Capitve nuts

[McFrancis]

I'm looking for suggestions on some form of captive nut to allow me bolt something down to the deck. The previous owner had used a sealant and just had the bolts resting in the holes, but this was not very secure, and I would like a mechanical connection.

I have access to the underside of the deck before I bolt the item down, so I can place something under the deck but I'm not sure what to use. I've thought of pronged tee nuts, or perhaps something with epoxy, but any suggestions are welcome.

The item I'm trying to bolt down is the lazerette locker at the aft of a Westerly Seahawk. Once it is in place, I cannot access the underside, so anything I use needs to be able to be fixed in place and left. The deck is balsa-cored.

 

[SimonX]

I'm looking for suggestions on some form of captive nut to allow me bolt something down to the deck. The previous owner had used a sealant and just had the bolts resting in the holes, but this was not very secure, and I would like a mechanical connection.

I have access to the underside of the deck before I bolt the item down, so I can place something under the deck but I'm not sure what to use. I've thought of pronged tee nuts, or perhaps something with epoxy, but any suggestions are welcome.

The item I'm trying to bolt down is the lazerette locker at the aft of a Westerly Seahawk. Once it is in place, I cannot access the underside, so anything I use needs to be able to be fixed in place and left. The deck is balsa-cored.

Depending on thickness and type of materials, Rivnuts, Jacknuts or Tapex inserts
RIVNUT® blind rivet nuts and RIVSTUD® blind rivet studs | Böllhoff
JACK NUTS THREADED INSERTS
Tappex Threaded Inserts for plastics, woods, metal alloys & composites

 

[ash2020]

I'd be happy to 3D print something like this, for a small consideration.

 

[dunedin]

Threaded s/s plate is often used by builders instead of individual nuts.

 

[Poignard]

How about Big Heads? With the flanges fixed in place by epoxy.

https://bighead.co.uk/wp-content/uploads/dlm_uploads/2024/05/bigHead_SF1_S38A_TDS.pdf

 

[Bodach na mara]

I'm looking for suggestions on some form of captive nut to allow me bolt something down to the deck. The previous owner had used a sealant and just had the bolts resting in the holes, but this was not very secure, and I would like a mechanical connection.

I have access to the underside of the deck before I bolt the item down, so I can place something under the deck but I'm not sure what to use. I've thought of pronged tee nuts, or perhaps something with epoxy, but any suggestions are welcome.

The item I'm trying to bolt down is the lazerette locker at the aft of a Westerly Seahawk. Once it is in place, I cannot access the underside, so anything I use needs to be able to be fixed in place and left. The deck is balsa-cored.

On my Seahawk the locker is fixed down, presumably on a sealant like CT1, with what look like self-tapping screws, presumably stainless. I have not had occasion to remove one to investigate. Self-tapers are used in other locations such as for security sprayhood and canopy fittings. These have been OK mainly, except for the ones securing the fitting for the frames. I replaced these wiyh bolts and it was a pig of a job. It really needs two people working with one inside holding a ply backing plate which holes are bored through it, then applying nuts to the bolts and holding the spanner while the person outside tightens the bolts. By the way there is no way that you are going to get to half of the nuts if you use them under the lazerette rim. The ones to the rear and port sides are too close to the transom and topsides to get even a finger up. And I'm not sure about the rest.

 

[Bouba]

An oversized washer

 

[Boathook]

How about Big Heads? With the flanges fixed in place by epoxy.

https://bighead.co.uk/wp-content/uploads/dlm_uploads/2024/05/bigHead_SF1_S38A_TDS.pdf

They don't like selling small quantities and don't seem to have a distributor.

I wanted some M3 with a rectangular base And they had around 100 left from some project. I took the lot as this was the only way of getting some.

Ideally I could do with some M5 ones, about 12 so I'm presently cutting stainless bar, drilling and tapping instead.

 

[thinwater]

I'm looking for suggestions on some form of captive nut to allow me bolt something down to the deck. The previous owner had used a sealant and just had the bolts resting in the holes, but this was not very secure, and I would like a mechanical connection.

I have access to the underside of the deck before I bolt the item down, so I can place something under the deck but I'm not sure what to use. I've thought of pronged tee nuts, or perhaps something with epoxy, but any suggestions are welcome.

The item I'm trying to bolt down is the lazerette locker at the aft of a Westerly Seahawk. Once it is in place, I cannot access the underside, so anything I use needs to be able to be fixed in place and left. The deck is balsa-cored.

You can get T-nuts that are secured with small screws. Those could be epoxied as well. The screws hold it during installation/the epoxy makes it rigid and very permanent.

Thread a small backing plate and bond that.

 

[Bodach na mara]

Re-reading the original post , I realised that the OP has the locker "tub" out if hr has access to the underside of the deck . in which case he could fix wooden strips round the aperture to take the screws that hold it doen. I also take back the suggestion to use CT1 as a sealant. That may make future removal a demolition job. I'll attach a photo of the Seahawk lazerette to clarify the problem. Note how close the rear edge is to the transom.