Dumb question aboout drilling into hull

[vjm]

Originally Posted by reed1v

Is this seacock likely to be hit with anything like stored items, or loose items that could hit it if things really got rough?

No. It's is under the sink, the cabinet is tiny, no shelf (and I would not install one), and it is a contained space.

[vjm]

Originally Posted by Cheechako

Not a bad idea at all...

This is very interesting. Based on what I am seeing online, I need to drill a pilot hole, then drill with the bottoming tap. I have a couple questions, if anyone has the time.

Is this kind of installation as strong as through bolting to the hull? If not, is it sufficiently strong for a small seacock?

I am assuming the machine screws are then put in with the heads in the interior of the boat, holding the seacock to the hull. Is that right? Would I just bed the machine screws in whatever adhesive I use on the seacock?

Thank you so much. This is really helping me think through my options.

[fallingeggs]

Originally Posted by vjm

This is very interesting. Based on what I am seeing online, I need to drill a pilot hole, then drill with the bottoming tap. I have a couple questions, if anyone has the time.



Is this kind of installation as strong as through bolting to the hull? If not, is it sufficiently strong for a small seacock?



I am assuming the machine screws are then put in with the heads in the interior of the boat, holding the seacock to the hull. Is that right? Would I just bed the machine screws in whatever adhesive I use on the seacock?



Thank you so much. This is really helping me think through my options.

Hey, you got the seacock off! Odd that you didn't have a thru-hull.

That is what the makers of my boat (Sabre) did. A flush thru-hull well epoxied in and two lag bolts and bedding from the interior. I would do it again. They built up the fiberglass in the seacock area, so no need for a separate backing plate. I can't comment on whether your hull thickness is enough to skip the backing plate, but I would trust/follow anything from Maine Compass's website linked above.

I bedded with 4200, which many folks like. The adhesive isn't the primary method of attachment; you don't need the strong 5200. Can't comment on your proposed glue.

As for the bronze quote above, while very valid, no need to worry with Spartan. They are top quality; made in the USA for decades.

Edit: Maybe I read wrong and you have a thru-hull. All the better!

Sent from my iPhone using Cruisers Sailing Forum

[Aqualibrium]

You don't mention what the hull material is This is critical.
Timber, fibreglass is assumed by some, if so solid fibreglass or composite like so many hulls, if so what type of composite, foam, balsa strip plank.
The actual hull material needs to be known before advice can be given.
Core material needs to be removed and replaced with a material that prevents warter ingress to the core and also provides a compression collar to ensure there is no crushing of the hull when tightenining up thru hulls or bolts screws etc!

[mitiempo]

Originally Posted by vjm

This is very interesting. Based on what I am seeing online, I need to drill a pilot hole, then drill with the bottoming tap. I have a couple questions, if anyone has the time.

Is this kind of installation as strong as through bolting to the hull? If not, is it sufficiently strong for a small seacock?

I am assuming the machine screws are then put in with the heads in the interior of the boat, holding the seacock to the hull. Is that right? Would I just bed the machine screws in whatever adhesive I use on the seacock?

Thank you so much. This is really helping me think through my options.

It should be virtually as strong as through bolts if done correctly. I wouldn't bed the bolts in sealant but epoxy. No reason for sealant as they are not through the hull.

[mitiempo]

Originally Posted by Aqualibrium

You don't mention what the hull material is This is critical.
Timber, fibreglass is assumed by some, if so solid fibreglass or composite like so many hulls, if so what type of composite, foam, balsa strip plank.
The actual hull material needs to be known before advice can be given.
Core material needs to be removed and replaced with a material that prevents warter ingress to the core and also provides a compression collar to ensure there is no crushing of the hull when tightenining up thru hulls or bolts screws etc!

Alberg 30 - uncored fiberglass

[vjm]

Originally Posted by Aqualibrium

You don't mention what the hull material is This is critical.
Timber, fibreglass is assumed by some, if so solid fibreglass or composite like so many hulls, if so what type of composite, foam, balsa strip plank.
The actual hull material needs to be known before advice can be given.
Core material needs to be removed and replaced with a material that prevents warter ingress to the core and also provides a compression collar to ensure there is no crushing of the hull when tightenining up thru hulls or bolts screws etc!

Mine is also uncored fiberglass.

[vjm]

I just wanted to say thank you to everyone for helping out. This past weekend I relapped and lubed the seacocks that are looking good, and fitted the new Spartan seacock which is perfect. I also took apart and relapped one of the other "good" seacocks and found that while it is the only one that opens and closes easily, it also has a badly scored plug that is too far gone to make a seal. So, I need a new one there too. I am glad I checked before hitting the water.

On the drilling front, I am all set. I got the appropriate bits (HSS) and have about 50% of the silicone bronze machine screws I need, with the others arriving soon.

I decided to drill through the hull for all the seacocks and fasten with the machine screws, covering over with a vinylester filler, bedding in the seacock and the screw with sikaflex 291, and using teflon tape on the through hull threads. Next year, when she comes out again for soda blasting, I will replace the through hulls and add fiberglass backing pads under each seacock.

Thank you all so much. I had kind of a panicky moment there, because I want to get this girl out of the yard and closer to me ASAP, without ruining or sinking her in my haste. Everything is corroded to the point of immobility which adds to the frustration. Each job that should take 20 minutes takes a day due to deferred maintenance issues. It's frustrating.

With your help, everything I do to her makes her safer and better than before. thank you so much for all the wisdom and help.