Prior to our summer break from project Mako, we completed bedding in two 3/4" sheets of Penske core in the transom. It's been strategically pickling ever since ;) Our goal now is to encapsulate the transom and move on to the stringer replacement. We're a long ways from the finish line, so it's time to get rolling. We're shooting for this Mako floating pretty next summer.

A quick chalk talk and we've got our game plan. Next step - lay cloth inboard of the transom. We again chose 1708 biaxial cloth for inside the boat, two layers to be exact. We wet out with 105/205 West System. 1708 Biax builds bulk quick with lots of impact and load bearing strength. Sounds exactly right for a transom. Prior to layup, we meticulously prepped the surface with the following steps:
- buttered a fillet joint edge into the bottom to make a gradual curve for best bond.
- rounded all sharp edges from top and corners.
- cleaned cured epoxy surfaces with soapy water and a scotchbrite pad to remove amine blush.
- Wiped area clean: on w/ clean acetone soaked rag and immediately off with clean dry cotton cloth in other hand. This step can be omitted over foam core and wood substrates (see surface preparation article)
- Abraded any smooth areas with coarse 80-120 grit sandpaper and dust off (not necessary over any porous substrates.)
We then placed the cloth inside the transom dry and traced the contour with a sharpie
The cloth cut was 5" beyond the transom contour to tab it over, around and under all connecting surfaces. Alternatively, you might cut the transom fabric exactly to size and then tab the perimeter with cloth tape.

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This woven biaxial pattern faces out, ("laces out Dan!") random mat faces core. |
The thinking is random oriented mat fibers hold more resin and make the best mate to rough surfaces. Thus, mat is the go-to first layer over core and 30 year old woven roving to prevent a resin-starved weak bond. Nobody wants that oh so evil word- DELAMINATION- oh the horror! 1708 integrates mat one side, cloth the other, making it an excellent base. With the sharpie outline showing proud, we stuffed the cloth like a bedsheet into place aligning the black outline to the contour. We then chased out bubbles with some laminating rollers to minimize air entrapment.





As we left her to cure overnight we noticed it's awful quiet round here- music! - knew we forgot something. The radio's coming back next week. Once dry, we'll have a rock solid transom, cored with high density, high strength foam (penske) and reinforced with 2 layers of 1708 on both sides of the core.
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