Modifying The Beam

The beam of the various boats can be mocifted on the boste of the frame tflnwnsky*» h pages 6 to 10. The rrtCDdmum hcrw» ti the beam h 20 % which means that the maided beam increase from 1.35 m to 2-20 m,

As an «cample hew this is done b taken the from« from midship and forwaid.

Start wtth the vridest frame and multttv the half beam vrtth the chosen factor of Increase, fri this cow - 1.2, Draw a Ine parole! wtth file bate ttne and malt off tie new beam.

From this new sheerpdnt draw a line paf atet vittti the otd sldeframe and frqnjfer the length of the rideframe- B qnd mail! off Ihe newchfrwpotnt. Draw the new bottom frame. Draw a line at right angle to the side -frame through the old sheeipofrit. Measure the distance C from the new ¿teeipolnt down to this

On the next frame, draw a Rne thrombi the sheerpolnt and at right an^e to the sldeftame. Draw o para lei Ihe at a dtetance - C.

Mufflplr the ha*beam of this frame wfth the focttw — 1.2 andmaVofltiB new sheapdnt an the pavdel ttne draiwi oartot

Transfer the length of the otd ¡¡Jdeframe « E to the new skteframe In the »me way as done for the midship frame. From the new chhepdnt dttiwthe new bottom frame,

PLANKED BOATS - TIMBER

TYPE A

A timber of medium weight, between 650 kg/m3 and 750 kg/3 when air-dried This heavier timber has two important advantages compared with a lighter timber:

  1. It will hold fastenings such as nails and bolts well and in a wooden boat the strength is mainly dependent on the fastenings.
  2. Heavier timber is usually more rot resistant than lighter timber and this is important in parts of the boat that are difficult to change such as frames, keel and the stem.

Through experience, boatbuilders have been able to determine which local timber is suitable for these items and it is safest to follow their advice. The more known timbers of type A are oak, iroko, kapur, afromosia, opepe, guijun and teak, but there are many other species that might be known locally as suitable.

TYPE B

A timber of relatively light weight of between 500 kg / m 3 when air-dried. The timber is mainly used for planking and deck, and the most important quality is low movement in service, that it does not swell or shrink much with changing humidity. Known timber suitable for this is mahogany, Douglas fir and European redwood, but there are many other species.

QUANTITY OF TIMBER FOR THE BOATS

Below is given a list of sawn timber required for the various planked boats. Timber for the building jig is given on page 25.

The quantity includes a wastage factor of 25 %. The wastage factor could be lower or higher dependent on the quality and the length of timber available. Longer lengths of timber gives less wastage. However an advantage of the cross-planked bottom is the utilization of short lengths of timber.

TYPE OF TIMBER

DIMENSION FROM SAWMILL

TOTAL LENGTH OF TIMBER IN METRES

MM |

INCH

5.2 M BOAT

6.3 M BOAT

7.4 M BOAT

8.5 M BOAT

25 x 150 |

1 x 6

7

9

10

12

38 x 150 |

1 1/2 x 6

32

39

45

52

A

38 x 200 |

1 1/2 x 8

15

18

21

25

50 x 150 |

2 x 6

18

2

20

22

75 x 150 |

3 x 6

4.5

5.5

9.5

10.5

100 x 200 |

4x 8

1.4

1.4

1.4

1.4

A m3

0.54

0.65

0.76

0.86

20 x 150 |

3/4 x 6

63

76

90

103

B

25 x 150 |

1 x 6

58

70

82

94

25 x 200 |

1 x 8

34

41

48

55

B m3

0.58

0.70

0.82

0.95

Total volume A + B m3

1.12

1.35

1.59

1.81

AIR DRYING OF TIMBER

After sawing, the timber must be stored under a roof protected against sun and rain. The drying time depends on the season. During the dry season a 25 mm plank will dry in 3 months, but it will take 9 months during the rainy

PLANKED BOAT 5.2 M - TIMBER

19

FOR THE OTHER BOATS MULTIPLY THE LENGTHS WITH THE FACTOR F : 6.3 M BOAT. F - 1.2. 7.4 M BOAT: F - 1.4. 8.5 M BOAT: F - 1.6.

TYPE OF

TIMBER

DIMENSION FROM SAWMU. mm

TOTAL LENGTH m

SAWING INTO SMALLER SECTIONS mm

TOTAL LENGTH m

PLANED DIMENSION mm

ITEM NUMBER

A

25x150

3

75 75 25 1 1 1

6

20x68

©

4

50 50 50 25 1 1 1 1

12

20x44

©

38x 150

8

38 | |

8

32x143

©

14

75 75 38 |

28

32x68

©

10

I I I

30

32x44

©

38 x 200

14

1

14

32 x 193

©

1

38 L

100 100 1 1

2

32x93

©

50x150

7

50

150

7

44 x 143

©

5

75 75 SO |

10

44x68

©

6

50 50 50 50 | |

12

44x44

©

75x150

3

75

150

3

68 x 143

©

1.5

75

75

75

3

68x68

©

100 x 200

1.4

100x200

1.4

93x193

©

B

20 x 150

57

70 1 1

57

15x 143

©

2

75 75 20 1 1 "I

4

15x68

©

4

50 50 50 201 ! 1 1

12

15x44

©

25x150

58

25 1 1

58

20x 143

©

25x200

29

251 1

29

20x193

©

** 1 I 1

10

20x93

©

PLANKED BOAT 5.2 M - TIMBER 20 PLANKED BOATS - FASTENINGS

ALL FASTENINGS MUST BE HOT DIPPED GALVANIZED

Hot dipped galvanized fastenings have a dull grey and rough surface because of a thick zinc-coating. Electroplated fastenings which are also sold as "galvanized" have a shiny, smooth and silvery surface. The zinc coating is very thin and gives no protection in salt water.

Always specify "hot dipped galvanized" not just galvanized.

THREADED BOLT
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