Need some help repairing soft spot in floor

[Stan Bright]

Hi folks

I have a flybridge boat with a soft spot in the floor on the starboard side. It's right up against the wall of the bridge. (Excuse my terminology..) I need to repair it, but I need some help getting the balsa out from under the wall of the bridge. It's about 8 inches wide. I was going to cut out the accesible part of the floor and chisel out the balsa but don't have a clear view on how to try to get it ALL out from under the wall of the bridge. The spot in question is approx. 12 x 16 inches, with about 8 inches of under the wall. Does anybody have any ideas? Removing the bridge is not in the cards.. Thanks in advance.

-Stan

[fasteddy106]

A photo showing the location would help a great deal.

[Stan Bright]

I'll have a picture up tonight.

[gonzo]

Make some kind of hook

[Stan Bright]

Well.. I went down to the boat and my Brown Berry decided to crash..so no picture tonight. How critical is it to get ALL of the balsa out? Using a hook, is a great idea I'm concerned though that there may be some leftover crap in there and I don't want it to keep spreading. I'm still hoping there's some kind of trick to do this. Thanks for the suggestion Gonzo.

-Stan

[fasteddy106]

Did you figure out where the water intrusion is coming from to cause the soft spot?

[Stan Bright]

I think so. There is a grab rail that runs the length of the bridge and one of the bolts is loose on it. I didn't think it was a big deal since walls of the bridge have two drain holes on each side. My arms aren't long enough to get at the back of the bolt. I bought a round access port, but was hesitant to cut a 6 inch round hole to install it. Actually the hole wasn't the big deal, it was the small screws which attach the port. I'm not real sure how to drill into fiberglass so it won't split. (Other than careful consideration to the size of the drill and the screws.) The other thing is the screws with which the bridge is secured to the roof of the house. They're bedded with something (I've had the boat 3 years so some of these things are guesses.) like white caulk or 4200. I'm in the process of rebedding them all.

-Stan

[mark775]

The key; "figure out where the water intrusion is coming from to cause the soft spot"
And, rebedding is but a temporary solution.

[Stan Bright]

Mark775, I don't understand what you're saying. How/why do you feel rebedding is a temp solution? I'm looking for and stopping the source of water intrusion PRIOR to cutting out the old balsa and replacing it. Am I missing something? I hope you aren't thinking that's all I'm doing. That's not how I work. I'm still hoping that somebody with some experience doing this sort of repair will come forward with a tip on how to get the wood out from under the wall of the bridge.

-Stan

[alan white]

The soft spot you feel is the last stage of the kind of deterioration that is surely found elsewhere in that area.
Before going too far, map out the water infiltration by drilling test holes starting at the soft spot and work outwards. It may be (ans probably is), that you have a much larger are to contend with. If the wood core is wet but white (light) in coloir, it's probably possible to dry it out. If it's brown or black it rotton. You'd be surprised how sound a rotton core can be and still have enough stiffness to seem okay.
Getting at the hard to reach area will be challenging. It may have to be done from below.

[Stumble]

Stan,

It is critically important to get out all of the rotten balsa. Since any remaining moisture can continue to cause rot. I also suggest cleaning out the core with bleach to try and kill the rot spores.

Personally I work a little differently than Alan's method, since I don't like drilling the test holes. I start with a larger hole where I know the core is rotten and start to clean the core out from there. Then working outward from my initial hole I drill aditional holes as needed to get more rot. The end result though is that you have to keep going until all of the rot is gone, then come back and replace the core you took out. In small areas this can be with an epoxy fill, or poured in high density foam. However if the area is big enough I recommend replacing the balsa with balsa.

[mark775]

32747
I forgot a backing plate and was unwilling to edit. You see, If you simply "rebed" the offending stanchion base, you are not much better than the lazy, no-good, piece of dirt that bedded this the first time. It is the wrong way to do it as witnessed by thousands of like situations. When the stanchion is wiggled, it compresses the core, the stanchion can wiggle more, eventually allowing water ingress. A little ruined balsa remaining is the least of your worries - STOP THE BLEEDING!
Now, the cleanest way is to countersink each hole a bit so that you form a 5200 gasket at each penetration. You can bed the whole base area, if you desire, then scrape up squeeze-out then clean up with de-natured alcohol but be advised that most of these castings are somewhat hollow and it will require thought as to how much and where to goo. Take the time to get the alcohol or your work will look like every other shmuck's. Size your bolts for length. Install bolts and almost seat base, then apply 5200 for a neat job. 4200 is for people that don't care what things look like. It's short open time causes hurry.

[mark775]

One other thing. Nuts and lock washers, rather than nylocks, are best in this and many other non-critical applications. You will appreciate when it is time to rebed in twenty years.

[Stan Bright]

Thanks for the advice. The spot is on the floor of the bridge, or else you could say roof of the house, where the bridge attaches. The area in question is approximately 10 inches of the floor that goes under the wall of the fly bridge. Cutting out the exposed part of the bridge is duck soup. The tough part is under the wall. It is held on with a series of #10 screws spaced about 8 inches apart on both sides of the wall. I'll be scraping and chiseling it out. Depending on how that goes, I might be cutting a slot from the outside to remove 100% of the rot. I would rather not cut that slot, because cosmetically it will be a P.I.A. but I can't think of a better way to get all that rot out. If anybody has any other ideas, speak now before I make the cut.

-Stan



The closest stanchion to where I'm working is for the ladder to the bridge but it's about 5 feet away from the soft spot, but making an epoxy "puck" to attach the stanchions is a great idea and should be done at the factory for all boats.

[mark775]

The water got in where all those scews are? Can you photo?

[fasteddy106]

You might want to think about a flex drive for a cordless drill and a long drill bit to remove the rot. If you have the space it could simplify removal of the rot. Both tools are available at Home Depot or Lowes. If the rot area is not too large you get structural foam from the site below fairly reasonable....

http://www.uscomposites.com/

[PAR]

The bottom line is you need to expose the core, remove what's bad, replace it, then bond the cutout back in place. Sometimes, you have to be fairly inventive to get around things. I've hung upside down inside lockers or hatches to access a tight spot to preform a repair. Welcome to the wonderful world . . .

It wouldn't be hard to use a hook, bent scraper or other device to gouge out the core. Lots of thickened epoxy and a replacement piece of core will get it done. It only has to be pretty on the outside.