Real chance of capsizing?
- Thread starter srimes
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This is the one I have on my H26. Very important when sailing down wind to have some tension on the vang. I loosen mine when working to windward.
On a downwind leg the fastest way to get a boat back on its feet during a broach is to blow the vang. This causes the boom to immediately rise and depower allowing the boat to come upright.
This is the one I have on my H26. Very important when sailing down wind to have some tension on the vang. I loosen mine when working to windward.
View attachment 183056
When going upwind or on a beam reach dumping the traveller will also depower the main and allow the boat to come back up.
Releasing the main on a reach will do the same, depower the main, however there is a lot mainsheet that needs to run free and be taken back in. Downwind releasing the main doesn't do much as the sail is already out.
I agree with dlochner. I don't believe you were in any danger or really in any situation to get excessively worried by. When the waves are breaking around you and the boat is no longer controllable, then you can start to worry. However, the poor pooch did not seem to be having much fun and it is apparent you telegraphed your fear to him/her. Poor thing.
Boom vang is my next project! Think I can scrounge most of the parts already. I do need to decide on how to attach to the boom:
bail:
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(scroll down) Boom Bails and Hangers
Yeah the pooch got spooked. Sent her down below to relax until we got back to the river. This was her first time sailing, and I thought she did great. Much better than when I took my wife and daughter!
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BOOM BAIL, ROUND, WITH BOLT/NUT
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Yeah the pooch got spooked. Sent her down below to relax until we got back to the river. This was her first time sailing, and I thought she did great. Much better than when I took my wife and daughter!
The waves in your video weren’t breaking. They had whitecaps on the crest, which is not the same as a breaking wave.
a breaking wave in deep water on ocean is very similar to one on a beach. The primary characteristic is that the front face of the wave Is vertical and the back side rolls over and crashes down the front. A large mass of water from the back face of the wave falls and accelerates due to gravity. This falling weight, paired with the rotational kinetic energy of water molecules in the breaking wave, can roll a boat.
Breaking waves are quite different from whitecaps. Whitecaps occur when only the crest of the wave is blown sideways, so that there’s a bit of foam on the top. White caps occurs when wind and current differ In velocity by about 15 knots. There’s enough wind to push a comparatively small mass of water sideways.
Whitecaps don’t pack enough kinetic energy to roll the boat. A small mass of water is blowing sideways. With whitecaps There are no vertical wave faces and you can steer down the face at some angle.
in a breaking wave has a large mass of water crashing down vertically. You can’t steer down the vertical face of a breaking wave.
[on edit: after I have re-read this, I want to say that I’m far from being an expert about how waves work. I have gone the thru the math more than once, so I have a rudimentary understanding, but it’s far from complete.. so if I’ve materially mis-stated something, I Invite and welcome correction]
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Measure the distance between the jaws and try to find one that just slips over the boom. Then pop two rivets in the holes
The concept of vanishing point/angle of stability cannot be directly applied to predict or explain the motion of a ship in a dynamic seaway.
The angle/point of vanishing stability is a calculation done under specific set of assumptions about the ship and sea state: The ship is assumed to be in level water in a calm seaway, and the forces are allowed to reach static equilibrium at infinite small increments of heeling angle. Therefore, Predictions based on the statical stability curve cannot be used to predict capsize angle in a rolling seaway.
More specifically, The statical stability curve analysis assumes that the center of gravity of the ship and the center of bouyancy create an internal couple which counteracts the external heeling force, in flat water. The Center of bouyancy is not a fixed point, it moves as different parts of the hull are submerged. It follows that the Center of buoyancy is not the same when the boat is in level water as when it’s beam-on to a very tall, vertical face steep wave.
the following quote is from the US Naval Academy course EN400 Principles of Ship Performance, chapter 4, section 4.3 . (Emphasis is added by me)
EN400: Principles of Ship Performance
EN400 page for Naval Architecture & Ocean Engineering at USNA.edu. Updated Wed Mar 12 13:07:08 EDT 2025.
