Originally Posted by MarkJ
You two youngsters just don't listen to moi!
I suggested putting it to a product engineer.
We thought you were too busy drink good red wine and thinking about playing with velvet
The french (open 60's and g class multis) have looked at this problem (actually a slightly different problem . . . their focus is preventing the loads from breaking the boat, not preventing capsize) and concluded fuses
were the answer. That does not mean they are right . . . perhaps their engineers are also distracted by red wine and velvet
I don't understand the reluctance to a clew fuse:
1. I am sure in cruising mode you don't want/plan to ever fly a hull
, and lets say 5 degrees of flying hull
is the most acceptable. If you set the fuse at the 15 degree righting moment you have a 3x safety
factor (the righting loads are almost linear at that part of the curve) so, it will 'never' blow in normal conditions but could save you from a capsize
2. If the fuse breaks, the clew is going to go up (due to leach loads), and the clew/boom is already high on these boats, so the sail is going to pose no safety
issue. The boom is going to recoil when the load is let off (as Joli said). I don't have any sense how much/how hard with a low stretch sheet. But it is pretty high and out of the way on these cats (especially the Atlantic's) and you could trap it with a normal preventer. All in all, it does not sound like a serious problem, especially given it will only happen just before capsize
3. The fuses
and easy to make and cheap
and easy to replace. It's just a spectra lashing. We could all make one up next week, without engaging harken
to do 5 years of product development. You could call up one of several french riggers who do this and ask them to make it happen, or as any good cruiser would, do it yourself . . . You need the 15 degree load, and the actual breaking strength of some spectra rope
. The NA should have the expected 15 degree load, or if not, someone like North sails
could make an excellent estimate. Or you could buy/rent an inexpensive load cell and just go measure them yourself, or do a standard incline test. All of which would give you enough data to size the fuse - remember you have a 3x factor so this does not need to be super precise. Then you call up New england
ropes or Samson
or Yale and tell them what you want to do and ask if they will make and break some lashings for you to proof test the right number of turns on the lashing (or just go with the rated loads).
4. I personally think the 'automatic' feature of the fuse is better than the 'manual release' approach Mark and others are proposing. First, from a mechanical reliability
perspective, the fuse has no moving parts
and will certainly still work after several years of not being used (in fact it will work 'better and better' over time due to chafe and uv), while the manual releases are all vulnerable to freezing after not being used for several years. Second, I am looking precisely for something that will work when I am distracted or not paying attention or out of commission for some reason. The manual release does not seem to fit that basic criteria.
Honestly the fuse seems like a 'no brainer' to me. . . . no downside and the possibility it might save a capsize.
awareness/reefing approach to preventing capsize is obviously best. But it's also obviously a delicate balance, much much more than on a mono.
First you have just spent a whole pile of money
on this performance machine. Even if you know you 'should', how likely are you to want to 'cripple' it by sailing around with a reef whenever there is a cloud in the sky. This is easy to dismiss sitting ashore, of course we all say, we will do whatever is proper seamanship. But then you are there on passage
, in 10kts of breeze, with a few squalls around and you realize you could get in a whole day sooner if you put the full hoist up. You 'know' the boat is very stable and safe, if you can get a little more boat speed you can probably sail around the squalls. Are you going to sit there with a reef in?
Second, as Kettlewell says, the wind/weather is really unpredictable. You can sail around a corner in 20kts and then be surprised by 50kts. You can get a 60kt 'dry microburst' out of an almost cloudless sky. You can be sailing thru a whole series of squalls that all look the same and all have only 20-25kts except the one with 50kts. Very often the gribs (and every other forecast) are just plain wrong. So, sometimes we are just very surprised.
Third, fatigue and distraction are deeply integral to double handed passage
making. I at least find it impossible to be 100% alert, and 100% efficient, and 100% making good decisions. I try to save up energy in the 'safe times' so I can be more alert in the unsettled times. But see point #2, sometimes I am simply taken by surprise when I am not alert or thinking clearly. It may simply be that these performance cats should have three or four on board for passagemaking . . . but for us that's not 'cruising' as we know it.