WW2 MGB 81 Motor Gun Boat Restoration - Interior Part 1/5 - Laminating & Shaping Hull Frames

1942 MGB 81 Motor Gunboat Restoration - Interior Part 1/5 - Laminating, Spiling & Shaping Hull Frames
Berthon was awarded the contract by Portsmouth Naval Base Property Trust (PNBPT) for the restoration and re-engining of the famous 1942 Motor Gun Boat MGB 81 (MGB81)
Berthon’s history with the Motor Gun Boats (MGB) and Motor Torpedo Boats (MTB) goes all the way back to 1939 when numerous MGB and MTB hulls and complete boats were built or fitted out at our boat yard during World War Two.
Each new frame is made up of 12 planks, made from flexible, light ash and a heavier stronger utile (hardwood), these are glued together to make a strong and flexible frame. Every pair of frames is a different shape, as the curve of the MGB hull becomes more pronounced as it gets closer to the front. This meant that every time a new set of frames is laminated the jig has to be adjusted, even if it is only by a few millimetres. After the main shape has been formed a template is set up along the original beams’ position, and a more accurate shape is taken. This is done with a spiling block.
Spiling can be an art form in itself. It is generally used in carpentry and shipbuilding, when the dimension is taken from a straight line, a mould’s edge or rule staff, to any given side or curve of a plank’s edge.
This is then placed in the jig and clamped in place to create the correct curve. Once it has had time to fully dry it is cut into two halves to form 2 individual and identical frames, one port and one starboard. This process is repeated 24 times to create 48 new frames. This is a perfect teaching opportunity for our apprentices since spiling and making up laminated frames for the old wooden craft is not an every-day ask in a modern boatyard; however, for those of you following the RIPPLE (1925 35’ Berthon built boat) restoration a similar task was undertaken. Mostly the odd frame in a wooden yacht is sistered as a quicker and cheaper option albeit doubling up means more weight.
The template is lifted off and laid out on the new timber to be cut, the marks are then transferred in reverse using the same spiling block. A continuous line using a fairing batten then joins these points.
When it comes to replacing an old plank or panel the most obvious way is to copy it by simply tracing around the old one. However, getting an old plank out without it breaking or distorting is much easier said than done. Especially one that is water damaged and rotten.
The new frame is then cut to shape and fitted into place in the original position. To get the perfect fit, as spiling is accurate but not perfect, the frame is finally planed in position until it is a seamless fit.
MGB81 Restoration playlist - • 1942 MGB 81 Motor Gunb...
Engine Removal
Part 1/3 - Aft Superstructure Removal - • WW2 MGB 81 Motor Gun B...
Part 2/3 Stripping Engine Room - • WW2 MGB 81 Motor Gun B...
Part 3/3 - Engine Removal - • Video

[@user-nh4ux7rw7p]

Amazing photography & story. So pleased to see apprentices engaged in this work. It seems to me that there are so many areas of this type of work where we are loosing expertise by those in the know do not have a forum or opportunity to pass there passing skills downto the next generation. More funding is clearly needed.

[@modernwoodboatbuilding]

May I ask what adhesive you use? Looks like resorcinol.