What You Don't Know That Can Sink Your Boat

[Frank Vernet]

A cautionary tale for all....with pictures.

This winter's big maintenance/upgrade project is all about Sirius' motor - the original Universal 5424. I had it pulled a few weeks ago to replace two broken mounts, remove/replace the leaky main coolant pump, address the rusty engine bed, etc and now have the luxury of unprecendented access to the engine compartment (duh!) and a chance to look at everything closely. I decided to replace the traditional stuffing box with a dripless seal and replace the cutlass bearing. The work is being done at Herrington Harbour North. They went at it Monday and discovered the following:

This is where the shaft log hose started:


With a simple twist, the hose came off:


As you can see the hose is “wasp waisted” where the hose clamp had been installed. The clamp was not bearing on the bronze shaft log casting. The hose engagement on the bronze shaft log is about ¼”:


Looking at the bronze tube, you can see that there was almost no contact between the bronze casting and the hose:


This is the orientation in the boat. You can see that there was no hose clamp on the shaft log. Up in this picture was Up in the boat, so the wasp waist is on the bottom of the system and would have been hard to see:


The deteriorated shaft log seal and it looks way older than 5-6 years:


As I had the shaft, cutlass bearing and prop replaced professionally 5-6 years ago, I never suspected that the installation was so poorly and dangerously done.

So a lesson for us all - inspect closely this linkage and water barrier that is buried deep in your engine compartment. Had mine failed, as it surely would have, it wold have been a truly threatening situation.

[JWSutcliffe]

Scary stuff, although I can assure you a lot of us have found not-so-good conditions in the shaft log area. Difficult access in our boats makes routine inspection difficult if not impossible. Even adding a dripless seal is not a perfect solution, since the rubber bellows is surprisingly thin and susceptible to damage. Should mine fail, there is no way I could access it myself. My only answer to this is to carry a wax toilet seal ring in the emergency supplies locker. If all else fails, the soft wax can be easily pushed into the gap between the stern tube and prop shaft (or just the empty stern tube if the prop shaft is gone.) Since I inspect my prop zinc several times a season and have changed it underwater I know I can stay down long enough to shove some wax in, assuming the weather conditions are not adverse.

[Jim Cornwell]

Underway with any kind of a sea running, diving on the shaftlog to plug it from outside would be extremely dangerous, it seems to me. If the hull rose and fell on you in the water, your neck or back could be injured and you'd be done for. What's needed is some magical flubber-like substance that could be shot in from inside the hull. Something like "Great Stuff" sold at Home Depot for sealing cracks and air leaks at home but with instant set in the presence of water and pole-mounting. I wonder if there is such a thing. I'd carry some, because I'm in a cold sweat right now thinking about a significant leak way back there in the inaccessible gloom.

What I do carry, in addition to a variety of tapered cedar plugs is a selection of foam "nerf balls" that can be jammed in any odd shaped opening(and are great at keeping nesting birds out of the open end of Yankee's boom). But these wouldn't help with a gusher around the shaft.

Bill Crealock was really on to something with the engine access hatches in all those Pacific Seacrafts of his....

[Gary H]

My new to me CD22D presently sits with its Yanmar engine removed for repairs so this is a perfect ime for me to inspect the mysterious stuff behind the engine. Only problem is, I am not sure what to look for. Any pointers would be appreciated. I was planning on repacking the stuffing box but what else should be inspected?

[Frank Vernet]

My new to me CD22D presently sits with its Yanmar engine removed for repairs so this is a perfect ime for me to inspect the mysterious stuff behind the engine. Only problem is, I am not sure what to look for. Any pointers would be appreciated. I was planning on repacking the stuffing box but what else should be inspected?

Gary,

In addition to the above, assess the condition of the teak blocks that seat the intake and outflow thru-hull seacocks. I am replacing the sea-water intake teak block as it is rotting, seeps and will have to be replaced in the not too distant future. May as well do it now while the engine is out of the way.

[JWSutcliffe]

Jim:

I agree, not the thing to do with a sea running. Have gone over the side while underway to clean the engine throughhull strainer, but that was in quiet seas. The only possible equivalent of your suggested magical flubber-like substance that I know of is what I rely on as my final fallback ....... adequate hull coverage insurance.

[Johnd]

Flex Seal™ - Liquid Rubber Sealant in a Can! | Official Site

Maybe this stuff would b useful?

[Maine_Buzzard]

How about the Forespar Truplug?

http://www.forespar.com/Truplug/index.php

I also saw somebody doing a demo at last year's Boatbuilder's show with a foam or wax sealant. I looked at the exhibitor's list, but did not see it. I may revive the thread in a few weeks. I like the toilet wax idea. a ring or two will fit right in next to the diapers in the first aid kit.

