How to fix cracks in hull to stern tube?

[Cheechako]

That is pretty strange crack. I havent seen anything like that. One wonders if something metal got caught in the prop in the past and flailed around under there? Due to the amount of grey filler all around, I would be real tempted to grind a lot of that away and laminate some glass layers over the whole thing. Then grind and fair smooth.
It may be just fine filling it, but...

[Don C L]

Yeah I'm with Cheechako on this, really curious how that crack got there in the first place. I sailed a Downeast(er) 38 many years ago so I know they are pretty beefy there so I am inclined to agree it is probably not a structural problem. I have had good luck with Marinetex but I believe the negativity stems from it being below the water line and the bond of the new resin to old is especially important. So adequate prep and a less viscous resin mix would ensure it gets into the nooks and crannies and fibers better.

[Eastward ho 24]

I wonders why not marine Tex also? Although I discounted it's use for this application after making up a test batch. I think it's to thick to penetrate or absord into the laminate . The stuff isn't cheap I got the big kit and it's a 5:1 mix which is hard to meter beind as it's so thick. I'm sure I could do it right just a little more of a pain in the ass doing so with the stuff laying around. Seems like some really good stuff though. Where would it be good for.

[Eastward ho 24]

It's not an impact crack, or anything hitting from being Tangled in the prop. For lack of a better description looks like how mud cracks when dries. Almost as if the fairing was put on so thick that when it dried it cracked. But couldn't see that being the case since epoxy doesn't "dry". The boat has sat on the hard for a few years, then was in the slip through the freeze of winter for a season or 2. I'd say over the last 8 yrs it hasn't moved other then back and fourth to the lift and when the mechanic took it out to keep the motor up. Maybe some moisture froze in there or that's how the PO put the shaft log in there. Or vibration issues....

[Don C L]

Originally Posted by Eastward ho 24

Maybe some moisture froze in there or that's how the PO put the shaft log in there. Or vibration issues....

Boy, none of those sound good. Has it been in the water since those cracks appeared? No leaks?

[TrentePieds]

Eastward:

You say: "I’m not sure the difference in stern tube ,shaft log,cutlass bearing..." Fair enuff. A great number of people - even yotties of long standing - are guilty of "terminological inexactitude, so let's knock the confusion on the head before we get into the repair procedures,

Shaft log: No frozen snot boat has a real shaft log. When "auxiliary engines" were first fitted to boats and ships, which were in those days of wooden construction, a real "log" (a piece of timber) was fitted on top of the "keelson" (the main longitudinal member of the hull which you would prolly call "the keel") The after end of the Shaft Log butted against the stern post, and the fore end was dead-ended somewhere aft of the engine compartment. This Shaft Log and the stern post were bored fore'n'aft to accommodate the propeller shaft and it's associated gear. Frozen snot boats, being monocoque, have neither Shaft Log in that traditional sense, nor Stern Post. What they often have, though not always, is a metal weldment that bolts onto the bottom and/or the transom of the hull. This weldment, even though it is not a "log" and doesn't look at all like a piece of timber, is nowadays called a "shaft log"

Stern Tube: It was necessary when using a wooden Shaft Log to protect the bore in it from ingress of water. A metal tube - the Stern Tube - was therefore inserted throughout the length of the Shaft Log and through the stern post imbedded in bedding compound, usually "red lead".

On a modern "shaft log, this "stern tube" is an integral part of the weldment and is clearly visible since there is no actual log to encase it.

Stuffing box: Affixed to the fore end of the stern tube is a primitive bearing called a "stuffing box" because i9n days of yore you needed to "stuff" it with cotton twine impreganted with tallow. The fore end of the stern tube had a "cup" on and that cup had an internal taper. On the outside of the cup was a thread so that another, larger cup could be screwed onto it. This cup had a straight bore and was a "slip fit" on the propeller shaft. When you screwed this external cup down onto the stern tube it squizzed the "stuffing" (the impreganted twine) down into the conical cup so it constricted around the propeller shaft. You tightened the cup until, when the shaft was turning, water seeped in around the propeller shaft into the bilge at a rate of a drop every five seconds or so. That is what provided the lubrication and cooling for the turning shaft. These days we have far more sophisticated stuffing boxes.

Cutless Bearing: The term is “cutLESS bearing”, not cutLASS bearing”. It has nothing whatever to do with the weapon called a “cutlass”. A cutless bearing is a bearing “without cuts”, i.e. a cutLESS bearing. The appellation was orginally a “brand” name, way before the concept of “brands” even existed. A “plain” bearing at the outboard end of a propeller shaft would inevitably collect particles of dirt and be scored (“cut”) thereby. The bearing design you know, a fluted sleeve of “rubber” (these days, “neoprene”) permits the flow of water through the flutes to flush out any grit as well as to cool and lubricate the bearing, which therefore is maintained free of “cuts”, i.e. it is a “cutless” bearing.

