97 Maxum replacing old transduce with new one through transom hull cored need help

[gica]

Hi guys so the 1/2 foot below water line hole is about 1inch wide and 1 1/2 deep with at least 1/2 inch wood core in the middle and fiberglass 1/2 inch inner outer layers. the original hole was 3/4 and don't know what was used to plug it since I didn't do it. Had to enlarge because the Laurence 3d Structure transducer cable ending is that wide.
I will make the hole round with a hole saw and I wanted to know what to use to plug it with the cable going through.
I can cut a dowel and epoxy it but what epoxy to use to also do the inner exposed wood.
Then do I use resin and fiberglass cloth in layers on a beveled surface if so which is safe to use epoxy or polyester resin?
And then the gel coat or whatever to get some kind of closeness to the blue color. Maybe use a neutral one and mix in a color additive, don't know.
Have been reading for 2 days and haven't seen anything that shows all this.
I need to use this in salt water by the way.
So any help is greatly appreciated. Thanks in advance.

[gulfstar37]

Little confused on what your trying to do here. So a little more information would help with maybe a photo or two.

The part that needs clarification is relating to "I will make the hole round with a hole saw and I wanted to know what to use to plug it with the cable going through".

Are you asking how to install the underwater transducer or how to seal wiring underwater?

Again a photo or two would be helpfull.

[gica]

The hole is not round and if I want to put a dowel I have to cut into it with a hole saw and make it round it would be easier to cut the dowel then. I am trying to close the existing hole with the transducer wire inside and avoid drilling another hole above even though this is what most suggest to put it above waterline somewhat.

[gulfstar37]

Ok I see what you have and trying to do. Just to recap what I see in the photo, you have a surface mount transducer with the instrument wire that is routed on the outside of the transom of the I/O boat. This wire is currently routed through a hole close to the waterline. Is that correct?

Couple things come to mind. If water egresses into the hole, it will surely compromise the 1/2" wood core and the transom integrity will suffer or fail completely. As you know this is not good.

I'm going to refer you to a utube channel "boatworks today" within the last couple months of weekly vlogs, he has completely disassembled and rebuilt a Burtrum runabout transom that had water intrusion into the core. Good source of real life issues of boats.

Anyway I tend to agree with some of your previous advice suggestions. It's really hard to seal a wire by itself going through a bulkhead, transom, or deck especially if it potentially can be submerged. There are special through deck fixtures that may help.

https://search.defender.com/?expression=Wire+seal

I've also seen round rubber seals of similar construction for wire penetrations. Don't believe either is rated for submersion.

Usally for something like this application you see the instrument wire enter up higher on the transom or even on the deck where the possibility of submersion is eliminated and only water splash or rain is the threat.

So permanent fix, in my opinion, would be to pull back the wire through the current hole. Prepare that hole for fiberglass, core, fiberglass repair. Coat with color match gel coat, buff and drill new hole higher up on transom using a seal similar to above. Google Gougeon West System. On their website you can download several manuals on how to prep and repair fiberglass holes. Quite detailed. They also have a free knowledgble technical staff you can call.

Good luck.

[gica]

OK I will take out the cable and fix the hole to avoiding the core being water contaminated. Can you walk me on the most efficient steps for that?
Want to cut a wood dowel for the inner core part using maybe marine epoxy adhesive and drench the whole area in it. After that bevel the area and use epoxy resin and some proper mesh in layers on top? I heard the epoxy gets hot and you have to be careful not to ignite. I know gel coat over epoxy is not recommended so should II use whatever the recommended primer and then gel it with some color pigment for my mica mist 97 blue tint?
Let me know if there are some particular resins meshes primers and gel coats I can use.
I already have the west system fiberglass boat repair kit from here:

https://www.amazon.com/WEST-SYSTEM-1...NsaWNrPXRydWU=

And Evercoat Marine Polyester Gel Paste from here

https://www.amazon.com/FIBRE-GLASS-E...gateway&sr=8-3
Let me know what else I might need. I know it's not a major job but wanna do it right

[gulfstar37]

Sounds like you have read quite a bit on the process you need to follow. Keep in mind this will take you a little time to complete especially if your not familiar with epoxy or polyester and fiberglass. Following is just one way to make the repair. There are many more but the general process will be the same.

