tranducer mounting

[hankster]

while in the process of cleaning up the transome (removing the bottom paint ) i encounterd three holes from a prior transducer mount that I had not known was there. the bottom paint was hiding them. Anyhow in the process of using a steam cleaner to clean up the hull I blasted out some of the silicone that was sealing the old holes. Upon further inspection i noticed that they were not sealed that well in the first place because the silicone pulled right out. So i used a slightly larger than than the hole drill bit to remove the remainder of the silicone and found a bit of blackish wet wood fibers as well. so I just incresed drill bit size untill I jot to what I thought was good wood in all the holes. AM I doing right here? Now I want to fill in the holes with Marine tex but am complexed on how to make sure I fill the hole completelly with the putty. Any tricks to this? or just keep jaming it in there untill I think their filled. Or should I be going a diffrent route?

[thataway]

Unfortunately, no surprise there. One should NEVER use silicone to fill holes in the transom, some PO did not do you a favor. You have a wet core. Next take a Dremel tool, or you can put a bent coat hanger in your drill and undercut the fiberglass. (see the posts on how to prepare holes in the transom). You want to be down to completely dry wood. You want to have the undercut fiberglass for strength to keep epoxy in place. You want to went out the dry wood with thin epoxy before you put in thickened epoxy. If the holes are small, Marine Tex should be OK, but be sure that the holes are completely filled. I would also use a counter sink, and flare the outside of the hole to give a bit more surface for the MarineTex to adhere to.

You might consider drilling pilot holes for the Starboard into these epoxy plugs you will now have in place. Check around for any other areas filled with silicone.

[Ray]

I just re-did my transducer mounting. I had to re-fill in some old holes and make some new mounting locations.

I did the "hollow-out-the-core" thing and back filled with epoxy.

The problem with filling is getting it all in there and filled with no voids. I had a thought and tried it out - it seemed to work really well. I drilled ANOTHER hole , albeit a small one, to allow filling the void.

I drew up a picture of what I did:



As I said, it worked well for me.

Ray

[hankster]

I can see your using some kind of liquid epoxy that you can shoot thru a syringe to fill the void. That wont be the case using the marine tex putty. Any paticular brand or type. I'm not that familiar with epoxy or fiberglass for that matter.

[Ray]

Epoxy is not hard to work with at all - it's not rocket science to use well. (although there is plenty of technical stuff available to turn it into rocket science, if you like that sort of thing!)

Might make sense to buy some and experiment with mixing and some plastic cups. Good skill to get good at. You'll learn a lot.

Lots of internet how-to's around including Gougeon Brothers web site(s) http://www.epoxyworks.com/

[Sunbeam]

You're getting good advice on how to handle the holes. I agree that you want to get all the wet or damp core out. I like to use a Dremel #115 bit (when I have a large enough hole to fit it in). I use a dental pick on smaller holes - it's amazing how well it will "grab" core and pull it out.

After vacuuming out the hole, I clean with acetone or denatured alcohol, then tape everything off (to avoid sloppy mess) and wet out the inside of the hole with neat (i.e. plain/liquid) epoxy. I either paint it in with a pipe cleaner or a bent acid brush or I sometimes inject it in with a syringe, let it sit and soak in, and then suck it back out (which leaves the soaked in stuff there). Next I fill the hole with thickened epoxy (colloidal silica usually, or structural filler).

As was mentioned, filling a "blind" (no outlet) hole can be tricky because it's easy to get air pockets (which is not good). I have used a number of ways to get around the problem.

1) Use a syringe (if you don't thicken the epoxy too much you can still run it through a syringe) and start with the tip at the back/bottom of the hole. Start filling and as you do slowly withdraw the syringe, filling as you go. A variation is to tape a piece of tubing onto the end of the syringe (such as heat shrink tubing).

2) On really deep holes or ones that have a lot of "upper cave" where you have back cut, method #1 might still leave air in that upper cave part. I have put a second piece of tubing in the hole alongside the syringe, with the inside end up in the "upper cave." Then I use the syringe (in the back of the hole) and a lot of pressure to flood the hole with thickened epoxy. Air will come out the secondary tube. A fair bit of epoxy will also flood out the hole, but if you plan for that you can re-use it for the next hole(s).

3) Sometimes I drill a small second hole at a high point (depends on situation/cosmetics), sort of like Ray shows, only I then fill from the bottom hole and let the air come out the small upper hole. Sort of like filling the lower unit on an outboard. When epoxy starts to come out the upper hole you can tape it off and nothing will leak out the bottom hole, so you can tape that off at your leisure (after withdrawing the syringe).

If you don't want to buy all the various epoxy/fillers/etc., I have recently been trying out WEST System's "610." This comes "pre-made" in a caulking tube and either mixes itself as you press it out through a special mixing tip, or you can dispense it and then mix it sort of like one of those 5-minute-epoxy tubes (then put it in a syringe). It is thickened with colloidal silica. WEST say that it can also be used to wet out holes (even though it is thickened). I'm not sure how they do this, but they have it formulated so that when you push or move it it thins out, and when you stop it thickens up and just sits where you put it. Pretty slick! Although it's around $22 a tube (no way you would build a boat with it!), for small jobs I think it may actually save money because you can mix a very small amount, go through fewer gloves, it's very tidy, etc. I'm going to keep a tube "in stock" from now on. My only wish is that they made it in a smaller tube so I didn't have to carry a full-sized caulking gun around to dispense it.

There might be some places I would want to wet out with neat epoxy before using 610, but then I would be comfortable wetting out with it in many situations. They also say it will wet out up to 12 oz. cloth, but I've still always used traditional epoxy for that (so far).

WEST sells small syringes, or you can get them on Amazon, etc. (the ones with the longer plastic cone shaped tip are called "catheter tips").

Note that epoxy has insufficient UV resistance, so it needs to be painted or gelcoated over to protect it.

Couple of "random" tips:

1) Along with all the other protective gear, I wear disposable nitrile gloves. I don three or more on each hand, then I can just pull off a contaminated one mid-job and keep on going with the fresh one that's behind it.

2) On smaller holes I tape right over them with blue tape and then cut out the hole with an Exacto knife. Sounds putzy but I find it works out well when all is said and done (with epoxy, I find that prep/protection is always worth it over just hoping not to make a mess).

Good thing you caught the silicone (don't get me started! and are taking care of this now

[hankster]

LOVE the six10 epoxy!!! did my best to dig the holes out of the wet wood. then drilled them once again to be sure. but nothing over a 1/4. then bought the 610 and a couple of small syringes... filled them from back to front, let em dry and...
WALA.... holes are filled!!!! to my satisfaction!!! thanks for the hook up!!!

[Sunbeam]

Cool! Glad you posted back about how it went

For a long time I was all "old school" and felt like "I don't need to buy that fancy-schmancy, expensive, pre-mixed stuff; I've been making my own for years, after all." Well, after ignoring that voice in my head and trying the 610, I found that I really like it and I now consider it a great tool in the epoxy box. And I have saved a fair bit on blue tape, gloves, and Tyvek suits (I still use all three with it, but don't go through nearly the volume as it's so darned tidy to work with).