Leveling Bridge Deck

[jeffg]

Hi,
I have just bought a 30 year old Trawler that had a previous repair to the bridge deck for delamination. The repair left the deck with a hollow (almost 1” low in the center) that collects water and has over time has found it’s way into the repair and also into the salon. How do you suggest I repair the rot and then create a convex surface to shed the water away from the center and off the sides of the boat?
I am considering laying in 3/8 plywood and then laminating several more layers of 3/8s ply to create the desired profile and then filling around them to give the deck a flat, but convex surface.
Does anyone have any other suggestions?
Thanks,
Jeff

 

[Lepke]

I guess when the deck was repaired it was probably flat or convex and too much weight caused the sag.
I suppose there are wood beams underneath. First inspect them for cracks going lengthwise to ensure they were strong enough and aren't the cause of the problem. The beams should dictate the crown. When I built boats, I made crowns 1" for every 10' of width. More in commercial boats.
When sanding the existing fiberglass, use very coarse sanding disks. I use 40. The deeper groves give much better bonding. Use epoxy not polyester resin. Any fill, use an epoxy filler.
If I were doing the repair, I would cut out the top down to the beams and out past the concave spot to good wood. Then build up from that. My preference would be to re-glass the whole top so there is a continuous fiberglass cap.

 

[cool beans]

I have seen 2 instances of repairs that pooled water.

First, a rotten deck that had sagged over the years and when repaired, the owner didn't jack the roof back up to it's original profile. The sag was glassed back into the deck.

Second, a rotten cockpit floor that bounced was repaired with balsa and weighted down with sand bags to ensure an even compression over the core. The bottom skin wasn't supported so the weight caused it to cure into a slight spoon shape.

If I were you, while repairing, I'd try and jack the deck back up to match the existing profile of the surrounding deck. If you still have a depression, I'd fill and fair it in with appropriate foam then shape and glass over. . .also what Lepke said

 

[psneeld]

Heck...my boat hadn't been previously repaired, but still had a low spot on the flybridge.

After tearing off the teak deck, I cut a section out and replaced the loose teak blocks with ply and reglassed the cut section of fiberglass deck back in.

It still is a low spot, but now that it doesn't allow water into the core, it sheds off eventually with just a slight roll or people shifting the cg.

 

[rwidman]

I'm certainly no expert on the subject but it seems to me that adding several layers of plywood would be a lot of unwanted weight high above the waterline. Usually, thee best way to fix a bad repair job is to rip it out and start over and do it right.


You might call a couple of pros and ask them for detailed estimates and ask exactly how they would do the repair. You might find it worthwhile to have one do it after getting prices.

 

[RT Firefly]

Greetings,
Mr. j. IF you're going to proceed as Mr. cb suggests (jacking up the deck to match the existing/original profile) I would suggest OVER jacking the deck to allow for natural sagging after the repair is made and the jack is removed. Not a silly amount, just a bit.

 

[DHeckrotte]

JeffG, perhaps you've read this elsewhere:

Presuming the patch is as badly done as you've made it sound: Remove every part of the previous 'repair', and every bit of further damage to the original construction. With any kind of luck, you'll have the bottom 'glass skin of the original cored construction remaining intact. You will not be able to walk on / put weight on that skin, so support it from below if the affected area is too big to reach over. Push that skin back up to where it belongs. Grind it clean. Bed new chunks of core, matching the original core thickness, in epoxy. Laminate new 'glass to the new core with epoxy and be sure to scarf it on to a prepared/ground tapered edge of the old top skin. Fill the glass pattern and any unevenness with epoxy filler. Finish with paint and nonskid to match the rest of the boat.

Imagining /hoping that the patch is not that bad: Find and cure the leaks; the patch should not be leaking just because it holds water. If it is leaking then the above method counts. If the repair is really good enough and stiff enough, grind it clean, fill with any reasonable (polyester or epoxy) filler, refinish.

Good luck!

 

[psneeld]

I think on my flybridge, the lower "skin" was so thin I doubt it was structural.

Be careful about replacing the core if you don't make sure it isn't needed for support from the sides and cabin beams.

Otherwise, you may just wind up with the sag again.