www.usna.edu
“The curve of intact statical stability assumes the ship is being heeled over quasi-statically in calm water. Quasi-static means that the external moment heeling the ship over is doing so in infinitely small steps so that equilibrium is always present. Of course this is impossible, but it is an acceptable idealization in the modeling of ship stability. Be sure to realize that the predictions made by the curve of intact statical stability can not be directly applied to a rolling ship in a dynamic seaway. The dynamics of such a system, including the application of additional external forces and the presence of rotational momentum, are not considered in the intact statical stability curve. However, the intact statical stability curve is useful for comparative purposes. The stability characteristics of different hull shapes can be compared as well as differences in operating conditions for the same hull type.“
Judy B
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Judy, on points that require calculation I willfully defer to your superior academic expertise. My knowledge of hull design and stability issues is based years of being in tippy boats, from scaring the you know what out my little brother in our El Toro as I put the rail in the water, to running canoes and kayaks down white water rivers and streams, to sailing bigger boats.The concept of vanishing point/angle of stability cannot be directly applied to predict or explain the motion of a ship in a dynamic seaway.
The angle/point of vanishing stability is a calculation done under specific set of assumptions about the ship and sea state: The ship is assumed to be in level water in a calm seaway, and the forces are allowed to reach static equilibrium at infinite small increments of heeling angle. Therefore, Predictions based on the statical stability curve cannot be used to predict capsize angle in a rolling seaway.
More specifically, The statical stability curve analysis assumes that the center of gravity of the ship and the center of bouyancy create an internal couple which counteracts the external heeling force, in flat water. The Center of bouyancy is not a fixed point, it moves as different parts of the hull are submerged. It follows that the Center of buoyancy is not the same when the boat is in level water as when it’s beam-on to a very tall, vertical face steep wave.
the following quote is from the US Naval Academy course EN400 Principles OD Ship Performance, chapter 4, section 4.3 . (Emphasis is added by me)
EN400: Principles of Ship Performance
EN400 page for Naval Architecture & Ocean Engineering at USNA.edu. Updated Wed Mar 12 13:07:08 EDT 2025.www.usna.edu
“The curve of intact statical stability assumes the ship is being heeled over quasi-statically in calm water. Quasi-static means that the external moment heeling the ship over is doing so in infinitely small steps so that equilibrium is always present. Of course this is impossible, but it is an acceptable idealization in the modeling of ship stability. Be sure to realize that the predictions made by the curve of intact statical stability can not be directly applied to a rolling ship in a dynamic seaway. The dynamics of such a system, including the application of additional external forces and the presence of rotational momentum, are not considered in the intact statical stability curve. However, the intact statical stability curve is useful for comparative purposes. The stability characteristics of different hull shapes can be compared as well as differences in operating conditions for the same hull type.“
Judy B
For me the simple story is when forces get out of balance, bad things happen, like the mast points down and the keel up. I'll leave it to the Naval Architects and Engineers to do the calculations.
Interesting... not sure what can be learned or taken away from that video. So we have a lot of theoretical talk about a Mac25 in questionable trim and helm getting quartered by a small wave. Not sure what is to be learned here.
I’m going to write a little about Broaching in waves and wind.
I will define a broach as an abrupt loss of steering because the rudder becomes ineffective. The bow can round up or down, and if the sails are up, it usually ends up with the ship’s beam to the wind and waves.
Both wind and waves can contribute to a broach. A gust can heel the boat, lifting the rudder out of the water. And wave action can lift the rudder out of the water at the same time.
There is another factor contributing to loss of rudder control, in addition to lifting the rudder out of the water by wave or wind/ heeling. The other factor is the speed,of flow over the rudder compared to the speed of the water circulating at the crest of the wave. This is a major contributing factor to broaching when the boat and the wave direction are on similar courses.
Consider a ship being overtaken by a wave traveling in the same general direction. At the crest of the wave, the orbital flow of water can is in the same direction as wave’s propagation and the boats course, and the speed of the water at the crest may be the same as boat’s speed. The rudder loses effectiveness steerageway. The helmsman is unable to control the boat and it may broach, going beam to wind and waves.
Considering that both wind and waves contribute to a loss of rudder control, there are two main strategies to avoid broaching When sailing deep angles.
