Screws through Fiberglass

Is it ok to drill through and send screws through fiberglass? I am going to send screws through the side pannels to suport decking on the inside and I was origionally going to try to mount all screws then flip the boat back over to fiverglass over all screw heads. I feel like this would be more durable, but then I could not easily get to the screws again. So now im thinking I will fiberglass first then screw through the hull, applying 1500 to all holes. Whats everyones opinion on doing this? Is one way a much better idea? Seems like fiberglassing first will be easier.

 

OR should I fiberglass before even assembiling the hull while the boards are flat?

 

Thanks as always. Plywood just got in!!!

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Permalink Reply by Rod Hughes on March 2, 2011 at 7:35am
even though they are stainless if you epoxy over then they will  corrode here is a link on what happens if you epoxy stainless http://www.alberg30.org/maintenance/Steering/CreviceCorrosion/
Permalink Reply by Randy Dersham on March 2, 2011 at 1:17pm

This is a common thread that mixes two different characteristics of SS screws and comes to an incorrect conclusion.  

 

1. it is true that without oxygen the SS surface coat will not protect the alloy screw; however, the alloy itself still has very good strength and anti corrosion properties.

 

2. Crevice Corrosion requires contact with water.  The point is that water collects in crevices and stands on the screw or bolt causing corrosion.  If the screw is embedded then there is no chance of standing water. The point of the embedding in epoxy is to water proof the fastener and prevent any water from following the screw into the wood as the wood and SS expand and contract at different rates.  It is true that there is some level of water in the wood and that the stainless will not have it's oxide coating; however, there is not enough water to cause extreme fastener failure beyond some staining from the surface.

 

I have repaired 20 year old boats with SS screws embeded in the bottom and the SS screws are holding up great.  I've also repaired boat bottoms with galvanized screws and in every case they have rusted out.  The damage from water to the wood is much faster than the damage to the embedded SS screws. So embedding that fastener to prevent any water from entering at the screw is the most safe and long lasting method to follow.

 

CLICK HERE to go to the wiki link to the info about crevice corrosion and it's nasty friends.  They all require a lot of exposure to water for the damage to occur. 

Permalink Reply by lhedrick on March 2, 2011 at 7:21am

I'm not quite with you on the screws supporting the deck.

 

The deck will sit on top of some form of virtical support which makes up the compartmants.  At the sides it will rest against the side wall.  A fly line deck up front will be fitted and them just rest in place as the sides taper downward.  After the fillets are added you can stand on it.   What are the screws for? For support under the deck you can add some plywood blocks epoxied to the side wall.

 

I would seal the area with epoxy fillets.  5200 is about 20 dollars a tube and I find it difficult to work with.  I would also remove any screws which are not requiered.  If you cover them with epoxy they are very difficult to remove later for any kind of repair.  With S&G no screws are left in the boat.  I would assume many are used to attach things to frames in the other case.

 

As for glass, I assume you are putting on exterior glass after the hull is together.  The panels will resist bending if you glass them first and then try to wrap them around the frame.  You can pre glass inside curves and they still bend.

 

The following is not a wood boat, it also not a framed boat but, it's a boat, the construction is s&g.  You can look at the photos just for ideas.  Just pretend it's all wood.  You can also just think of the plastic bulk heads as being plywood.  The process is the same.   The web site has some photos of the deck segments and their supports.

 

mountaindogs.net/plascorehull

 

Sorry folk, this is for information only and just pretend you are looking at wood.

Permalink Reply by Ben Kittell on March 2, 2011 at 9:58pm

I am screwing in the supports that you mentioned to the side wall. I know that I will not be jumping up and down on my decking, but I can not garentee that someone else will be so Im going with the better safe then sorry approach.

 

Already got a bunch of 5200 at a steal, hopefully I will figure out a good way for working with it.

Permalink Reply by lhedrick on March 3, 2011 at 7:49am

Okay, I think I have the image in my mind now.

 

I looked at my images and I guess I didn't include any of the contact/attachment points at the sides which are under the deck.

 

I would use epoxy for this with strips of plywood.  Scribe a line on the side which is the bottom of the deck.  Then cut plywood strips and glue them to the side.  You can use 1/4 and do 2 layers.  Never through out marine plywood scrap.  I find ways of using every piece over time no matter how small.  All you need is a ledge for the plywood to sit on.  When the deck goes on put thickened epoxy on the ledge and the underside of the deck.  Finish with a fillet on top.

 

You can use screws through the side to hold them in place then remove them the next day.  A framed boat will be very stiff and the epoxy bond all around the boat at the deck joint will lock it together even  more.   The epoxy will cure in 1 day,  the 5200 will take 5 days or more.  The 5200 is great stuff and you will find other uses for it.  My shop is cold and 5200 is taking 2 weeks to cure.

 

One tool I use almost ever day is a 23 gauge micro pin air nailer.  The pins hold things in place until epoxy bonds take over.  They are so small they are invisible.

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