Q's on Fastening Starboard(tm) Handrails to Cabin Top

[ObiQuiet]

Hi, I have the starboard plastic handrails from CD, and plan to bed them with Bed-It-Butyl tape. I've read all I can find on the topic, but have a question that I've only found conflicting info on:
How best to attach the rails to the boat? This is of course from the inside, through the cabin top, up into predrilled handrails. It needs to hold up under load.

Which is sufficient or necessary?
A) Wood screws
B) Wood screws plus some kind of epoxy or glue to hold the threads in the starboard
C) Through bolts, using a press-in threaded fitting in the starboard
D) Through-bolted, with a full washer/nut on the top side. This would involve making an oversized hole and a cap in the rail. I've not found any mention that this is necessary for this application.
E) Something else?

Thanks!

 

[Ward H]

Starboard is slippery and can deform slightly so screws won't hold well.
Not much sticks to starboard so glue and epoxy is out.
That leaves through bolting, with bolt head coming in from the outside and washer/nut on the inside of the cabin. Drill a hole in the top of the hand rail, put in the bolt and fill with a plug, called a bung, when finished. You can make bungs using a bung cutter. This is normally done with teak but should work with starboard but I have no experience doing so.

 

[MikeHoncho]

Starboard is HDPE. Take a look at this link;
https://www.ipoly.com/faq/can-i-screw-hdpe-sheet
If you don't predrill or predrill with too small of a size the edges will bow out but once in, the screws are very, very difficult to remove due to friction/heat. I've fabricated many wake gates for wakeboard boats with it and have never had anything back out or strip out. I have pulled the "threads" out of the material from over tightening using a impact driver.

 

[Ralph Johnstone]

the screws are very, very difficult to remove

As @MikeHoncho said, but he left out a few very's.

Get a scrap of Starboard and practice to determine the correct pilot hole dia. without bulging or cracking the exterior. Also use the longest screw possible.

 

[ObiQuiet]

Thank you for the replies! Practice is definately good advice, that bulging is unexpected. As is the need to clean out the debris from the drill.

It seems like
* It's difficult to get the parts to draw together, even with a wood screw.
* It's possible to strip the hole while doing that, as MikeHoncho noted.

 

[MikeHoncho]

Thank you for the replies! Practice is definately good advice, that bulging is unexpected. As is the need to clean out the debris from the drill.
If you're shedding two pieces together with both pieces engaging the threads of the screw they won't come together tight unless done so with both pieces clamped together or once tight, backing the screw out then tightening down again.

It seems like
* It's difficult to get the parts to draw together, even with a wood screw.
* It's possible to strip the hole while doing that, as MikeHoncho noted.

 

[Ralph Johnstone]

* It's possible to strip the hole while doing that, as MikeHoncho noted.

Odd, never had a problem with stripping threads IF the screw is long enough and the pilot hole is as tight as is practical (without bulging). Practice, practice, practice.

 

[ObiQuiet]

Given the cost of the handrails and the importance of pulling them tight to the cabin top, I'm wondering if going with a threaded insert for a bolt is a good idea. Plus the recommendation on the byutl tape to tighten a bit at a time.

That way I can get the inserts placed on the workbench, rather than worrying about messing up a hole when working upside down...

Good idea or bad?

 

[Ralph Johnstone]

I'm wondering if going with a threaded insert for a bolt is a good idea.

Don't see how this would be a fraction of the strength of a #10 screw screwed into the handrail.

The only way to do this is to experiment with scrap Starboard first if you've never used it before. You will be more than impressed with its strength at holding a #10 screw with the correct pilot hole. Without this, you risk ruining the rail(s) you have.

 

[MikeHoncho]

I think its really easy to over think this. Over size drill the hole for the cabin so threads do not engage, drive the screw into the rail using an appropriate sized pilot, bed in butyl. Go sailing. If you don't want to drill a larger hole in the cabin do the same, it won't suck down tight, back it off and tighten it down. The second time it will suck up because the threads in the material will now be there. Don't over tighten and strip it out.

 

[mermike]

It's best not to use the force of the screw to pull two pieces together. It's far better practice to clamp them in position, then fasten. I've learned this from multiple boat builders, as well as my own experience. You can cobble up custom-sized clamps with scraps of lumber and hardware.

 

[ObiQuiet]

Good advice on not over thinking it. I don't think I can clamp the handrails to the cabin top... Open to ideas there...