Y.A.T - Yet Another Trinado

A Tornado based trimaran project

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The hull sandwich laminate will be transitioned from foam- to wood -core at the gunwale.

Here a 8x70 wood (pine) plank is mounted for the gunwale, it's positioned 10 mm below the last jig batten to be in level with the deck. The foam and wood core will be join at the center of the second batten.

The wooden plank is held by screws from the inside to be easily removed later, when the hull is turned over. 

The gunwale wooded plank mounted.

The hull sandwich core laminate will also be transitioned from foam to wood at the keel. 

The keel board (8x70 pine) is mounted with screws from inside.

From station 5 the wooded keel board narrows to meet the bow plate. Two small wooded pieces are are placed beside, to form the sharp hull at the bow.

These are to be glued together to the bow plate.
To prevent the battens to be glued, they are wrapped with plastic.

The keel plank, side pieces and bow plate are glued together.

Its been raining for days, so I spend one day to build a shelter.

Its time to start cutting the foam.
I started at the bow as this requires most adjustments.

I use staples to fix the foam to the frame battens, I found this to be easiest and quickest. The staples are 14mm and foam is 10mm, so they enter the battens by 4-5 mm.
Later, when the hull is turned over and battens are removed, the staples can be pulled out from the inside using a pair of pliers. There will be a small cavity from the staple, but I will just close it with some epoxy pudding.

The foam is moved back from the front edge of the bow plate, as the hull fiberglass outer skin needs to be well attached to the bow plate,  as shown with the brown tape on this picture. 

Foaming completed

All foam joints are glued with thickened epoxy, the foam is also glued to the gunwale and keel board.

Setup for cutting fiberglass pieces

Laying up the first layer of 3.

I placed the first layer diagonal over the hull to create some torsion stiffness.

The first layer is also placed from the gunwale board over the center and to the water level mark on the opposite side, when the fiberglass cloth is placed from each side they will overlap over the center and there will be twice as thick lamination below the water level.

To place the fiberglass cloth diagonal was not as easy as I thought, it was difficult to get all the air "bubbles" out from the cloth and at the same time have the cloth lying attached to the foam.
I needed to make some small corrections to the cloth and it ended up twisted and it did not behave like I wanted. There reason for this is of course that the hull has both concave and convex surfaces, not like a normal sailboat hull that is convex or flat panel - where the cloth can be "stretch" over the surface, - is of course much easier.

I ended up with some air bubbles that could not be pushed out. I need to remove all these "bubbles" or wrinkles before applying the next layer



I also did a sloppy work on some of the foam joints, not putting enough epoxy putty and fairing the joints.
The cloth got wrinkled in some of these areas, with air trapped inside.

This also need to get fixed before applying the next layer. 

This result is what I need.
Smooth surface over the staple






I use 10 cm wide strips of fiberglass to laminate the bow plate to the hull foam. (2 x 280g) 

Epoxy putty 

Lamination completed for the outside.
The hull has 4 x 280g fiberglass below  the water level, 3 x 280g on the sides.
The layers near the bow area are 8 x 280g, stretching back over the keel board.




 Next: Fairing the outside