Sea state is today reported on a scale from the World Meteorological Organization from 0 (calm) to 9. (Wave height is given as significant wave height, which is defined as a middle of the highest 1/3).

If an anemometer is not used and exact wind-speed reported, the wind force can be reported with the Beaufort scale from 0 (calm) to 12 (hurricane) deduced from the wind’s effect on the sea.

A very good table summing both scales is given at the UK Met-office:
[www.metoffice.gov.uk]

However after seeing wind and sea being stated in different sources (KTB’s and books) I get a bit confused.

- Did the Germans use today’s scales in their weather reports?

Here are a couple of excerpts from Jordan Vause’s otherwise(?) excellent book “U-Boat Ace. The story of Wolfgang Lüth”:
Page 109-110: …. and by the twelfth the boat was logging winds of over forty knots, and a sea state of twelve to fourteen.

Gale (Beaufort 8) ends on 40 knots, and severe gale (force 9) and more starts at 41 knots. But a Sea State of 12-14???

On page 128 in the same book one can read
“…. a sea state of seven was recorded was recorded about 180 miles southwest of Port Elizabeth on the morning of 8 November. The Panamanian steamship Plaudit was sighted….rainy weather and heavy swells conspired to upset the boat’s trim at a critical moment during the first torpedo run at 0815. U-181 followed the Plaudit for ten hours as the torpedo tubes were reloaded. By noon the weather had worsened, the sea state hovering between seven and eight.”

By today’s scale sea state seven to eight would be 7-9 m significant height, with max waves 10-12.5 m. Would a U-boat fire torpedoes then? Would it be able to reload?

“….At 2055 Lüth lined up and fired again. The Plaudit was hit this time.”

“It didn’t sink so he gave the order “Artillerie klar” !!
U-181 approached the Plaudit’s stern, the sea state now registering ten. The attack went slowly (!) ….finally after eight hits the Plaudit sank by the stern.”

According to today’s scale a sea state of 10 doesn’t exist, it stops at 9 with a significant wave height of +14 m.

Even if the sea state had been confused with the Beaufort scale here, – force 10 would be storm with significant wave heights of 9 m. I find it hard to believe that torpedoes would be fired, and certainly no artillery would be used.

I’ve seen this way of reporting wind and sea in other books as well, but never of the same magnitude as used in this book.

If I look in the KTB’s of U-992 and U-995 which I have in front of me now, I find wind and sea that corresponds nicely with today’s scales.
For example WSW 4-5, 3-4 (3-4 I presume is sea state) SW 5-6, 4-5 or SSW 6-7, 5-6 and so on.

- Or could there be other scales used by American authors that is confusing me?

I know the Americans use an extended Beaufort scale at times, but I thought that was just to subdivide the “Hurricane” step. – The first time I was confronted with this was when a team from National Geographic was filming me sending out a (fake) storm warning (on their request) for the North Sea. When I wrote force 11, they said it wasn’t enough and that I had at least to write force 13. I wasn’t aware of the extended scale at the time and was of course shaking my head of these “amateurs”!

Does anyone know more about the scales used for wind and waves I would very much like to hear about it.

Best regards
Vidar