Crack next to rudder post, general advice needed....

[Olly75]

Hi all
I've recently discovered a crack next to my rudder post. I'm going to haul out in a couple of weeks and am looking for some general advice on how to get it fixed. I will be employing professionals to do the work but would like some knowledge before they start discussing how they think it should be fixed!

Externally the crack is 90mm from the rudder stock and about 100mm long. Internally the crack is not visible but you can see where the inner layer of fiberglass has delaminated and is allowing water in. I've attached a couple of photos of the inside delamination.

Any advice/ knowledge is welcome

[Searles]

Grind out until the crack disappears when the area is crack tested with dye and accatone ,find out if the base for the rudder stock tube or bearing in the layup ,this may not be simple fix .⚓️⛵️

[neilpride]

It is an easy fix, although you will have to peel on the outside too, I would delimit a wide area around the rudder post on the inside, you will have to deepen the crack with a grinder, if you go through do not worry, also on the outside, do it in a V-shape, Now on the inside, once the crack is covered, in that area you have delimited I would start to reinforce from the rudder post to the limit of the area you have delimited with FG, increase the thickness of the laminate including the rudder post.

[Nicholson58]

Is the boat under warranty? Looks clean and not old.

Is those a cantilevered rudder? Did the rudder receive an impact?

What boat?

Is the crack outside in the same location?

My thought is that grinding out as Searies says is where you start. Follow the leak path to expose delaminated structure. This could go from inside and outside. In the end all damaged structure needs to be discovered and a plan for replacement formulated. You may want more structure than the original design. Do not leave any damaged layup as this is a future path of ingress as well as a stress riser under load. I would use only epoxy.

[Searles]

The big question ,is how did this happen ,something has caused the cracking and probable delamination ,is the rudder stock bent and stressing one side ,investigate .⛵️⚓️

[Olly75]

Thank you for the responses!

The boat is a Bruce roberts 44, built in 1979 so not new! But in relatively clean condition

It either happened through hitting a log (I'm in indonesia...) and know of one log strike at night, or more likely when I met a reef- this was a slow impact on the bow and when I dived it didn't look like the rudder or skeg had impacted, and there is no visible damage to either.

My initial nightmare thinking was to grind out both inside and out, including removing the rudder stock and bearing and then fibreglass over the whole lot and after creat a new opening for the bearing. But could I just grind round the stock and leave it in place (assuming it's not damaged as well)?

At the moment I can't tell if the rudder stock is bent, as there is a fiberglass sleeve around it that rises above the waterline to prevent ingress if the bearing starts leaking.

I'm not expecting an easy fix, just hope to be able to avoid the nightmare scenario!

[Olly75]

Ps... I think the hull is around 20mm thick in that area...

[catsketcher]

As the others have said - you need to grind it out from both sides. It is like what a dentist does, grind out till you have nice solid glass laminate, both inside and out. I would also remind you that you need to grind the vee at a very shallow angle, don't just do a 45 degree deep vee - I would do about 8 or 6 to 1 (maybe 4 in a pinch) to get the glass lying in the same plane as the loads and give a lot of bonding area to the deeper laminates.

I would use epoxy and lots of +- 45 fabric. I would not use choppy and polyester for this - you want strength and shear strength. West 105 and double bias faric is great at conforming to different shapes. Start thin at the bottom of the crack and widen out (or do this upside down with wider on bottom). I might have to add some thickener with the epoxy on the first layer of glass to get it to sit properly on the ground out old laminate. Then wet on wet and glass it up in up to 5 layers or so with peel ply on top. The laminates can look a bit dry when you stack them like this but the resin from the previous layer will help wet out each subsequent layer.

The good news is that it is underwater. This makes the outside glassing job so much easier. It can be easier to fix a hole properly under the waterline (as long as there is no core damage). Although it seems counter intuitive, a hole below the waterline can have extra glass added and no one will ever know. You then cover the extra glass (with its slight but smooth bump) with very orange peel antifoul which hides lots of sins and then to top it off, you pop it below the water where no one will ever see. Much easier and stronger than having to do tricky work to get a strong laminate on the topsides to stay below the surrounding glass so you can add fairing compound and then you have to fair, again and again and then paint a large area.

