Posts Tagged ‘tanker’
The wonders never cease in the world-famous Sailing Anarchy Forums, where people say the strangest things. Like yesterday, when Anarchist ‘bgytr’ calculated the real-world efficiency of the fantastical sail-powered crude carrier we featured earlier in the week. Do his numbers check out?
As a nav. arch. student, I did a thesis paper on wind assist for commercial ships. Basically the price of fuel needs to be so high for it to work that it is not feasible. Also, tankers routinely take green water over the deck. Those little sails would have to be pretty dern heavy to stand up to that. And just everyday industrial conditions on a tanker are pretty friggin rough. Maitenance costs of another system onboard- not reasonable.
A simple computation, under ideal beam apparent wind at 20 knots:
Assume those sails are roughly 80 feet high by 20 feet chord. = 1600 ft^2
Lift= 0.5 r*v^2*A*C
C: lift coefficient (give a fairly generous C of 2.0)
r: air density taken as 0.0023769 slug/ft^3
v: 20 knots = 33.8 ft/s
A: area = 1600 ft^2
Force from one sail = 4300 lb of thrust per sail. x 20 sails = 86000 lb of thrust. A typical tanker of that size will crank out 80000 hp or more at about 17 knots => 1.5 million lb of thrust.
Multiply the sail thrust by about .7 since the leeward sails will be in the wash of the windward sails => 60,000 lbs of sail thrust under ideal conditions.
60,000 / 1,500,000 = 0.04, or a 4% thrust benefit. Not worth it when you factor the drag under headwind conditions, maintenance costs, weight, etc. And that calc was for pretty much ideal circumstances. Actual thrust benefit under a range of conditions would be way less.
September 24th, 2015 by admin
With gasoline at around $2.00/gallon in much of the USA, commercial wind power is rapidly receding into the world of science fiction, but we’re not ready to give up just yet, so we dusted off our favorite VLCC rendering from just a couple of years ago when fuel was twice the price. It’ll happen again, and when it does, we hope this rigid-winged Panamax-size concept comes alive. It comes from Sauter Carbon Offset Design, and between the wings, solar power, and a narrower, shallow-draft hull, designers calculate the Deliverance to use less than half the fuel and earn billions more over her life than a non-hybrid ship of the same size.
More over here.
September 22nd, 2015 by admin
With the Youtube video approaching a million views (making it one of the most-viewed sailing videos in the history of the interwebs), a Southampton magistrate yesterday dropped a cool £100,000 penalty on navy officer Roland Wilson for breaking three COLREGS requirements before scratching the Hanne Knutsen’s anchor. (1) He failed to keep an adequate lookout, (2) he impeded a large vessel in a narrow channel, and (3) he impeded a vessel constrained by his draft.
The 100k (called ‘costs’ by the court) will likely be covered by Wilson’s insurance policy, but he’ll still need to come up with another 3 grand in fines. Wanna know more, or do you know more? Hit the thread. And before your next regatta in a TSS zone, you might want to read up on How To Avoid Huge Ships.
October 25th, 2013 by admin