Rob,

My recollections re capsize of monohull dinghies: there is nothing worse than attempting to right the boat with the mast to windward.  Watching someone attempt to do this knowing that the craft would capsize to leeward over the top of them bordered on the hilarious – tempered by the fact that it had the potential to be somewhat tragic.  Multihulls wouldn’t normally be seen to suffer this fate.  However, I have two concerns:

1.       The strut commences at 45 degrees below horizontal, so presumably ends up at something like 45 degrees above.  If the lazy sheet is fouled or cannot be released, then the rig will not feather.  The boom would be restrained to windward in a caught aback situation.  Even if the strut need only be rotated through 45 degrees, the rig still would not feather in a fouled situation.

2.       With wind loads capable of capsizing the craft, I have a slight concern that a fouled sheet during righting could lead to diagonal capsize over either of the bows of the short float if caught aback.  The problem is compounded by the kinetic energy of righting craft.

I think it’s a great idea and worth pursuing and would benefit from having the rig to windward.  There appears to be no great obstacle to overcoming the observed concern.  The lazy sheet should be free to release with care taken to avoid fouling.  As Larry pointed out: “The problem is that all these still require some active intervention right at the time when you are wet, cold, exhausted, panicked, and trying to counteract 1,000K loads while balancing on a relatively unstable platform”.  This isn’t the place where OHS procedures are followed to the letter.  In the recent C-Class champs, the Cogito skipper fell overboard whilst foiling; the thing that kept him with the boat was the mainsheet wrapped around his leg. 

 

How would the sheet fuse cope with the pitch pole situation?  After all you’ve identified this as the main concern.  The dynamic forces involved in pitch pole mean that the point of no return is reached at a lower angle of heel than for leeward capsize.  A 30 degree fuse is sufficient?  I suspect it is but have no empirical evidence to base this upon.

 

Regards,

David

 

From: harryproa@yahoogroups.com.au [mailto:harryproa@yahoogroups.com.au]
Sent: Tuesday, 21 October 2014 11:55 AM
To: harryproa@yahoogroups.com.au
Subject: Re: : Re: [harryproa] Bucket List harry forum

 

 

The buoyancy of the mast is plenty.  As soon as the mast hits the water, the boat swings round so the mast is upwind.  if the mast was removed, the boat would right from the windage on the hull, beams and tramp.

 

The boom has 80 kgs/176lbs buoyancy (200 was a good guess), which should be enough, especially as any waves and the wind are both working to right the boat.  

 

You are right about pulling the boom beneath the water.  There is a strut required.  It is attached to the mast at deck level and the lazy sheet runs through the end.  The strut sinks to ~45 dgrees and the sheet can be tightened, pulling the boom under the water.  

 

A lee float was not considered for the following reasons:

1) weight in the wrong place

2) complexity

3) they may stop a sideways capsize, but that is much less likely than a pitchpole.  In a pitchpole, the bow goes in and then the boat capsizes to leeward.  Almost certainly, the first part of the float to get wet will be the top.  Then, it will make it impossible to right the boat without outside assistance.  

 

If the sheet fuse is used, capsizing will not happen.  I certainly do not wish to encourage people to capsize, just because the boat can be easily righted.   

 

Foils are complex and prone to damage when they hit things.  This is not what Bucket List is about.  If you want a foiler, then it would be better to start from scratch, as the boat would be very different.  

 

regards,

 

rob

 

On Mon, Oct 20, 2014 at 10:13 PM, captian_rapscallion@yahoo.com [harryproa] <harryproa@yahoogroups.com.au> wrote:

 

I think the boat could be righted the way Rob suggests, as long as there is enough flotation in the mast and boom, but I think that in order for there to be enough flotation, some kind of mast and boom float(s) will be required. The boom float will likely need 200lbs of buoyancy to work in any kind of swell, and I think it would be difficult to winch the lazy sheet from the skyward hull enough to right the boat in flat water - much less in 5' to 7' waves.

I know Rob is all about flat panel hulls these days, so instead of a leeward pod on the leeward hull like jezzaro, how about a cylinder like hull on the leeward side of the hull to help prevent capsize. It could be inflatable, so it shouldn't add too much weight. Seriously, if the goal is to provide a boat people can charter in a race they have never done before, sailing a type of boat they have never sailed before, I think training wheels aren't such a bad idea. Error! Filename not specified.

I've righted my 32'cat at least a half dozen times using the mast float, so I have an idea how much force it takes to right a bigger boat. I can tell you that without some kind of gin pole to change the angle of the lazy sheet there are going to be some significant issues with the righting procedure, and a nacelle or leeward pod will give you the needed reserve buoyancy to help prevent capsize, and provide the needed angle the lazy sheet would require to right the boat.


Rob,

Why not go all the way and make the boat a foiler??
Error! Filename not specified.

Use the foil configuration found at the bow of C-fly on the leeward hull.



 

 

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