[Steve Laume]

I redid Raven's hose when I had the engine out a couple of years ago. It is not an easy job to get in there and replace that thing, even without the engine in the way. I had to chip away a bunch of filler and then redo it afterwards. A longer bronze tube would be a big help. After seeing these pictures, I am very glad I did the work myself. That job was just plain sloppy. The guy who was tightening that hose clamp must have know, or should have known it was not doing it's job properly. I am a bit surprised it didn't start to spin with the shaft. I think you would have known that something was not right when it slipped off and started to spin.

What I am really interested in knowing is just how much water would leak past the shaft bearing if the stuffing box was not there. Is it gallons per minute or hours per gallon? Although this is a very serious situation, I believe it would probably fail when the engine was running. I think you would hear the thing flopping around back there and begin to investigate. So then how much water was coming into the boat would be a crucial question. Even with the engine running, I can't imagine that a bilge pump couldn't keep up.

Diving on the thing while underway would not seem necessary. Nor would trying to goop the whole thing up from the inside. You would probably just make a big mess and still have a trickle. I do like the idea of carrying some plumbers wax. That stuff could also find other uses. Great for wood screws and makes for an excellent grip on your oars. I am always amazed that in today's world of synthetics we still use bees wax to seal our toilet bowls.

The worst case scenario would be that the hose popped off when the engine was shut down for the day. You would then leave the boat with the leak just beginning and no way to know about it. I still wonder how much water would come in with a tight fitting shaft bearing, Steve.

[Maine_Buzzard]

My father the Civil Engineer just choked on a doughnut, but if i use a common flow measurement equation, a 1/2˝ hole 4' underwater will flow almost 7 gallons per minute. Even if the slots in the cutless cut that in half, I'd hate to be the one on the manual pump.

I'm replacing the stuffing hose before Guppy splashes.

BTW, a new prop shaft was $340, including a face cut on the coupling and new keys.

[Zeida]

My word, Frank! Those pictures are really scary. I am also paranoid about that part of Bandolera. We share the same engine.
But on most every haul out I make it a point of checking that hose, clamps, bolts, shaft, etc. super carefully.

[Neil Gordon]

My father the Civil Engineer just choked on a doughnut, but if i use a common flow measurement equation, a 1/2˝ hole 4' underwater will flow almost 7 gallons per minute. Even if the slots in the cutless cut that in half, I'd hate to be the one on the manual pump.

At 7 gallons a minute, how long will a CD 28 continue to float?

[Steve Laume]

I do not possess the knowledge to do the calculations but before we start asking how long our boats would remain afloat it might be a good idea to reevaluate the figures.

I realize the 7 GPM was a rough estimate served up with a disclaimer, based on a 1/2" hole, 4' below the water line. I would still like to believe the the shaft in a good cutlas bearing would not equal a 1/2" unrestricted hole. We are only talking about a number of grooves that would measure in the 32's of an inch. They are also 4" long so there would be resistance to figure into the flow. Depth would make a great difference also. The bottom of my keel is a bit over 4' below the water line but the shaft exits less than 2' below the water line. This depth could be further reduced by heeling. So what is the calculation for eight or so pin holes with 4" of resistance 2' below the water line? Make each one 1/16" for ease of calculation.

While the idea of a wax seal on the outside seemed like a good solution at first glance, it might make matters worse. It could work to seal off the water flow if the shaft wasn't turning. If you did run the engine it might serve to starve the cutlas bearing of lubrication causing rapid wear and generating heat. The turning shaft would probably break the seal and your problem would return in a greater magnitude.

Note to self; inspect the hose and keep it in good order. If anything should ever go horribly wrong; run the engine as little as possible, sail the boat hard to induce a goodly amount of heel and keep up with a pumping schedule based on the water flow. Use the manual pump to conserve battery power if needed. Once you made it to a protected area, break out the water proof duct tape.

That hose looked extremely scary but I still doubt if it would sink you unless the boat was unattended. Rather than how long it would take to sink, I am always more interested in how long it would take to reach the floor boards.

Always the optimist, Steve.

[Duncan]

At 7 gallons a minute, how long will a CD 28 continue to float?

Fresh water or salt

About four hours, on those assumptions, but the shaft log obviously won't leak at that rate because it isn't four feet underwater.

The point, I believe, is that shaft logs are a vulnerable point. I have a "dripless" bearing, but I think that maybe this sort of fitting makes us careless. Isn't every hole in the boat a potential disaster?

[Jerry Hammernik]

My 28 #341 does not have a shaft log hose. It seems like the 28 may be the only model that doesn't. I'm wondering why. And why they didn't build others without the hose. It would seem like one less potential failure point. Am I missing something obvious?