1) ease or depower the Sails, especially during gusts
2) steer so that you don’t lose flow over the rudder at the crest of the wave.
John mentioned strategy #2 in a previous post in this thread:
On Johns boat, easing the mainsail works well as he sails down the face of the wave. But although it may seem counter intuitive to some, if your the boat accelerates a lot as you surf down the face of the wave, you may want to sheet the main in as you accelerate down the face of the wave. That’s because your increased speed causes the apparent wind to moves forward. When you reach the trough of the wave and change course to steer higher, you can ease the mainsail again as you steer diagonally up the face of the next wave.
I will define a broach as an abrupt loss of steering because the rudder becomes ineffective. The bow can round up or down, and if the sails are up, it usually ends up with the ship’s beam to the wind and waves.
Both wind and waves can contribute to a broach. A gust can heel the boat, lifting the rudder out of the water. And wave action can lift the rudder out of the water at the same time.
There is another factor contributing to loss of rudder control, in addition to lifting the rudder out of the water by wave or wind/ heeling. The other factor is the speed,of flow over the rudder compared to the speed of the water circulating at the crest of the wave. This is a major contributing factor to broaching when the boat and the wave direction are on similar courses.
Consider a ship being overtaken by a wave traveling in the same general direction. At the crest of the wave, the orbital flow of water can is in the same direction as wave’s propagation and the boats course, and the speed of the water at the crest may be the same as boat’s speed. The rudder loses effectiveness steerageway. The helmsman is unable to control the boat and it may broach, going beam to wind and waves.
Considering that both wind and waves contribute to a loss of rudder control, there are two main strategies to avoid broaching When sailing deep angles.
1) ease or depower the Sails, especially during gusts
2) steer so that you don’t lose flow over the rudder at the crest of the wave.
John mentioned strategy #2 in a previous post in this thread:
if you steer down theface of the wave before the crest of the wave reaches the rudder , you can get going fast enough to maintain flow over the rudder and to prevent loss of steerage and a broach. If you initiate the turn just as the wave starts to lift the stern, you can usually get enough acceleration to maintain flow over the rudder.
On Johns boat, easing the mainsail works well as he sails down the face of the wave. But although it may seem counter intuitive to some, if your the boat accelerates a lot as you surf down the face of the wave, you may want to sheet the main in as you accelerate down the face of the wave. That’s because your increased speed causes the apparent wind to moves forward. When you reach the trough of the wave and change course to steer higher, you can ease the mainsail again as you steer diagonally up the face of the next wave.
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To some heeling way over is fun. Two things to remember. First you could go over way to far and not be able to recover risking not only your own live but the lives on board with you too. Could be an offical inquiry with time served you know where. Secondly, you may probably scare the hell of those loved ones and friends who will never go sailing with you again.
Once I demoed a boat to a young couple with the husband at the helm pushing the envelope or heeling way over due to adverse weather conditions thinking it was fun while his wife was visibly shaken scared to hell. I took the helm back and went in. She was crying. On shore i refused to sell him a boat and gave him a severe tongue lashing for scaring his wife to include a comment to continue, there will be a divorce. He should apologize. Years later, I saw that fellow at a show with his wife and children. He thanked me for saving his marriage. Later I did sell them a boat. He also thanked me that all children were concieved on a sailboat. two kids.
Once I demoed a boat to a young couple with the husband at the helm pushing the envelope or heeling way over due to adverse weather conditions thinking it was fun while his wife was visibly shaken scared to hell. I took the helm back and went in. She was crying. On shore i refused to sell him a boat and gave him a severe tongue lashing for scaring his wife to include a comment to continue, there will be a divorce. He should apologize. Years later, I saw that fellow at a show with his wife and children. He thanked me for saving his marriage. Later I did sell them a boat. He also thanked me that all children were concieved on a sailboat. two kids.
It's usually difficult to capsize a boat. There are many factors involved, but generally I've heard it takes a rogue wave at least as tall as your mast to hit you broadside. Some sailing events used to require your boat meet a minimum "capsize ratio" to qualify, although I don't know if this is still done today.