Box over Thru Hull

[thinwater]

Yes, I had a paddle wheel failure. No poor maintenance and the only warning I got was when my daughter told me there was water on the floor. The cause was never obvious, but I think an o-ring may have slipped when it was reinstalled after cleaning; it was pulled during the survey and it was our delivery trip). It did NOT leak for 2 days before at the dock.

In my case, it was in a bulkheaded compartment , which someone had fitted a hose through without sealing. I jammed a rag around the hose, pumped the main hull, and sailed home (2 days).

Yes, a plug would have slowed it, but remember that you can't hammer a plug into plastic. It's also not a lot of fun working elbow-deep in 35F water.

I think putting through hulls in bulkheaded compartments is VERY smart. When I later installed AC, I put a bulkhead in to protect the through hull. In my case that was mostly a matter of glassing inside and existing cabinet. It won't always be practical. I would not box over it unless it needed the protection from kicking or similar, and the lid would need to be easy to remove (wingnuts or just strew off).

 

[Captain Larry-DH]

Recently I read about a boat that sank due to a speedo paddle wheel thru hull failure.
This is the only thru hull on my boat.

Is there any value to building a water tight or near water tight box with removable lid
over the fitting to minimize potential flooding due to failure?

I haven't heard of anyone doing this.

This is a great idea if properly executed, and used to be done as a standard thing in ships. I think it's something boat builders should bring back, as a surround to the standard through-hulls. It was called a "sea chest". The key is to build the walls of the box high enough to be above the waterline. https://en.wikipedia.org/wiki/Sea_chest_(nautical)

 

[JohnShannon]

I think it is an excellent idea. The Box would have to come up above the waterline. So it might intrude into the cabin. I think in the end boats sinking isn't a huge problem for the manufacturers (maybe it is for the particular sailors) that would require them to solve the problem. From time to time an unsinkable boat is released this costs more and they don't seem to sell. Well Pogos are unsinkable and folks seem to like them.

 

[topcat0399]

It would be fairly easy for me to build glass in a box for my thru hull fitting.
It lives just in front of the bulkhead that forms the rear wall of the Vberth just behind my 4-5gallon water jugs.

So once again I will take all of the various and excellent views I have been blessed with receiving on this topic and make my own decision as I always must. I'll try harder to keep dumb jokes to myself.

I am a land locked trailer sailor in the middle of cheeseland. There is no such thing such as other boats and/or other sailors to rely on or share ideas or practices with. I don't know how other boats are rigged and this is the only sail boat I really ever been on. There are no sail lofts or marinas. For now I will struggle along until the day comes when I can put the boat into the river system and head for the Gulf....

 

[dlochner]

It lives just in front of the bulkhead that forms the rear wall of the Vberth just behind my 4-5gallon water jugs.

A critical piece of information. If the jugs come loose and start banging against the through hull, it will be at greater risk than if nothing is around to hit it. Securing the jugs or protecting the through hull are possible solutions.

There are 2 avenues to the through hull failing. One is the fitting itself gets busted or cracks. This is a pretty low probability event and it would take something hitting it with considerable force to make it break. The other problem, and one that @thinwater seems to have experienced is the transducer being installed into the through hull improperly. There should be at least 1 O-ring around the transducer to seal to the through hull and then a cap that threads down on the through hull fitting. If the 0-ring is damaged or missing and/or the cap cross threaded or not screwed down well water will find its way in. The solution to this problem is to make certain the transducer is installed correctly.

 

[BigEasy]

You can build the enclosure; however, you really need to have a means of accessing the transducer to clean it.
My speed transducer is located in the forward bilge area that is enclosed by the hull liner grid; nothing else in that compartment. Floor boards protect the transducer from accidental impact within the hull. I actually use the manufacturer's custom fitted blank plug most of the time; the paddle wheel plug fouls every 2-3 weeks during the summer, on the Gulf Coast. I use SOG on the chart plotter most times on day sails. If I am going on a weekend cruise, I will place the paddle wheel and then remove it, to prevent it from fouling. To prevent the paddle wheel from cracking, be sure to remove it and place the blank plug on haul outs to prevent the Travel Lift sling from breaking the paddle wheel.

 

[topcat0399]

Wherever I build or install something into the boat I always try and imagine inverting. The water jugs are well secured and the transducer isn't in any danger from them. The danger would be from doo dads I might toss down in there.

I don't see boat slings in my future (yet) but going on and off the trailer luckily the paddle wheel seems to always clear OK.
Do I need to make a habit of pulling the transducer and installing the plug while trailer loading?

My biggest worry would be running the paddle wheel onto a rock.....

 

[topcat0399]

Yes, I had a paddle wheel failure. (snip)
Yes, a plug would have slowed it, but remember that you can't hammer a plug into plastic. It's also not a lot of fun working elbow-deep in 35F water. (end snip).......

Care to expound on that?

 

[dlochner]

My biggest worry would be running the paddle wheel onto a rock.....

If you drive your boat up on to some rocks at a fast enough speed to damage the through hull, you will have bigger problems than a damaged paddle wheel.

Essentially what you are asking is a risk assessment and management question. Is there a risk of the through hull failing? Yes. How likely is it to occur? Not very likely. How can the risk be managed and mitigated? Proper installation, good maintenance, and routine inspections should be adequate. More elaborate solutions are possible as are less productive options, like a hope and a pray that it won't fail.

There are other risks, like rigging failure, life line failure, rudder failure, centerboard pennant failure that are more likely to occur with equal or greater catastrophic results. Time and money spent on those items will reap greater safety dividends than building a sea chest around a through hull.

The biggest risk to safety is skipper inexperience. Time on the helm in a variety of conditions builds experience, there just isn't any shortcut to get experience, although asking questions and learning always helps.

Keep sailing!