Crooked or warped transom

[GSX455]

I cut out a template for the new transom. The old spacing in the well and transom thickness was 1.25 inches, I have one piece of 3/4" plywood cut out, it is straight against the middle, but at the edges or side of the boat there is a gap. See photos. Is this normal? Do I try to wedge another piece of wood in between to straighten the stern in the rear fiber glass near the drain plug?
When I try to put both pieces together it leaves this gap at the corners. Because I do not want to cut the exterior glass, it is 5/16" thick and in good shape.

 

[chevymaher]

Is it just the crown in the wood? Can it be pushed into place. I drilled and used the tie downs on mine. Bolted that part down as soon as it went in.

I made mine intentionally with the crown of the wood so the edges your showing touched and the center which was clamped had that gap.

 

[gm280]

When I replace my transom, I used a sheet of ply wood on the outside of the transom to help clamp the new wood to teh fiberglass. The made sure the transom was absolutely straight. It is just a straight backer board to help make things straight and solid. You also need to make some clamps to help with this.

WOG designed these clamps and they are really easy to make and use;

 

[Bondo]

See photos. Is this normal?

Ayuh,...... It may well be the way the hull was built,.......

Many transom are not flat, 'n true,...... except where the motor/ drive mounts,......

Some have a curl forward, 'n some have a curl aft,.....

 

[GSX455]

The top of the transom is straight, but I needed about 3/8" spacing in the rear to fit another piece of plywood. Those clamps from WOG are the ticket! I will get some 2"x4"s & bolt & washers. I now remember seeing those in the how-to stickies, but they were buried somewhere in tab 39 or so.
Can I make my transom thicker than the original, or should I not because my cap won't fit?

 

[gm280]

The top of the transom is straight, but I needed about 3/8" spacing in the rear to fit another piece of plywood. Those clamps from WOG are the ticket! I will get some 2"x4"s & bolt & washers. I now remember seeing those in the how-to stickies, but they were buried somewhere in tab 39 or so.
Can I make my transom thicker than the original, or should I not because my cap won't fit?

You can make the transom at thick as the engine will fit. Any thicker and the engine may not fit anymore. So check the engine mounting brackets and see how much it can take. Most are between 1 1/5" to 2". But it all depends on the engine needs.

 

[GSX455]

gm,
I have a 90 HP Johnson out board. I'm not sure but I think the max HP rating for a 16' x 4' beam boat would be 70 HP with a 19" tall transom, I'm close enough to 20" tall that a 1.5" thick transom should hold 90HP, but I want to do it right.

Thank you!.

 

[Scott Danforth]

You need to make the transom clamps like those shown above.

 

[GSX455]

I found the clamp design to clamp the wood to the transom, is the WOG design folks talk about? I was going to use 2"x10" x 8' on the back to get the fiberglass good and straight and use 4 clamps.
I ran out of exterior plywood, so I had a piece of 3/4" birch plywood 2' x 7' laying around. From what I've read birch plywood does pretty good in water. Yeah or nay on gluing this to the other 3/4" plywood?

I'm going to use Titebond III. with clamps and SS screws, based on the other methods on the forum, should I leave the screws in or take them out and back fill w/ resin? The Seacast reviews did not say nice things about folks who left screws in.

Thanks again.
Steve

 

[JASinIL2006]

I took the screws out and filled with resin.

As for your plywood, the potential problem lies with the glue. Exterior plywood uses a glue that is very resistant to a boil and steam test. Interior plywood does not, and is much more likely to easily the laminate in the face of moisture.

 

[GSX455]

I've reinforced the birch plywood and glued the 2 pieces together with almost the entire bottle of Titebond III. I have about 50 screws and 6 clamps, Then 3 coats of epoxy, should seal this up for good.

2nd question: Standard advice is to move all evidence of previous tabbing. When I ground away the last of the floor and all signs of wood it had a recess for 1/2" plywood. Kinda handy reference, so keep this or grind away the last 3 " down to glass fabric? I'm well below where the stringers were tabbed in.

 

[GSX455]

I had read the procedure remove all old tabbing and stringers in how-to's. But after watching another rebuild on YouTube; apparently you're supposed to leave the center stringer in for hull support. I ground down to glass in most areas that I need to tie into.

Is the hull too unsupported for me to step back into to lay the center stringer? Here's a side view all the way from the edge to the center channel. I left one 3" wide seam of resin around the center stringer to add some rigidity when I step into the boat, which is a tri-hull.
Thanks,
Steve

 

[GSX455]

Question about tabbing in transom: Transom clamped, glued in and tabbed in with 1708. Went with vinyl ester over plywood sealed with epoxy, and it wetted out and stuck pretty good. Finishing up with tabbing over the whole transom with CSM followed up by 1708. Is it okay to let the first layer cure, or do the layer(s) all at once?

 

[GSX455]

Update:
All 3 stringers installed, center tabbed. It's been slow progress; way too humid in Georgia to work on the boat after 11 AM. How do you wrap the end of the stringer, or do you leave it open and just coat with more resin? Other 2 stringers will be installed later in the week.

I have one large piece of biaxial, and then add a second tab halfway up the sides for the center stringer. This boat will be ridiculously strong when its done.

Hoping to install the floor next weekend and then fill with foam. :thumb:

 

[GSX455]

After stingers are glassed in, do you grind down plywood floor flush with the bottom of the hull, or buildup the side gaps with fiberglass and wood strips? The 48 inch plywood is 6" shy of fitting the whole floor. Any suggestions for what is the best way to put in a floor? It's finally getting there, with the stingers and plywood.

 

[Baylinerchuck]

Hey there GSX, looking good. Any gaps in bonds to the hull can be filled with 1/4” chop reinforced thickened resin, called hairy peanut butter. Then tabbed with 1708 once all the nuns are smoothed over.

To answer the previous question, all bare wood should be wrapped, (encapsulated), in fiberglass. VE or polyester resin is not strong enough on its own to use as a coating. It will crack.

To answer the question before that in post 13, wet on wet layups are the strongest. That is, once the bottom layer has kicked, but is slightly tacky, proceed with the next layup.

 

[GSX455]

Baylinerchuck,
Thanks for the advice. Gaps filled with plywood, peanut butter and holes cut for pouring foam. This is the year I get the boat in the water. How many gallons of PU foam would I need for a 15 foot boat?

 

[88 Capri (2022 SOTY)]

Baylinerchuck,
Thanks for the advice. Gaps filled with plywood, peanut butter and holes cut for pouring foam. This is the year I get the boat in the water. How many gallons of PU foam would I need for a 15 foot boat?

I have a 16-17 foot boat and I will be using 2 one gallon kits but probably only using half of second. It will depend on the size of the areas and how many you will be filling. I forgot most of my geometry so I have been purchasing as I go. In my rebuild I have found temperature and mixing is critical to get the best reaction.
It says a one gallon kit is approximately 8 or so cubic feet depending on temperature etc.

 

[JASinIL2006]

The amount of foam produced is also a function of the ambient temperature. If you are mixing and pouring near the low end of the prescribed temp range for the foam, your yield will be less. If it’s warmer, you get a more energetic reaction and greater foam volume.

 

[GSX455]

I used US composites 2LB. foam one gallon each part A & B. It managed to get most of the areas under the deck. Should I build flotation boxes with a 90 HP outboard? Motor weighs 350 pounds. It has 60 pounds flotation per cubic foot and I have almost 8 cubic feet under the deck. It was about 65 F, so at the lower end of ideal temperature.
Other questions: When re-joining the cap to the hull, do most folks make a new cap wooden rail to secure the top?