Plumbing Thru Transom

[jmb23802]

I purchased a used boat recently and one of the things that needs attention this off-season is re-sealing the hole where the speedo tube passes through the transom. The prior owner added a transducer to the transom and ran the transducer cable through the same hole in the transom with the speedo tube. Both the speedo and the depth finder seem to be working ok but I have never seen the cables strung through the transom this way. Since I have to re-seal the hole in the transom because the PO used silicone instead of much better options commonly available, am I fine to leave both cables in the same hole (assuming they are not pinched when I get in there) or is this bad business and I should separate the transducer cable into its own dedicated passageway?

I would rather not drill any more holes in the transom, but if I am just inviting trouble the way it is currently setup, then I will just have to drill.

Thoughts?

 

[Rickmerrill]

I think reducing the number of holes is a good idea as long as you can seal it up good. I'd seal the wood with either epoxy or fill it with PB (enlarge hole if required) and drill a new hole in that. That way if the sealant fails the wood is still protected. Then I'd put some 4200 in it. No sealant lasts forever, most claim 20 years but that's probably in ideal conditions so I'd probably replace it every several years as a maintenance item.

 

[UConnMRB]

I will not be able to directly address your question, for I do not possess the knowledge needed. I can tell you though that a few pictures will help the experts. Most people open a free photobucket account and post the image code links to their thread. Not only will pics help in the advice they give, but also, everyone loves to see pics of other peoples boats!

 

[Woodonglass]

I'd drill a 1" hole through the transom. I'd then cut a piece of 3/4" PVC to the length of the depth of the transom. I'd us a hack saw to cut some notches in the pvc to allow the Epoxy something to "Bite" into and then mix up some thickened epoxy and glue the PVC pipe into the hole. Run the lines thru and call it good. If you put the hole up high you won't have to worry about sealing it.

 

[Rickmerrill]

Dog-gone-it! I took the line out about putting the hole above the waterline. I've seen some where they hold the speedo tube with those clips that screw...right into the back of the transom.

 

[jmb23802]

So far, it sounds like the two lines through one hole is not a problem as long as everything works. That's good.

I like the pipe idea - being a freshwater boat with an I/O and a euro style hull (Four Winns Freedom 170) I would prefer to keep the stern aesthetics clean and I'm afraid putting a pipe high enough to avoid water would not be the best fix from a cosmetic perspective (speedo thru-hull is currently level/below the water line), but I still like the approach. Maybe I will do the pipe on the current speedo hole then seal it up with 4200.

Taking it a step further, I have to take the boat to the FG guy for some keel repair before Spring so while he is applying gelcoat on the keel he could gelcoat around the hole and make it look like a factory job. Plus, since the PO put silicone in there, drilling the hole out a little bigger is probably going to be the best and quickest approach to getting a silicone-free hole anyway.

Rickmerrill - what kind of clips are you referring to? My boat has a pitot tube shield that turns the tube down and protects it from impacts on the bend, but I don't think there is any sealing action from this...?

 

[Rickmerrill]

Sorry for the confusion, don't know what they are called but the three little clips holding the speedo tube straight.

If your going to have some gelcoat work done anyway this might be a good time to plug up that old hole and put a new one up higher. There's a reason some people are Supreme Mariners and others are CPOs yah know...