’97 Starcraft Corroded Transom Repair using Pourable Ceramic

[DaleH]

Well I finished up the 'V' and formed the port corner ... and she fit into place, albeit off in a few spots, namely the corners of course. I might just find a tin shop where they may let me use their planishing hammer in exchange for some adult beverages for the crew ...

But at least this worked ... now to fit it, then rivet her back together ... and THEN pour the ceramic core transom material.

 

[Johnny]

after looking at the Harbor Freight planishing hammer, all it is is the Air Chisel in a frame.
So, I was thinking about modifying some of the chisels with different style heads.
I guess a heavy duty block of lead or iron anvil would work as the backer.
LOL I think everyone has at least one of these things in their garage somewhere. (I have 4).
So I have several bits that I will never use. I have a piece of 1/2" x 2" x 24"
steel bar that I can cut off pieces with the angle grinder cut off wheel and then weld
the heads onto the chisel bit. Then, shape on the grinder to different styles.
Less than $20 and you have a very nice Planishing Hammer with custom heads!!!

 

[Johnny]

Dale, about how many square inches are you working with on the corners ?
I guess I am interested in how long the annealing lasts under the hammer
before it needs to be reheated.
I have worked with sheet steel in car bodies quite a bit, but, never aluminum
to the extent you are doing now.
I guess common sense tells you when it is about to crack or split by the sound or feel ???

muy bueno hombre

 

[DaleH]

NEW Transom Piece Fit:

New piece 95-99% fitted, just need to do a little more 'tin knocking' to make sure she fits all corners and profiles.

Starcraft told me to clean & prep the surfaces well, then put 3M vinyl foam tape on the hull, wetted with Plio-Bond waterproof rubber cement. I already use this for dressing saltwater flyfishing shooting head connections and it works great. Now I just need to get a BIG bottle of it.

Plus I will also dip the rivet w/ 3M 5200 before bucking. I will also prep the mating surfaces w/ epoxy-based acid etching zinc chromate ... as I want this to be the LAST transom this boat ever needs.

For Johnny:

BUDGET? Oh heck, I blew that a LONG time ago ... I'm only in 'knee deep', but I dove in, LOL!

AREA: I first annealed the good 1/2" + on either side of my line, but that wasn't enough. Where metal needs to shrink (my case for outside corners) or expand, the ENTIRE surface being worked needs to be annealed. I had to do a few spots a few times.

 

[Johnny]

wow - looking good Compadre !!


Thanks for sharing !! very educational indeed








.

 

[rdhammah]

All I can say is my Captain does good work! Dale - that looks awesome!

 

[DaleH]

Latest Update ...

Well, life got in the way, and that included taking in two girls (ages 11 & 16) to live with us after a death in the family, so I had tons of other priorities besides working on the boat. But my crew (RDHammah) came by and together we got the transom fitted in and riveted in place!

I think the pictures help tell the story, but if you had any questions - ask away. I put 10-24 bolts and nuts, using large fender washers, in at various spots just to hole the positioning of everything. Then I drilled for the rest of the holes. And I will say - EVERYTHING lined up! Sweet!

For those who need details, the sealing tape is a 3M closed-cell vinyl foam that Starcraft recommended. All surfaces were prepped and zinc-chromated beforehand. Then the tape lain down, black 5200 applied and then off to riveting we went. I used a $20 Haba Freight air hammer at 75 PSI, with the special brazier head tool and it worked flawlessly.

As they say in Boston ... WICKED PISSAH!

 

[Johnny]

Them there is a whole passel of rivets !!
=D>
Great work - from tear down to tear it up to putting it all back like new.
awesome tutorial !! Can't wait to see the Transom Pour, when you get to it.

 

[DaleH]

Them there is a whole passel of rivets !!

If I recall correctly, we'll set almost 300 rivets putting the new stem in place. We did good - so far we only replaced 2 or 3 poorly set ones, typically where the tail kareemed off to one side and didn't sit flush or square.

 

[DaleH]

Starboard stern completed:

Not too bad ... I wonder if Starcraft is hiring? I'm just thrilled that the new replacement transom piece that I hammer formed went into place and is now locked in place permanently! Now to complete the aluminum bracing inside the transom and get ready for the pouring of the new ceramic transom compound ... which is how this post originally started, LOL :shock: !

Details - - - - - -
Jay-Cee 3/16" rivets, 1100F alloy, brazier head
Haba Freight $20 air hammer
Borrowed compressor, set at 75psi

Time for a cold one!

 

[CMOS]

Fantastic. =D>


CMOS

 

[DaleH]

Thanks for the comments guys! It's been a long road, but I'm beginning to see the light, as the ...

