T-Nuts and other nut alternatives

[thinwater]

There is an active tread on another forum (Yahoo group) where own/builders are discussing the merits of eliminating visible bolts from deck hardware. The boats (Corsair and Farrier) do not have liners, so you can see everything and some say bang your head on them, though I have not had that problem. I suppose most of us have used T-nuts a few times, though generally a backing plate and nut is more common.


(there are MANY types, this is just the most common)




So what are the pluses and minuses?


Plus

• Invisible, or nearly so.
• Nothing to snag or hit.
• No need to hold the nut while tightening or removing equipment. This can be pretty important sometimes.

Minuses

• Cost (depends on the style--some sex bolts are $$$).
• Strength. most are full strength, but working in the backing plate may be more complicated.
• Harder to tighten in many cases. Often the bolt head is just a Phillips head.
• Sealing. Turning the bolt while tightening sometimes reduces the effectiveness of the bedding, leading to leaks and possibly core failure.
• Impossible to cut loose if seized. And some of them will.

I'd like a clean liner, but I don't like the negatives and would rather stare a the nuts. I like the ease of service. I only use T-nuts or sex bolts where one of the pluses is overpowering. To me, structure is always more important than looks. But not everyone feels that way.

[thinwater]

Nothing? Someone must have experience.


Threaded and/or embedded backing plates are another variation.

[Lake-Effect]

I've only used T-nuts on wood; this is just my speculation:

1. T-nuts were designed for wood. I don't like the idea of the T-nut's spikes driving into fiberglass; I suspect they wouldn't penetrate cleanly, they'd make a mess of fractures around the hole
2. I like extra backing on fasteners - big washers or a drilled plate - for support and as a surface for sealant on the underside

So don't throw out those acorn nuts just yet...

[thinwater]

Originally Posted by Lake-Effect

I've only used T-nuts on wood; this is just my speculation:

1. T-nuts were designed for wood. I don't like the idea of the T-nut's spikes driving into fiberglass; I suspect they wouldn't penetrate cleanly, they'd make a mess of fractures around the hole
2. I like extra backing on fasteners - big washers or a drilled plate - for support and as a surface for sealant on the underside

So don't throw out those acorn nuts just yet...

There are many Tee nut variations, many do not have the spikes. That's just the wood version. Available in SS.





Yes, I've used acorn nuts. Not really a fan, but sometimes.

[Reefmagnet]

I prefer acorn nuts and stainless steel backing plates. Or just use a thicker backing plate and cut the threads into that. I can't see how those things would anchor properly into fibreglass or metal. You'd need to use wood backing? And won't the end of the bolt poke through in most cases, anyway?

[Lake-Effect]

Originally Posted by thinwater

There are many Tee nut variations, many do not have the spikes. That's just the wood version. Available in SS.

Ok, but then how do you stop something like that from turning freely as you attempt to tighten from the top? Either you have to make MORE holes for little screws, or you concoct some sort of wrench that will have pins in 2 of the holes. Granted that would be more likely to be close to flush on the underside... but even 1/4" of screw extending beyond this will lacerate the scalp if you bump into it.


There's no headliner in our boat, either. I've incorporated some of the exposed screws into supports for internal trim, grab bar, etc.

[jimbunyard]

I only use them when they're absolutely necessary, usually in furniture building or repair.

[Cheechako]

I often drill and tap into fiberglass for non stressed attachments. I like T nuts in the right places though. They are available in SS.

[LeeV]

I can’t make a suggestion because I never had any issues with hardware in my Condor 40, F31UC or the Corsair 36. For some it may be a matter of taste, maybe?

[thinwater]

I'm not hearing complaints from people that have used them. They don't seem to fail, and the threads are typically 2x as long as standard nuts.


I've mostly used them for hardware that was frequently moved:
* Vices and stops on a work bench.

* Climbing holds (climbing wall).
* Furniture.
* Winches that had to be removed for service (in combination with a backing plate) where the nuts were terrible to get to. Smaller boat. On a larger boat I'd use nuts.

I've had insert plates; an absolute bugger if they seize. I've threaded backing plates; once I had to install a genoa track, so instead of dropping the liner, I snaked a long, thin, pre-threaded plate in. Getting the far bolt started was tricky, but after that it was fast. I've threaded FRP. Many of us have used threaded inserts in spars or similar. So basically, I'm looking at SS Tee nuts and inserts as one more specialty tool.



The sailors that use them extensively seem happy with them. I'll leave it at that.

[Training Wheels]

I prefer nylok nuts, think they look fine. I hate acorn nuts. I only use t nuts on something low load where it needs to be flush, or it’s inaccessible. I am interested in the sex nuts, though!

[HopCar]

Nutserts, Rivnuts and Wellnuts are usefull when you don’t have easy access to the back side. I’ve used them when I need to fasten something to the outside but the fastener goes into the space between the hull and liner.
Nutsert® Threaded Insert

[foufou]

Barrel nuts I believe they are called. Like a T nut but without the prongs. Only down side is the ones I have found have a small Philips drive. But also serrating on the under side of the large head

[CarinaPDX]

I am a big fan of barrel nuts - they look nice and are low profile, unlike acorn nuts. They are different from T-nuts because they are closed and the bolt has to be cut to the exact right length.

I also use threaded inserts in some specialized applications where I expect to need to remove the bolt often.

I often use a bolt with a plastic knob with the inserts.

I'm not really a big fan of T-nuts although they could be very useful in some applications. They are designed for wood and I would not use them with fiberglass or epoxy.

Greg

[HankOnthewater]

I have used T-nuts with the sharp spikes in timber furniture, both repair and new. I would be hesitant, as others in up-thread, to use them on fibreglass. I must say, never seen SS versions.
I have nutserts on the boat, complete set in SS, but sofar never had to use them (on the boat). Have used them frequently on cars, trucks, trailers etc.

I shopped for small barrel-nuts the other day, could not find them in SS in 3/16 or 5 mm.

Back to the original question about boats without headliners and nuts sticking out. I have glued wooden strips either side of a row of nuts ie for genoa track), to prevent scalps being dented or ripped open.