Recommended sheet length for spinnaker and topping lift

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Recommended sheet length for spinnaker and topping lift

Postby lorenzo lee » Tue Sep 18, 2012 11:40 am

Can anyone provide the recommended sheet/rope length for the DS II spinnaker sheet and topping lift sheet. Thanks in advance. Lorenzo
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Postby GreenLake » Tue Sep 18, 2012 3:09 pm

On the rigging measurement tab on the site it says 32 feet for spinnaker sheets - you could go a little higher, I think I used 35 feet each. Better to have just a little extra, and, if you find it's too much, to trim it down, rather than the other way around.

The length of the topping lift would depend on where you cleat this off. For example, I use a fixed length topping lift with a bit of bungee in it, and use only the downhaul to make any adjustments. So for that, it's hard to give any "standard" suggestions.

3/16 diameter.

The Rigging Measurements can be found under "Technical Info" in the box above. It's a bit outdated - wire halyards are not what I'd recommend :)
Last edited by GreenLake on Tue Sep 18, 2012 5:38 pm, edited 1 time in total.
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Postby jpclowes » Tue Sep 18, 2012 4:54 pm

A good rule of thumb is twice the length of the hull of the boat. Our boat is just under 17 feet, so 34 is what I would go with.
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Postby navahoIII » Sat Oct 06, 2012 9:13 am

I'm seriously considering adding a topping lift. Given that the line would have to run up most of the mast (on ours it would be at least 20 feet) and then angle down to the boom end, wouldn't 40-45 feet of line be closer to the requirement?
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Postby Breakin Wind » Sun Oct 07, 2012 9:45 pm

navahoIII wrote:I'm seriously considering adding a topping lift. Given that the line would have to run up most of the mast (on ours it would be at least 20 feet) and then angle down to the boom end, wouldn't 40-45 feet of line be closer to the requirement?


If you assume a band 2 to band 3 measurement of 20.5' and a boom length of 10', then the the topping lift line would have to be at least 42.8 ft. which is the length of the mast (band 2 to band 3) plus the ange from the mast top to the end of the boom.

I don't know how to create exponents on my iPad but the angled length is the hypotenuse (c) of the mast height (a) and boom length (b) right triangle.
(c*c) = (a*a) + (b*b)
(c*c) = (20.5*20.5) + (10*10)
(c*c) = (420.25) + (100)
(c*c) = 520.25
c = 22.8
Line (minimum) = 22.8 + 20.5
Line (minimum) = 42.8 ft.
Allowing some extra line for knots, cleating off the line and for the case when you may choose to lower the end of the boom to the deck, 45-48ft is probably reasonable.

I suspect the 32-35 ft. measurement being talked about is for the spinnaker sheets also asked about.

Thanks - Scott
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Postby GreenLake » Mon Oct 08, 2012 12:37 am

The term "topping lift" can be applied to both the line that holds up the boom as well as the line that holds up the spinnaker pole (I'm not saying that the latter is necessarily either the correct or preferred term, but people definitely use it).

In the context of the question it's easy to make the assumption that topping lift is indeed meant in the spinnaker context. (Ant that was the way I answered in my initial reply).

Merely to hold up the boom, you don't need a line that goes first up the mast and then down again - for a big boat that would make some sense, but for the DS it's overkill.

You can just tie a line to an eye strap fairly high on the mast and then secure the bottom end either on the mast (for when you are not using it), or in a cleat near the end of the boom (for when you are using it).

If your main purpose is to hold the boom up when the sail is flaked on the boom, then the topping lift might not need to attach all that high on the mast - below the spreaders might work.

The advantage of such a simple system is that you would save the expense of a block at the top of the mast, and the weight penalty of running a doubled line up the mast.

A topping lift left on the boat while it's on a mooring might need to be a bit sturdier, but for temporary use I would be comfortable with 4mm (or perhaps even 3mm) Robline or equivalent - 3/16 would be over-dimensioned, and unnecessarily heavy (and bulky - think drag).
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Postby Breakin Wind » Mon Oct 08, 2012 12:26 pm

Another educational moment brought to me by the fine folks at DaySailer.org.

