@paul_20241009190957797 Great questions. Per the weight, it will depend upon the species, since some types of kelp have air bladders (pneumatocysts) and/or different morphologies that impact whether they are floating, sinking, or neutrally buoyant. All of these things may also impact drag forces in different ways.
@david_bailey has done some analyses looking at the weight of kelp underwater as it compares to when it's out of the water. Could you share some of your findings, Dave?
Per the tool limitation: 400 feet may seem a bit arbitrary, but it was based on a few of factors 1) the typical amount of seedstring on seed spools from nurseries in the NE U.S. and Alaska was between 200-400 feet at the time we built the tool 2) depending on the site and conditions, much longer longlines can be more challenging to manage and 3) we had to stop somewhere. There's some pretty complicated coding happening in the background, so limits are important in this context.
Paul, I use 3% as an underwater weight estimate for sugar kelp. I suspect that percent varies at different stages of growth and applies best at end-of-season harvest time. Cliff
@clifford_goudey , @kendall_barbery Thank you both for your contributions! It is so cool to see such an active community! Thank you very much for sharing the anchor weight calculations with us. I am mostly considering Saccharina latissima and Ulva lactuca species-wise. I am not familiar with weight expressed as a percentage. Is it a percentage of the out-of water weight? Like if we have 10 lbs/foot of rope out of the water, then in the water we have 0.03 lbs/foot? If you don't mind me asking, how do people get to that figure usually?
Paul, That percentage is the underwater weight divided by the out-of-water weight. In the case you mention, 10 lbs of harvested Saccharina biomass would be 10 x 0.03 = 0.3 lbs underwater. That is a useful calculation when trying to figure what sort of flotation is needed to keep things from sinking out of sight. Check with a phycologist to see if those two species are suitable for your planned location. Cliff
@paul_20241009190957797 Great questions. Per the weight, it will depend upon the species, since some types of kelp have air bladders (pneumatocysts) and/or different morphologies that impact whether they are floating, sinking, or neutrally buoyant. All of these things may also impact drag forces in different ways.
@david_bailey has done some analyses looking at the weight of kelp underwater as it compares to when it's out of the water. Could you share some of your findings, Dave?
Per the tool limitation: 400 feet may seem a bit arbitrary, but it was based on a few of factors 1) the typical amount of seedstring on seed spools from nurseries in the NE U.S. and Alaska was between 200-400 feet at the time we built the tool 2) depending on the site and conditions, much longer longlines can be more challenging to manage and 3) we had to stop somewhere. There's some pretty complicated coding happening in the background, so limits are important in this context.
If you are trying to assess potential drag forces and anchor size needs, you might be interested in this document, which describes some of the calculations that are happening in the background: https://media.hub.greenwave.org/wp-content/uploads/2022/04/13213926/Calculations-to-Determine-Anchor-Size.docx.pdf
If your head is spinning, consider contacting @clifford_goudey or another marine engineer for support.
Hope this helps!
Paul,
I use 3% as an underwater weight estimate for sugar kelp. I suspect that percent varies at different stages of growth and applies best at end-of-season harvest time.
Cliff
@clifford_goudey , @kendall_barbery
Thank you both for your contributions! It is so cool to see such an active community! Thank you very much for sharing the anchor weight calculations with us. I am mostly considering Saccharina latissima and Ulva lactuca species-wise.
I am not familiar with weight expressed as a percentage. Is it a percentage of the out-of water weight? Like if we have 10 lbs/foot of rope out of the water, then in the water we have 0.03 lbs/foot? If you don't mind me asking, how do people get to that figure usually?
Paul,
That percentage is the underwater weight divided by the out-of-water weight. In the case you mention, 10 lbs of harvested Saccharina biomass would be 10 x 0.03 = 0.3 lbs underwater. That is a useful calculation when trying to figure what sort of flotation is needed to keep things from sinking out of sight.
Check with a phycologist to see if those two species are suitable for your planned location.
Cliff
@clifford_goudey Gosh I'm bad at math. Thank you for explaining that to me and for the advice!!!
@clifford_goudey , @kendall_barbery
Thank you both for your contributions! It is so cool to see such an active community! Thank you very much for sharing the anchor weight calculations with us. I am mostly considering Saccharina latissima and Ulva lactuca species-wise.
I am not familiar with weight expressed as a percentage. Is it a percentage of the out-of water weight? Like if we have 10 lbs/foot of rope out of the water, then in the water we have 0.03 lbs/foot? If you don't mind me asking, how do people get to that figure usually?
Paul,
That percentage is the underwater weight divided by the out-of-water weight. In the case you mention, 10 lbs of harvested Saccharina biomass would be 10 x 0.03 = 0.3 lbs underwater. That is a useful calculation when trying to figure what sort of flotation is needed to keep things from sinking out of sight.
Check with a phycologist to see if those two species are suitable for your planned location.
Cliff
@clifford_goudey Gosh I'm bad at math. Thank you for explaining that to me and for the advice!!!