How to secure plastic console on deck

[ba_fisher]

I am trying to put a plastic console onto a 4.2 meter fiberglass RIB. The top of the rail is about 1.1 meters, and two adults may be grabbing onto the rail in rough seas. So there may be quite a bit of leverage towards the bottom of the console where it meets the deck.



The console is made of 5mm thick roto-plastic. The base is about 40x40cm.





Is it ok to just use stainless screws to secure the console onto the deck? If so, what size screws should I use? How much spacing should I put between the screws?

Or, should I cut a round hole on the deck so that I can use bolts instead? I can cover the hole with a round deck access hatch.

Please help a newbie. Thanks.

[Nos4r2]

Originally Posted by ba_fisher

I am trying to put a plastic console onto a 4.2 meter fiberglass RIB. The top of the rail is about 1.1 meters, and two adults may be grabbing onto the rail in rough seas. So there may be quite a bit of leverage towards the bottom of the console where it meets the deck.

Attachment 103072

The console is made of 5mm thick roto-plastic. The base is about 40x40cm.

Attachment 103073

Attachment 103074

Is it ok to just use stainless screws to secure the console onto the deck? If so, what size screws should I use? How much spacing should I put between the screws?

Or, should I cut a round hole on the deck so that I can use bolts instead? I can cover the hole with a round deck access hatch.

Please help a newbie. Thanks.

If you want a really brutally honest answer, use a different console. That one really doesn't sound up to the job you're describing. Nothing sticks to that plastic well enough to glue it, and the dimensions are such that it is just going to rip it out of the deck if 2 adults are hanging onto it in rough seas.

The only way I'd even consider fitting that would be to put a stainless strip on top of the inner flanges and screw down through that-big screws (though not so big they go all the way through the deck) , sealed with Sikaflex 291i or equivalent and about 1.5" between hole centres.

I still wouldn't take it out in rough weather though.

[ba_fisher]

Thanks for the tips with the stainless strip. I will also add an angled piece of stainless at the bottom of the opening to add extra strength.

Frankly I would only go out in good weather with this boat. I just don't want it to break up in pieces the first time it hits a big wave.

We will also try to hang on the straps on the tubes instead. The driver would have to hang on the steering wheel, though.

For other types of consoles, do people usually just use screws ( when there's no easy under deck access)?

[Nos4r2]

No, either GRP or screws and Sikaflex 291i or the equivalent. The screws don't actually do much apart from pull the console down onto the deck as the sika hardens. Thats where the real strength is.

[ba_fisher]

What if I bolt a stainless strip to both sides of the flange, and then screw the whole thing down with Sikaflex 291i?

[Nos4r2]

Sika doesn't stick too well to stainless or that rotomoulded plastic IIRC. You could improve the adhesion by roughing it up, but realistically after a while all the sika will be doing is stopping water getting down the screw holes into the deck.

[John Kennett]

As said, I wouldn't try to rely on adhesive with the roto-moulded console, and if you're not using adhesive then screws won't be up to the job.

You could put a drilled stainless steel strip along the flange then bolt it down through the deck.

[ba_fisher]

I will probably cut an access hole on the deck so I can through-bolt it. I need to avoid cutting into the stringers. Will a good stud finder be able to tell me where the stringers are?

[Peter_C]

If it were mine, I would use 4-7 bolts probably 3/8", and cut a hole to gain access. Then drill out 4-6 pieces of stainless in order to facilitate bolting it between two plates per side. Without seeing it first hand I wouldn't know what way is best. Without a drill press, stainless is tough to drill though, and without a grinder even harder to cut.

Originally Posted by ba_fisher

I will probably cut an access hole on the deck so I can through-bolt it. I need to avoid cutting into the stringers. Will a good stud finder be able to tell me where the stringers are?

Let me know when you find a good one please. I tried to use mine tonight to locate framing...it failed.

You should contact the manufacturer for advice on location. Unless you can see the stringers with a really bright light? Is the hull rotomolded?

[ba_fisher]

Originally Posted by Peter_C

You should contact the manufacturer for advice on location. Unless you can see the stringers with a really bright light? Is the hull rotomolded?

I have asked the dealer that sold me the boat for a blueprint of the boat. Hopefully that will steer me clear of the stringers. Not sure how the hull is manufactured. I looked inside the bow locker and don't see any stringers.

Could there be no stringers even in the main part of the hull?