RELIANCE’S Telescoping Topmast

I had an email question on RELIANCE’s telescoping topmast from Lawrence Kurkey that I thought I would reply via blog post. He asks “Would you please explain to me how this was accomplished?” 

The wooden topmast had a sheave at its base and a slot through which a fid could be inserted that would pin the erected topmast in place.

The mast was a fabricated steel structure with hollow “donut” rings and angle iron stringers providing a framework upon which the rolled steel plates were riveted. Thus, the topmast could be lowered or raised through the hollow “donut hole.” The mast was a 26″ diameter straight stick that tapered at the very top. There was a retaining ring at the mast top and another about eight feet lower which kept the topmast centered. 

The 330′ long topmast halliard, or topmast heel rope as it was called, was seized to the inside top of the mast, then lead through the sheave in the base of the topmast and then to another sheave on the other side of the top of the mast. The hauling end of the heel rope was taken below deck through a fairlead to a below deck winch alongside the base of the mast. This winch mechanism was installed as an upgrade shortly after RELIANCE was turned over to the Syndicate. Before that, I seem to remember it was taken to blocks and pad eye at the base of the mast.

I enclose sketches of the topmast, topmast heel rope mechanism, and boom construction to illustrate the operation.

Boom construction is shown because its construction is very similar to mast construction, and it is a sketch I have on hand.

Topmast illustrations were included in blog postings from January/ February 2013 timeframe and you can refer back to these postings.

L. Francis Herreshoff notes in his books that RELIANCE had a topmast ratcheting mechanism, but I have not yet found drawings that show that. BTW, you can find a picture of RELIANCE dismasting during a race in the Rosenfeld Collection at Mystic Seaport. This occurred when the fid was placed improperly. Also in the Mystic Collection, I believe, is a notation in Iselin’s Journal on this incident.



Topmast sketch


Sketch of Boom



Telescoping Topmast Operation

4 thoughts on “RELIANCE’S Telescoping Topmast

  1. Richard S. Usen

    All the riveting I’ve done, had one person inside bucking and the other running the gun outside. Did they have someone inside bucking and how did they keep him cool? It must have taken him a long time to get ready to work at the start of his shift.

    1. Herreshoff Marine Museum/America's Cup Hall of Fame Post author

      Thanks for the question about how did HMCo buck the rivets from inside the spar. I’ve heard Halsey Herreshoff mention that they had a young lad crawl inside with a lanyard attached to his ankle to haul him out if he were overcome. I enclose a sketch of the boom construction, noting that at maximum diameter it was 21 inches, and of course tapering at each end. The gaff had a maximum diameter of 13.5 inches and tapering. The hole in the rings through which this lad would have had to have crawled was a maximum of 15 inches for the boom and 9 inches for the gaff. So, I’m not sure about the lad, but if you have a spare child hanging around maybe we could arrange for a test!
      As seen on the drawing, the upper half-round and lower half-round 14 foot long plates overlap, so at least one half of the 7 foot overlap could be riveted in the open. No problem. I have to believe therefore that HMCo had some sort of jig that could be inserted to “buck” the inside when the next overlapping plate was added. But, then again maybe HMCo had “buckles rivets?” Perhaps someone knowledgeable about riveting could help us, PLEASE!
      We note that rivets on the mast, boom and gaff (as well as hull) were ground flush. Can’t see them in any pictures and therefore you couldn’t see them in our model scale – WHEW!


        My riveting experience has been heavy in the aircraft field but I’ve also done some steel riveting as well. The rivet is pushed through the hole in the two pieces of structure and held in place w/ the pneumatic rivet gun. The bucker holds a heavy bar against the small end of the rivet and while the man w/ the gun holds the rivet all the way in the assembly. When both men are ready, a burst of hammering w/ the gun mashes the small end of the rivet. A properly driven rivet expands to fill the assembly and also has the small end mashed so that it holds its position. Steel rivets are usually driven red hot but otherwise the process is the same. In either case, there is continuous communication between the team doing the riveting. Improperly installed rivets must be drilled out and replaced.

        I shudder to think about rescuing a riveter who passes out from heat or fumes inside a 100′ pipe after crawling through a bunch of 15″ rings.

        Today there are one-side rivets for aircraft and likely for industrial applications as well but I never heard of such way before WW-1.

        Dick Usen

        T-33 #100



  2. Sandy Lee

    I with you, but I cannot believe that someone small enough could fit inside the boom or gaff since the maximum diameter of the hole was 15″ in the former and 9″ in the latter; and then each had significant lengths with tapering. Must have either had an internal jig or single sided rivets. Other turn-of-the-century industries must have riveted pieces together in confined spaces. Steam engines, ships? Wonder what their solution was? Perhaps it is all in the assembly technique? I don’t know, but like you have wondered. BTW “buckles rivets” should have been “buck-less rivets” in my first note — but my cellphone decided it could correct my spelling and I didn’t catch it. Technology is so great – the human interface can make errors at the speed of electrons!


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