Lifeline stanchion mounting hardware

[PlaneTom]

Greetings,
A question on the mounting of a lifeline stanchion.
Catalina 310 #73
The forward stanchion at the starboard gate took a hit. The stanchion itself is bent a little, but I think I can straighten it OK, a small bend.
As you can see in the first pic, it pulled the mounting screws up from the deck. They unthreaded out the rest of the way fairly easily for screws that haven't moved in many years. No stripped threads or other damage on the screws. No bits of thread stripped from another component either, they came out clean.
With a small pick I can feel what appears to be threads in the material below the upper surface of the deck. They are fairly fine thread machine screws, I'd be surprised if they were threaded into the core material.
I can't find anything that tells me what hardware (nuts, washers, etc) might have been installed under the deck as backing. In the Owner's manual that I got with the boat, it shows the deck plan. At that stanchion it just lists five circled item numbers at that stanchion, but there isn't a parts list to tell me what each item is.
I've called and left emails for Catalina Support and Engineering departments, but no answer in 3 days.
I tried to open up the cabinetry to look at the underside, but I haven't found any reasonably easy access. What I need to remove is the back panel of the bay just to the right (aft) of the microwave. I'd rather not disassemble a bunch of it to find out it wasn't necessary. I've removed screws from the woodwork below it and at the back, but it doesn't budge. Either parts stuck together afte 24 years or more hardware I haven't found.
Does anyone have diagrams or experience remounting that stanchion, or showing exactly how it was installed?
I guess it's possible that the screws were threaded into a Helicoil insert in the deck, but I don't want to assume that.
Any thoughts and ideas appreciated.

 

[Joe]

This suggestion might be a shot in the dark, but whaddya got to lose. That is to call Garhaurer Marine for their input. Specifically ask for the person who would handle issues with lifeline stanchions. I wish I had his name for you, it's on the paperwork when I refitted my boat in 2016/17 and all that stuff is down there. There's a good chance much of your boat's hardware is Garhaurer stuff... especially the stanchions...(yours look like mine, but that's not much of a verification since most bases look the same no matter the maker. ) If so, perhaps he might have an idea or two that could you.
For what it's worth, it is my belief that all Catalina stanchions are through bolted with some kind of backing plate or large oversize washers, same as my 45 year old Cat 27.

Give it a day or so before you call, someone here may have some direct experience. Also, you might get a response from the factory... 3 days isn't that long. Okay, wish I could be more helpful. Good luck.

 

[Ward H]

I guess it's possible that the screws were threaded into a Helicoil insert in the deck, but I don't want to assume that.

I think it's highly unlikely Catalina took the time to install helicoils into the deck fiberglass. Most likely there is an imbedded aluminum plate.

Can you take a look at the bottom of the deck in another location that is easier to access?
On my C30 the stanchions upright had a threaded rod that goes into the dock and on the base plate two machine screws. All had washers and nuts. Looks like on your boat they just used machine screws.
The other method used on my boat for the rear pulpit stanchion was an imbedded aluminum plate under the pulpit's rear support stanchions. I could see the "hump" of the plate when looking up from underneath. When my pulpit made contact with a piling two of the screws pulled up like in your photo. They had pulled out of the metal plate. I drilled the hole clean for the fine thread machine screws and put washers and nuts under them since I had access.

Since the machine screws pulled up with no raising of the fiberglass my guess is there is an aluminum plate under the stanchion plates. Especially since the 2 screws on the toe rail apparently were easily removed. If they had nuts and washers they probably would have just spun.
Try drilling a small hole somewhere under the plate to see what material the bit pulls up and how thick it is. That will give you a clue.

I'd try drill and tapping for the next size larger machine screw.
Or maybe drill new holes in the base further back from the corner and drill & tap for the same size machine screws.

 

[jssailem]

Does anyone have diagrams ..... remounting that stanchion, or showing exactly how it was installed?

No experience with the Catalina 310. Other modern boats, like Catalina, were designed with built in backing plates. The fact that you have machine screws holding down the stanchion base would suggest there is a piece of aluminum sealed into the fiberglass with tapped threads for the stanchion base. The damage to the base would cause me to examine deck for indication of surface cracks to the fiberglass. You will want to repair that area if needed. Keeping water outside of the boat is a primary requirement. If the screws have just pulled out of the backing plate and the rest of the deck is solid, then you may be able to just retap the plate and use a slightly larger screw.

 

[PlaneTom]

Thanks for the input. I had considered all the different ways they could have mounted it, but until I can get a look at the lower surface I don't want to assume anything.
If the deck is wood core and they used a nut and washer for backing, that might be my worst case, it may have pulled the nut and washer up into the core, meaning a bigger repair in an awkward spot.
If it is an aluminum plate, drilling and tapping for a larger screw would be easiest and could be done from the top.
Helicoils are actually fairly easy to install, especially into wood, and I could do that from above. I have seen them set into wood cabinets for mounting stuff before. That's why it occurred to me as a possibility.
I'll work at that cabinet access more today. I do have a fiber optic scope, maybe I can get it into an opening and see what I need. I tried removing that electrical outlet, but there is almost no slack in the wiring, I'm not sure how they got it in there in the first place.
I guess I'm also just spoiled. 43 years of maintaining large aircraft, mostly corporate/private jets. Interior furnishings and components are generally fairly easily removed, both for maintenance access and for inspections. Plus, all of it is well documented with good drawings, parts lists, instructions. And their engineering tech support hotline is answered 24/7.
First I'll make sure I can straighten that small bend in the stanchion. Small enough that you have to look close to see it, but the mounting screws don't quite line up as it is. Catalina Direct has new stanchions, but they are a beefier design with different mount hole spacing. Then I would definitely have to access the underside for backing hardware at new mounting holes.

 

[PlaneTom]

No experience with the Catalina 310. Other modern boats, like Catalina, were designed with built in backing plates. The fact that you have machine screws holding down the stanchion base would suggest there is a piece of aluminum sealed into the fiberglass with tapped threads for the stanchion base. The damage to the base would cause me to examine deck for indication of surface cracks to the fiberglass. You will want to repair that area if needed. Keeping water outside of the boat is a primary requirement. If the screws have just pulled out of the backing plate and the rest of the deck is solid, then you may be able to just retap the plate and use a slightly larger screw.

That is what I've been hoping for, a backing plate I can retap. It would be nice to confirm it with Catalina, I'll keep pestering them.

 

[jssailem]

Use a pick and poke it into the holes of the fiberglass skin deck. You should be able to feel the metal surface.
I they had used nuts and backing the screws would not have spun out. The nuts would just spin under the deck and the screws would still be in there.
Wou can test with a pick or try a matching tap to the screws you removed. See if you can chase the threads.