Observations on being Hove to in Heavy Weather: Launching and Recovery of Ship's Boats [ A Ships Perspective ]
Exchanges with Richard Woodman: Elder Brother of Trinity House; Master Mariner (FG)
noted Nautical Historian & Author
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From: David Garside
To: Richard Woodman
Dear Sir,
I recently purchased a copy of "Fiddlers Green" and am slowly, on account of the minuscule print and my less than 20/20 eyesight, making way through a most enjoyable read.
Your account, of Phemius's waltz in and about a hurricane's centre (pages 115-120); Of the trials of her crew, their drawn out struggle to stave off disaster and the spirited persistence of her Master, is outstanding. However, in crediting his ship's salvation to the soothing effects of
oil poured through the latrines, I do wonder if credit was given to the wrong phenomena.
The SS Arabian Prince, a small 3 hold 10
knot Mediterranean trader, whilst en-route to
Malta suffered an
engine breakdown somewhere north of Cape Bon. Winds at the time were gale force and as we
lost steering the vessel hove to with the
wind almost directly abeam.
Initially heavy seas breaking against our starboard side landed green
water on
deck and sent heavy spray sheeting high into the air. Then slowly, under the press of
wind, we commenced a steady set to leeward whilst the displaced
water, drawing under the
keel, roiled to the surface.
As we drifted downwind this up-welling water, now extending well to windward, served as a wave and swell dampner. Breaking seas which reached into the disturbance simply melted away and the ship's motion was greatly eased.
Oil slicks do not drift upwind and it is very doubtful a deep drafted vessel would set to leeward more quickly than would a surface oil slick. This being the case it's difficult to see how oil trickled through a ship's latrine could have made it's way to windward.
On the other hand a curtain of vertically disturbed water, equal in
depth to a ship's
draft, is a most formidable barrier to any horizontally propagating surface wave.
Sincerely yours
David Garside
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Dear David,
Sorry about the small print and the typos. I also attach a couple of significant corrections to Fiddler's Green. Re your point. you may well be right.
In the event, as far as the book was concerned I was keen to rely upon
Captain Evans's own account for purposes of historical verification.
However, like you I have observed this many times, first when I was serving in Ocean Weather Ships in the North Atlantic and we lay a-hull and drifted to leeward at 4 knots. I wrote a paper for the Nautical Institute some years ago in which I described techniques for lowering boats in bad weather, having had many years of experience thereof in Trinity House Vessels when servicing aids to
navigation.
Often there was a better smooth to windward than to leeward and I never ever lowered a
boat on the leeward side with my ship beam on, the poor
boat cannot escape from the ship's side and can end under the lee
anchor.
Best wishes,
Richard
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Norwegian Gem, unlike Arabian Prince, had full control of the situation, She is fitted with three 2.4 MW bow thrusters and twin 19.5 MW Azipod (swivelling)
propulsion units. Her Master, even when hove to, can
head his ship anyway he wishes.
Faced with a madly confused sea & swell and a rising 35
knot (or so) wind he chose a median heading. Keeping wind and sea on his starboard side, with his ship setting to leeward as the wind (for the main part) dictated.
Norwegian Gem: At 294 meters
LOA, 32.2 meters Beam and 8.3 meters
Draft, and assuming a block coefficient of 0.8, displaces about 63,000 metric tons. When setting to leeward (at 1 knot) a large percentage of that weight (of water) is forced under her
keel every minute of the drift. The resulting windward side upwelling simply obliterates all wave trains and much of the incoming swell.
Note: Drifting sideways at 1 knot Norwegian Gem traverses 57.5 times her own beam width each hour - approximately 1 beam width per minute.
As and when I am able to submit my lifeboat recovery video you will clearly see the resultant vertical disturbance, roiling and boiling to the surface. The absence of waves and the greatly reduced incoming swell. In the last moments of the video one can also see the side kick of the forward thruster.
AND, for those who cling to the notion that Sanctuary was to leeward of the Gem the sea and swell motion, relative to the Gem, is also readily observed.
QB