Pop rivet hooks to NB roof to secure catch cover

[Amh300]

Hi,

I had a quick search on the forum for this topic but couldn't find anything (i'm sure it's been covered somewhere). 

I just bought a cratch cover from cover systems (who are excellent btw) and now have to fit it. I am thinking of pop-rivetting lace hooks to the gunwale and sides and roof of cabin of my NB (see photo attached of hook). Here's what I think I have to do:

 

1. Buy pop rivets. I think I need to get a waterproof rivet - something like this https://tinyurl.com/y7c27kzp

2. Buy a rivet gun - something like this https://tinyurl.com/y8sgjy6d

3. Buy some silicon to coat the underside of the lace hook and underside of the rivet

4. Drill holes in correct places

5. Pop the rivets

 

I've never done this before, so I have a few questions:

The lace hole size is 5mm so is a 4.8mm rivet the size to go for? 

How long would you recommend the rivet to be? Is there a standard steel roof thickness for NBs? The range seems to be between 8mm and 20mm. I'd guess that 12mm would be ok?

If the rivet is 4.8mm does that mean the hole size has to also be 4.8mm (a stupid question, I know)

Is it sensible to use a silicon for extra waterproof-ness? Any recommendation for which type of silicon?

 

Sorry for all the questions but I'd rather ask than s##ew it up!!

Thanks

Andrew

[mrsmelly]

Good quality stainless self tapping screws into pilot holes with sealant will do it amicably.

[Amh300]

Oh, ok - well that sounds like a much cheaper and easier option. I hadn't considered self-tapping screws! Thanks for the suggestion.

[X Alan W]

You can buy blind end rivets a smear of "Goo" when inserting the unclenched rivet  I wouldn't put hooks on the gunwales (trip factor walking along)are the sides of the cover long enough to hang below gun whale level to run water down the outside's of the hull sides?

[Jen-in-Wellies]

Steel narrowboat roofs are typically 3, or 4mm thick sheet. There are always odd ones, but a 20mm thick steel roof would be so heavy it would capsize the boat! Possibly this thickness is the roof plus strengthening ribs every couple of feet plus lining. Cabin sides are typically 4 to 5mm. Hull sides around 6mm.

 

A 5mm hole will be fine for the drill size. The pop rivet expands as the central steel pin is pulled by the riveter, taking up the slack. Sealant shouldn't be necessary. The expansion of the rivet should seal the hole. The rivet gun you link to should work nicely. The rivets should be shorter. Thick enough for the hook, roof steel and a few mm beyond.

 

The 4.8mm comes from the rivets initially being in imperial size. 4.8mm is as near as makes no difference 3/16".

 

Hope this helps.

Jen

Edited November 3, 2018 by Jen-in-Wellies

[Amh300]

Thanks Jen, v helpful!!

[Sea Dog]

I wouldn't dream of using aluminium pop rivets in a damp, mild steel roof because of dissimilar metal corrosion. However, my boat builder did for the same function as you're contemplating - the boat is now 10 and they're perfectly fine!

[pearley]

6 minutes ago, Sea Dog said:

I wouldn't dream of using aluminium pop rivets in a damp, mild steel roof because of dissimilar metal corrosion. However, my boat builder did for the same function as you're contemplating - the boat is now 10 and they're perfectly fine!

You can get stainless steel rivets but still dissimilar metals. And you need strong wrists if using a normal pop rivet gun. I used an air operated riveter when fitting security locks to vans. 

Edited November 3, 2018 by pearley

[Chewbacka]

1 hour ago, pearley said:

You can get stainless steel rivets but still dissimilar metals. And you need strong wrists if using a normal pop rivet gun. I used an air operated riveter when fitting security locks to vans. 

I’ve used stainless rivets and it takes both hands and a mighty squeeze to get them to pop, and I needed a rest after doing just 4, so if you go for stainless try to find a gun with long handles for more leverage.

[GUMPY]

Drill the roof 4.2mm tap the hole and use M5 stainless machine screws with some silicone on the threads, is the proper way to fix them

Edited November 3, 2018 by Loddon

[WotEver]

3 hours ago, Amh300 said:

Is it sensible to use a silicon for extra waterproof-ness?

No. Use Sikaflex or Marineflex. 

 

32 minutes ago, Loddon said:

Drill the roof 4.2mm tap the hole and use M5 stainless machine screws with some silicone on the threads, is the proper way to fix them

No. Machine screws and Sikaflex or Marineflex is the proper way. Silicon is the spawn of the devil. 

[Boater Sam]

I doubt that you have room on those hooks for a rivet gun head.

Drill 4.2mm, tap 5mm ( bit of grease to ease the tap )  and use 5mm button headed allen key machine screws with non silicone sealant is the best way. Then when you snap a hook off you can easily replace it. Button heads don't snag on things.

Silicone sealants can cause rusting on steel.

[Amh300]

Thanks everyone - excellent advice here ?I'll upload some photos once I'm done.  

[GUMPY]

1 hour ago, WotEver said:

No. Use Sikaflex or Marineflex. 

 

No. Machine screws and Sikaflex or Marineflex is the proper way. Silicon is the spawn of the devil. 

I was using silicone as a geneic term for stuff that fills any voids

To be honest if you tighten up the machine screws properly you don't need sealant as there is no way the water will get through the threads.

 

On reflection I might use copper ease, at least it would fill any voids and when you want to get them out it will be easy, unlike silkaflex

Edited November 3, 2018 by Loddon

[WotEver]

30 minutes ago, Loddon said:

On reflection I might use copper ease, at least it would fill any voids and when you want to get them out it will be easy, unlike silkaflex

Sounds like a plan. I’m a fan of copper ease. 

[Detling]

23 hours ago, Boater Sam said:

I doubt that you have room on those hooks for a rivet gun head.

Drill 4.2mm, tap 5mm ( bit of grease to ease the tap )  and use 5mm button headed allen key machine screws with non silicone sealant is the best way. Then when you snap a hook off you can easily replace it. Button heads don't snag on things.

Silicone sealants can cause rusting on steel.

Before you do that check that an M5 bolt fits through the hole on the hook. Mine hooks use M3 bolts not M5 the only problem with M3 is the blooming taps snap easier, so buy 2.

[Chewbacka]

3 hours ago, Detling said:

Before you do that check that an M5 bolt fits through the hole on the hook. Mine hooks use M3 bolts not M5 the only problem with M3 is the blooming taps snap easier, so buy 2.

Or drill out the holes in the hook to 5mm

[ditchcrawler]

I once read someone suggesting liquid PTF thread sealant on screws in a boat roof to make them boat water tight and easy to remove