MacGregorSailors.com

It is about time I got started on a mod for our '01 X to stiffen the top of the mast above the shroud and forestay attachment point. I'd like to find a source for a jumper strut that would fit my boat. The stays I'll do myself. Does anyone on this site know where I can find such a piece? Maybe someone in the S-F Bay area, as I've seen lots of jumper strut rigs on smaller keelboats there.
Thanks for your help,
Dave Mason

Dave,

I've never seen or heard of a 26X owner adding mast support above the forestay. If anyone HAS done so, I hope to read about it here - in your thread! ???

I don't recall that anyone ever published their intention to raise the forestay hound (maybe only 6 inches higher). so there's been no significant sidewise loading above the upper shrouds by a jib. The mainsail, of course, doesn't add too much load up in that final 5-feet of mast.

The guys who are flying an assymetrical rely on the backstay for adequate reinforcement. I'm hoping to see more about your idea, and other responses.

Fifteen years of sailing I have never heard of a jumper strut, so I looked it up:

The jumper strut is usually used only on jibhead rigs to reinforce the upper part of the mast. The jumper strut is located on the forward side of the mast jutting out horizontally forward, and combats the strain of the mainsail pulling aft on the mast. The JUMPER STAY passes through the strut, and is fastened to the mast at each end of the stay. The jumper strut is usually positioned to bisect the length of the jumper stay. Diamond stays and jumper stays are not required on all boats; just on those masts which require additional support.

So now I know that I've never seen one either!

Wow! This is really cool. Were getting into mast design.
Hold mouse pointer on view until button for full view appears, click on it.I believe well find the jumper struts on fractional rigs with a tapered mast. The smaller section usually above the spreaders reduces windage. The Jumper strut is necessary to control the amount of bend in the upper mast, to make the bend (used to flatten the mainsail) smooth while maintaining the strength of the mast with the backstay applied.

Dave, why is it that you want to do this.??

Thank you guys for your responses. Scott, the reason I think I need this is my assymetric spinaker is too big for the length of the mast so I fly it off the masthead and when I do the top section of the mast flexes to leeward. Scary! It wouldn't take much of a puff to snap that skinny stick off with such a big piece of canvas up. T-T, thanks for the diagram. Where did you get it? I'd like to find a better print of it that is more legible. And the definition is going to be helpful in describing what I want to potential suppliers, if any should be found. I don't think Sailrite has anything like it but I can't get into their website for some reason.
Meanwhile I'm thinking of building a strutt but worry about getting it smooth enough not to tear the jib when tacking.

Hey!, maybe I should convert the Mac to a masthead rig instead? Any thots?
Dave

Hi Dave

When I converted my mac19 to a cutter rig with a 4 ft bow sprit I bought a set of 3ft spreaders from my mac dealer. I cut them down to 2ft installed them on the mast at approx the 3/4 point up where there is a bolt hole in the mast for attaching it to the mast crutch as I have a roller on my mast crutch I never bolt the mast to it I also installed a second mast hound at the same point . The top shroulds run through the top 2ft spreaders witch are swepted backwards same angle as the lower 3ft spreaders, the second set of "middle" shroulds run through the lower 3ft spreaders along with the top shroulds side by side to do this I bought new alum. spreader end fittings from the mac dealer I filed out the v slot in the spreader end fittings "not the caps' to a square slot just barely wide enough to accomedate both shroulds as the shroulds must be side by side not on top of each other in the spreader end fittings. The second set of shroulds now run down an attach to the same chain plates as the other shroulds still debating whether or not to add a second set of chain plates. I could have attached them to the mast 6ft up where the baby stays attach giving you the diamond stays . I fly my genoa from masthead to 3ft out off the bowsprit , 4ft out off the sprit is a spring loaded block to run a future spinaker. the stay sail runs from the 3/4 point of the mast to the original bow forestay chain plate hopes this helps you out

john shields.

Dave Mason

Left click on the JUMPER STRUT DIAGRAM above, when enlarged, place mouse pointer on the enlarged diagram, when the second enlargement button appears in the right lower corner, left click on the button. The Diagram should be full size and clear.

Thanks, John, et al for your responses. I decided to forego the jumper strutt mod in favour of raising the upper shroud two feet to help support the top section of the mast. My forestay attachment point is already 12 inches higher due to the lever device at the bottom below the furler drum. All I did now was insert two 24 inch pieces of aluminum alloy flatbar between the chainplates and the turnbuckles, and re-drill the mast for the 3/8ths bolt up top, so now I've got a semi-masthead rig, I guess. Eager to test it out!
Dave