Came aboard this morning to go over boat and clean up and have noticed a pretty deep crack in the stern. It seems to be on the top inboard a bit about 30 cm from transom but looks like the crack has made it way to the transom.how have i dont this i wonder? Backstays too tight? Climbing up the stern on outboard? Battered around by 3 m seas on tuesday? Hittind the sand bar??
Bit of a worry!

First thing to do is check whether it is a gel coat crack, or through the glass structure. Can you see inside to check?
Your transom has already been modified, and it is certainly not a good idea to climb on board by clambering over a motor way out the back of the boat.

That doesn't look to be just a gelcoat crack, seems to have been some serious stress there.

Is that glass over a wood core? If so you might have to take a plug to see what's happening. Polyester on wood can be a problem because it can become a bit porous and cause dry rot. It's time consuming but not a major drama to replace a transom.

Steve's boat has what appears to be an extended transom, with the motor on a bracket on that. Loaded way more than the original design, but the crack may be related to the modification and a stress concentration point. My guess is it has cracked where some reinforcing stops.

Needs a detailed investigation of the internal structure, as it is non-standard.
More pics please. A closer look seems to show this is the cross coaming and not the side. That may be easier to fix.

May be related to getting towed off the bar ?

Need a.picture showing better location.
Definitely not a gelcote crack.
Difficult to tell without seeing location of backstay or outboard mounting but both rigging to tight or stress from to much weight on transom could cause.

Drill a 3/8 hole near the crack and see what condition the core is in, If it's ok patch the hole with epoxy bog. That's a structural crack and unfortunately you need to deal with it whatever the cause, but wether it was over tensioned back stay or outboard or whatever it is not good. We need to see some photos from further back to give some collective wisdom (wild surmise) about how to make a repair. If the core is good, maybe just a grind and chamfer and some double bias tape, then general reinforcing to stop a repeat. Sand and a layer of 250 double bias in epoxy or vinyl ester both sides. I would double up the reinforcing for 300mm in the centre.

Good luck.

When i was towed off the bar i was also using the ob. There was no sudden jolts. It was a gradual dismount.
There was a jolt when after i was on the bar a gust came before I got the jib down.
The ob has a good reinforced area of 4mm stainless steel on the inside of the stern.
I may have started a small crack as i stupidly used that section as a work bench trying to panel beat a sheave with a hammer during mast work.
My stays are between 11-13 %of their breaking strain but they are much tighter than they were. One of the backstays locking nuts has even got a cut through it ive recently noticed. I will loosen the forestay and backstays back to their original tensions.

Its not just through gelcoat. It seems to be some dort of stress crack.

I also dont know why some keep saying my stern is modified. My stern is like alot of tophats. See here.
My stern is exaclty like this one and many other tophats mark 1s. Some mark 1s like philips have a semi well in transom but alot dont either- like mine. Theres another tophat in my bay exactly like mine and ive seen many others exactly like mine so im curious why somethink my stern/transom is modified,strange or different.

Not from the sandbar. It looks suspiciously like some moron has run into your transom with a power boat. Repair as per PhoenixStar but I would stick with epoxy.

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Sectorsteve said..
I also dont know why some keep saying my stern is modified. My stern is like alot of tophats. See here.
My stern is exaclty like this one and many other tophats mark 1s. Some mark 1s like philips have a semi well in transom but alot dont either- like mine. Theres another tophat in my bay exactly like mine and ive seen many others exactly like mine so im curious why somethink my stern/transom is modified,strange or different.

Steve, it's the silver fern on the stern that's doing it .

That's it uncle bob

Mmm i dunno ramona. More likely ive overtightneend. Had a feeling i did regardless of using the gauge.
Im always overtightening stuff...

Steve,Your Top Hat is a normal Mk 1 . The crack is only in the cockpit coaming ? Saying this the Top Hat Mk 1 was moulded in 3 sections the hull the deck and the cockpit . I'm only guessing ? but looking at your photo I think it's the gelcoat/bog that is cracking . I would hit it with a grinder or a chisel and see what is happening ,but my guess is it's old age and a dickie repair . If it was structural the transom would have a crack where the deck joins the hull .Remember the hull is one piece and the deck and is bonded to the hull . Top Hat website is where you should have a look and join .

Cheers Bear
X TopHat Mk1

I tend to agree with ramona.
The back stay would have to be seriously tight to do that. Extra stress by over tightening plus a hard nock from behind maybe

I'm thinking Steve is right, it looks like the cracks, there appear to be more than one, are a consequence of an overtight rig and the hull being worked in a seaway.
I'm home next week so could motor over one day and we could put two heads into a cause and solution. Payback for the help you gave me getting away to Lord Howe. Let me know if you want to.

Thanks jbear. Yeah i need to open this in tophats forum. Im a member. It is just the coaming correct. Its not running down the transom fortunately but the crack is big and runs right across that coaming. Yes john theres a fair few cracks and we got battered around 3 out of four days. Ive a bit of mast bend and im as tight as i can get on the backstays. Would love for you to have a look.
I will really be getting a good rigger to go over her prior to next years qld trip. Probably sooner rather than later as now theyre more available.
For now ill loosen the fore and backstays as they were pre mast.

The radiating cracks in the stern look to me like you've been hit. I'd be checking with my insurer b4 I did anything.

Steve That crack is an infil that the Mk1's had ,The outboard motor sat on the transom . But my MK1 had an inboard and an infill panel filled the gap and that crack is the infill panel that has been glassed in .

