Breakwater Design


Not necessarily true… FLIP uses 3 modified 750 lb fluke anchors. No, I don’t remember which document I saw it in, or if I caught it in passing from Scripps Institute, or another site. It’s one of those things that stuck in my head and I don’t necessarily know how to back-track it.


The anchors can cost comparably next to nothing, it’s the mile of rope on each anchor that costs you $millions.

(Jonas Smith) #103

Not if it’s moored using a tension leg system. There is no vertical movement with that form of anchoring system.

Of course it will still cost millions…


As I recall, the DeltaSync report says this clearly

It boggles my mind that people discuss breakwaters. You might note that my contest entry does NOT have a breakwater, just for these reasons. There are ways to solve the wave problem using form and floatation. It is much more difficult for non-buoyant structures made of concrete, and so for that reason I doubt any realistic seastead will be made of concrete.


I totally agree.

[quote=“jwliberstead, post:104, topic:821”]
It is much more difficult for non-buoyant structures made of concrete, and so for that reason I doubt any realistic seastead will be made of concrete.
[/quote]I disagree :blush:

If well built ferrocement boats (made in the 70’s) are still cruising the oceans, there is no reason whatsoever that a well built concrete seastead shoudn’t be floating in 2060 if built today,…


Damn I have time these days…

I believe we should concentrate our efforts in developing energy dissipating/absorbing connectors between floating platforms.
Of course the requirement list is quite challenging :cheap, reliable, scalable, big reach, allow energy conversion, …

I think I found the perfect technology:

Hydraulic artifical “muscle” with water as a working fluid.

They are easily scalable, dont rust, easily movable, no moving pieces, high efficiency, relatively low price with potential for big economy of scale , clean (using water as a working fluid), mechanically powerful (30x on some metrics compared to cylinders), big elongation, tunable…

Water hydraulic motors are even existing today:

Just need to increase the size of those “muscles” for our need…



LOL, I think we should concentrate on building and operating 1 (ONE-LIKE IN THE FIRST ONE) floating seastead and worry about “developing energy dissipating/absorbing connectors” later,…


Too late, it already exists:

Damn, I wonder why they prefer to load snowbirds and french roulette experts at port Everglades to cruise in circles offshore South Florida instead of anchoring in international waters and build a free self sustaining society on it…

Energy costs, nah I can’t be it…

Just imagine that burning thousands of tons of bunker fuel doing nothing for days yields a better cashlow for Royal Caribean than ferrying the muppets offshore of a anchored “seastead” that could easily be 10x the size for the price…
A true seastead is not an immobile Oasis of the Seas.
It will have to generate power cheaper than coal, fuel or nuclear powerplants on land, otherwise all you gonna build is a retirement community…

(Larry G) #109

It only uses 7230 GALLONS OF DIESEL FUEL PER HOUR. Sure, that’s a great model for a seastead.


[quote=“thebastidge, post:109, topic:821”]
[/quote]Of course. There are using diesel generators to produce electricity. There is no single solar panel or wind generator on ANY cruise ship.

On any size seastead you can cover 100% of you electric power need with solar panels and wind generators (that includes propulsion, if electric drives are installed). See bellow.


False. Oasis of the Seas exists, but it is NOT anywhere near being intended as a permanent residence. Their business model is “Cruise Ship” for a reason. The crew comes and goes, the ship comes and goes, it’s only purpose is to carry people on expensive vacations.

(Larry G) #112

Not correct. from the exact same wikipedia article, and only a couple lines below what I talked about earlier:

The ship’s power comes from six medium speed marine diesel generating sets: three 16-cylinder Wärtsilä 16V46D common rail engines producing 18,860 kilowatts (25,290 hp) each and three similar 12-cylinder Wärtsilä 12V46 engines producing 13,860 kilowatts (18,590 hp) each. The fuel consumption of the main engines at full power is 1,377 US gallons (5,210 l; 1,147 imp gal) of fuel oil per engine per hour for the 16-cylinder engines and 1,033 US gallons (3,910 l; 860 imp gal) per engine per hour for the 12-cylinder engines. The total output of these prime movers, some 97,020 kilowatts (130,110 hp), is converted to electricity, used in hotel power for operation of the lights, elevators, electronics, galleys, water treatment plant, and all of the other systems used on the operation of the vessel, as well as propulsion. Propulsion is provided by three 20,000-kilowatt (26,800 hp) Azipods, ABB’s brand of electric azimuth thrusters. These pods, suspended under the stern, contain electric motors driving 20-foot (6 m) propellers. Because they are rotatable, no rudders are needed to steer the ship. Docking is assisted by four 5,500-kilowatt (7,380 hp) transverse bow thrusters.

Additional power comes from solar panels fitted by BAM Energy Group, which provide energy for lighting in the promenade and central park areas. The installation cost US$750,000 and covers 1,950 square metres (21,000 sq ft) on deck 19.

3/4 of a million bucks in solar array in addition to the 7 thousand gallons of diesel per hour. Not to mention the ~1/2 acre dedicated to the solar array.

Yeah, that math doesn’t work out. PV Solar doesn’t pencil out for land vehicles, it doesn’t pencil out for water propulsion either. You’re not going to get 97 MW of power out of the PV solar arrays that will fit on this area of floating platform. Even if you scale down power consumption by a factor of ten for everything except propulsion (down to ~3MW for all other items), you still need something other than PV Solar to provide the 60,000 kW for propulsion.

This is a small city with 6,000 people entirely dependent upon artificial systems providing life support. Typical “off-grid” power budget calculations figure on something like 8kWh/day for a minimalist family survival. Multiply that by half the people on the ship just for a cocktail-napkin quality of SWAG and you get 24000 kWh/day or 24 MWh/day. Call it a family of 4 on that 8kWh/day budget. 6000/4*8kWh/day is 12000 kWh/day or 12 MWh/day. PV Solar isn’t going to generate that much power per day even if every bit of the ship were covered in PV arrays with no room left for anything else.

