Rebedding flybridge. What to use? Best practices?

[stormchaser]

Hello all,

It's time to rebed the flybridge on Saraswati. The plan is:

- Remove screws, squirt bedding stuff in hole, put screws back in
- Run bead of bedding maerial/calk around the edges/seams.

That's just my idea...not sure if that is the right way to do it. I don't have the ability to remove all screws then lift the flybridge to get bedding material under it without hiring a crane, which would be quite expensive. How have y'all rebedded your bridges? I am also going to rebed all the railings and all other stuff that penetrates the upper decks.

But, is my plan acceptable? Even worth it? Any suggestions on what to use? I was thinking of 3M Fast Cure 4000. But what does everyone else use?

 

[bobk]

3M 4000 ought to be fine as it resists yellowing.

If you want to remove and lift the bridge, the easy way to do it is have the yard lift it with the travel lift slings. Just place a few athwart ship stiffeners on the after part of the bridge to prevent it from buckling. Yards do this all the time for overland shipment. But if you are going to rebed it after lifting, be sure you have a way to index the screw holes quickly or the caulk will start to set on you before you get it done. Or use a slower setting caulk.

Bobk

 

[stormchaser]

If my plan sounds ok, rebedding without lifting, that's what I'd rather do. I suspect it is the screw holes that are leaking a bit. No soft spots but I just noticed the screw holes for the lights right above the sliding doors are weeping water, so I know water is getting in the deck somehow.

Secondary question...how do I dry the deck so it doesn't begin to rot? I was thinking of drilling a couple of small drain holes in the aft corners of the overhand, by the doors to the aft deck. Lets air in, and any water out.

 

[MikeP]

When I rebedded all the screws back in '05 - I seem to remember there were over 200 - I used 5200. I wanted the best stuff there was for a job I never wanted to do again. So far..no leaks. I did not do any bedding/resealing of the FB itself. I don't see any reason to do that - there are drainage holes in the slides of the FB on our 53 anyway so water ends up inside the FB whenever it rains/boat is washed. It seems to me that adding sealant under/around the joint would just tend to keep water in that area.

FWIW 5200 is not a disassembly issue for screws. They will unscrew just fine out of 5200 with a power screwdriver.

 

[stormchaser]

FWIW 5200 is not a disassembly issue for screws. They will unscrew just fine out of 5200 with a power screwdriver.

Really? That is the only reason I was thinking 4000 rather than 5200...in case I ever have to back them out again.

 

[Vincentc]

What about removing the screws, wrapping the threads with butyl tape and reinstall. See the thread installing windows with butyl tape. However if you have water in the core, it seems you should address that.

 

[MikeP]

"Really? That is the only reason I was thinking 4000 rather than 5200...in case I ever have to back them out again."

I'm a 5200 fan and use it where many folks prefer something less tenacious. I have had to pull screws out of 5200 on several occasions - never due to a problem with sealing - and a decent power driver pulls them without any great difficulty. Actually, you can pull them with a hand screwdriver though that is more work than you want to do if there is more than one screw!

 

[robertm]

We resealed all of the flybridge screws on our 53 due to leaks that required replacement of the salon overhead. Our process involved removing the screws, cleaning out all of the old sealer, redrilling the holes, filling up each of the cavities with a thick mixture of epoxy and cabosil using a syringe, and cleaning up the original seams and removing any old seam sealer that would come up with a scraper (both the outside and inside seams where the flybridge edges seal to the cabin top). After the epoxy set, we redrilled the holes to accept #10 screws and sealed each screw and each seam with 5200. Messy, tedious and probably overkill, but no leaks or problems after 4 years.

 

[saltshaker]

I did this on 3 boats ago. I drilled drainage holes below to allow any trapped water out. I lifted the bridge just enough to put pieces of 2x4s to support the bridge. I did this so I could get everything cleaned up and have better access to all the screw holes. I cleaned out all the holes, shot epoxy in each and then used an epoxy filler to fill each hole. Sanded it all smooth then re-drilled each hole. I didn't use 5200 because I had concerns about removing the bridge in the future. My concern wasn't about being able to remove the screws but the bonding between the deck and the bridge where the caulk squeezed out. I think I used Boatlife but can't remember (it was about 20 years ago). I did not seal the bridge to the deck, only the screw holes. When finished it was solid and no leaks.

 

[Maynard Rupp]

We did ours 8 years ago. First...DO NOT use 5200. You will not be able to remove it ever. Use 4200 for all the inside beads. When you get your head inside each compartment you should see a sealing strip between the flybridge piece and the salon roof. If there are missing areas, as we had, fill them with 4200 from the inside Next remove every screw, (probably about 200), and stick the nose of the 4200 caulk tube in each hole and squeeze the trigger. After a few you will get the feel for how hard to squeeze to get the hole full without a big mess on the outside. Replace each screw as soon as the hole is filled. Remove the overage with acetone. Now tape both sides of the outside edge leaving about a 1/8" opening on both the horizontal and vertical surface. This is to seal the outside. You need to use 3M 4000 caulk for this job as it is UV proof and 4200 is not. The problem is finding a fresh tube of 4000 as it isn't very popular. Now make a bead that goes almost to the edge of each tape. Next wet your finger, (spit is OK), and wipe your new bead to give it a nice radiused look. After each 6 feet, remove the tape and finger wipe again to remove the tape ridge. Don't wait too long for this as the stuff will start to cure. That will do the trick for a long time. Remember...NO 5200!!!

 

[stormchaser]

Is there any point in doing the seams/joint? As nothing penetrates the deck, is it only ascetic?

 

[TopHattandTails]

Unscrew each screw. As it comes out, squirt 5200 in the hole, rescree hole. 5200 and screws are fine.

 

[stormchaser]

As everyone says 4200 is fine and only some say 5200 is ok...I picked up some 4200. But question...for the rest of the week, we are expecting scattered showers/storms. Think it's ok to get this done even if they are exposed to rain before full cure? Or should I hold off? The tube seems to indicate that it NEEDS moisture to cure...but is full rain too much?

 

[jim rosenthal]

It will cure no matter what you do or don't do. It will cure faster if the humidity is higher. Those caulks are moisture-activated urethanes.

 

[Angela]

Now tape both sides of the outside edge leaving about a 1/8" opening on both the horizontal and vertical surface.

Thanks for the excellent tip on caulking, Maynard. I think I just did the best caulk job I've ever done.

 

[Mambeaux]

Well.....how did this turn out?

 

[stormchaser]

In progress, about half done. Damn there are a LOT of screws, but it's easy so far. I was planning on finising this week, but it's pouring and I have plans Wednesday and Thursday...maybe Friday?