How to fix cracks in hull to stern tube?

[Eastward ho 24]

I’m not sure the difference in stern tube ,shaft log,cutlass bearing, so pardon the confusion when I describe my situation. After stripping down the antifouling I noticed some cracks 2-3 inches in the stern tube hull joint. The cracks look like how mud would crack when dried up. I just got the boat so I have no idea how long they have been there but, there was paint in them, so I assume for a while.. It looks like the fiberglass ends and (there was some of the red low density fairing compound ?)to encapsulate the stern tube and make the transition. The cracks aren’t in the laminate just in that red fairing crap. Is this how this is usually done? I would have thought this would be an area for sure to use high density filler and or glass laminate. Any how I got the Dremel out opened them up and put a little bevel in them and drilled a hole at the end to dissuade the cracks from running. It looks like I ground right through, Which was shocking to think that’s all that was there. seems pretty shoddy.it’s a Downeaster 32 the rudder is in the way of pulling the shaft, and removeing the rudder you might as well say is impossible. To pull the shaft I’d have to lift the motor and slide it foreword under the motor. And by all means I’m not trying to get into that. I took a few pics. My plan was to fill the cracks with west epoxy and high density filler. Then I have orderd some west system 727 episize biaxail cloth I was gonna lay 2 layers over the whole thing. Or looking at the pictures do you think I should grind out a bigger beveld round hole and layer a few patches in there the glass over that, rather then thick end epoxy in the cracks? Any advice? Materials sound right for the job? I was considering filling the cracks in with marine Tex and glassing over all that. But I’ve never used anything other then west and I’ve never had a problem with their stuff. I’m in all out panick mode is this as bad as I’m making it out to be?

P.s I’ve used 1708 in the past and the string that holds the fibers together doesn’t “dissolve” in the epoxy. I assume this is the case with the west system too. In the description it mentions a light string to hold it together. Is this gonna be ok below the water line?

[skipmac]

If this helps.

Stern tube - hole or tube in the hull where the prop passes out of the inside to the outside.

Shaft log - in yachts it is usually a bronze casting that is mounted on the inside end of the stern tube.

Cutlass bearing. A tube shaped bearing, usually bronze outside, rubber inside lining that supports the prop shaft outside the boat, close to the propeller.

[Orion Jim]

Shoddy application of fairing compound (body filler). If you find voids just grind them out and apply fairing compound in a more workmanlike manner. It is not structural.

[Eastward ho 24]

So I have the bronze tube inside and you can see from the Ickes a flange with 2 bolts bolted into the hull. So that’s a shaft log? And inside the shaft log is the cutlass bearing? No stern tube then. My other boat has a fiberglass tube glassed into the hull I assume that’s called a stern tube. Each of these has a cutlass bearing inside them?

[flyingfin]

Do Not Use Marine Tex! First, make sure the underlying structure is very dry. Hit it with a hair dryer, then shoot it up with MEK or acetone, wait a day or two, then hit with the hair dryer again. If uncertain, use more MEK and wait longer.

Once you know it is dry, blow it out with compressed air. Then start to fill the crack. Use a good structural fill. A two part epoxy resin mixed with loose, chopped strand and micro spheres. Build it up in layers 4-8 hours apart depending upon ambient temperature. Then finish with two layers of cloth to span the crack, each saturated with epoxy resin. The first cloth should be one-inch cloth wider than the crack, the second cloth should be one-inch wider than the first. Hit it with another layer of epoxy resin mixed with cabosil or microsphers, then finish the entire area with fairing compound. Dont worry about what it looks like, it is underwater! You want to make a structural repair, not a cosmetic one

[skipmac]

Originally Posted by Eastward ho 24

So I have the bronze tube inside and you can see from the Ickes a flange with 2 bolts bolted into the hull. So that’s a shaft log? And inside the shaft log is the cutlass bearing? No stern tube then. My other boat has a fiberglass tube glassed into the hull I assume that’s called a stern tube. Each of these has a cutlass bearing inside them?

Hard for me to tell perfectly from the photos but yes, in your case, looks like there is a shaft log in the hull and most likely inside that is a cutlass bearing. One might call the hole where the shaft log is installed the stern tube.

[Eastward ho 24]

That made my day! I’m thinking it’s major structural and picturing motoring along and the whole stern desinegrating and going down! Should I grind all the red filler out and refair with some high density? NOT STRUCTUAL! Haha I think I stared at it today in 20degrees for an hour with a tee shirt and smoked 2 packs in frustration contemplating how the worlds gonna end.

[Eastward ho 24]

Does it look like I’ve ground out the cracks enough? I kinda wanted to keep as much in there that wasn’t cracked but I also know there Needs to be a bevel there for surface area for bonding. I could put a real bevel on it but was thinking it’ll be glassed over so it would hold all together

[jimbunyard]

If you're sure they are surface cracks only, then fill it with whatever you want, paint it and go. No real need to glass over it; that will just make the 'patch job' take longer.

The fairing compound looks an awful lot like automotive-type bondo, not good for underwater use. Also looks like someone has bondoed (or whatever it is) over bottom paint, not so good from an adhesion standpoint.

If it were me, I'd grind it all off and start over, there's not much there and the peace of mind knowing what's under the filler, and that whatever it is has been taken care of in a permanent manner is worth the slightly longer time it will take.

Epoxy or good quality polyester resin will work equally well, the important thing is to use a filler designed for underwater applications. Epoxy may have an advantage in that the availability of the proper materials in the quantities you'll need for such a small job may be better...

https://www.westsystem.com/filler-selection-guide/

[rognvald]

Eastward,
My opinion is that your repair is not strictly cosmetic but partially structural since it encases the stern tube. I would grind it out, fill with West System Hi-Density epoxy, fair and then use some 1708 biaxial cloth to cover/seal your repair before priming and repainting. If done properly, you won't have to fix it again. I hope this helps . . . Rognvald

[Eastward ho 24]

Id say this is great news thanks! Only issue is making the but end where it is at a 90 degree angle I'm thinking of encasing the bolts into the glass repair and the day it needs fixed I'll have to cut it out. The bolt on the top and bottom they just go into the glass to hold the log ?

[flyingfin]

Here is good video on how to make West epoxy putty repairs, all the way up to peanut butter consistency for working upside down! Dont be tempted to save a few dollars - always use epoxy resin when doing repairs below the waterline

https://www.youtube.com/watch?v=qRCi...eature=related

[skipmac]

Originally Posted by rognvald

Eastward,
My opinion is that your repair is not strictly cosmetic but partially structural since it encases the stern tube. I would grind it out, fill with West System Hi-Density epoxy, fair and then use some 1708 biaxial cloth to cover/seal your repair before priming and repainting. If done properly, you won't have to fix it again. I hope this helps . . . Rognvald

This would be my guess but without a close look, it's impossible to be certain how structural or not the cracks are. That area does need to be structurally sound so if the cracks lead farther into the glass than is obvious from the photos or there's any delamination I would go for a more aggressive repair.

[boatman61]

I'd suggest WS epoxy with WS high density to just below the surface's then finish of the last couple of mm with a low density filler and sand till fair.. with three coats of epoxy painted on the finished surface area.. just to be sure.

[Geoff H.]

Curious about the "do not use marine-tex" comment. Can you please illuminate? Thanks!