Panope
Super Anarchist
I THINK so.
But I am an amateur with this stuff.
I hope people like Zonk will read that report and chime in.
Steve
SV Seeker
- Thread starter blunderfull
- Start date
I THINK so.
But I am an amateur with this stuff.
I hope people like Zonk will read that report and chime in.
Steve
Panope
Super Anarchist
Actually, trim will go the other way. Stern will become lighter.
The fore/aft location of the fuel will not change (it will only move lower).
But, the old tanks themselves are going away. I just weighed the first (of 2) cut-up fuel tank. 60 pounds X 2 = 120 pound lighter by the stern.
I will build a small day tank of about 10 gallons that might weigh 25 pounds or so.
Fah Kiew Tu
Curmudgeon, First Rank
I kind of doubt that. You're replacing ~180 litres of air in the void space with the same volume of diesel massing ~0.85 kg/litre. What do you think that's going to do to the buoyancy?
Yeah some of that will be offset by the removal of the fuel tanks but I really can't see the stern becoming lighter.
I went through this recently when I was thinking of adding a false keel section to improve stiffness. Once I did the figures and had my engineer buddies check/do all the calcs I got over the idea - insufficient gain for the pain when the AVS was more than adequate.
But it wasn't going to be hard to add sufficient buoyancy via hollow keel spaces to offset the entire added 350kg of steel mass therefore needing MORE lead ballast to counter the increased buoyancy.
FKT
From the report.... " a boat with rigid hull made of polyethylene was hanged on davits behind the stern transom."
.....
The wind blew from SW to W with variable strength of 2 – 5 [Beaufort]. The yacht had been initially powered by engine, however as the wind strength allowed sailing, 5 sails were raised: mainsail, main staysail, foresail, jib and flying jib, which made up for practically full set of sails for close hauled course (Figure 1). Sailing on the port tack, the yacht reached speeds from 2 to 3.5 knots."
Ha ha. Sounds familiar
There is a lot in the report that is estimated/guessed etc. I just skimmed it.
Really hard to apply it to BST Seeker except:
- narrow beam hull with bulwarks that didn't have enough freeing ports
Seeker has huge bulwarks (never noticed before) with very small freeing ports
I'm not sure where the height of the bow opening is; it would act to dump some water but because it's essentially on centerline still won't dump water trapped by the bulwarks when the boat is heeled
- yes the estimated GM of Seeker is lower. A 1m GM is basically OK in most cases
- the boat that sank didn't have a very watertight deckhouse either so limited buoyancy from the deckhouse when it was over on it's side. If your deckhouse isn't watertight, it becomes a liability as it floods and traps water on the low side.
.....
The wind blew from SW to W with variable strength of 2 – 5 [Beaufort]. The yacht had been initially powered by engine, however as the wind strength allowed sailing, 5 sails were raised: mainsail, main staysail, foresail, jib and flying jib, which made up for practically full set of sails for close hauled course (Figure 1). Sailing on the port tack, the yacht reached speeds from 2 to 3.5 knots."
Ha ha. Sounds familiar
There is a lot in the report that is estimated/guessed etc. I just skimmed it.
Really hard to apply it to BST Seeker except:
- narrow beam hull with bulwarks that didn't have enough freeing ports
Seeker has huge bulwarks (never noticed before) with very small freeing ports
I'm not sure where the height of the bow opening is; it would act to dump some water but because it's essentially on centerline still won't dump water trapped by the bulwarks when the boat is heeled
- yes the estimated GM of Seeker is lower. A 1m GM is basically OK in most cases
- the boat that sank didn't have a very watertight deckhouse either so limited buoyancy from the deckhouse when it was over on it's side. If your deckhouse isn't watertight, it becomes a liability as it floods and traps water on the low side.
Panope
Super Anarchist
Moving a mass in the vertical direction does not affect fore/aft trim. It matters not which space is emptied or filled.
Titilingus
Member
It's good to have a Naval Architect onboard. Hopefully Dough will listen to your advice and background skills in marine architecture, design and engineering, and make adjustments. /s
It would have been far better to have had a naval architect from the very get go. Unfortunately, that is not how Dugg learns. Dugg is now at a point where the list of things or adjustments required to ever allow that BSO to actually get insurance, the required permits for passengers(researchers) and actually sail convincingly is too long and expensive to remedy. That BSO is doomed to putzing around protected bays close to sheltered shores.
