Here is an Ingenious Setup for Raising a Rather Large Mast

[caguy]

I was prompted to dig into the plans from my Luger 30 project. The Luger has a 34' mast and uses a gin pole that is attached to the fore stay with a tang. It uses the sheet blocks to hoist the mast. So far all of this is pretty common in raising a mast solo.
The unique feature of this setup is in the shroud tensioning device. This is the first time I've examined it closely. The short aluminum pole that runs along side the upper shroud has a block that tensions the upper no matter what position the mast is in by essentially creating a pivot point that is even with the tabernacle. Not only does it tension the shrouds as it goes up it also provides stays for the gin pole.

This system can be used for any masthead rigged boat where the side shroud are aligned with the mast.

 

[kpgraci]

Re: Here is an Ingenious Setup for Raising a Rather Large Ma

I was puzzled by why there was only a forward support line 41111 and no corresponding aft line, I suppose with the mast being raised from the back only the forward line would have any actual tension, and the rigid arm holds the baby stay pivot point in place.

Very clean.

 

[Joe]

Re: Here is an Ingenious Setup for Raising a Rather Large Ma

I echo kpgraci's concern. It seems the aluminum strut, 41124, has insufficient support. Not only aft but also side to side, and might allow the gin pole itself to sway.

But I'm no mechanical engineer and if this system allows a solo mast raising effort, it's a pretty cool solution.

 

[tkanzler]

Another problem with that setup is that, at least if I'm reading those sketches correctly, you're bending the shroud over a sheave. That type of wire rope construction isn't made for bending (large strands, not many of them). Unless, of course, you use a large sheave and a flexible construction wire rope for the shroud, or use a compression post that also serves as the termination for the shroud, thereby eliminating the wire rope bending over a sheave.

 

[Joe]

Another problem with that setup is that, at least if I'm reading those sketches correctly, you're bending the shroud over a sheave. .

I thought so too, at first. But that would be just too stupid.....looking closer, there are only 2 sets of shrouds.... Uppers and Lowers... the strut fits between the two at the chainplates..... The strut only supports the gin pole's guys...

 

[caguy]

Another problem with that setup is that, at least if I'm reading those sketches correctly, you're bending the shroud over a sheave. That type of wire rope construction isn't made for bending (large strands, not many of them). Unless, of course, you use a large sheave and a flexible construction wire rope for the shroud, or use a compression post that also serves as the termination for the shroud, thereby eliminating the wire rope bending over a sheave.

The sheeves are about 2.5 inches. I don't think there needs to be that much pressure on the shrouds. As Joe points out it only supports the sway.

 

[JohnS]

Re: Here is an Ingenious Setup for Raising a Rather Large Ma

Maybe a better solution(?):

Instead of a block for the upper to bend around, cut the upper at the hinge point, put an eye on one end and a fork on the other.

The lower segment of the upper shroud runs inside the tube, and the pin that joins the upper and lower segments goes through the tube as well. The hole in the tube for the pin should be elongated to allow for varying tension in the shroud.

The aft wall of the tube is notched to allow the wire/fitting to swing down parallel w/ the deck.

 

[caguy]

I'll check the uppers for damage at that point the next time I'm at the boat. I don't recall seeing any on initial inspection but I was not focused on that particular spot. I like the set up not only for it's simplicity but because it also supports the gin pole as well and the mast from side sway. It also seems more stable than using bridles. The boat is under sail for that size boat but the mast is rather large in diameter.
I don't like the tabernacle setup and will change it to a hinged plate.