Now, the little engines we use are quite rattley, vibrating affairs, and the connexion twixt them and the assciated propeller shaft is primitive. Ideally a “flexjoint” should provide that connexion, but for reasons of cost containment (I assume) builders do not provide that. There are several possibilities , but the best IMO is based on the Hardy-Spicer Constant Velocity joint. Two of those on a short intermediate shaft inserted between transmission output flange and propeller shaft input flange will compensate for any misalignment of engine with shaft and preclude transmission of engine vibration to the sterngear and in consequence preclude the kind of stress cracks you appear to suffer from where your stern tube goes through the bottom of you hull.

Insertion of such a joint would IMO be impractical in your case. It would be a major, major and expensive retrofit :-)!.

You can get by with the sort of repair you've already undertaken. Once you are into it, it's not so bad. The objective is to build up the thickness of the existing layup, as it came from the factory, to something that will last a suffient number of years before another repair becomes necessary. If I were you, I would determine the thickness of the existing layup by drilling a 1/8” hole right through it, somewhere within the cracked area, and testing the thickness with the tongue of a vernier caliber. Then, observing all the niceties of doing work in fibreglass, I would, over an area enclosing the stressed and cracked area, lay up an equivalent thickness on the outside of the hull and an equivalent thickness on the inside of the hull.

I hope your new toe rail on the EH24 turned out well :-)

TP

[Eastward ho 24]

Yes it's been in the water every summer for about five seasons I don't know how long the cracks have been there but I know they were painted over and the guy at the yard told me the boat was painted 3 years ago so I would assume the cracks have been there for 3 years I was getting a lot of water in the bilge well I wouldn't say a lot but more than I'd like I assumed it was from the stuffing box but since it's stuffing box is so far packed into the back I just let it pump until Hall out which then I repacked the stuffing gland and I noticed the cracks on the outside so I really hope the stuffing box was leaking and it wasn't coming through the hall at the cracks

[Eastward ho 24]

After sitting on it and thinking I decided I'm going to ground out all the fairing at least all the red stuff get down to the laminate And fair with high density filler and a liar or two of by biaxaill Matt. I'm just hoping when I take all the red stuff out it's not so much that the shaft log will move

[Mike Banks]

It is hard to tell from the photographs, but that looks to me as though your vessel may have been been grounded at some time--and the crack might well be a result of the propeller striking some solid object such as a log.

Hopefully it is just the result of poor quality control when the vessel hull was being laid up.

Best to be on the safe side and have it checked

It sounds daunting--but I think you can find out how bad the crack is using ultrasound. I am not sure how they do it--but I believe it works from sound waves reflected from the discontinuity of a fracture, and that it will detect delaminations as well as breaks.

If it turns out to be bad news--and I hope it is not--here is how I would fix it.

Firstly you have to get a clear area in which to work. If this means removing anything, no matter how daunting this may seem, remove it. At the same time replace any bearings glands etc before replacing what you removed--sooner or later one may have had to do it anyway.

Now you can get to work--and grind away all of the glass and filler.

What you need to do is to get down to the original laminates in the hull to check them for rupture. That crack may well have deep roots--and bogging the exterior is not going to replace the missing hull integrity in such a vital area, if that crack is as serious as I suspect it may well be.

Once you have removed most of any damaged outer glass laminates and polyester resin from the area, see if you can spot any fracture planes or tears in the glass fibres. They usually break or are dislodged from the resin, leaving tiny cracks which are sometimes visible in the light of a bright torch or portable flood lamp.. If you do not see any damage, perhaps it was only the surface resins that fractured--in which case you are lucky--you will not have to replace an entire section of hull and splice it to the surrounding sound hull structure.

Now you have to replace all you ground away as well as the laminates that are suspect. If your boat was built using a chopper gun, the area around stress points at least should have been woven rovings and perhaps some chopped strand matting. You may need to replace the basal layers with rovings if you can--they are a bit stronger, and you will need to use epoxy resin in your new laminates--they will bond to polyester and they will need to be faired into the existing hull as you gradually build up the hull thickness to original dimensions, finishing with woven rovings (pleat them or cut and overlap them to make them fit, using small spots of five minute Araldite to hold the pleats or doubled sections.. I prefer quick epoxy over heat setting glue sticks) and then you can apply epoxy-cabosil bog to get your surface more or less true to the original--then sand it back and finish with a fairing compound of phenolic micro balloons and epoxy resin.

When cured, prime the area using an epoxy primer, and an epoxy or heavy polyurethane outer paint system, followed by the usual barrier coats and anti fouling.

