Mounting Stanchions

[RaymondR]

It appears that the solution to how one transfers the high bending moments generated by stanchions are transferred into the hull structure is being approached from a limited viewpoint by solely considering the deck portion of the hull structure. Since the "corner" section, where deck connects to hull, provides a comparatively stiff and strong part of the structure, could a solution which transfers the stresses into both deck and hull side components of the hull structure provide better transfer o f the stresses.

[Bowdrie]

Originally Posted by RaymondR

It appears that the solution to how one transfers the high bending moments generated by stanchions are transferred into the hull structure is being approached from a limited viewpoint by solely considering the deck portion of the hull structure. Since the "corner" section, where deck connects to hull, provides a comparatively stiff and strong part of the structure, could a solution which transfers the stresses into both deck and hull side components of the hull structure provide better transfer o f the stresses.

Sure, just make the base plates much larger in area and out of thicker stock, along with heavy sockets, and then use stanchions of ~1-1/2" schedule 40 pipe.
Stress transfer on the typical little base with 1/4" fasteners and a flimsy piece of small thin wall tubing sure ain't nothing to write home about.

[RaymondR]

Originally Posted by Bowdrie

Sure, just make the base plates much larger in area and out of thicker stock, along with heavy sockets, and then use stanchions of ~1-1/2" schedule 40 pipe.
Stress transfer on the typical little base with 1/4" fasteners and a flimsy piece of small thin wall tubing sure ain't nothing to write home about.

Rathe than just use flat plates on or under the deck use angle pieces or "knees" bonded to both the deck and hull sides is what I was suggesting.

[Bowdrie]

Originally Posted by RaymondR

Rathe than just use flat plates on or under the deck use angle pieces or "knees" bonded to both the deck and hull sides is what I was suggesting.

Yeah, I kind of figured that.
The way fiberglass boats are built, with a deck dropped onto a hull, that kind of installation might get a little difficult to do, and how many buyers want a row of exterior plates running down the sides of their boat?
Anyway, it's seldom that the bases fail, most of the time the stanchion tubes themselves bend/fail.
It's still true that if the lifelines cannot slacken, whether by pulpit flex or the lines themselves stretching, a force from inside the lines has a hard time bending the tubes outboard.
Of course, an outside force pushing in on the lifelines will easily bend the tubes inboard, that's a no brainer.

[s/v Jedi]

The strong stanchion bases are bolted through the deck as well as through the toerail. Our stanchions have four bolts through the deck plus two bolts through the toerail. On the outside of the toerail is a small stainless plate that has two threaded studs welded to it and at the stanchion base have acorn nuts.

Also, the core in the deck tapers out to solid fiberglass where the stanchions mount. This tapering to solid glass should happen at every spot where high load hardware is mounted.

[GordMay]

See Alan Mighty’s several contributions, at:
“LIFELINE TENSION” ➥ https://www.cruisersforum.com/forums...on-209232.html

And Darrell Nicholson’s article @ Practical Sailor:
“Check Your Lifelines, Save Your Life” ➥ https://www.practical-sailor.com/saf...save-your-life

Both quantify lifeline tightness.