How many holes in one's hull are too many?

[HeadedToTexas]

I am planning an electronics upgrade for next winter. Part of that upgrade will be modern sonar. We have simple Uniden and HawkEye depth finders at the lower and upper helms respectively. Of course the new electronics will not use the same legacy transducers.

I am weighing the pros and cons of keeping the legacy depth finders versus removing the old transducers and using one of the existing holes in the hull to mount the new transducer. Redundancy is good, though both are electronic and subject to the whims of power. We already have what feels like a bunch of through hull fittings. How many is too many?

 

[DavidM]

Every hole is a risk: Unsealed core leaking water into it, thruhulls leaking or catastrophically failing (came close on a 15 yo boat, probably an electrolysis problem), losing prime on an A/C pump connected to other devices (not a risk but a benefit for independent thruhulls).

Only you can decide whether the benefits justify the risk.

David

 

[O C Diver]

My boat had 5 seacocks and 4 transducer protrusions including 1 with a massive faring block that looked like the bow of a boat in front.

Back in the 90s, I was running a charter boat for a friend of mine. At 18 knots we struck something. The transducer was in a similar faring block. It sheared the faring block and the transducer off flush with the hull. Miraculously no water came in, because the transducer shaft and nut were secured by 5200. Ever since then, I've avoided protrusions that the leading edge isn't flush with the hull.

I have one seacock (for my sea chest) on the bottom, the pumpout seacock on the transom, and 3 transducers are essentially flush with the bottom. All other holes were properly ground out and filled in with fiberglass.

Just because you aren't using a seacock or transducer doesn't mean it can't fail.

Ted

 

[Mac G]

As DavidM said, every hole is a risk.
If you can re-use an existing one then that is one less new one.
That being said, however, our GB has 27 thru-hull fittings - 14 below the waterline and 13 above the waterline.
Found and inspected and memorized location of every single one of them inside and out when we first bought the boat and before we started steaming so I would know their condition and location in the event of an emergency.
So the total number is not as critical as being aware of them, inspecting them, and making sure they are all in good condition.
I plan to add 2 more above the waterline for new holding tank vents because my existing set-up is deficient and poorly designed in that regard.
Have never been afraid to drill a hole in a boat as long as it is backed-up with a good game plan, executed properly, installed properly, and routinely inspected and maintained going forward.
Good luck with your project.

 

[marcs]

There is no one answer, but if your new electronics can display output from the same transceiver at both helms (ie. you are only adding one new one) I'd look at replacing one of the existing transducers with a new one and leaving the other as a backup.

It would depend on how easy it is to reuse the existing hole for the new transceiver.

 

[HeadedToTexas]

Reusing the hole to mount the new transducer would be the way to proceed, unless there is enough value to having a back up depth sounder. I don't have a frame of reference to judge how often the depth input on modern MFDs fail. If it did, it sure would be nice to simply flip on the old sounder.

 

[psneeld]

Reusing the hole to mount the new transducer would be the way to proceed, unless there is enough value to having a back up depth sounder. I don't have a frame of reference to judge how often the depth input on modern MFDs fail. If it did, it sure would be nice to simply flip on the old sounder.

Yes..... a backup sounder is a nice thig....

 

[O C Diver]

I have 3 depth transducers. 2 are on the NEMA 2000 network and 1 is a video display on my MFDs. The video transducer died last spring. Very reassuring to have backups until hauling out in the fall.

Ted

 

[tego]

Perhaps you could use an in-hull transducer for your backup? I have two transducers mounted in my hull this way and they both read to at least 200' (I don't have any deeper holes in the river to check their ultimate depth readings. They're simply imbedded in pure silicone in my bilge at the bottom of the keel of my Albin 27FC (you can't do this if your mounting point is a cored part of the hull). My keel is about 1/2" thickness of solid fiberglass. I did this on several vessels when I ran the wood shop at Rybovich about 15 years ago. Ben

 

[Bacchus]

Perhaps you could use an in-hull transducer for your backup?.... Ben

Ben beat me to it but above would be a strong contender IMO.
In hull Xdcers work well especially for emergency / back up use unless your hull is cored below WL.

 

[HeadedToTexas]

Yes..... a backup sounder is a nice thig....

Very reassuring to have backups until hauling out in the fall.

Very reassuring indeed. Thanks all.

 

[Hippocampus]

Tego has is right. Other choice is to put speedo and depth inside a box glassed to the hull with a watertight removable lid. Use a water tight path for wires or a conduit brought above the waterline.

 

[old-School]

Any hole that is not absolutely essential.

 

[Don L]

How many is too many?

When water comes IN the opening you reached the 1 too many point