Sefuller, I am most likely doing what you're doing. I replaced my welded-all-in-one stanchions with a set of (used) Schaefer bases and mounted them
on G-10 blocks, for their inboard bolts, to as to mount the outboard ones right on the aluminum toerail (properly insulated with tape of course). Water passes under the gap between rail and G-10 block; this faciliates the drip hole too (too often clogged in 5200). For the farthest-aft ones, the bases need to be mounted half on the cockpit coaming, so the Schaefer ones don't fit. I am considering cutting off the old ones, welding in a sleeve, and installing the stern pulpit leg over that. For the rest I'll either cut the welded feet off the stanchions or else get new ones.
Steve Dashew cautions strongly against welded-all-in-one stanchion-base assemblies. He makes the very good point that if you lean on a piling or bulkhead, the stanchion will transfer its bending load to the base, which in turn transfers it to the deck. Done often enough, this will lead to wreaking in the bolt holes and inevitable water intrusion (I saw this on every boat that was damaged during Storm Sandy). Installing G-10 blocks in the deck core isn't always good enough-- really
almost never good enough. That's only good to keep core from being affected and getting wet. Stanchion bases need really wide, expansive backing plates under the deck-- as large in area as you can make them, bonded well against flexing. Once the mounting bolts are drawn up snugly, the wide area of the backing plate will inhibit the flex.
Dashew also makes the point that the little rattling of stanchions in the bases is actually the safeguard you get against the mounting base wreaking in the deck. If you impose too great a load at the top of the stanchion, the stanchion tube will bend at the top of the base well before the arm-and-moment has a chance to work the base's bolts in the deck. And that would be a good thing in that case-- it's easier to replace a bent stanchion tube (which is still sort of doing its job) than to mend the weakened deck (with which I wouldn't leave the dock).
Dashew and many others (including me) warn against using the stupid little 1/4-20 set screws. There's not enough meat for them to thread into and they're too easily stripped, lost, loosened and rusted. To be truly secure, the stanchions and bases should be through-drilled (
in situ, for the fit) and bolted with a long-shank-short-thread 1/4-20 hex-head and locknut. Ignore where the existing hole is-- turn these so that they are roughly parallel to the rail, to keep people from cutting bare feet on the bolt ends (turning them outboard might look ugly and increase chances of losing the locknut overboard). They'll wiggle no matter how you drill them. These do not have to be (indeed
should not be) tightened to holy heaven. Snugged up against the base, with appropriate tension, is enough. The least you should do is to drill these and tap the cast base on the far side, threading the bolt into that. But these will always be one of those things, like cotter pins in rigging turnbuckles, that you inspect every day under way.
Heavy tubes aren't automatically the best thing for stanchions. They add weight; and too much metal and not enough space really increases the tendency to bend, just under a (slightly) higher load. One Cherubini 48 had solid rods for stanchions, custom-made, very heavy. You could kill a pirate with one of those things. But in my opinion this is false security and definitely false economy. If you're really worried, carry two spares on the boat (even the tubes are good anti-pirate weapons). And remember
no lifeline system should require stanchions' removal to remove and replace the cable (I've seen too many that do!).
One more thing: a collar on a stanchion at one end of the lifeline system, with a tensionable cable run down to the deck, will allow you to maintain appropriate tension in the whole system. Attaching them directly to the pulpit results only in a really weak, twisty, unsightly network that I refer to as 'tuning the pulpit' -- no matter how or where you tension them, the pulpit will just keep bending. The surety against wobbly lifelines is to tune them appropriately, which means getting the too-flexible pulpit(s) out of the picture and rigging the system like it's really rigging.
