SEALER FOR FLOOR PLATE

[drsethsr]

Hey,

I had to remove the floor plate in order to access the bilge pump, which was not working.  I used a knife to cut through the sealer.  After replacing the bilge pump, I fitted the plate back down, which went back in snugly.  What do I need to do to make this watertight.  Do I need to completely remove the sealer that I cut, or can I get away with just putting some sealer in the cut line that I made to remove the plate.

It looks like to completely replace the sealer I cut, it would require one or two caulking gun cartridges.  What material should I use?

I also need to install a transducer on the transom.  What material do I need to make the holes waterproof?

Dr. Seth Anderson
1991 Osprey 200

[RickK]

Hey,

I had to remove the floor plate in order to access the bilge pump, which was not working.  I used a knife to cut through the sealer.  After replacing the bilge pump, I fitted the plate back down, which went back in snugly.  What do I need to do to make this watertight.  Do I need to completely remove the sealer that I cut, or can I get away with just putting some sealer in the cut line that I made to remove the plate.

It looks like to completely replace the sealer I cut, it would require one or two caulking gun cartridges.  What material should I use?

Do you have any pix of what you're talking about?  Seems like a lot of caulk to seal an inspection plate.  
Here's how to post pix.

I also need to install a transducer on the transom.  What material do I need to make the holes waterproof?

Dr. Seth Anderson
1991 Osprey 200

3M 5200 will work well for you.  Dab the hole and then coat the screws after you put them through the base or wire clamps and before you put them in the holes.

[LilRichard]

The best way to mount ANYTHING to a transom is to overdrill the holes by a size or two, fill with thickened resin, then redrill with the proper size bit... this leaves a layer of resin in the hole to avoid any water intrusion... then follow Rick's instructions on 5200 in addition.  The last thing you want is water in your transom.

[aqua70]

Any above/below waterline  caulk /silicone should work for the plate.
Over drilling the hole and filling it and then redrilling it could create a problem. The problem is when you redrill it using a smaller size bit it may disturb the bigger hole that you drilled and filled already resulting in the first hole that you drilled becoming detached or loosened.
     We tried this method on a 2x4 and the original hole that was filled detached from the wood.
     The best analogy I have is it is like placing a cork in a hole and drilling into the cork. Then the cork loosens up and the screw in the cork pops out with the cork.
    Number one, when mounting a transducer you want to drill as small a hole as possible to accomodate the screws. Use plenty of caulk/silicone whatever you choose. The pressure of the screws along with any swelling of the exposed wood should swell around the screws and have enough self supporting pressure to seal the drill hole.

[LilRichard]

I respect everyone's opinions, but I would rather have a layer of resin between the screw and the wood... gives you more protection.  I have overdrilled holes and backfilled many, many times with no issues.  You can always use epoxy for added security if you choose.

[John Jones]

Small stuff like transducers I just use 5200.  Bennett Trim Tabs recommends dipping the mounting screws in epoxy.  I was not comfortable with that alone.  I mounted the trim tabs with no sealer.  I then took them back off and just slightly overdrilled the holes and filled with thickened epoxy.  The next day I redrilled and dipped the screws in epoxy to re-mount the tabs.  No sign of problems and it's going on 3 years.

Motor mounting bolts and such I firmly believe in the overdrill/fill/re-drill procedure.  I have never had a plug work loose.

[aqua70]

If it works for You than go with it. I encountered a problem with it. We tried your suggestion back in March and maybe it was us, maybe it was the boat, but it did not hold. We had the advice of the local Marine Railway guy who services the bottoms of the local scallop, clam, fishing fleet. He advised us to drill the smallest hole possible and caulk it. "Why disturb more than you have to?" That was his opinion.

[gw204]

The best way to mount ANYTHING to a transom is to overdrill the holes by a size or two, fill with thickened resin, then redrill with the proper size bit... this leaves a layer of resin in the hole to avoid any water intrusion... then follow Rick's instructions on 5200 in addition.  The last thing you want is water in your transom.

That's exactly what I did...to every single hole in the transom of my Grady after I bought it.  I removed everything but the thru hulls (that had been recenly rebedded) and the bracket.  As for every other hole, I drilled them to 1/2" diameter and 1/4" deeper than the screw required.  The inside of each hole was painted with unthickened epoxy and then the hole was filled with epoxy thickened w/ cabosil.  The unthickened stuff was used first as it allows the thickened stuff to bond better with the existing substrate.   Do it this way and you'll never have to worry about one of the plugs breaking free.

[ddd222]

if u are replacing an old transducer, then filling the old holes w/ resin like gw204 suggested is a good idea. If u are mounting a transducer for the 1st time, drilling the suggested diameter w/ the suggested bit, and dipping the screws all the way down in 5200 or boat life before u lock them in should be sufficient.
     I actually had to relocate my transducer 1/2 inch deeper on my transom after install, i had a 4 foot rooster tail when the boat went on plane, so try to get it right the 1st time