory, a terrible thing to trust...

[Chad]

I need to sort the ends of my spreaders. I was thinking just a groove for the stay, with a small hole behind that for a small lashing. Sorta like this:

spread tip.jpg

I saw Ron's solution which was a groove and then the stay captured by a glass plate:

100_3635.JPG

(Ron's spreader build notes are at: http://iceboxi550.blogspot.com/2010/02/ ... aders.html )

I can't tell how far the solid tip of my spreader goes- it feel like about an inch when I tap on it. Anybody recall what they found when they drilled their spreader tips?

[jray]

Chad, I did the same as Ron adding the top spreaders. Ron built his own, I opted to have C- Tech build mine. Ron's approach is a great way to route the extra stay. Wish I had paid closer attention to his blog. I drilled a secondary hole 1/2" inside the one CTech provided and found a solid core, so within two inches from the tip the lower spreader is solid. At least on mine. I'm seriously thinking about filling what I've done and following Ron's example. Less stays attached to the mast while on the trailer.

I'll get a exact measurement and a picture tomorrow.

[jray]

35d80uo.jpg

The measurement from the outside of the spreader to the center of the inner hole is 1.6" Still had solid material through at that point. How much or how close to the core it is ??? I still like how Ron did his and the direction you are thinking about. I would cap the ends to keep the stay from coming out of the slot if it ever got slack. That would be a interesting problem to have while under power

[Chad]

Great, thanks Jon!

I ordered my spreaders "blank", so no drilled holes yet. I've only got one shroud at each spreader tip, so the inner hole is just for lashing. I figured it would be less than an inch from the tip.

Edit:
I already glued stuff to the root of my lower spreaders so this wouldn't work, but for my as yet un-bothered uppers I measured the tip depth with the skinny stick method. 1.75" of solid material, so plenty for my needs:

upper.jpg

[Kevin]

I opened up the initial hole drilled by c-tech so that it's a "key hole" arrangement. I have a piece of shrink tube on the shroud that will hold it in the end of the spreader and I tape over the end as well. That has worked fine so far, but not completely happy with the setup. I am planning to add 2 small holes at the front and back of the spreader and then use a short piece of lash-it to secure the shroud and allow removal. (part of my spring check list) I'm only dealing with a single shroud at this point though. My setup allows me to leave my shrouds connected at the chain plate and I remove the t-balls at the top end for transport.

[Kevin]

Oh, and Chad, what was that source for smaller diameter "dynex-dux" like line? I may need some to complete my spring rigging change tasks.
k.

[ryderp]

I like the idea of a slot with lashing to hold the spreaders to the shrouds. However, how are you guys securing the spreader vertically? Are you putting swage balls above and below the spreader or is the lashing good enough?

I'm almost done with my lower spreaders (I think that I over-built them). I'm planning on attaching them to the mast with a pivoting rather than fixed connection like I see in some of the photos. Is there any reason to have a rigid "V" rather than pivoting spreaders?

Phil

[Kevin]

Fixed is simple and it's also the way they came from c-tech. It's a pretty solid arrangement and pretty bomb proof. But Ron proved that you can mess it up when his compression post gave way in 25 knots with his humongous kite up. If by pivoting you mean setting different angles with a bracket then you can find lots of example of that. The viper for example has smaller spreaders and a metal bracket on the mast. The c-tech setup is all carbon. If by pivoting you mean to allow the mast to rotate, then you need to chat with Chad about what he is doing because I think that's an order of magnitude higher on the complexity scale.

[Chad]

I like the idea of a slot with lashing to hold the spreaders to the shrouds. However, how are you guys securing the spreader vertically? Are you putting swage balls above and below the spreader or is the lashing good enough?

I'm almost done with my lower spreaders (I think that I over-built them). I'm planning on attaching them to the mast with a pivoting rather than fixed connection like I see in some of the photos. Is there any reason to have a rigid "V" rather than pivoting spreaders?

Phil

I just plan to rely on the lashing to hold the shroud to the tip- I think I can get it tight enough, and a little rigging tape can be added to help if needed. Not too worried about it.

