Y.A.T - Yet Another Trinado

A Tornado based trimaran project

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Sandwich construction:

Various sandwich pieces:

Test pieces:


Material test Extruded Polystyren (XPS)
Extruded Polystyrene (XPS) is perhaps not commonly used foam for boat building, but it can be used for smaller boats as it is relative strong and priced 10% of a traditional boat building foam.

Foam comparison. I've made some tests with various foam materials. Some material are easily obtain in a house building material shop others from boat shop. I needed to see how well epoxy adhesive to these materials and make a comparison on compressive strength, I believe that god adhesive and reasonable god compressive strength its whats needed to prevent de-lamination of a foam sandwich construction whenever exposed to excessive forces. (like a crash). I've made various test with following material:

Material = Extruded Polystyren (XPS)
Density = 32 kg/m3
Compressive strength = 300 kPa

2. Sundolit
Material = Expanded Polystyrene (EPS)
Density = 30kg /m3
Compressive strength =200 kPa

3. Divinycell H60 (Green)
Material = PVC foam
Density = 60kg /m3
Compressive strength =900 kPa

4. Finnfoam F700 (Yellow)
Material = Extruded Polystyren (XPS)
Density = 42kg /m3
Compressive strength =700 kPa

The best for boat building would be F700, this is a isolation board produced by Finnfoam Oy (Finland) that has a higher compressive strength than a normal isolation board. This board is normally used for isolation of rail road track bed. Finnfoam has specially produced the thickness I need, 10 mm.

F700 compared with the others:

  • F700 has the highest compressive strength.
  • Its priced 10% of traditional core material
  • It will create a lighter sandwich laminate as it does not absorb excessive epoxy under vacuum. (its cells are smaller)
  • On sudden impact it does not get crushed but sponges back, its less brittle.
Compressive strength comparison simple test.
Two different material are placed in vise and compressed, then its easy to see which material has the 
highest strength.

Platon Komfortskiva vs. Finnfoam F700

10 mm Platon Komfortskiva (purple)

10 mm Finnfoam F700 (yellow)




After Compression:
5 mm Platon Komfortskiva (purple)

10 mm Finnfoam F700 (yellow)

Divinycell H60 vs. Finnfoam F700

15 mm Divinycell H60 (Green)

10 mm Finnfoam F700 (yellow)



After Compression:
5 mm Divinycell H60 (Green)

10 mm Finnfoam F700 (yellow)