Old screw holes - what to do

[sidechoke67]

I just installed a new fishfinder and had to drill new holes for the transducer. I am debating between filling the old screw holes with MarineTex, or putting the old screws back in with 4200. Putting the old screws back in is easier, and leaves the holes in case I ever go back to the old style transducer. However, the MarineTex will look better, IMO.

Are there any other obvious pros/cons that I'm missing? Anyone ever do one or the other and with they had done something different?

Thanks for any thoughts and info.

 

[Mark42]

Re: Old screw holes - what to do

You pretty much covered it. Marine Tex the holes or put back the old screws with 4200. I would chamfer the holes and fill with marine tex, and sand flush. If you ever want to use the old transducer, just drill out the holes again.

 

[grego]

Re: Old screw holes - what to do

Why didn't you just enlarge the existing holes "problem solved". or maybe I don't get it. you can glue a trasducer down to the inside of the hull with rtv, no drilling needed. I may not be reading this right? can you explain why you are drilling??

 

[sidechoke67]

Re: Old screw holes - what to do

I had just a depth finder on my boat. I replaced it with a fishfinder/depth finder. The pattern for the new transducer is completely different from the old transducer. I already drilled the new holes for the new transducer, but now need to fill the screw holes from the old transducer. In both cases the transducer is on the stern.

The real draw of putting the old screws back in with 4200 is that the temp requirements for 4200 are lower than MarineTex. The 4200 says it is OK to use at 55 degrees, the MarineTex seems to really want 70 degrees for 24 hours. In upstate NY, we don't even have a high temp forecast above 65 or so for the next 10 days. I wish I had read all the labels before I drilled the new holes...if I had, I would have waited and started this project in the middle of summer when temps are more accomodating. Right now, these screw holes are the only thing stopping me from boating.

Thanks for the responses!

 

[Mark42]

Re: Old screw holes - what to do

....

The real draw of putting the old screws back in with 4200 is that the temp requirements for 4200 are lower than MarineTex. The 4200 says it is OK to use at 55 degrees, the MarineTex seems to really want 70 degrees for 24 hours. In upstate NY, we don't even have a high temp forecast above 65 or so for the next 10 days. I wish I had read all the labels before I drilled the new holes...if I had, I would have waited and started this project in the middle of summer when temps are more accomodating. Right now, these screw holes are the only thing stopping me from boating.

Thanks for the responses!

Can you put a heat lamp on it? Not too close, you don't want to start a fire. Even just a heating pad laid over it would probably work to cure the epoxy. Epoxy cures faster with higher temps. If you used a heat lamp and kept the temps up in the 90's for a few hours, it would probably be cured well enough to use.

 

[tboltmike]

Re: Old screw holes - what to do

Over the years, my transom collected a number of obsolete screw holes. During my restore, I decided to remove the old screws, ream out the holes and swab in a thin slow set epoxy, MAS system, to soak in as much resin as possible. At the same time is soaked wood dowels in the epoxy. They were sized to fit snug in the holes. The remaining epoxy was thickened with fumed silica to make a thin paste and this was swabbed into the holes. The dowels were coated with the paste and driven into the holes. The dowels were cut short enough to drive about 1/8 inch past flush with the transom. The epoxy was thickened more to form a non sagging past to cap the dowel end and screeded flush with the transom.
There were some 10 screw holes to fill. The slow setting MAS system allowed just one batch to be mixed.
Next, I cut a piece of 1/2 thick PVC sheet wide and tall enough to cover the holes. 3M adhesive was used to secure the PVC over the holes. This now acts as a sacrificial mounting plate so that the transom is no longer compromised.

 

[grego]

Re: Old screw holes - what to do

Am I NOT getting this??? Why are people drilling to use a transducer?

 

[sidechoke67]

Re: Old screw holes - what to do

Am I NOT getting this??? Why are people drilling to use a transducer?

My understanding is that it gets a more reliable signal when the transducer is mounted on the stern, as opposed to going through hull - especially on fiberglass boats. Plus, it has a temperature sensor built-in, which I like for fishing - the transducer has to be in the water to pick up the temp.

 

[Tim Frank]

Re: Old screw holes - what to do

Company called Lee Valley Tools in Canada sells a pretty neat plugging system for holes in wood....actually 2 of them.
First option is great for screw holes. It is low-angle tapered cutter that you run in the hole that needs to be plugger. It is the same taper as a standard pencil sharpener produces. Once you have tapered your hole, you rune a piece of dowel through the pencil sharpener, and plug the hole with the resulting taper. You can buy "blank" pencil lengths also....i.e. the wood blanks never went through the lead adding process and are solid.

Second type uses tapered wood plugs for 1/4"...3/8"...or 1/2" holes. You use a tapered plug cutter bit to cut the plugs, then the "correct" drill bit to open or ream the hole to match the plug.
Tapered plugs seat much tighter than cylindrical plugs.

They do mail order sales and their catalogue is on the web. Better description can be found in that than mine here.

These are woodworking tools, but I can't see any reason that they would not be superb in this marine application.