Best way to fasten bow rails?

[nola mike]

My bow rails are treated as olympic grade gym equipment by my guests. They are not. OEM fastened with wood screws through the glass and into who knows what (if anything) beneath. They have ripped out more times than I care to count. Tried repairing holes with glass, epoxy, using embedded machine screws, more wood screws, etc. So finally the ends corroded off. Got new ends with a different screw pattern, so I can go into virgin substrate. The back side is completely inaccessible from the inside. I'm not afraid to make big ugly holes on the topside. It needs through bolting and ideally some kind of backing plate I think, although 3 completely new holes per end (2 before) might be worth trying first? Rivets? Rivnuts? Not sure how thick the current system is, whether there's ply backing, whether that's rotted, etc...

 

[Jeff J]

Interesting problem. The issue I see with rivnuts and blind rivets is they are likely to crush fiberglass while being set. They also need to be the correct length so knowing the thickness of the material is kind of critical. Fiberglass isn’t always uniform.

Is the rub rail the mating line for the inner and outer hulls? What size are the original screws?

 

[Scott Danforth]

Rivnuts eventually just spin in fiberglass BTDT, have two rivnuts that require someone to reach up underneath with a vicegrip just so I can pull a bolster

got a pic of the location?
Best is an access panel opening (behind a cushion or bolster) and a chunk of aluminum as a backer with tapped holes slather the aluminum with a bit of 5200 to hold it in place while you bolt it in

second best is a chunk of white oak as a backer with wood screws

 

[Scott Danforth]

only images I could find spelunking on the web of an early 80s Conroy is this.



pull the side bolsters, make a 6" access hole , then a simple patch panel or a deck cover over the hole and replace the side bolster

or put speakers in the 6" hole

 

[Jeff J]

“Rivnuts eventually just spin in fiberglass BTDT, have two rivnuts that require someone to reach up underneath with a vicegrip”

I have the exact same experience where they are used in aluminum. Even the rivnuts that have the tabs don’t seem to hold long.

 

[nola mike]

Yep, that's my boat. Well, sure Scott, of course I know the correct way to do it
Problem is that in addition to the vertical fiberglass behind the bolsters, is that the whole area is foamed in. I'm guessing there's some sort of a wood backer in between the foam and fiberglass, which I'm also guessing has rotted nicely after 40 years of being enclosed.
As far as the rivnuts--would they hold initially? If i could tighten them down and maybe throw a little loctite on there, if they spun out when trying to remove I wouldnt be in a worse position than I'm in now, right?
1. What about a drywall togglebolt type of solution? Would need something that wouldn't rust in a day.
2. Could also cut 1 or more holes topside, and slip a metal backing plate through the hole, and sandwich with another one. This would be preferable to cutting a hole (probably 4) behind the bolsters and then cursing while trying to remove enough foam to get to the back.

Again, my boat is not what you'd call a trailer queen. Like myself, It's less about looks as I get older and more about just being able to function...

 

[airshot]

“Rivnuts eventually just spin in fiberglass BTDT, have two rivnuts that require someone to reach up underneath with a vicegrip”

I have the exact same experience where they are used in aluminum. Even the rivnuts that have the tabs don’t seem to hold long.

When I mounted my tree kickers in my side x side, I used rivnuts and coated the outside with " goop". After it dried they have never come loose even removing the kick bars for cleaning. Mounted them in 2019 and still solid.

 

[Scott Danforth]

Yo will need to cut foam away

Riv-nuts don't work in fiberglass

 

[Pmt133]

Only other thing I can think of is to plate the area around the end of the rail... effectively making the rail end formers big rail end formers. Wouldn't look great but the load would be very spread out at least.

 

[nola mike]

Yo will need to cut foam away

Riv-nuts don't work in fiberglass

Not cutting foam. Prepared to die on this hill.
I REALLY want riv-nuts to work though.

Only other thing I can think of is to plate the area around the end of the rail... effectively making the rail end formers big rail end formers. Wouldn't look great but the load would be very spread out at least.

How am I fastening the plate?

 

[Mc Tool]

How much trouble do you want to go to ....I have a cunning plan but it would involve a fair bit of faffin about and a bit of a weld .

 

[froggy1150]

Riv nuts/nutserts WILL fail. They are made for sheet steel. You can drill a hole in the center of your rail pad big enough to get a welded nut/fender washer combo thru the hole and glue in place x 4.
Also hilti toggler will work but they dont come in stainless. They kinda work like butterfly toggle bolts except for it's a single piece of solid steel without hinge and they retain themselves after installed so bolts can be removed without backer falling

 

[Pmt133]

Not cutting foam. Prepared to die on this hill.
I REALLY want riv-nuts to work though.

How am I fastening the plate?

Lots of wood screws and bed the plate onto epoxy.

 

[redneck joe]

getting inside with a backer plate and thru mounting is the only real way but the kiwis usually have a good redneck idea up their sleeves especially since i looked up the word 'faffin' which while not listed i'm sure involves beer.

 

[Grub54891]

Don’t overthink it. Here’s what I did as I’m restoring my 85 Larson. The holes will be covered by the cushions, and give access to wiring and such in the future. I scraped the layer of foam with a flat scraper, didn’t take much effort. Laid a flat aluminum bar in there from the hardware store under each point. Pre drilled before installing.
Edit: used 4000 on the screw holes and backing plates. Thru bolts and washers, nylock nuts, stainless.

 

[Scott Danforth]

^this is what I described in post #4

 

[redneck joe]

^this is what I described in post #4

yeah but hes got pictures......

 

[Mc Tool]

getting inside with a backer plate and thru mounting is the only real way but the kiwis usually have a good redneck idea up their sleeves especially since i looked up the word 'faffin' which while not listed i'm sure involves beer.

What I was thinkin ...coz if I take on something like this I dont want to have to have a 2nd go ...
Get some ¼"stainless plate ,cut to fit under the existing rail mounts but larger ,shaped to fit the hull ( cant see much detail from pic ) so as to have a larger footprint ( big as you can ) drill and tap to fit original mount and screw it on . Attach new plate to hull with something that doesnt require access to other side (take your pick ....maybe include glue ). Then make a 3rd plate drilled to fit under that cleat ( assuming that cleat is well attached )using longer attaching screws and then a bit of stainless flat bar ( maybe ¼" x1" ) welded between the rail and the plate under the cleat . Looks to me that maybe (again cant see detail )this bit of bar could be attached so as to give some triangulation thus adding sideways support to the rail Obviously there would have to be some clearance bent into the flat bar so the cleat wasnt obstructed . Then all you gotta do is dress/ polish the new bits of stainless .
Faffin ......Im pretty sure is a word my Grandmother used to substitute for the word she would normally use () when us kids wernt about . My Granddad didnt
Oh and yeah ....beer goes with everything

 

[Grub54891]

^this is what I described in post #4

Yup. And it’s solid!

 

[froggy1150]

And without pics..... it didn't happen