Whisker pole questions

[R Squared]

Is there any reason the wider diameter side is meant to be at the mast? It’s a lot easier to adjust the length with the smaller diameter side at the mast, especially with the larger poles that are three segments. From the standpoint of forces and torque, it seems like they’d be interchangeable.

The adjustable whisker poles are not intended to be used with the smaller tube as the inboard end.

 

[Kings Gambit]

Is there any reason the wider diameter side is meant to be at the mast? It’s a lot easier to adjust the length with the smaller diameter side at the mast, especially with the larger poles that are three segments. From the standpoint of forces and torque it seems like they’d be interchangeable.

Doubtful. Likely, the same reason that flag masts narrow at the “outboard” (up) end, etc. I don’t think one wants more mass at the long end of a lever arm than at its base. It’s the same as with telescoping boat hooks.

 

[Kings Gambit]

I once had a telescoping whisker pole with an endless line that I could stop to. a cleat at the inboard end of the pole while attached to the mast. One attaches the pole to the headsail then “clothesline” the telescoping part out from the mast. It required a bit of effort at times to get it fully adjusted. It was easy to take down by freeing the “clothesline” line from the cleat on the pole and pulling in the narrow end, etc. On big boats one does not want the heavy end of a pole where you’re trying to manhandle it to a lively headsail, etc., and set it.

 

[Davidasailor26]

Doubtful. Likely, the same reason that flag masts narrow at the “outboard” (up) end, etc. I don’t think one wants more mass at the long end of a lever arm than at its base. It’s the same as with telescoping boat hooks.

I don’t agree with the comparison. The base of a flagpole needs to hold up itself plus all of the weight above it, while the top only needs to hold up itself. It also needs to withstand wind resistance, which again is not going to be uniform along the height of the pole. That’s why it’s telescoped. With boat hooks the user holds one end while the other is free flying, so I agree there you want the user end to be sturdier and the free end to be lighter. With a whisker pole the far end is still supported by the leech of the sail, and maybe a topping lift too, so the weight out there doesn’t need to be wholly supported by the inner end. The design of the jaw on the mast doesn’t even allow the inner end to hold up any weight the same way a flagpole or boat hook can. When handling the pole it’s most common to attach the sail end first, so there’s not really a time when the outer end is unsupported.

As I see it the forces the pole is subjected to are:
- Compression or tension, which would be uniform along the length. The weak point here is likely the locking mechanism and not the pole itself.
- Bending from minimal amount of gravity, which would be symmetrical between the ends. This is probably negligible relative to the strength of the pole.
- Bending from gravity or the pull of the sail when the user is first attaching the pole to the clew. On poles with jaws at both ends the user needs to be at the sail to make that connection, so there’s not really much opportunity for this bending. On poles with pointed ends the user might exert a small amount of bending when holding the inner end of the pole and setting the outer end in the sail. I doubt a person could really generate enough force to bend even the thin end of the pole doing this though.
- Bending from the pole bouncing off the shrouds or forestay if mishandled. These loads will be concentrated on the outer end of the pole if it bounces off the forestay, or the midsection if bouncing off the shrouds. This is probably the most common failure mode.