farm design 101 Flashcards
longline
horizontal longline
the horizontal line secured in place by anchors and submerged ~1-2 meters below the water surface on which seedstring or kelp spores may be wrapped for ocean farming. Kept at depth through the use of buoys and sometimes weights. when it has kelp spores or seedlines on it the line plus the kelp are called the growline
growline
Horizontal longline that has been wrapped with seedstring or kelp spores
array
the longline system, consists of:
- a growline (Horizontal longline wrapped with seedstring or direct seeded with kelp spores),
- its place securing anchors and anchorline,
- its buoys and (sometimes weights) keeping it at depth
generally speaking a farm is composed of multiple arrays
single-line array
a beginner’s farm design which uses only one array (a single unit of the longline system, ie.e. growline + accompanying anchor system, buoys, etc).
recommend using the smaller 12” diameter, A-1 size for growline and tension buoys, [click] and something 16-20” diameter like the A-2 [click] for the anchor buoys at the end of the growlines.
5-Line Array
an intermediate farm design which uses 5 arrays (5 ocean farming ‘units’ i.e. 5 growlines with each growlines accompanying anchor system, buoys, etc).
- The 5-line array is best suited for drag embedment anchors, generally it requires a location with a sandy or muddy bottom where the anchor flukes can penetrate.
- This system works best under fairly constant tension, and it’s critical when cutting and assembling the lines that they’re cut to matching lengths.
-recommend the slightly larger A-3 buoys above the spreader bar and bridal system.
Multi-Line Catenary
an advanced and highly complex farm system that requires significant marine engineering expertise.
it allows for more densely packed longlines than other types of arrays, which may allow for increased production on a smaller footprint. It also requires fewer anchors and buoys than the equivalent setup using single-line arrays.
But the trade-off is that the anchors it does require are much larger. Similarly there are fewer, but much larger buoys used to maintain proper buoyancy.
The most critical part of this design is that the lines are pretensioned so they don’t stretch when deployed, and the system as a whole is kept under proper tension once it’s in the water. This keeps the lines from rubbing against each other or flagging, which could cause entanglement and loss.
-might use big buoys (like the A-6)
spreader bar
a bar used to hold apart parallel growlines as in a 5 line array farm design, general guidance is to use this and a buoy at least every 100 feet. usually arays are spaced 2’ apart
Use for kelp longlines is a fairly new concept, and farmers are still teasing out the best designs, and when and where additional buoys need to be added along the span of the longlines.
site footprint
the minimum area your site occupies in the water inclusive of all of your site gear,
while a site may appear to take up only the surface visible area where buoys hold up your longlines, on the bottom of the ocean a farm site is much larger because of the surrounded space taken up by your anchors.
the footprint of your anchors is the bare minimum you would need to lease in order to site this farm.
NOTE: consider giving yourself a 50’ buffer from your gear area on all sides and installing marker buoys in every corner of your site to make sure your gear is easily visible. Coast guard regulations also state you have marker buoys every 300 feet or less, so you’d need them on the long axles of your farm.
the anchor line
line that connects the longline to the anchor itself
the anchor line buoy
the buoy that sits at the connection pint between the anchor line and the growline
endline anchor
an anchor that sits on either end of the growline (attached to the growline by an anchor line)
it doesn’t sit directly under the end of the growline, it sits a bit farther out on either side and then is tethered to the growline’s ends by the the anchor line
tag line
the line that connects the anchor to to the retrieval buoy (the buoy used to help remove or adjust the anchors). There will be one on either side of a single line array
retrieval buoy
a buoy that sits above the line anchors on either side. It is attached to the anchors by the tagline.
