Help. Screw broke. Problem with installing underwater lights

[Amar Nanduri]

I am installing Lumitec underwater lights on my AR250. I used 5200 as sealant. One of the brass screws that came with the lights broke off at the head and I am stuck with a half entered screw. This was an hour back. How do I remove it ? Is it advised ? Can I fill the area with 5200 and seal it permanently? Picture attached.

 

[Dixemon]

Take the light off, remove screw with vise grip. Scrape 5200 off and try again. Did you pre-drill the holes?

 

[Bruce]

Is enough of the screw sticking out to be able to attach vice grips and remove it?

If not if the screw is in there with 5200 on the threads it should not leak or cause any problems.

If you need to get the screw out then left handed drill bits smaller than the screw would be a good option. Use a small left handed drill bit with the drill running backwards. It may spin the screw out. If not switch to a larger drill bit until the screw is removed from the hole. Once the screw is out you can fill the hole with 5200, let it cure, drill out to the size needed and use a new screw.

Or just fill it with 5200 the move the light a little and use a new screw.

 

[Amar Nanduri]

Is enough of the screw sticking out to be able to attach vice grips and remove it?

If not if the screw is in there with 5200 on the threads it should not leak or cause any problems.

If you need to get the screw out then left handed drill bits smaller than the screw would be a good option. Use a small left handed drill bit with the drill running backwards. It may spin the screw out. If not switch to a larger drill bit until the screw is removed from the hole. Once the screw is out you can fill the hole with 5200, let it cure, drill out to the size needed and use a new screw.

Or just fill it with 5200 the move the light a little and use a new screw.

Thanks Bruce. I tried both ways. I broke off the screw heads and removed the light. Then used a vice grip and able to get one screw out. The second one is stubborn and is sticking out only 5 mm. I will try to use a dremel now to cut the screw as close to the fiberglass as possible, twist the light a little bit and drill new pilot holes before screwing it back in.
I guess my pilot holes are too small and that broke the brass screw heads. I will try wider pilot holes next time.
One question. Can I use stainless steel screws instead of brass ? Will it react badly with brass ? Thanks.

 

[Bruce]

I guess my pilot holes are too small and that broke the brass screw heads. I will try wider pilot holes next time.

I did the same when installing my trim tabs in 2014. I drilled then filled with 5200. No leaks that I am aware of.

I have not used brass fittings so no idea how that combination would react once in salt water.

 

[zipper]

I hope the body of the light is bronze and not brass, it's just stronger. Brass screws are too soft unless you get the pilot hole dia. just right to twist it in and are usually for wood installation. S.S. is stronger, but you do not want a reaction to dissimilar metals in contact with each other.
I would use stainless and 4200 or Lifecalk to seal the screw where it contacts the brass to form a thin barrier between the two. 4200 is easier to release than 5200 if you ever need to replace them.

Galvanic and Corrosion Compatibility Dissimilar Metal Corrosion

Quality engineering and design requires an understanding of material compatibility. Galvanic corrosion (some times called dissimilar metal corrosion) is the process by which the materials in contact with each other oxidizes or corrodes. There are three conditions that must exist for galvanic...

www.engineersedge.com

The chart gives a .15V difference for harsh marine environment. Well within the bronze/brass to s.s. values.

The manufaturor of my bronze prop. uses s.s. hardware to hold it together. Although it does have a big zinc attached.





Based on the chart above you will be ok with the stronger s.s. screws.