Have your life boat ready to step into before the sailboat actually begins to sink but wait until it's actually sinking in the water before you hop on. Saying it like is that harder to put into a fortune cookie and doesn't read nearly as clever.
Self-righting keel question
- Thread starter Mossy Dell
- Start date
Awww. Fun.subject -too bad it's so old!
One thing I didn't see anyone pointing out and that no advertisers ever.bring up is...
If you are in weather big and bad enough to turtle you, it's not gonna be calm.
I know that sounds self evident but soooo many arm chair sailors seem to forget that a sea with a wave big enough to flip you will keep moving the boat around in extreme ways.
Which means it doesn't need to "right " itself from.some specific angle. Rather it only needs positive buoyancy and a heavy.keel.
Releasing all sheets certainly helps a good righting boat.to pop back up too!
ps.
The ideas behind multhulls was that you'd passagemake faster and be less exposed to adverse risk of this to begin with.
One thing I didn't see anyone pointing out and that no advertisers ever.bring up is...
If you are in weather big and bad enough to turtle you, it's not gonna be calm.
I know that sounds self evident but soooo many arm chair sailors seem to forget that a sea with a wave big enough to flip you will keep moving the boat around in extreme ways.
Which means it doesn't need to "right " itself from.some specific angle. Rather it only needs positive buoyancy and a heavy.keel.
Releasing all sheets certainly helps a good righting boat.to pop back up too!
ps.
The ideas behind multhulls was that you'd passagemake faster and be less exposed to adverse risk of this to begin with.
Here is a good article on stability:
Here is a graphic from the article comparing an Island Packet (blue) to a Tartan (red):
The higher righting moment of the Island Packet to the left shows that it will resist heeling about twice as much as the Tartan. The Tartan reaches vanishing stability at 120 degrees (where the red line crosses zero), while the IP is around 133 degrees (blue line crosses zero).
Extensive tank tests show that these curves are not so relevant in preventing a capsize. All hull shapes will capsize when struck on the side by a breaking wave higher than the beam of the hull.
The curves are critical for recovery from capsize (assuming the cabin is watertight.) The IP only has to tip over 43 degrees (180 less 133) in the waves from the inverted position to return to upright. The Tartan would have to roll over 60 degrees (180 less120) from inverted for the same result. The shallower depth of the IP curve on the right (inverted) side also means it takes half the rolling force from a wave to get to positive stability.
Here is a graphic from the article comparing an Island Packet (blue) to a Tartan (red):
The higher righting moment of the Island Packet to the left shows that it will resist heeling about twice as much as the Tartan. The Tartan reaches vanishing stability at 120 degrees (where the red line crosses zero), while the IP is around 133 degrees (blue line crosses zero).
Extensive tank tests show that these curves are not so relevant in preventing a capsize. All hull shapes will capsize when struck on the side by a breaking wave higher than the beam of the hull.
The curves are critical for recovery from capsize (assuming the cabin is watertight.) The IP only has to tip over 43 degrees (180 less 133) in the waves from the inverted position to return to upright. The Tartan would have to roll over 60 degrees (180 less120) from inverted for the same result. The shallower depth of the IP curve on the right (inverted) side also means it takes half the rolling force from a wave to get to positive stability.
I read the original posting and the responses and I was only left wondering if there was a reason for the question or if it was merely an academic inquiry with no specific purpose for boat evaluation.
To the advantages of wooden/buoyant spars: we have come to appreciate that internal halyards are aerodynamic, quiet, and clean. But if on a composite or alloy spare you were to go old school with all external halyards, the spar could be made buoyant. External halyards are easier to inspect and maintain.
Would I want to give up my internal halyards to gain this? Most days no. When laying on my beam ends yes...
Would I want to give up my internal halyards to gain this? Most days no. When laying on my beam ends yes...
How do you plan to make your mast 'more buoyant'? The only semi-practical way I can think of would be filling it with spray foam. Even if you could create air-tight compartments in the mast I doubt it would create enough positive floatation to make that much difference if the boat were to capsize. What ever method you used would undoubtedly create additional weight aloft. And not only are your halyards internal, but the cables for your mast lights are as well. How are you going to allow maintenance of them?
IMO large modifications to a boat should not be done unless you have a marine architect involved. There is a lot of inter-dependent things that go into the design of any vessel, and if some method of making a mast air-tight was a viable safety option, boats would be designed that way.
IMO large modifications to a boat should not be done unless you have a marine architect involved. There is a lot of inter-dependent things that go into the design of any vessel, and if some method of making a mast air-tight was a viable safety option, boats would be designed that way.
All good Points, For Brevity my post was not detailed. I was primarily responding the the earlier post about the advantage of wooden spars in this scenario and pointing out that modern spars can offer the same advantage. I have seen this twice in my career. In both cases the work was done by the spare manufacturer and was certainly an engineered solution. Not much weight was added as the spar was made air tight. On a 35 to 40 ft cruising boat this would add about 425 lbs. of buoyancy distributed over its length. Considering the lever arm it is a significant amount.
As for wiring maintenance, conduits were installed that did not open into the interior air tight column. One terminated at the spreaders and one at the mast head. If I were ordering a spare for the GGR I might consider this. I don't know if either vessel ever had to test the concept at sea, but it did not seem a ridiculous idea for a serious adventuring boat.