Screws in the header material

[jonelli]

Screwing into the header material

Just a simple question really... I have yet to add a new screw anywhere into the fiberglass header material on our boat. And, I wanted to ask what is the proper way of doing it? If I want to mount something inside the cabin on the ceiling, how long of a screw is maximum/recommended to go into the header, do you recommend to pre-drill a pilot hole (should I invest in one of those depth stops for drills?), what else should I know about or be careful of? Are there any areas that are no-no's where I should stay away from?

 

[Anonymous 121765]

Jon,

If wanting to attach to your overhead, remember there is 1/2" to 5/8" thk. coring material between the headliner & cabin top deck. Add to this the fiberglas liner & top deck thickness & your looking at about at least 1" total thickness.

The downside of this, as with my 1980 C30 is, that just because there is wood coring, some areas may not have this. Locate an area for what you wish to mount, tap for sounding to make sure have coring there first.

My cabin side walls have areas with NO coring at all, especially the areas around my portal openings that are very rough cut, so check first. Take the thickness of whatever you want to mount, add to this 5/8" & this is the length screw you want to use.

Another option is using a 2-part epoxy with a pre-designed base made of wood or composite material. A good epoxy WILL hold. Thickness will depend on the weight of what you want to hang pal. I've used both methods on my boat. If what you want to hang has more weight, the epoxied base together with the coring thickness will allow for a longer screw length, thus giving you more holding power.

CR

 

[Anonymous 121765]

Jon,

As usual I forget something.

When getting ready to drill your hole after knowing the length of screw you want to use, do this.

Measure the length & mark the drill bit with a magic marker or eq. Take some tape & set the top edge along this mark. Wrap the tape tightly so it will not move. Drill carefully do not push hard, let the bit do the drilling. When the tape meets the headliner or base plate, the correct length has been drilled.

CR

 

[jonelli]

Thanks, CR. I want to hang two little 5 pound speakers in the port/starboard corners against the bulkhead. I fabricated some painted steel "u-brackets" and am going to put two screws into the header on each side to hang them. I have a bunch of #10 3/4" SS screws but think they might be a little too long now. I'll have to go get some 1/2" screws to be safe.
I've never tried to put a screw into the header material, so I wasn't sure if it would bite like wood and self-tap or if I needed to drill a pilot hole. I'll definitely drill and use tape as the depth stop as you suggested. Thanks.

 

[Anonymous 121765]

Jon,

Re-read my posts pal, get the right size & length screws for the right job.

Let's look at what you want to do:

You have a speaker bracket about 1/8" thick. You have the 1/8" thk. headliner fiberglas. Then, you have 1/2" to 5/8" inch balsa coring (I doubt it if you have an older model, it's more like simple plywood).

So, let's add up these lengths:
1/8" speaker bracket thickness
1/8" fiberglas liner thickness
1/2" to 5/8" coring thickness.

Hence, when you add 1/8 to 1/8 to 1/2, you need a bolt length of a 3/4" long.
Second step would be to find the correct size bolt that fits closely to the hole diameter size in your bracket. This hole size is that size for a reason. This has been engineered for the ample size bolt for what weight you are attaching.

Just a few tricks of the trade pal.

ps: don't forget to tape off the correct drill bit length.

CR

 

[jonelli]

Thanks. I was thinking I didn't want to go more than 1/2" deep and was pushing it with 3/4" screws. I wasn't counting on a 1/8" thick layer of glass too. Yes, my brackets are 1/8" thick.

 

[Anonymous 121765]

Jon,

To feel more secure, mark the drill bit 1/8" less. If the screw is alittle longer, it will cut the extra threads when screwing down.

Just remember be careful, easy & methodical.

CR