What's holding the mast step to the hull?

Moderator: GreenLake

What's holding the mast step to the hull?

Postby EnglishmaninCNY » Sun Oct 18, 2020 8:20 pm

Hello All.
The mast step fitting (it looks like the one on the Dwyermast page https://www.dwyermast.com/items.asp?cat1ID=20&cat1Name=Masts&familyID=35&familyName=DM%2D284+Mast on my Daysailer II is held down with two bolts, but one is very loose and not very confidence-giving. The nut and bolt both turn together, so I can't tighten them up. Does anyone know what is holding the nut on below the sole, and if I undo the bolt, is the nut just going to fall off and be lost inside the hull? Any suggestions on how to tighten it?

Another question, as I'm learning about how to rig this boat. When I'm attaching the forestay, how hard should I be pulling on it to get it in place to put the pin through the bottlescrew? Currently I'm pulling as hard as I can with one arm, maybe 80lbs force, and this seems like a lot. Last time I tried, I rigged a foot loop so I could step down and use body weight to get it in place. I don't want to push the mast through the bottom of the boat, nor do I want the mast waggling around.

Many thanks in advance.
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Re: What's holding the mast step to the hull?

Postby tomodda » Mon Oct 19, 2020 12:06 am

Hi Brit!

I'm going to let more experienced hands (GreenLake) answer you on the finer points of DS2 tabernacle fittings. I drive around in a DS1, our tabernacle goes to a keelson on a solid hunk of brass, bolted side-to-side. However, I'll throw out two tips that I think hold for any Daysailer:

-I like to tighten my stays till they can be strummed at more or less a "G" - the lowest string on a guitar. Thwaaaaaaaaang.... You do it with a jackscrew in the DS1, the whole mast gets moved up and down on a bronze screw. It's rather tight and doesn't even begin to stress the keelson/hull combination.

-Use your fore halyard to get the mast up and keep it in place while you are attaching the forestay. How? Simple, just clip the "sail side" of the halyard to the stemhead - the fitting at the bow, it should have at least two holes. Then tension the halyard for all you're worth and tie it down. That should be enough that you can simply clip the forestay to the OTHER hole on the stemhead and it's still slack. To visualize what you're doing, think about how your forestay slacks off when you have the halyard fully tensioned in a fresh breeze... well, the jib luff and the halyard are holding up the mast in those conditions, not the forestay (it's slack!). Just do the same thing, without the sail. No footloops, etc needed. Of course, do this with your entire rig relatively slack, tighten it up to a "G (or whatever you think is right) after the forestay is clipped on and remember to slack it again before de-rigging the mast.
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Re: What's holding the mast step to the hull?

Postby GreenLake » Mon Oct 19, 2020 4:54 am

Nice description, Tom. I thought it was "F" that you should be able to strum, not "G"; maybe it depends a bit on conditions. For me, light wind conditions are more frequent, so I tend to think of setting up for them as "normal" - I know other sail areas where that would not be the case. Anyway, I'm not actually that musical, so I simply go for the point where the shrouds can be plucked and it sounds like a note, and not longer like rattling. On a DS1, with the mast jack, I can add a turn, if I want a bit more tension.

I actually had a friend bring a Loos gauge (for measuring tension directly) and with the length of my shrouds as they are set up, the correct tension (from some rigging guide) was 8 turns - an arbitrary number, because you really need to measure the difference between "just barely slack" to "full tension", whereas I count from jack all the way down. (Full tension, by the way, came to several hundred pounds in the shrouds, but I forgot the exact value, or which rigging guide we were using).

Even so, I usually sail with 6 or 7 turns only and it appears fine. My jib has wire in the luff, so tensioning the jib adds additional rig tension. So there's that. If sailing upwind in around 8-10 knots the leeward shroud is allowed to go slack on the DS. Maybe it was 10-12 knots, but anyway, it won't stay tensioned in higher winds. But you should start off with a good solid base tension.

I have a keel-stepped mast, so I'm also not that conversant with tabernacles. My understanding is that the pins mainly hold things in place / connected while the main loads are compression loads and those are transferred directly.
~ green ~ lake ~ ~
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Re: What's holding the mast step to the hull?

Postby GreenLake » Mon Oct 19, 2020 4:56 am

PS: rig tension has been discussed here before; it may take a bit of digging to locate relevant posts. If you do a google search with "site:forum.daysailer.org" added before your query, you may get better results than with the builtin search, btw.
~ green ~ lake ~ ~
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Re: What's holding the mast step to the hull?

Postby tomodda » Mon Oct 19, 2020 10:51 am

Correction - "G" is a middle string on a guitar, been a LONG time since I've picked one up. And it's not as if I have pitch-perfect ears, bottom line is the shrouds should be tightened enough to strum a note, not jangle around.

And you've answered Englishman's original question about the mast step screw: "My understanding is that the pins mainly hold things in place / connected while the main loads are compression loads and those are transferred directly." Exactly right, once the rig is tensioned, it's holding the mast in place. I wouldn't get too bent out of shape (ha!) over the loose screw.

Tom
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Re: What's holding the mast step to the hull?

Postby EnglishmaninCNY » Mon Oct 19, 2020 1:01 pm

Thanks to you both. I will use the job halyard method next time, I can see now that it will be easier than my first method.
When I bought this boat, all three bottlescrews had split rings in them, two in each, meaning they couldn't be quickly adjusted. To change the 'pitch' of the rigging, I would have to take out six split rings. I decided to take out just the two in the forestay, hence the wrestling with setup.
So my follow-on question is, do my bottlescrews need split rings in them for daily use? I think the previous owner left the mast up for the season, whereas I'm putting it up every time I sail. Are split rings only necessary if the boat is getting pitched about on a buoy? If I'm only putting the mast up for a day, are they going to work loose in that time?
Andrew
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Re: What's holding the mast step to the hull?

Postby tomodda » Mon Oct 19, 2020 2:17 pm

Ahn... so Bottlescrews = Turnbuckles. Two nations divided by a common language! Now, I my boat doesn't have turnbuckles (bottle thingies), but I've always secured them to keep them from loosening by using cotter pins, not split rings. I guess you COULD use a slit ring, but I can certainly see how it would be fiddly. I'd just replace with a set of cotter pins that you can reasonably manipulate by hand (or with handy pliers). Is your mast one-piece or two-piece (with a tabernacle at the cuddy roof)?
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Re: What's holding the mast step to the hull?

Postby GreenLake » Mon Oct 19, 2020 3:58 pm

I clearly read too much UK media, including boating magazines, so the bottle-thing just went under the radar. :D

That said, let's make a separate thread on reading materials.

About rig tension: I'm not sure how much adjustment is realistically called for from trip to trip. My sense is that you can go for a fixed setting. Although, for Tom and me, with the mast-jack, such adjustment is, in principle, possible.

You do want to secure turnbuckles because should one loosen up while under way, you'll have a tough time dealing with it. For split rings, a wrap of tape. For the clevis pins that attach the shrouds (or their turnbuckles) to the chain plates, it's even more important to secure any rings. If a pin pops out, you lose the mast overboard (if deck stepped) or bend/break it (if keel stepped).

Some people change their forestay and add a Highfield Lever.

Image
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