Its purpose is to help the farmer to remove or adjust the anchors
bridle
v-shaped line
- one that runs from the spreader bar to a buoy on the surface
- another similar one that runs from the spreader bar to a connection point along the anchor line underwater
direct marketing kelp farming
farmer does the work of processing and selling to consumers.
wholesale kelp farming
farmer sells kelp as an ingredient input to a wholesale buyer.
helical anchor
for use in sand, mud, and clay seabeds
100:1 holding power (a 10lb anchor can hold 1,000lbs of drag force)
Fluke anchor
for use in gravel, sand, and mud seabeds
20:1 holding power (a 50lb anchor can hold 1,000lbs of drag force)
pyramid anchor
for use in unpacked sand, soft mud, and silt seabeds
10:1 holding power (a 100lb anchor can hold 1,000lbs of drag force)
mushroom anchor
for use in unpacked sand, soft mud, and silt seabeds
4:1 holding power (a 250lb anchor can hold 1,000lbs of drag force)
concrete anchor
for use in most sea bottom types
1:2 holding power (a 2,000 pound concrete anchor can hold 1,000lbs of drag force)
drag force
force on your growline
= current x the length of your growline x the biomass per foot of growline
drag force –> holding power –> anchor size
You need to know Drag to determine the best anchor size and holding power for your kelp arrays
To calculate Drag (N), in Newtons, you need to know:
the Current Velocity (V), in meters/second
the Length of your Growline (L), in meters
the Biomass (i.e. weight) of the kelp along the growline (B), in kilograms/meter
Drag (Newtons) = Force x Length x Biomass
N = F x L x B
In this equation, F is the Force affected by the Current Velocity (V), and is represented in Newtons/kilogram
F = au^b = (16.82 x (V^1.43)
(in this equation a and b are constants; and u = V)
Once you have calculated N, a simple conversion will yield Drag (D), in pounds, on your growline
Drag (in pounds) = D
D = N x 0.2238090795
Now that you have estimated the Drag on your growline, you can do some trigonometry to determine approximately how much Holding Power (H) you will need per anchor. For this equation, you’ll need the recommended Anchor Scope (S) of your preferred anchor type (i.e. if the Anchor Scope Ratio is 3:1 the depth of water at Mean High Water (MHW), then Anchor Scope = 3; if the Anchor Scope Ratio is 5:1, Anchor Scope = 5 and so forth). A scientific calculator or Excel will come in handy.
H = D / Cosine x (Tangent x (1 / S))
The Cosine is the trigonometric function that is equal to the ratio of the side Adjacent to an acute angle (in a right-angled triangle) to the Hypotenuse. And the the Tangent is the trigonometric function that is ratio of the Opposite side to the Adjacent side. See the diagram below.
anchor scope
length: depth
lines
The most important factor is its density. The density will determine if the line floats, sinks or remains neutrally buoyant in the water.
Polypropylene line
This type of line floats, it is usually not recommended for growlines, traditionally used for lines near or on the bottom of the farm
You may want to use floating line for the portion of your anchor line closest to the anchor and to the bottom, to try to keep it off the seafloor, but whatever is in the top couple meters of the anchor line should be sinking or neutrally buoyant.
Nylon, polyester, and natural fiber lines
these are typical sinking lines.
In general, sinking or neutrally buoyant line is best for your growlines, floatation buoy lines, and any line within the first couple of meters below the water surface to reduce entanglement risks, such as with a marine mammal, and because seedstring can become damaged if a line floats to the surface.floats
polyester and polypropylene blend lines
these lines are neutrally buoyant
In general, sinking or neutrally buoyant line is best for your growlines, floatation buoy lines, and any line within the first couple of meters below the water surface to reduce entanglement risks, such as with a marine mammal, and because seedstring can become damaged if a line floats to the surface.floats
polyform buoys
a type of buoy commonly used ocean farming, but equivalents with similar buoyancy are also fine.
buoy notes
buoys should be large enough, and there should be enough of them, that you can maintain the proper buoyancy of your gear. minimize their use where you can. Too big, or too many buoys might create excessive drag in bad weather, and the more buoys you have, the greater chance there is of your gear getting snagged by floating logs, tide rips, and debris. It might take some practice and finagling to get your buoy setup to act the way you want, but you’re always sort of looking for that sweet spot between proper buoyancy and minimal use.
