Club Technical Data Render Order Form Photos Keel Hull Construction Deck Hardware Rigging Sail Plan List of Plans Dimensions Layout Description

MULTICHINE 31
Hull, Deck and Interior Construction

Rendered figures: www.ideebr.com

The most successful method for amateur construction adopted by us is undoubtedly the plywood/epoxy building technique in its variation, the so-called ply-glass building method, which means sheathing a wooden structure with marine plywood and then encapsulating its outside with a thick layer of fibreglass lamination, using epoxy resin to saturate the glass reinforcement.

The transverse framing consisting of bulkheads or semi-bulkheads prefabricated on the workbench is assembled over the building grid

The secret for a well-succeeded operation resides in the assumption that, even though the process is laborious, there are no real difficulties in accomplishing the tasks involved in the construction, allowing the amateur to perform the whole building with a high degree of self-confidence.  

Since the construction of partitions and furniture of the internal layout, as well as the superstructure follow the same process, and since the transverse part of these components is prefabricated at the workbench, the whole building process is a straightforward job and the building may be compared with reading a thrilling book, when at each chapter new surprises are unveiled, giving great pleasure along the way until the launching day.

  Transverse and longitudinal structure already assembled.

Boats built this way, if properly made, last for a lifetime, requiring very low maintenance. Besides they are immensely rigid and strong for their weight. Actually practically every component of the construction collaborates for its structural integrity, since the plywood/epoxy building method, where every single component is bonded to the others, produce authentic mono-block structures. 

Hull sheathed with marine plywood ready for the fibreglass lamination.

The Multichine 31 stock plan is intended mainly for amateur construction. Taking into account that labour is the most expensive component in building costs, considering that the challenge of making your boat with your own hands is an enjoyable hobby, home building may become an excellent investment.

The whole building process is turned towards assisting the inexperienced builder. A comprehensive building manual, together with a very clear to understand set of plans with level of detailing seldom found in other designs, makes the MC31 a good choice for the do-it-yourself builder.   

Laminating the fibreglass encapsulation wetted with epoxy resin.

The plywood/epoxy building method is becoming very popular in recent years, and presently is a favourite for custom construction. We at B & G Yacht Desing started employing the system during the seventies and most of our boats built according to this method remain in excellent conditions. It is no wonder that the number of our clients who opt for plywood/epoxy construction never stop increasing.

The turned over hull with the transverse part of the interior and deck structure already in place.

List of Materials

1
Hull
1.1 Hull sheathing - 10mm marine plywood 63m² **
1.2 Chines - 40mm x 25mm 0.0025 x 0.04 x (9+9.3+9.5+9.5) x2 0.0746
1.3 Cold Moulded Keel - 4 x 10mm marine plywood 28m² **
1.4 Stem 1.90 x 0.09 x 0.16 0.0274
1.5 Stem cap 1.90 x 0.03 x 0.08 0.0046
1.6 Floors 50mm x 110mm 0.05 x 0.11 x (1.21+0.73) 0.0107
1.7 Sheer Clamp 0.025 x 0.04 x (2 x 9) 0.0182
1.8 Propeller Shaft Skeg 2x 0.02 x 0.2 x 0.5 - Gross 0.0004
1.9.1 Engine Bed: longitudinal bearers (4) x 0.04 x 0.02 x 0.7 0.0022
1.9.2 Sides - 10mm marine plywood 3.52m² **
1.9.3 Cap (2) x 0.06 x 0.02 x 0.75 0.0018
1.10 Wooden Reinforcement under the mast step 0.025 x 0.2 x 0.3 0.0015
1.11 Stem Reinforcement 0.050 x 0.140 x 0.490 0.0034
2
Deck
2.1 Deck and Cabin top - 10 marine plywood 32m² **
2.2 Cabin Sidewalls - 3 x 10mm marine plywood 7m² **
2.3 Transom Platform - 10mm marine plywood 3.52m² **
2.4 Carling 2 x 0.025 x 0.05 x 5.5 0.0138
2.5 Central Deck Stringer 0.025 x 0.10 x 4.4 0.0110
2.6 Cabin and Deck Beams 0.025 x 0.05 x 34.6 0.0437
2.7 Cockpit Beams 0.025 x 0.05 x 15.0 0.0188
2.8 Intersection of Cabin Top with Cabin Sides 2 x 0.020 x 0.05 x 1.7 0.0034
2.9 **** *** **
2.10.1 Cockpit, Cleats 25mm x 25mm 2 x 0.025 x 0.025 x 1.7 0.0021
2.10.2 50mm x 25mm 1 x 0.025 x 0.05 x 8.4 0.0105
2.11.1 Coaming - Transverse Cleats - 10mm marine plywood 0.9m² **
2.11.2 Longitudinal Cleats 4 x 0.025 x 0.025 x 1.46 0.0037
2.11.3 Bottom Structure 2 x 1.9 x 0.35 x 0.02 0.0266
2.11.4 Sheathing - 10mm marine plywood 3.52m² **
2.12 Deck Hardware Reinforcements Thickness = 0.025 0.0387
3
Transversal Components
3.1 Frames at Bulkheads 0.025 x 0.05 x 43.0 0.0538
3.2.1 Frame Joining Floors - Single 0.025 x height x 14 0.0245
3.2.2 Double 0.05 x 0.110 x 8.5 0.0468
3.3 Bulkheads and interior walling - 10mm marine plywood 53m² **
3.4 Transom - 20mm marine plywood 3.52m² **
3.5 Transverse Members on Bulkheads & Interior
3.5.1 Cleats 25mm x 25mm 0.025 x 0.025 x 35.0 0.0219
3.5.2 Cleats 50mm x 25mm 0.025 x 0.05 x 4 0.0050
3.5.3 Rails 70mm x 20mm 0.02 x 0.07 x 5.1 0.0071
3.6 Chain-plate Wood Reinforcements 4 x 0.025 x 0.110 x 0.95 0.0105
3.7 Wooden Pillar to Support the Mast 2 x 0.25 x (0.10+0.11+0.05) x 1.83 0.0238
3.8 Floorboards'  Trim 0.02 x 0.04 x 4 0.0032
3.9 Floorboards'  Cleat 0.04 x 0.10 x 3.8 0.0152
4
Longitudinal Components
4.1 Sheathing - 10mm marine plywood 56m²  
4.2 Floorboards - 15mm marine plywood 7m²  
4.3 Fore & Aft Longitudinal Components
4.3.1 Cleats 50mm x 25mm 0.025 x 0.025 x 35 0.0219
4.3.2 Cleats 25mm x 50mm 0.025 x 0.05 x 5.0 0.0063
4.3.3 Rails 150mm x 20mm 0.02 x 0.1 x 8.1 0.00243
4.3.4 Rails 70mm x 20mm 0.02 x 0.07 x 8.8 0.0123
4.3.5 Trims 50mm x 20mm 0.02 x 0.05 x 46 0.0460
4.4 Floorboards' Trim 0.02 x 0.04 x 5.0 0.0040
4.5 Floorboards'  Cleat 0.04 x 0.04 x 5.0 0.0080
5
Fibreglass Reinforcement Lamination
  Weight g/m² Area weigth of fibre Thickness
5.1 Hull Mat 450 g/m²        
    Cloth 800 g/m²        
    Mat 450 g/m² 2950 g/m² 36 m² 106kg 5mm
    Cloth 800 g/m²        
    Mat 450 g/m²        
5.2 Deck & Transom 3 x Mat 450 g/m² 1350 g/m² 32m² 43.2kg 25mm
Roberto Barros Yacht Design