Spreader angle is a tuning opportunity (that I don't have with my unrestrained pivots). By deflecting the shroud forward or aft from the plane of the chainplate/mast tang, a smaller or larger portion of the wire's tension is used to push the mast forward or at the spreader ("poke" in rigger speak). Adjusting your lower shroud does the same thing. By adjusting the spreader poke, you can use less or more lower tension. With less lower tension, you can let the mid-mast sag to leeward for instance, which is fast in some circumstances. Etc. It's just a case of managing the distribution of tension to get the mast to do what you want.

[Chad]

Oh, and Chad, what was that source for smaller diameter "dynex-dux" like line? I may need some to complete my spring rigging change tasks.
k.

The best I found was Marlow's D12 Max78, which is a heat set prestretched dyneema sk78. Dux is heat set prestretched sk75.

The D12 is available from Bainbridge. I've got their rep's info on another 'puter, if you want to pursue it.

I started a thread on SA last year that yielded some good info, I'll dig up the link if I can. There's some other similar line out there, but it's very hard to get in small boat diameters and quantities.

Here's the link:
http://forums.sailinganarchy.com/index. ... &p=2961446

[Chad]

To follow up a little, last year I bought some spectra "whatever-90" (I think this was a waste) from the rigger at West Marine ("Super Delagate"), and I've cut it up into a bunch of pieces for various purchases and such. I also bought some of the 1/8" Plasma roap from "sloansailing" and I'll be using that for my topmast shrouds.I've just received some good ol Amsteel Blue (it's not necessarily blue, btw) from Fisheries Supply for misc other purchases and lashings.

I never pursued the top end spectra variants from Marlow and Maffioli. If my guess at the typical shroud pretension is right (about 400# ?) it should be possible to do all the boat's standing rigging with one of those two lines.

[Chad]

SpreadTips.jpg

Spreader tips done.

[ryderp]

I've fabricated collars to attache my spreaders to the mast. Is there any advantage to having the spreaders be removable from the mast? My original thought was to have a clevis pin hold the spreaders in the collar and then be able to remove the spreader at any time. However it would be a lot easier just to epoxy the whole thing together. Any thoughts?

spreader collar.jpg

[Kevin]

Nice looking part. How are you attaching it to your mast? And what's the mast profile (doesn't look round).

Mine are all glued together. The only drag about that is during transport and when carrying the mast through a rather crowded garage. Otherwise, I have few complaints.

A note about the viper setup. They have a metal tab that the shroud goes through (swagged ends so it's captive). It fits into a slot in the end of the spreader and is positioned in and out using a pin. This allows adjustment of the rig by changing the spreader length (less than an inch of adjustment). I looked at it with interest but decided it wasn't worth retrofitting such a setup to my rig. I'll just tweak the shroud tension the old fashioned way for now.

Kevin.

[ryderp]

I'm using a Dwyer DM4 aluminum mast so the collar was formed around a cut-off piece that will be the compression post shortly. I bought a West System aluminum etch kit to prepare the Aluminum mast and I'm intending to use epoxy to attach the collar.

Phil

[Kevin]

Cool. Is the inner most layer of the collar glass versus carbon ? I've used that trick a few times to isolate AL from carbon the other way around, AL fitting on the carbon spar.

Kevin.

[Chad]

After sanding and etching the aluminum, consider G-Flex if you can get it. The collar and the mast have very different stiffnesses and expansion rates.

[ryderp]

Thanks for the comments.

The inside two layers were glass (the white line in the photo) to keep these things from becoming batteries when mounted on the aluminum.

G-flex is a good idea. I'll pick some up.

I'm thinking now that I'll just permanently mount the spreaders in the collars. I'm a bit concerned about cracking around the clevis pin hole if I make them removable. Also it occurred to me that the spreaders on our e-scow are removable, but I've not taken them off in the 15 years I've owned the boat.

Phil

[ryderp]

How long are the spreaders supposed to be? I think that I made mine longer than they need to be. Better long than short - I can trim them to size, but I need to do that this week.

Phil

[Chad]

Here's what 600mm top, 1100 mm bottom looks like. Ignore the diamond arrangement for the top shrouds if you like- they can just as easily be taken to the chainplates, either over the lower spreader tip or directly.

i550_rig_aft.jpg

I think the "stock" C-Tech lengths are 600 and 900, or 24" and 36".

[ryderp]

Thanks - I trimmed the top spreaders to 30" and the bottoms are 42" This looks just about right now.

Phil