I would not be worried about the crack too much. You could do the job yourself, especially if someone who builds composite boats could tell you what to do, but I don't think the job will be too hard. You may like to add some gussets onto the rudder stock at the bottom and then glass these with more +-45 fabric (400 or 600gm) to better help with distributing the load from the bottom of the rudder to the hull skin. (I would think triangles about 250mm up the rudder post and along the hull, coved and glassed with 3 layers of 600gm would be nice and help stop any more cracks developing)

cheers

Phil

[s/v Jedi]

I don’t agree that it must be ground from both sides, at least not yet. You must determine the side it is closest to which I guess is the inside. Then grind from there until it is gone, then see how much you have left. If there is a lot of good structural fiberglass left on the outside, then I would not remove that.

On the inside, you need to grind a 12:1 bevel so measure the depth it was grinded out, multiply by 12 and mark that outline. Now grond a smooth bevel to that mark.

Build up after good cleaning with denatured alcohol, starting with just brushing epoxy resin, then a full covering layer of 1708, wetting it out and adding smaller patches to fill it up, using the thin aluminum roller to work out air and excess resin.

If there is less than 1/2 of the thickness left after grinding, or if there is any doubt on delamination then repeat the same procedure from the outside.

[AKA-None]

I don’t think I need to point out you should be hauled when you do this 🥴

[capt jgw]

Bruce Roberts design. Do you know who built it? A lot of them were back yard builds and there's no way of knowing if anything was done right. Anyway I'd over build the area all the way around. It broke once so probably wasn't strong enough originally.

[Olly75]

Originally Posted by AKA-None

I don’t think I need to point out you should be hauled when you do this 🥴

[Olly75]

This is all great stuff, thank you. I'm defo not going to do this myself, I have learnt over the years that fiberglass isn't my strong point!

The boat was professionally built at the Vannoy shipyard in Washington. As far as I understand they built 7 and mine was number 4.

[PippaB]

At least for the inside I think the approaches are too complicated. A 12:1 bevel is nice, and can make a smooth, fair patch, but the from the pictures I would guess fair is not a requirement at this location. And grinding a nice bevel around all the obstructions could be a challenge.

On the interior I would grind out the crack to find its extents, and to get it dry. Then fill with epoxy bog that uses a structural fiber additive until flush with the interior surface. Grind down the interior just to get a clean, relatively smooth surface out to the same 12:1 dimensions, and then lay a tapered patch on top of the crack to the same laminate schedule as you would use had you beveled. This will create a bit of a lump where the patch is applied, but if the area is not cosmetic and a lump is not objectionable then it could be a lot simpler than trying to put in a bevel in that location.

I would probably grind the crack on the outside as well, fill with the same structural bog, and put in a small bevel and patch to make it look nice, while relying on the interior patch to provide the laminate strength.

YMMV and conditions on site may warrant an entirely different approach.

[s/v Jedi]

Originally Posted by PippaB

At least for the inside I think the approaches are too complicated. A 12:1 bevel is nice, and can make a smooth, fair patch, but the from the pictures I would guess fair is not a requirement at this location. And grinding a nice bevel around all the obstructions could be a challenge.

On the interior I would grind out the crack to find its extents, and to get it dry. Then fill with epoxy bog that uses a structural fiber additive until flush with the interior surface. Grind down the interior just to get a clean, relatively smooth surface out to the same 12:1 dimensions, and then lay a tapered patch on top of the crack to the same laminate schedule as you would use had you beveled. This will create a bit of a lump where the patch is applied, but if the area is not cosmetic and a lump is not objectionable then it could be a lot simpler than trying to put in a bevel in that location.

I would probably grind the crack on the outside as well, fill with the same structural bog, and put in a small bevel and patch to make it look nice, while relying on the interior patch to provide the laminate strength.

YMMV and conditions on site may warrant an entirely different approach.

We can only hope you will hire a pro too when you ever need a similar repair