Mariner 31 Mizzen backstay??

[SwampSailor]

Good morning all!

I completed the purchase of a Mariner 31 yesterday that is in liveaboard shape but not sailing shape. My primary use will be sailing so began the process of assessing the needed work on rigging/sails yesterday.

In the attached pic, I have just raised the mizzen sail and while snapping this pick I realize the backstays on the mizzen are anchored to a very rickety solar arch that has been broken free from the deck so in effect there is no backstay. I used line to anchor the arch rather hastily but as I was pondering the problem in bed last night and looking at the pics from the owners association, I can’t seem to find a good representation of how a backstay on a Mizzen with a boom extending beyond the transom should be anchored. Does anyone have any pics to be shared showing the proper split stay arrangement of a Ketch, or better yet a ketch with a solar array?

[Sailmonkey]

I don’t think that’s a backstay, rather it’s a solar arch support!

[SwampSailor]

I wondered that as well, the solar arch is thin wall tubing and not exactly robust. There is a split forestay on the mizzen with fore facing spreaders creating an angle on the stays and it’s a relatively short mast but the more I thought about it last night the more I worried something wasn’t quite right.

[Sailmonkey]

Looking at the line drawing, it’s rigged just like our ketch. No back stays at all on the mizzen.

We don’t need backstays on ours, and if we decided to rig and run a mizzen staysail, I’d probably just rig a pair of running backs.

[JD-MDR]

My Cape Dory 30K is like that. I think the shrouds is sufficient. I wondered about it also. Another CD 30K here, newer model, had the spreader angled forward and no backstay or forward shroud. I have both shrouds but no spreader on the mizzen.

[bailsout]

On my Herreshoff 28 modified ketch, there is no typical backstay for the mizzen. I do have two running back stays which I have never used and I always fly the mizzen: it’s the first sail up. The only “running” backstay is the wire that runs from the mizzen masthead to the end of the mizzen boom which is tensioned by the mizzen sheet which pivots off a bale on the rudder post. I believe the Mariner was an H-28 knock-off.

[JD-MDR]

Originally Posted by JD-MDR

My Cape Dory 30K is like that. I think the shrouds is sufficient. I wondered about it also. Another CD 30K here, newer model, had the spreader angled forward and no backstay or forward shroud. I have both shrouds but no spreader on the mizzen.

I guess the spreaders are probably angled aft

[TrentePieds]

Can't really tell from your pic how your MAIN standing rigging is set up, so think about this: The Main and Mizzen standing rigging NORMALLY work as an integrated unit. But on ketches of this size it was conventional, back when this boat was young, to take MAIN STANDING backstays to the rail as far aft as practicable, allowing the main boom to clear them. The two masts are then essentially independently stayed, and the MIZZEN S/R does not, then, take part in supporting the MAIN against a load from aft. There is then no real need for a triatic stay to take forces from the main to a mizzen backstay, and therefore no real need for mizzen backstays to support the mainmast.

Depending on the forward acting forces generated by the mizzen, it may then, in a boat of this size, be possible to handle those forces without a backstay on the mizzen mast at all. Taking the aft lower mizzen shroud to a point some distance aft of the mast, but not so far aft as to interfere with the working of the mizzen boom, may then be all that is required to handle the forward loads on the mizzen.

In bigger boats with greater loads RUNNING mizzen backstays may be necessary.

Think about the fact that when running before, the mizzen on a ketch like this really doesn't contribute anything since its projected area, with wind dead astern, falls entirely within the projected area of main and headsl wung out. So, when running, don't wear the mizzen - ergo no forward acting load on the mizzen mast.

As the wind comes further forward and you set the mizzen, the boom will, most often, be in far enuff that the forward acting vector will be small enuff that the lower shroud (which is lead aft of the mast) can take it and the thwartships vector is shared by the forward and after mizzen shrouds and the Mizzen topmast stay.

So set up as indicated by the general plan provided by Sailmonkey, and I'm sure you will be alright.

You might like to spend spend a few bux to run this past a yacht designer/naval architect.

TrentePieds

[dfelsent]

Moonbeam is set up along the lines TrentePieds describes. The main backstay splits fairly high up, and ties to chainplates well aft of the mizzen.
There is no triatic.
The mizzen is about the size of a J-24 main. The mizzen lowers are led forward. About a 7/8 rig. The spreaders are swept aft, and the cap shrouds go to chainplates aft of the mizzen mast.
The runners go to the transom corners.
I sail with the runners on by default. When reaching, downwind, or with the mizzen staysail I ease the leeward runner. That’s a low priority.
Jibing I’ll over trim the mizzen, then take up the lazy runner. Then jibe the main and jib as if she were a sloop. After that I’ll ease the new leeward runner and the mizzen sheet.
Sounds messier than it is. Tighten sheet and runner. Jibe. Loosen runner and sheet.

The runners are a 4:1 block and tackle with built in cam cleats tied to wire to the mast.

[MartinR]

Yes, that looks like an arch support. The mizzen boom looks awfully long, though.