1994 Sylvan Pro Select 19 Restore

[DaleH]

One is to buy two sheets of 3/4 ply (I found some ACX fir for $50 a sheet) and wood glue together, then seal with Old Timers.

Second option is one sheet of 3/4" and one sheet of 1/2" glassed with 2oz mat between and sealed (either with more resin or OTF). This would leave me about an 1/8" thin. I'd fill that space with a .125 aluminum skin inside the rear transom metal. I would use 5200 and clamp in until cured prior to inserting the transom board.

WHOA BOY ... is that panel shown the rear-most outside transom skin? If so, I believe I can see evidence of chloride precipitate corrosion in the aluminum skin and while you can remove it where you see it on the surface, it can keep corroding internally, as it feeds on itself.

BEFORE you start adding a new transom core, you really, rEaLlY, REALLY need to check that transom skin out well! I had a Starcraft, wood non -PT transom, but the wood wasn't sealed with any sealer. It held saltwater, which becomes an electrolyte, especially were stainless steel hardware is used on the boat. My transom skin looked like that and if you see "white" in between the inside and outside layers, you need to grind it all out. Look at the picture attached of my old transom wood, where the boat was under shrink-wrap and hadn't been used for 2-years and when I tore out the wood, it was still weeping a salty, decomposing ooze!

In my case I has BB-sized holes end up being 5/8" diameter. It reached the point where I had to make the decision to fhuggedabout salvaging the original transom skin and put in new ones. That ordeal (will NEVER do it again ... ) is well documented in my signature ...

Check the perimeter of your transom skin, perhaps there's enough usable and good material there to put a new piece inside. Tip - NEVER apply goop, e.g., 5200 or epoxy to an un-primed tin skin and never used silicone on tin as most use an acid base as a curing agent. Wash bare tin with straight white vinegar and scuff with a good scouring pad, then let dry. Then prime with a good zinf-chromate primer. Sandwiching UNprimed/prepped tin between substrates and/or apply products like 5200 WILL cause corrosion to the unprotected tin.

If that hull were mine and usable, I would rivet a new panel of 5052 to the inside, maybe even with a layer of fiberglass in between, then dry fit a piece of 3/4" ply where there were dimples made in the wood to allow for the rivet tails, so that piece can lit perfectly flat to the hull. Then I'd add a layer of glass. Then another 3/4" panel of wood and perhaps an inside tin skin - if needed and if room. All panels would have the edges wet-out a few times with Raka epoxy (https://www.raka.com) 1st, and coated. Messy, but I'd even consider install after another coating and installing everything wet to almost kicked.

Essentially I would be laminating and gluing that new transom together! I'd also put in some large 'L'-shaped brackets to tie the transom skins to the sides of the hull. Grease your SS bolts for fixing things while they cure. For final install, I'd use SS bolts with adhesive-lined heatshrink on the threads, and nylon washers under all boat heads and washers.

And for added safety factor ... please add a Johnson "high water" bilge alarm, only $80.

For your floor, if well supported, I see no need for 3/16" stock, when a panel ~0.100" would do it.

 

[DaleH]

Tip - Pre-plan all holes in your new wood transom. If using 1/4" SS bolts to tie it together, drill 1/2" clean-cut (forster bit) holes and fill with expoxy. Then re-dry fit and drill thru w/ #'rd drill above 1/4" bolt size for the bolts. This leaves permanent water-proof epoxy plug around your bolt holes. Likewise for the OB, if affixed with 1/2" SS hardware, drill 3/4" holes and completely fill.

Tip - Wet-out ID of holes with std thin epoxy mix and then when kicking (curing, will be tacky) fill these holes w/ somewhat thickened mix, maybe to consistency of mayonnaise. I always coat my panels first, then put duct tape on one side and fill from the other ... haven't had a hole drip epoxy yet whilst curing.

 

[Spoondragger]

I did grind and vinegar wash prior to appying the JB to fill the voids. There are maybe a dozen holes through the skin, the largest of which is less than an 1/8" after grinding.

Mine was out of water for about 6 month and was quite damp, but not leaching anything. This has been a midwest freshwater boat for its life and will never see salt water.

My purpose for wanting to glue in a new "subskin" would be for additional water-proofing to keep the transom board dry. I'm not confident rivets would accomplish this. Once primed, would 5200 work? The aluminum skin does not appear to be pitted or corroded to the point I would lose structural integrity of the skin. Do I need to worry about this or will thorough sealing of the wood with epoxy and sealed fasteners accomplish this?

It appears the wood was untreated/unsealed, which I would assume was the largest contributor to its failure.