Outside rear-most transom panel is ready!

And now I'm prepping the inside transom panel and supporting braces. The transom will be formed with 1-1/2" channel with the 2 skins or panels on either side. Across the bottom is the squared 'S'-shaped piece original to the boat, that Starcraft put in place to hold the bottom of the wood. This was stripped, cleaned, neutralized and then coated with zinc chromate and riveted back in place.

Essentially this structure will form a cofferdam that will be filled with the ceramic pourable compound. That main U-channel you see will have 3/4" holes bored all along the sides of the piece, not so much to lighten it, but to allow the semi-vicious (flows like honey or thick maple syrup) compound to not only weep through it, but around it and ALL over it to essentially mechanically LOCK it in place once the compound cures.

I'll have a hybrid transom, of aluminum outside and bracing, complete with a homegenous, synthetic compound that is totally impervious to rot or saltwater. Plus all internal aluminum will be encapsulated within it. I also plan to not cut down the height of the transom, as Starcraft had 3 heights across the stern ... full transom height, a step-down of 2" lower on each side for a good foot or more run to the center and then the cut-out height. I plan on leaving her full height, plus to narrow the OB opening.

Getting ready for the big pour !

P.S. - I will say either I got lucky or I'm good ... but I drew a centerline on my replacement transom piece and after riveting it permanently to the boat ... the line was not only square up and down ... but was deads nut on the money ... not even 1/32" to the left or right ... when I would have been happy with +/- 1/8" or so ... but she was dead nuts CENTERED 8) .

 

[DaleH]

Pour complete!

Well .. after a LONG delay due to pressing family matters, the transom is finally all poured ...

Once I had the area all fabricated, akin to a cofferdam if you will, i.e., a metal structure that formed a 'pool' that the liquid thickened ceramic polyester resin mix can fill (sealed for no leaks) then the entire process took less than 2-hours, maybe just over an hour, as I didn't really clock it. Plus I had a little emergency fixes to stop a small leak, just so I didn't get stuff all over the inside of my new transom.

Attached are the photos of the mix and the final result after pouring. We did not get any pictures taken of the pour, as well quite simply ... it is anti-climatic! Just mix the material and pour away!

Ideally this concept and product is NOT for everyone and only I chose it for my use on a boat to be used expressly in saltwater, as I already had to replace :shock: (not repair) the transom piece due to salt impregnating & permeating the unsealed wooden transom. Cost-wise it is more than good marine ply with epoxy coating. But the compressive strength is 7X greater than plywood, while being a tad more flexible and lighter in physical weight. As a bonus, it will never absorb water and is impervious to chemical attack once cured.

If it works ... there is also a video attached, showing the mix, where the viscosity is about that of a McD's milkshake.

 

[DaleH]

... video did not upload ...

 

[Johnny]

good job Dale. Glad you didn't have any problems or surprises.

 

[DaleH]

Glad you didn't have any problems or surprises.

... had a little surprise with the hardening, but it all worked out in the end ... just took a little longer than anticipated.

Update:

Not the prettiest yet ... as my plan was to prime/paint enough to hang the OB motor ... but she's on and I'm getting her rigged and ready for her 1st test run with a new aluminum transom inside and outside ... whew!

 

[DaleH]

FWIW a few guys PM'd me and chastised me for not posting pictures of the final product whilst floating ...

Added the 60hp, flawless performance to 40mph

 

[Stumpalump]

Nice to see it in the water! Congratulations! My best buddy as a kid had a 16' Starcraft with a Merc 60. Well, his parents did but we had the keys and they let us have at it. It was a 1979 and it flew! What year is yours? Tin lasts forever so was well worth the work you did. =D> =D> =D>

 

[DaleH]

Nice to see it in the water! Congratulations!

Thanks ! It was much more work than I had planned for, so I'm glad I didn't pay a lot for her ...

What year is yours? Tin lasts forever so was well worth the work you did

This one is a '97. Besides the new transom, with the motor off, I tipped the hull up and checked every rivet for integrity, then cleaned the hull up really well, then coated everything on the running bottom w/ SteelFlex.

Well, no - not in the salt, as the saltwater environment can be BRUTAL on tin boats! On my '79 12-footer, unprotected (no prime, no paint, no anti-fouling) rivets started giving away due to oxidation. I lightly tapped against the rivets on the bottom this Spring and about a dozen rivet heads flicked off w/ zero effort. Luckily I now have the tooling/tools to replace them all. Next Spring I'll fix them all, then SteelFlex thst hull. As my boats are in the water 24/7.

 

[KrazyAboutTin]

Awesome job!
Thanks for sharing it