Springstay location question

[mariner2k]

Hi, My current ketch has a springstay which ends part ways down the mizzen. There is a jumper strut that picks up some of the load, but ends about 5' from the top, then there are just the backstays.
My old ketch's stay went to the top of the mizzen. My concern is that there is not a lot of support if I wanted to go up in the bosun's chair. It appears that I'd be depending on the strength of the mast to support me.
Would I be better off either adding another stay or moving the existing one to the top?
Thanks, Kevin

After reading through the forum, I found some info on the subject and realize that I needed to add some information.
My main mast does have two backstays, independent of the mizzen. ( I know). I have sailed the boat for a season as a sloop while I rebuilt the mizzen. Not bad in a good breeze. Once again my concern is hauling my 210 lb. m ass up the mizzen. The unsupported top looks a bit like my weight would not be compressing vertically, but bending back.
Also I would like to be able to re-rig so I can fly a mizzen staysail if possible. Tough to do with the lower spring stay, I'd love to lose it. The old ketch had no back stay on the main. It depended on the spring stay. When I re-rig the main I could change to a split back stay.
Thanks, Kevin

[Brion Toss]

Hello,
Big can of variables there. The best thing would be to have no springstay. Moving the current one to the masthead would simply amplify the (now unopposed) pull of the jumpers. It isn't likely that your weight would be a significant load for the short cantilever up top; I'm much more concerned about not having a mizzen stays'l. So consider a reconfigured system, with aft-angled uppers over raked spreaders, forward-led intermediates, aft-led lowers, and no springstay. What is this boat?
Fair leads,
Brion Toss

[mariner2k]

Hi Brian,

I PM'd you a photo link.

The boat is a 1988 47' ketch made by Arthur Muller of Muller Boatworks, NY. He had been a shipwright for his entire life. His yard built wooden commercial fishing vessels, they did work for the Coast Guard and were the original builders of "American Pride" schooner. (though since then many changes have been made). This is the boat that, upon his retirement, Arthur built for himself.... As his son told me, to keep him from the nursing home. She's very well built , and from what I've been told he far exceeded the safety factor on the scantlings. Mr. Muller became ill before she was finished but did get on her a few times from what I understand. The yard is still around today. I got her from the second owner who very much let some things go.
I'm muddling through the formulas in your book, but before I go any farther with the calculations I have to do an inclination test to find the righting moment. Unfortunately all of the engineering for the boat was lost due to flooding from hurricane Sandy. Eventually I would like to rig her to be able to fly a mizzen staysail.
The mainmast is independent of the mizzen, but it appears the springstay is there to support the mizzen.
Are you suggesting that forward mizzen intermediates could possible help alleviate a springstay? I'll have to give that a look. The spreaders are angled aft. The lower shrouds are actually fairly high, going fore and aft, just under the spreaders and the jumper strut. When I change the mainmast, I can change to a split backstay. Is there any advantage to having a double backstay at all?

Thanks, Kevin

[Brion Toss]

Hello again,
Got it. Your lower shrouds are indeed high, which means the forward one is well-positioned to keep the entire mast pulled forward. The jumper stay pulls the head of the mast forward, and is opposed by the aft-raked uppers. The jumper also pulls forward at the level of the radar, which is unopposed, but not likely to destabilize this mast. Finally, the jumper strut pushes aft, and is opposed by the forward lowers.
So the aft lowers don't have much to do, except to add to the load of the forward lowers. But again, not much harm done. I don't see what the springstay is accomplishing; try sailing with it slackened, and see if the mizzen shows any inclination to move around. I'm betting it won't. If the mast is stable without it, remove it.
Fair leads,
Brion Toss

[mariner2k]

Thanks Brion, I'll give that a try come the warmer weather. (New Englander here)

[mariner2k]

Hi again, Just so I can measure it out, what should the angle/height be for the forward lowers to support the mizzen? The height looks decent from a visual reference, but I'd like to be sure on the angle. I'll deal with the main backstay(s) when I get it down.

[Brion Toss]

Hi again,
Hard numbers would be better than I-think-that's-enough-angle at this point. Height up, distance out, and distance forward will give us our vectors. Could be time for a consult, if you don't want to work those numbers yourself.
Fair leads,
Brion Toss

[mariner2k]

Hi, I'm not sure what to make of the angles I calculated regarding mizzen lowers.
If you were to consider the distance of the shrouds forward of the mast as a plane, the angle would be just under 5 degrees.(X two shrouds) The angle from the mast to the actual chainplate is just under 9 degrees. Two questions arise:

First are these angles adequate?

Second, a more general question, does the fact that there are two forward lowers as opposed to say one straight forward(theoretically resembling a baby stay) make up for what appear to be shallow angles?

I do also have the fittings and a chainplate astern to add lower intermediates if necessary. Also,it is a deck stepped mizzen.

[Brion Toss]

Hello again,
Those are steep angles, in both planes. You can likely improve the forward lead by moving the chainplate forward -- you just have to stop before you interfere with main boom swing. But the lateral angle is a bother. Just to humor me, would you share the numbers you based those angles on?
Fair leads,
Brion Toss

[mariner2k]

And humor you I shall! On one of the angles I plugged in the wrong value. On the other I took a more careful measurement and the angle was actually a bit less.
So the angle from the mast to the chainplate turned out to be 14.5 degrees. The angle going on a forward plane is only 4.09 degrees.

Numbers are as follows:

Mast height to connection is 286"
Center of mast to where chainplate meets the deck is 74"
That angle should be 14.5 degrees at the top.

On the other:
mast height to connecter is 286"
going directly forward is 20.5 inches.
That angle is 4.09 degrees.

Disclaimer: I haven't done this in a few (35+) years I could be wrong.

Would I be correct in assuming that lower shrouds aren't design or located to support a mast fore and aft with any significance?

Thanks, Kevin