All of this before you even get to propulsion. Solar is a supplement, not a replacement for traditional power generation.


That’s 330 watt-hours per hour, which is actually pretty luxurous for survival mode. It’s 3amps at 110vac, so that could sustain a baby superinsulated fridge, power a few lights, keep a radio and small radar going. It could keep a fan and feed controllers going on a combustion heater. It could power a small 1-liter per min water pump feeding a RO system. And most combinations of various things. Your laptop will run on it’s internal battery while the fridge ran. You’d have plenty to live on, on a small scale, with no waste allowed. All that said, storage batteries wil be your severe weak point, if you are using solar panels. Which is why i hope to make otec work, on top of (or rather underneath) solar PV and thermal solar boosting. But you can see, a measely 3amps@110vac from the otec at night would get you thru just fine enough, not counting propulsion or hvac (altho hvac can be a side effect of otec).


OTEC in the news…
(August 23, 2015)


Hmm, lil confused after reading the webpage. Hasn’t there been a working otec plant in Hawaii for 20 years, with the cold water being sent to aquaculture bins before returning to the ocean? There’s also a wave energy project off the usa marine corp base in Hawaii. How is this new otec plant, the same size as the old otec plant, different?

And oops, should we move this to an engineering or energy thread?
From :

(Jonas Smith) #116

Cruise ships are not seasteads…

You know what, nevermind. Don’t let these guys deter you, Adrien.

I am trying to use my “ability to be constructive or useful to others rather than purely negative towards their ideas” and “ignore that which doesn’t meet [my] standards rather than burying the meat of the conversation under a bunch of extraneous comments and chasing off well-meaning people who want to join the conversation.”

Get your hands on a used cruise ship, anchor it in international waters, and build a free self sustaining society on it.



Bull shit. BS.

YOUR math doesn’t work out. Not mine.

Who gives a shit about “land vehicles”,…??? Who said that anything about 6,000 people??? Since when do we compare seasteading with cruise ship business???

Do not tell me that the FACTS that I know and researched to be SO are not true…

[quote=“thebastidge, post:112, topic:821”]
Solar is a supplement, not a replacement for traditional power generation.
[/quote]Really??? What the F@#$% you are talking about???

I lived on solar ALONE on ALL of my sailboats FOR YEARS MAN…



I urge those posting here to
(a) stay on topic – nominally BREAKWATER DESIGN


(b) state your disagreements more respectfully.

Below the following line, I’ll hope to see polite, engineering discussion of breakwaters.

(Jonas Smith) #119

Everyone’s math is the same.

From looking at those pictures I tried to calculate the area of PV panels. I’m assuming that’s a 40’ sailboat. Using that for comparison I calculated the two stern panels at 40’x15’, the midship ones at 70’x7.5’, the two bow ones at 40’x5’, and the pentagon at 25’ per side. That gives a total of 3725 ft^2 (or 356m^2) of PV panels.

I then used NREL PVWatts calculator to calculate the total power from such a system. I used the (TMY2) KEY WEST, FL location and drew out a 346m^2 area using a tilt of zero degrees (since those panels look like they are mounted flat) and left everything else default. It calculated that size system would be 52kW DC, have an initial cost of $3.30/Wdc ($171600 total cost), and generate a total of 73,049 kWh per year assuming a solar radiation of 5.13kWh/m^2/day at Lat 24.55° N and Lon 81.75° W with a fixed roof-mount system at 0° array tilt and assuming 14% system losses and 96% inverter efficiency.

That’s comparable to 4 to 5 US homes in Louisiana. Not sure if that’s enough to supply an electric motor big enough to move that structure at 10 knots.

Are my calculations close to what you’ve looked at?

EDIT: Oh, and to stay on topic. Breakwaters are important to create sheltered waters around the seastead for marine activities, not just to protect the seastead itself.

(Larry G) #120

I actually do believe a ship could be used as a seastead- that is, a floating place where people live and work full time, with some degree of autonomy from land polities.

However, it could not be run like a cruise ship business model. I do not believe seasteading will ever be supported by that particular kind of opulent tourism.

PV is NOT going generate 60 MW of propulsion for a vehicle/vessel/seastead that size. PV doesn’t generate enough juice for propulsion of any type of vehicles. It generates enough for toys to play with for short periods of time. Everything else that uses electrical propulsion gets its power for grid generation or on-board internal combustion engines turning generator heads.

PV solar has a time component, it’s not instantaneous power. It takes time to charge batteries. The bigger the batteries, the more time. The bigger the batteries, the more cost to build, maintain, house, and move them. (Vessels, particularly aircraft and spacecraft have to do the math on weight of fuel as a function of range and maneuverability all the time. The differential in dry weight of my boat vs the weight of my boat with fuel, water supplies, and gear is significant.) The more power you need for the application, the more time it takes to accumulate. PV has a definite role in supplementing other forms of power. No point in wasting fuel on walkway lighting. Anything that requires small amounts of periodic electricity is a good bet for PV Solar.

I’m very interested in sailing large structures using kite sails, and I think it has great potential. It’s also going to be less responsive than massive engines generating thrust. It’s simply physics. TANSTAAFL.

You can budget down to a few kWh per day per person, but that’s not a business model that will generate billions per year in tourism to support a massive cruise ship infrastructure.

You made a factually incorrect statement, and I corrected it. (No solar panel on any cruise ship). I went on to expand on the OP point using the actual numbers published about that vessel. Get over yourself.