Don't hold your breath. Doug has shown little desire to consider any advice from anyone, particularly experts.
Fah Kiew Tu
Curmudgeon, First Rank
Rethinking this, I'm in agreement - what I was planning on doing isn't the same as what you're doing. With a deeper keel structure only partially filled with ballast I was adding void volume below the WL and you're not.
FKT
Olsalt
New member
Generally speaking a smaller Yacht is safer then a a bigger vessel. It seams like most tall ships can't recover from a complete knockdown and if you react wrong to a gust or in high waves there is a possibility for the boat to go down.
But lots of traditional sailing ships are still around. Well a lot of them unfortunately also sank and there are still a few accidents every year.
I'm not defending SV Sinker in any way. But I just question if it's fair to apply the same standards you would use on a yacht. From her size and appearance she is somewhere in between a yacht and a ship. (Still a lot of mistakes were done)
But lots of traditional sailing ships are still around. Well a lot of them unfortunately also sank and there are still a few accidents every year.
I'm not defending SV Sinker in any way. But I just question if it's fair to apply the same standards you would use on a yacht. From her size and appearance she is somewhere in between a yacht and a ship. (Still a lot of mistakes were done)
Sail4beer
Usual suspect
Glad you think it’s going to sink too. How can we Sealion this into a positive?
kent_island_sailor
Super Anarchist
That thing is not remotely close to being a "ship". A much better analogy is that very few to none of the powerboats that you see on lakes and rivers can recover from a knockdown or capsize yet most of them don't sink. This is due to some clever engineering, they don't have sails and they don't go in the ocean.
Olsalt
New member
But a lot of the Haikutters and Naval Trawlers (KFK) do have sails and they were designed to sail the ocean. There are multiple examples in history that went down after a knockdown. The Albatross made famous by the film White Squall, the KFK Gotland sunken in only 6Bft, the Pamir one of the last fright carrying sailing school ships or the Concordia built in 1992.
Doug made some stupid design choices, no doubt, but it's closer to a "traditional" sailing ship than a sailing yacht.
By the number of ships that didn't recover after a severe knockdown I doubt that most sailing ships would recover after one...
kent_island_sailor
Super Anarchist
fukupananvil
Member
- 240
- 133
"Doug made some stupid design choices, no doubt"
End it there.
tane
Super Anarchist
- 1,001
- 305
"design", like "calculations", "evaluations", "towing-tank-tests"???
"choices" like evaluating different combinations of variables in boat-design???
IIRC the Krauts have an untranslatable phrase in "Platt" for this kind of "boatbuilding":
"nach Schnut & Mul" (both vernacular for "mouth")
"choices" like evaluating different combinations of variables in boat-design???
IIRC the Krauts have an untranslatable phrase in "Platt" for this kind of "boatbuilding":
"nach Schnut & Mul" (both vernacular for "mouth")
Sail4beer
Usual suspect
He’s German, IIRC…
I kinda woke up on the wrong side of the bed today. It's really not a big deal to me. Just find the double standard interesting. Once had an HR person ask me why I don't like sauerkraut. I asked her if she would ask a black person who didn't like watermelon the same thing. She was speechless.
As I'm sure you're aware, Albatross was initially a very seaworthy design which was heavily modified by subsequent owners (changing rig, adding heavy boats above deck) without consulting a naval architect, which led to its loss. A sister ship which was not so modified (eye of the wind) is still sailing safely to this day.
Pamir was loaded with cargo in a way which was not consistent with how it had been designed nor how it had been loaded on most of its voyages - the grain was loose, rather than sacked, so it was able to shift significantly, which led to the loss.
Concordia had leeward watertight doors open and was on autopilot in an area with unsettled weather. The bridge watch wasn't sufficiently trained so tried bearing away under autopilot instead of turning it off and turning manually - wasn't ever knocked down, but because the pilot couldn't bear away, boat heeled enough that open watertight doors were submerged and the boat downloaded.
Not familiar with Gotland.
Pride of Baltimore (original) had unsecured deck openings too far off centerline and no watertight bulkheads in service to being a fully "traditional" design - also sunk by downloading like Concordia.
Have you read "Tall Ships Down"? If not, you should take a read - it goes into a lot of detail about the failure modes of some high profile big sailing ship sinkings, and the cascade of failures that lead there.
Doug's BSO is much more in the size class of a yacht than any of the above ships, and it appears to have scarier stability issues than all of the above except for possibly the Albatross.