This is not going to be considered a structural repair and plugging the core hole with a wood dowel or exterior plywood is perfect for this.

First is to mask off the whole area including the transom you don't want any resin to drip on or run down. This includes on the interior side of the transom and don't forget the floor ground ect. Once it hardens it is very hard to remove.

Easiest way is to use a hole saw same diameter as dowel and drill out the hole on the boat but you can use exterior plywood and make your own plug by using the same hole saw on the plywood and save the wood plug from the saw interior. This can then be glued in the hole with epoxy or polyester resin that has been thickened with microfibers that you may have in the West kit you mentioned. You will want to leave the surface of the plug below the surface of the outside so additional fiberglass patches and fairing compound can be applied after preparing for fiberglass patches.

From here I will again refer you to the utube channel "boatworks today" episode hopefully copied here

https://youtu.be/kxWDhwfCgNE.

If it worked out right you should just have to click on it to view it. Seeing him do the rest is a lot easier than me trying to describe it. He talks about the pros and cons of using epoxy vs polyester so you can decide which you want and goes through the process of completing the repair.

As far as the resin generating heat (exothermic reaction to cure) is correct however this can be controlled by not mixing up larger batches and keeping spread out. So use common since and caution. Many epoxy manufactures make several different types of hardener, fast, slow, to alow working time for the ambient temperature and time to cure. So don't mix a pint or more of epoxy in a plastic cup and let it set. It will generate a lot of heat maybe to the point of foaming, smoking and possibly ignition.

Another thing is to use personal protective gear such as rubber gloves, eye protection, and a respirator especially in enclosed areas. Old cloths or coveralls is always a good thing while working with this stuff.

Enough said again good luck!

[gica]

I think I watched every video this guy has and he is very informative. My question is if I use gel coat and therefore have to use polyester resin for the gel to stick to wil the polyester and gel combo be impermeable enough for salt water? Will it blister because of the below water location?

[gica]

https://www.youtube.com/watch?v=GwS4YgoGFm8

[gulfstar37]

gica, I don't think anyone can guarantee any boat coating will be blister free forever. There are many variables that contribute to blister causes I'm sure you can search even in this forum. Frankly there is a lot of debate over what the actual causes are. Even new boat manufactures have limited warranties covering their product. So you use engineering controls to minimize the chances. Epoxy construction, vinylester resins and coatings.

For underwater bottom waterproofing controls, epoxy coatings such as easypoxy, interpertech and others are additional coatings applied prior to applying antifouling bottom coating. Some manufactures even claim their antifouling help to provide some waterproofing properties.

The vast majority of boats, especially older boats use polyester based resins for construction. Normal gel coat is just basically that same polyester resin that is tinted with a coloring agent applied prior to the laminating fiberglass. That's probably the major reason why usally polyester is normally used with gel coat repairs and epoxy is over coated with a paint. I've heard you can color epoxy although this does not seem to be the norm. One downside of epoxy is it will degrade with UV Ray's. Could be one reason painting over epoxy is done.

Maybe I'm missing from your photo of the hole your talking about repairing is where the current transducer wiring going through the transom is actually underwater or will this get an occasional back wave that will cover over for a second or so?

[gica]

It's right below the water line.

[gica]

So I covered the old hole wasn't too hard I have worked on fiberglass repairs before. I have taken the boat out since , in salt water mind you, and the repair is great.
I still want to put the wires for the Lowrance 3D structure scan transducer through hull above the water line. Are there any brass or plastic fittings that the wires could go through? the book says the hole diameter is 33mm(1.3"). I wanted to make it look good not just a random hole with some sealant. A cover of some sort.