Cheers Bear

theres no evidence of impact on my stern. Theres no evidence of any sudden impact anywhere.
Ive been with my boat every day for the last 2 weeks except nye where i had a mooring at callala bay right in close amongst alot of other boats and next to some friendly people spending the night as were many in the bay sleeping aboard.
anythings possible i guess, but im from my experience with these things its always my trial and error actions that cause these things so im not about to blame anyone else.
If id been hit, i would notice it. theres no impact. its like the coaming has been pulled apart which is probbaly what happened.
The main crack opening is on the top of the coaming.

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jbear said..
Steve That crack is an infil that the Mk1's had ,The outboard motor sat on the transom . But my MK1 had an inboard and an infill panel filled the gap and that crack is the infill panel that has been glassed in .

Cheers Bear

good man cheers bear!

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jbear said..
Steve That crack is an infil that the Mk1's had ,The outboard motor sat on the transom . But my MK1 had an inboard and an infill panel filled the gap and that crack is the infill panel that has been glassed in .

Cheers Bear

This is why I thought your stern was modified. The Mk1s I have seen have the outboard sitting on the transom, not in a well or on a bracket. Hanging an outboard off a bracket adds extra stress on the transom. A person using the outboard as a step adds still more stress. Probably your boat originally had an inboard.

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Yara said...

jbear said..
Steve That crack is an infil that the Mk1's had ,The outboard motor sat on the transom . But my MK1 had an inboard and an infill panel filled the gap and that crack is the infill panel that has been glassed in .

Cheers Bear

This is why I thought your stern was modified. The Mk1s I have seen have the outboard sitting on the transom, not in a well or on a bracket. Hanging an outboard off a bracket adds extra stress on the transom. A person using the outboard as a step adds still more stress. Probably your boat originally had an inboard.

You're totally right. It did have an inboard. But like many older tophats when the original motor dies the owner usually decides to replace with an outboard. My boat has been up the top of australia and had 3 owners. She was mostly used for sailing longer distances and was.set up for this. The transom is reinforced and the engine has extra supports in the form of a stainless plate. Ive never seen another tophat with rigging as heavy as this one. In fact many 30+ footers arent rigged as heavy as kia kaha. I still need to get things right but this boat isnt weak. If anyhing im the weaker in this relationship!

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jbear said..
Steve That crack is an infil that the Mk1's had ,The outboard motor sat on the transom . But my MK1 had an inboard and an infill panel filled the gap and that crack is the infill panel that has been glassed in .

Cheers Bear

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Sectorsteve said..

Yara said...

jbear said..
Steve That crack is an infil that the Mk1's had ,The outboard motor sat on the transom . But my MK1 had an inboard and an infill panel filled the gap and that crack is the infill panel that has been glassed in .

Cheers Bear

This is why I thought your stern was modified. The Mk1s I have seen have the outboard sitting on the transom, not in a well or on a bracket. Hanging an outboard off a bracket adds extra stress on the transom. A person using the outboard as a step adds still more stress. Probably your boat originally had an inboard.

You're totally right. It did have an inboard. But like many older tophats when the original motor dies the owner usually decides to replace with an outboard. My boat has been up the top of australia and had 3 owners. She was mostly used for sailing longer distances and was.set up for this. The transom is reinforced and the engine has extra supports in the form of a stainless plate. Ive never seen another tophat with rigging as heavy as this one. In fact many 30+ footers arent rigged as heavy as kia kaha. I still need to get things right but this boat isnt weak. If anyhing im the weaker in this relationship!

Steve,
Sorry I did not not comment before but I have very poor internet at the moment.
Bear is correct, it appears that the bog repair to the old joint has come undone.
That joint is not inline with the deck below but is about 20 mm offline so do not cut deeper than 5 mm or you will be going into the deck below.
Check under the centre, up inside, and see if there is any distortion to the glass work that has been done to fix the removable panel.
If not its only a gel coat/bog repair.
Mark 1's have about 5 sections for the deck plus the removable stern door which has been glassed in on your Top Hat and some joints are not that good.
Check on the outside of the transom to see if there is any bog coming out there as well.
Phillip

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Sectorsteve said..

From your video the reefing line on your boom looks like it needs to be further aft to give more foot tension when reefed.

Looks like the bog/joint on the transom infill plug starting to come out to me also.
Probably caused by the OB on the bracket rocking & rolling on your recent trip, putting stresses on those joints (most likely while it was raised & sailing rather than when it was being used).
I doubt the rigging tension is causing it (as you could kick out the middle of the transom & not lose any structural integrity), although having said that one problem of having over-engineered standing rigging sizes, is the extra tension that needs to be on it.

Someone on the Top Hat site has given good explanations of what mast rake & rigging tension is best on a TH (it might have been Bear or Tales).

After you have taken the grinder to it & repaired it, you can help prevent the OB putting extra stresses on the transom, by strapping the OB to the pushpit while it is tilted & lifted up, while sailing, just to stop or lessen that small "work hardening" if you like, of the bracket to the transom.

PS good video

Rather than making the repair....another option could be to "re-instate" the OB well.
That really is one of the real beauties of a MKI over MKII's & III's imo, is you can have the outboard sitting in the well & tilt it up to get it out of the water. Without having the hassles of it hanging all the way out the back on a bracket off the transom.
Maybe when MB is onboard with you having a look, he can shoe-horn you into one of the lazzarettes to have a look along the inside of the transom.
If the transom infill panel has been retro glassed in, it may be an option to remove it???
If it has been glassed in from day 1 it may be a little more involved, but worth some thought I reckon.
cheers