[guyrj33]

You won't really know what you're dealing with until you grid off all of the filler.

I suspect that you'll find the crack at the edge of the metal fitting. If it's not, then if the underlying fiberglass is cracked you'll need to grind the fiberglass back until you hit the bottom of the crack. If the crack is only in the filler you can just replace the filler, bu expect it to crack again in the future.

To repair the fiberglass grid a bevel at a 12:1 ratio with the depth of the repair and rebuild with glass cloth and epoxy resin. I recommend bi-axial cloth.
Do NOT use polyester resin for the repair. Bot yards use it because it's fast, not because it's strong.

By all means read everything you can find about fiberglass repair if that's the situation you find yourself in. West Systems has some ver good guides online.

[Henk Koornstra]

Regardless if it is cosmetic, it is preferred to be done correctly. Sailing will become one less worry, once the boat is back in the water. See the suggestions above how to fix. I would think that this work needs to end up with a new barrier coat, which has not been mentioned above.

Concerning your bolts. If you fiberglass over them, and you need access in the future, you will need to do the work all over in that area. Is it possible to remove the bolt, place a longer threaded pipe back in or a much longer bolt, and when you are all done, return the same bolt or slightly longer bolt to fasten the stern tube?

Good luck, a job well done gives you satisfaction, other jobs give you anticipation to have to do it again. Like an saying in my early career: “There is never time to do it right, but always time to do it over”.

[Eastward ho 24]

Man I loved that eastward ho 24 what a great built boat! Getting into this Downeaster I’ve found it to be anything but well built, or overbuilt. The hull is 1/2 thick in the keel, the ballast is encapsulated but doesn’t run the length of the keel so the aft 3rd of the keel is hollow 1/2”, 1/4” chainplates seem a little light for me so I upgraded to 3/8 bronze. The winches are pathetic, I think they may have been unable to decide if the mast should be deck stepped or a compression post so they half arsed both and the deck collapses and the post crushes.its got a lot of tankage (2) 50 gallon tanks with a single baffle running port to starbd. that are barely glassed in with a piece of light tabbing. Made of Rather thin ss both of mine are cracked and are under the floor with no access. Samson posts through the deck with one bolt into the bulkhead instead of down to the hull. The bobstay fitting is glassed in so you can’t inspect it’s condition. No scuppers other then 2 drains on each side that are through the deck the plumbed to drains in the outside of the hull. Huge cheap windows that cause the deck to flex, with no compression posts on the interior. No knees around chainplates that cause flexing that cause the hull deck joint to leak. Has a nice small cockpit that won’t fill with much water but in the event it does the port and strbd drains are plumbed into a tee into a single hose and exit at the stern on the port side only. There is a seam running under the keel that isn’t rallly joined well and looks like a huge crack running under the keel. I’d say the rigging is on the puny side with the stays and shrouds being 7/16 pins on 7/32 wire and 1/2 pins on 1/4 inch wire for the back and forestay, with no running back stays. I have the mast down and I’d say it’s a pretty substantial piece of aluminium from lefeil, no complaints there. Other then the wooden spreaders. A rudder that would be a major major job to service. I assume on the sailboat Data site they considered 100 gallons of water and 85 gallons of fuel as the ballast with empty tanks an infant baby crawling down the catwalk will have her rocking. The interior is beautiful with tons of room and lots of teak and the boat is very pretty. But hey what do I know. I sure do miss my little eastward ho

[Eastward ho 24]

By the way; what’s with the seam at the bottom of the keel? Do other boats have this? Is it possible the hull was molded in 2 halves and put together? I haven’t seen much but I’ve never heard of or seen a seam along the bottom of a boat that has an encapsulated modified keel.

[rognvald]

"What you need to do is to get down to the original laminates in the hull to check them for rupture. That crack may well have deep roots--and bogging the exterior is not going to replace the missing hull integrity in such a vital area, if that crack is as serious as I suspect it may well be. " Mike Banks


E,
This is very important as you don't want to do a cosmetic fix to something that needs more substantial repairs. Do it properly. Fix it once. Good luck and safe sailing . . . Rognvald

[Cheechako]

Originally Posted by Eastward ho 24

By the way; what’s with the seam at the bottom of the keel? Do other boats have this? Is it possible the hull was molded in 2 halves and put together? I haven’t seen much but I’ve never heard of or seen a seam along the bottom of a boat that has an encapsulated modified keel.

Many boats are done in halves, so that could be what the seam is. It often depends on the hull, and especially the keel shape and depth. You cant laminate down in a deep narrow keel well!

If you are worried about your stern tube going out of alignment, why not install the shaft (even temporarily) to hold it in place?