Armstrong, 2024

Midlength Mk I (Midlength FG)

1651mm long · 5'5"

457mm wide

105mm thick

55litres

Open in Studio See it on armstrongfoils.com

Sizes & Numbers

Listed by the brand, read off a photo, or worked out: where every number comes from

In one line

A finer nose than most. A rounded pin tail, a medium nose and gently curved rails.

derived · against the 77 other surf foil boards in the atlas, read off the outlines.

As listed by Armstrong

Armstrong Midlength Mk I (Midlength FG): every size as listed by Armstrong
size	length	width	thickness	weight
38 L	4’9 · 1448 mm	432 mm	89 mm	3.2–3.8 kg
45 L	5’1 · 1549 mm	432 mm	95 mm	3.7–4 kg
55 L	5’5 · 1651 mm	457 mm	105 mm	4.1–4.6 kg
65 L	5’9 · 1753 mm	483 mm	114 mm	4.6–5.1 kg
75 L	6’1 · 1854 mm	508 mm	118 mm	5.1–5.6 kg
85 L	6’5 · 1956 mm	527 mm	124 mm	5.6–6.1 kg
100 L	6’9 · 2057 mm	559 mm	127 mm	6.2–6.7 kg

Every size side by side, tails on one line, one scale

Next to your board?

Lay the Armstrong Midlength 55 L over up to four others, at one scale.

Compare with…

Generations

After it · Mk II X-Form, 2026

The Mk II X-Form 65 L is 25 mm shorter and 16 mm wider than the Mk I (Midlength FG) 65 L; its wide point moved 39 mm toward the tail. Open the Mk II X-Form

listed length and width · wide point derived

Mk I (Midlength FG) 65 L Mk II X-Form 65 L

The Armstrong Midlength over time

Shape & Rocker

From above, then from the side, true scale · the chosen size solid, the others dashed

Read off the 38 L outline · derived

54 %wide point, 778 mm from the tail

3.35length over width

346mm wide 12″ from the tail

4,907cm² of planform

Read off the 45 L outline · derived

53 %wide point, 815 mm from the tail

3.57length over width

336mm wide 12″ from the tail

5,286cm² of planform

Read off the 55 L outline · derived

54 %wide point, 887 mm from the tail

3.59length over width

352mm wide 12″ from the tail

5,965cm² of planform

Read off the 65 L outline · derived

53 %wide point, 928 mm from the tail

3.61length over width

363mm wide 12″ from the tail

6,699cm² of planform

Read off the 75 L outline · derived

54 %wide point, 996 mm from the tail

3.58length over width

388mm wide 12″ from the tail

7,612cm² of planform

Read off the 85 L outline · derived

52 %wide point, 1024 mm from the tail

3.67length over width

390mm wide 12″ from the tail

8,247cm² of planform

Read off the 100 L outline · derived

51 %wide point, 1040 mm from the tail

3.66length over width

410mm wide 12″ from the tail

9,228cm² of planform

Rocker of the 38 L · scaled from the 55 L measured

61 mmtail rocker, at the tip

8 mm12″ from the tail

18 mm12″ from the nose

99 mmnose rocker, at the tip

486 mmflat to within 3 mm, from 29 % to 63 % of the length

47 %of the length to the lowest point, from the tail

105 mmat its thickest, 48 % from the tail

37 mmlonger along the bottom curve than flat

Lay this rocker over other boards

Rocker of the 45 L · scaled from the 55 L measured

66 mmtail rocker, at the tip

10 mm12″ from the tail

22 mm12″ from the nose

107 mmnose rocker, at the tip

506 mmflat to within 3 mm, from 30 % to 63 % of the length

47 %of the length to the lowest point, from the tail

113 mmat its thickest, 48 % from the tail

39 mmlonger along the bottom curve than flat

Lay this rocker over other boards

Rocker of the 55 L · measured

71 mmtail rocker, at the tip

12 mm12″ from the tail

26 mm12″ from the nose

115 mmnose rocker, at the tip

524 mmflat to within 3 mm, from 31 % to 62 % of the length

47 %of the length to the lowest point, from the tail

124 mmat its thickest, 48 % from the tail · on the photo; Armstrong lists 105 mm

42 mmlonger along the bottom curve than flat

Lay this rocker over other boards

Rocker of the 65 L · scaled from the 55 L measured

75 mmtail rocker, at the tip

14 mm12″ from the tail

30 mm12″ from the nose

122 mmnose rocker, at the tip

538 mmflat to within 3 mm, from 31 % to 62 % of the length

47 %of the length to the lowest point, from the tail

136 mmat its thickest, 48 % from the tail

45 mmlonger along the bottom curve than flat

Lay this rocker over other boards

Rocker of the 75 L · scaled from the 55 L measured

80 mmtail rocker, at the tip

16 mm12″ from the tail

34 mm12″ from the nose

130 mmnose rocker, at the tip

552 mmflat to within 3 mm, from 32 % to 61 % of the length

47 %of the length to the lowest point, from the tail

139 mmat its thickest, 48 % from the tail

47 mmlonger along the bottom curve than flat

Lay this rocker over other boards

Rocker of the 85 L · scaled from the 55 L measured

85 mmtail rocker, at the tip

18 mm12″ from the tail

38 mm12″ from the nose

138 mmnose rocker, at the tip

563 mmflat to within 3 mm, from 32 % to 61 % of the length

47 %of the length to the lowest point, from the tail

147 mmat its thickest, 48 % from the tail

50 mmlonger along the bottom curve than flat

Lay this rocker over other boards

Rocker of the 100 L · scaled from the 55 L measured

89 mmtail rocker, at the tip

21 mm12″ from the tail

42 mm12″ from the nose

146 mmnose rocker, at the tip

574 mmflat to within 3 mm, from 33 % to 61 % of the length

47 %of the length to the lowest point, from the tail

151 mmat its thickest, 48 % from the tail

52 mmlonger along the bottom curve than flat

Lay this rocker over other boards

True proportions · dots at 10 mm and 12″ in from each tip · bracket: flat to within 3 mm · Measured on Armstrong's photo of the 55 L. Tail end set by Armstrong's photo convention, not checked by a person.