Having never used or even seen a spinnaker setup up close, my nearest (maybe) similar experience was watching kokko put a jib pole (is that the right name) on a downwind run for a wing and wing setup.
How does a spinnaker pole differ from that, and how is a topping lift used in that context?

As far as the boom topping lift, my priorities (no surprise) run a little differently as I'm more into convenience than speed at this point in my sailing experience and I find it very useful to be able to lift the boom up and out of the way when working at the dock. But that's all personal preferences.

Thanks - Scott
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Postby GreenLake » Mon Oct 08, 2012 1:02 pm

Scott,

the pole that holds out the jib is usually called a "whisker pole". It is usually fixed to a ring on the mast and to the clew of the jib. There are usually no lines attached to it.

"Topping lift" is a term for any line lifting a boom or pole, that's why we had the confusion. For the boom, the simplified system I described would require you lift the boom manually before cleating off the topping lift at the desired height. For the lightweight boom on a DS, that's a workable solution. You could also add a block at the end of the boom and cleat off the topping lift a bit further forward along the boom. That would allow you to adjust it when rigged, yet still not require another line to run down the mast.
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Postby GreenLake » Mon Oct 08, 2012 1:35 pm

Back to spinnakers:

When you add a symmetric spinnaker, you'll need 5 lines and a pole.

The spinnaker halyard and the two sheets are somewhat similar to the same lines on a jib. However, the difference is that there's no "tack" on the spinnaker, so no corner of it is tied down to the boat, and instead of both sheets leading off the clew as in a jib, each sheet goes to it's own bottom corner of the spinnaker. The sheets also run outside all the stays and are sheeted from points near the stern of the boat - that's why the sheets have to have twice the length of the boat (plus a bit).

In light winds, and heading nearly downwind, you can fly a spinnaker with just these three lines. The spinnaker will balloon in front of the forestay, and you control each corner of it with its own sheet.

If you add a spinnaker pole, you can push the sail out to one side, so it comes out of the wind shadow of the main. Initially, there's not a huge difference between a whisker pole and a spinnaker pole. However, especially in light winds, the spinnaker pole may be too heavy and would drag down the sail, if you didn't support it. Hence the addition of a topping lift for it (for small boats, this is tied to the middle of the pole, for larger boats you need a bridle, or you'll bend the pole).

In stronger winds, you have the opposite problem. The spinnaker isn't tied to the bottom of the boat, like a jib, so nothing prevents it from "skying". So, you add a downhaul (or foreguy) to the spinnaker pole. Between these two, topping lift and downhaul, you can set the angle of the spinnaker pole, that is raise or lower it, until you have it where you want it - usually horizontal.

Having to adjust two lines to get one result can be annoying. For a smaller boat, like the DS, it's possible to replace one of the two lines by a bungee (or a line with a short piece of bungee spliced in). That way, you can adjust the opposing line and the bungee pulls the pole into position.

Mine is currently rigged with a bungee in the topping lift, in his rigging guide Phill describes his setup which has a bungee in the foreguy.

Once you've rigged your pole, you pull on the windward sheet to position the pole at 90 degrees to the wind. (To make matters totally incomprehensible to the uninitiated, the sheet that's attached to the same corner of the sail as the pole is called a "guy", as "guys" are the lines that control the pole, while "sheets" are the lines that control the cloth. So your windward sheet is always the "guy").

With a pole, you can go nearly to a broad reach (at which point the wind comes from the side and the pole is as far forward as it will go, touching the forestay).

For casual sailing, a symmetric spinnaker wouldn't be my first choice - it takes a bit to get the hang of it and it's definitely temperamental. In moderate conditions it's possible to do it single-handed. It takes about one sailing season to get the hang of the basic operation. If you get an old spinnaker for cheap, or even free, and like puzzling your way through the rigging and running of it, why not.

Otherwise, if you have the money for the upgrade, rig a UPS. (See thread on that). That will operate more like a jib, and give you additional power in more upwind course, where you can't fly a spinnaker at all. But that's getting into another topic.

As this thread is (more or less) about rigging a spinnaker I've not addressed the in's and out's of flying it (and how to gybe one). I've found that it's nearly impossible to get that across in a description, but having seen it (and done it) a few times it all comes together.
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