Thanks for the tips, even following and searching frequently, a person can only remember so much! I'm excited to finish, but I don't want to take short cuts.

 

[DaleH]

FWIW a guy from my boatclub works for the company that owns/sells LocTite products and he said in their shear tests that by far the best adhesive on 'properly prepped' aluminum is Loctite E-30-CL, which I guess used to be known as Loctite glass bonder; it is clear and has a 30-min working life. I’ve never used it or seen it …

 

[Spoondragger]

Well, fir bcx plywood and Raka epoxy are here (classy guys at Raka). Aluminum is cut and fitted. Still need to finish the front section where the bow seating will go.

Installed two bilges to replace the 750gph (???). One 850 with a float switch and a 2000. Next I'll mock up where the kicker will be mounted and start on the transom.

 

[Johnny]

Dale - that LockTite is a two-part gun applied kit.
kind of expensive for the novice/beginner fixit guy.
entry level kits start at $50 and by time you buy the
gun and mixing nozzles, you are in it for over a $100.
(I have the same kit made by Lord Adhesives).
Raka Epoxy has my vote for the average Joe.


for a general purpose "polyurethane" adhesive/sealant, I have been using the
household caulk adhesives which tout a 30 year warranty and are
silicone free which makes them aluminum friendly.




stay far far away from 100% PURE SILICONE products that comes in contact with bare aluminum.





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[Spoondragger]

Well things are starting to come together. I have all the floor pieces fitted,which will be primed, painted, and reinstalled.

The transom is currently curing, and I'll dive into glassing it this week.

Looking ahead...there was a black tape seal between the splashwell and inner transom skin. What is it and do I replace it or use 5200/4200/4000 generously to reseal the seam?

 

[Spoondragger]

Anybody have input on the rubber/tape or using just 4200/5200 between the inner transom skin and splashwell?

 

[Johnny]

Spoon - I pulled out a lot of this tape from my Lone Star.
DaleH suggested a 3-M closed cell foam insulation tape, 1/16" thick by 1/4" wide
that I used to replace the factory original seal like you show and it worked fine. I found it on ebay.
I also called Gougeon Brothers (West System) for their recommendation as how
to proceed..... the tech guy said to use the existing gasket that you can salvage
and fill in the other areas with the 3-M foam tape then apply some West System G/Flex-650 epoxy to seal everything up tight.
there are several caulk-like materials (as mentioned in above posts) that can also be used to seal the metals back together.
avoid ANYTHING that contains 100% SILICONE !! Look for urethane products such as automotive seam sealer.
ask any questions you feel necessary prior to venturing into unfamiliar territory.

if it is just for between the hull and splashwell, you can use 3-M 5200 IF you prime the surfaces first.
5200 does not play well with bare aluminum.- or - 3M1755 electrical friction tape will work just as well.




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[Johnny]

also - could you shed some light on what you mean by ......
The transom is currently curing, and I'll dive into glassing it this week.

photos ? what is curing and what are you going to glass ?


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[Spoondragger]

On the advice of the guys at Raka, I laminatee two pieces of ACX fir ply together. Perhaps "curing" was the wrong word. Next, I put on two layers of epoxy per side,then a layer of biaxial cloth on each side, followed by two more layers of epoxy. Holes were then drilled oversize, filled with epoxy/silica, and drilled to proper size.

New aluminum to surround the board arrived today. I'll get pics up this weekend.

 

[Johnny]

wow - 150 years from now, someone will find that transom and tell
their grandkids that "they think" it came off an old aluminum boat 100 years ago.

good job !! looking forward to your photo update.



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[Spoondragger]

Here are a few pictures of my progress:

The floor is currently undergoing paint. I used a palm sander, etched with vinegar/water, primed with zinc chromate, and painted Kiwigrip with about a 10 minute window before rolling texture. I'll add more pictures.

 

[Spoondragger]

New aluminum to sandwich the transom board

 

[Spoondragger]

Well the transom is in! All aluminum was primed and glued to the transom board with 5200, then slid into the boat with more 5200 on the back of the rear aluminum piece. "Peanut butter" thick epoxy in the bottom "trough" to bed the transom and further guard against water intrusion. Clamped and bolted overnight and put on the cap today with a bead of 5200 to seal it up. I used aluminum shingle nails to replace the stock ones.

The motor goes on tomorrow, then I promised the wife a week break. Next will be connecting the new bilges and putting the splashwell back in.

On a side note, my "injury free" streak ended...sliced my thumb open while attempting to jam a punch into the transom holes to line them up before everything set up. Smacked a hose clamp and "get the first aid kit."

Despite the usual things that come up, things are looking good!