Need a certain amount of buoyancy to keep things afloat
For the small-to-med scale that we work on, we tend to size to keep things buoyant, but small enough to not get lifted up and carried away in a big storm - if possible (basically, we want the waves to wash over the farm rather than carry it away)
16” - 20” on ends / 12” + along longline (Polyform equivalents) for systems that are < 400’ long and have 5 longlines or fewer per array
Polyforms are really easy to use in this environment. Use something that will have hte equivalent buoyance but lots of other options.
buoy color
When thinking about buoys, you want something brightly colored so people see your gear. Yellow is on the perimeter, usually warning you gear inside. Different colors can signify different things.
chain
hardware connection recommended 10% of anchor line length for some anchor types
shackle
hardware connection for anchor to chain connection
swivel
hardware connection for anchor to chain connection, multipoint anchor
pear link
hardware connection with anchor line to chain connection with shackle
C Link
hardware connection with growline to spreader bar connection
serves as the connection point from the spreader bar to the growline.
anchor bend knot
a way to tie your anchor line directly to you anchor without using chain.
reduces chafe and wear and can be untied after it’s been under under a lot of tension.
butterfly loop
For the single-line arrays we use on our farm, we attach our growlines directly to our anchor lines themselves by using a butterfly loop (or any knot that will release after it’s been under tension) which we connect to a double-eyed pig-tail, rather than using any clips, links, or shackles. And then we tie the growline directly to that pigtail with a bowline.
kelp
have three main physical components of note: a holdfast, a stiff and knotty root-like structure that affixes it in place to a rock or on the ocean floor, a narrow stipe, and long delicate blades. But each species takes shape in dramatically different ways.
Depending on the species and location, an adult kelp blade may grow 20’ long or more in one growing season. (Some bull kelp can grow to over 100 feet.)
Well, when we farm kelp, we take advantage of its’ natural reproductive cycle, by collecting fertile parent tissue in the wild, and controlling the release of spores in a lab environment.
kelp reaches its sexual maturity typically in the fall. The dark, thick band down the middle, is called the sorus, which is the reproductive tissue. In the wild, when light, temperature, and salinity conditions are right, the sorus will release thousands of microscopic spores, that float through the water until they settle on rock or reef. If they’re fertilized, they’ll attach and grow to mature kelp blades. We replicate this natural occurring process in a controlled hatchery setting by carefully removing the sorus tissue from wild kelp and tricking it into releasing its spores so that they settle on spools of specialized string instead.
blade kelp
The pristine, trimmed blade is generally sold into food markets.
This could be:
- Minimally-processed, in a fresh or frozen form
- Value-added, processed into specialty food like pickles or kimchi, or
- Stabilized for us as an ingredient in consumer packaged goods, such as the kelp burger or kelp jerky produced by Akua
Non-food uses are generally more appropriate for the stipes, holdfasts, and bio-fouled portions of the blade.
- These may be used for agricultural fertilizer and compost, or potentially plastic alternatives.
- ongoing research as to whether kelp could be used as a biofuel, (no one is buying for this product currently.)
- Each of these markets requires different quantity, quality, and pricing
sugar kelp
direct market / cottage industry
Low Volume: 10s of lbs
High Price Point: $10-20+/lb
Food Ingredient Wholesale
High Volume: 100s - 10,000s of lbs
Low to Mid-Price Point: $0.45-8/lb
Non-Food Use
High Volume: 1,000s - 10,000s of lbs
Low Price Point: < $1/lb
sorus
kelp reaches its sexual maturity typically in the fall. The dark, thick band down the middle, is called the sorus, which is the reproductive tissue. In the wild, when light, temperature, and salinity conditions are right, the sorus will release thousands of microscopic spores, that float through the water until they settle on rock or reef. If they’re fertilized, they’ll attach and grow to mature kelp blades. We replicate this natural occurring process in a controlled hatchery setting by carefully removing the sorus tissue from wild kelp and tricking it into releasing its spores so that they settle on spools of specialized string instead.
inoculated spools
farmers remove sorus tissue from wild kelp and trick it into releasing its spores so that they settle on spools of specialized string instead. Over the course of 4-6 weeks we keep these inoculated spools in tanks of recirculated sea water, at just above 50 degrees F, controlling for light, dissolved oxygen, and nutrients. The spools are monitored daily to check for growth, like the microscopic sporophytes you can see on the photo on the left. After about a month and a half of tending, what appeared to be plain white seedstring only a few weeks prior starts looking like a fuzzy paint roller lathered in brown paint. And, at just 1-2mm in length, these baby kelp plants are ready to head to the farm.
when the spools are ready and air temps, water temps, wind, and other conditions are right, they are taken to the farm for outplanting.
