Wiring for Depth Finder

[BigDog9721]

I've got a depth finder that was wired on the outside(!) of the boat and need to have it wired nicely and cleaner on the inside of the boat... what is everyone's thought on drilling a hole just above the transducer on the transome and sealing it up and then wiring up the inside of the boat to the dash board? Any thoughts would be greatly appreciated!

 

[b_arrington]

I've got a depth finder that was wired on the outside(!) of the boat and need to have it wired nicely and cleaner on the inside of the boat... what is everyone's thought on drilling a hole just above the transducer on the transome and sealing it up and then wiring up the inside of the boat to the dash board? Any thoughts would be greatly appreciated!

That’s the normal way to do it. Drill a hole well above the waterline above the transducer and run it inside to the helm. Use a clamshell cover, and seal the hole with a good marine sealant like Life Calk or 3M 4200. Even better is to oversized the hole, fill with epoxy, then drill the proper size. This seals the core of the transom.

 

[BigDog9721]

i don't understand why you would oversize the hole...

 

[BillK2632]

Here is how I installed mine - like mentioned above sealed the hole with a good sealant and put a clamshell over it. Also sealed each screw as they were installed. This was years ago when I bought the boat, have had no problems.

 

[BigDog9721]

perfect... thank you so much! do you know what b_arrington means on the oversize hole?

 

[BillK2632]

Yeah, many boats have decks, hullsides and even bottoms that are wood cored, vs solid fiberglass - it makes them lighter and stronger. When you drill or cut through the coring you then run the risk of the now exposed wood coring getting wet, rotting etc. A best practice when cutting a hole through a cored hull is to cut the hole larger, fill with epoxy, then cut the proper sized hole. The epoxy permanently seals off the coring so you are not relying on a sealant that will likely start to leak over time. Another way to seal the cored hole is to coat the inside of the hole with epoxy, not as effecting as filling and drilling, but better than just sealant. In your case the transom is certainly wood cored. Basically plywood sandwiched between layers of fiberglass - if that wood starts getting wet from a hole for the transducer or even where the sterndrive cutout is, you end up with a rotten transom and a big repair. I usually coat the inside of the hole with epoxy and use sealant like BoatLife caulk - but what Brad says is the textbook way to do it.

 

[BigDog9721]

Got it. Thank you!