Broken Tailbone (Keel/Transom)


Mildly Thixotropic
Started all of this back in this thread:
And as of tonight I am down to this, chasing the cracks caused a couple loose pieces to come out near the transom:

Wondering if after replacing the missing wood block (I want the option of either gudgeon system) if I should remove more of the existing glass, the stuff that looks more tan and brown instead of green.
"I like the smell of 4:1 epoxy in the morning..."
200 GSM cloth and 300 GSM epoxy-compatible mat for the metric folks.
Fillet and upper corners of wood block are rounded over so the cloth lays in nicer.
Fun fact: if you stir your epoxy with a stick previously used for yellow pigment, don't be surprised when your fillet material (1 part mixed epoxy, 2 parts glass spheres, 1 part fumed silica) turns out looking like banana creme...

Leaning toward knocking a little more out and putting in a larger patch between the block and transom.

More bigger hole 1" (25mm) more progress glassing. Got to try out some new rotary tool attachments to grind and sand. Low spots were doped with fillet blend before glassing. Ran into trouble trying to bend the tab of mat 90 degrees up the channel in the transom and letting the last 1/2oz (15ml) of fast epoxy go 'exotherm' in the sun on an unseasonably warm early fall day. A few pinholes and some fairing to sort out but otherwise happy with the forward progress.

Rut-roh! What do they say about picking at things...? ;)
Would I be better off with a 'Shoreline' or 'blind' or '?- type' repair for this?
Not much room but here goes, the patch in front of the daggerboard seems to be solid:
Rut-roh! What do they say about picking at things...? ;)
Would I be better off with a 'Shoreline' or 'blind' or '?- type' repair for this?
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For the short term, I'd apply resin into the cut, fold "wetted" cloth over a putty knife, and insert it into the void. Slice the cloth fair, and dress it with more resin--or THIXO.

Trying to make the more-desirable "Shoreline" repair look invisible is a lot of work.
For the short term, I'd apply resin into the cut, fold "wetted" cloth over a putty knife, and insert it into the void. Slice the cloth fair, and dress it with more resin--or THIXO.

Trying to make the more-desirable "Shoreline" repair look invisible is a lot of work.
Thanks, I think I am following you here. Would a person want some fibers going across the crack/split/slot thing as well? I am not so worried about the repairs being invisible, just that they are sound and mostly faired.
Drawing is in Fusion360, scraper is from GrabCAD.
Some progress: worked on the tail to fill in the pinholes and divot from last weekend's patching. I used a heat lamp to warm the area before epoxy was applied and for a couple hours after. We went from near 90F ( 32C) last weekend to 50F (15C) this weekend with frost on the way for next week. I also chased the crack until there was stable material and it's now wider and 9" (22cm) long. I also found another wet divot nearby. I think I'll have room to slip in a backing piece under the crack.
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Got the patches in after preheating boat and patches under the heat lamp.
Hopefully the final result is more sturdy and neat than the look of the rigging.
Wedges and wood bits added after pipes and clamps seemed a touch loose.

I kept going to try to get a chemical bond between layers.
Cleared the rigging, added some epoxy with filler, and taped off for a topcoat of lightweight glass cloth and epoxy resin.
I should have prepped the area a little wider but wanted to get this much done as I may not get back to it for a while.
I decided to trim the top fiberglass and remove the tape before they epoxy was fully cured, to save some grinding and picking out bits of tape later.
Patch sanded and old bailer removed. A couple 'skipperdoodles' on the bailer side that will need filling/fairing.
At this hull thickness (.464"/11.8mm), will I need a 'long/old-style' replacement? Is this dimension smaller on newer boats?
At this hull thickness (.464"/11.8mm), will I need a 'long/old-style' replacement? Is this dimension smaller on newer Sunish?
I've only owned one "old" Sunfish, but that bailer had been removed, and the hole glassed over. Other Sunfish were from the mid-70s, and have never seen a thickness of .464"/11.8mm in that area. My guess is, you'd need the deeper cockpit drainer. (Or simply glue the original De Persia bailer back in place).
The De Persia I pulled is missing the ball, seal, nut, and top half of cap. Bottom half of cap is corroded into the through-hull. It was only held in with love and various forms of resin and caulking. A test-tube sized rubber stopper was keeping the lake water outside the boat.
Spring weather premitting, I hope to be back on completing repairs on this hull soon.
Q: For replacing the wooden blocking behind hardware in a 1960's Sunfish, is any hardwood significantly better than another?
I have some deconstructed pallet wood that seems suitable. I read recently somewhere that white oak, normally preferred for boat frames, is not good with epoxy. Plan is to use the original bronze rudder hardware on this one as my 'grudge match' sailing buddy is also using vintage foils and hardware.

So I will be attaching the blocking here under the deck at the transom, running left to right if the traveller knot is in the top of the picture.

Another day, another 25 cents Canadian....old patches ahead of the centerboard slot came off relatively easy and revealed an old crumbly wound.
I picked at the above hole until the edges were solid fiberglass. I pondered repairing it from the outside and repairing it from the inside by pulling a patch on a backer up to the hull. The spot in question is below a typical location for an inspection port between the dagger board case and the coaming. I recently parted out a small boat that had two inspection ports and I felt good about having a way to see into the boat and access it.

To reduce the number of flips, I taped off the repair area so I could add materials from the inside with gravity helping them stay in place and the tape and stir stick keeping them from sinking too far.

Then I cut the inspection port hole with a carbide blade in a sabre saw after marking its position on deck and drilling a starter hole, pretty much following the procedures by Lee Montes in his YouTube video
and Signal Charlie on their boat Sugar 2 1978 AMF Sunfish SUGAR 2 Intake Assessment

The center of the hole has 3 layers epoxy-compatible mat sized to the hole and the overlap onto the hull is one layer mat and one layer 18oz plain weave which would approximate the hull in its normal state, with the hull pre-coated with epoxy and the fabrics wetted out on a plastic-film covered board and placed through the inspectiron port and compacted with gloved fingers and a small fiberglass roller. I will remove the tape and sand the outside of this repair area and cover it with thin glass and epoxy the next time the hull is flipped bottom-up on the dolly.

The packing tape and stir stick mold worked well, just a quick pry with the plastic wedge to free the little bit that glued to the stick on the ends.
The curve is not perfect to the original (rocker is good but section is a bit off) but should be easy to sand into shape to continue.
I made a new block for the upper rudder mount and a mold to add gullwings from a piece of 1708DBXM to it to help tack it to the hull and to wrap the underside of the block without me having to mind it. Then I wetted out the inside of the hull and some initial strips of mat for bonding and hung the block inside the hull. 6oz cloth x 2 layers mat and 1 more layer 6oz all set with 4:1 epoxy. Both glassing steps were covered with peel ply so bonding surfaces can be stripped of blush and be ready to go without sanding.
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Yesterday I removed the hanging apparatus and added 2 more layers mat and 1 layer 6oz after using dowels and 5 minute epoxy to fill in the holes from hanging hooks. Tonight I sanded it down and was pleasantly surprised. I will need only a little filler and then can barrier coat it and add the rudder mount.

I discovered something at the bow. The existing handle is 'out of spec' position-wise and there is a thump-thump-thump inside the hull when it's moved, as if the blocking in the bow is loose. The glassing is also cratered in the factory handle position. The handle is still holding fast so I may repair this area next week with the hopes of sailing yet this weekend. I was thinking of laying plastic on the deck and glassing a patch to take the curve of the deck, then fitting that after removing the badly damaged glassing and loose block.

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