Desirable and Undesirable Characteristics of Offshore Yachts

[Panope]

I have an urge to whittle a hand full of hull shapes (with correct weight distribution and spar weights), take to the beach and see what happens.  

Steve

 

[IStream]

I have an urge to whittle a hand full of hull shapes (with correct weight distribution and spar weights), take to the beach and see what happens.  

Steve

That's Zonker's job, Steve. Yours is to test anchors. Stay in your lane.

 

[Panope]

That's Zonker's job, Steve. Yours is to test anchors. Stay in your lane.

Zonker DESIGNS the shapes.  I whittle and test (and film, of course).

 

[IStream]

Zonker DESIGNS the shapes.  I whittle and test (and film, of course).

Okay, just make sure you attach little anchors to them and I think you'll get by on a technicality.

 

[Panope]

Okay, just make sure you attach little anchors to them and I think you'll get by on a technicality.

I like that Idea.  

A recreation of the '82 Cabo disaster.

If I remember correctly, most of boats that did not drag ashore were using CQR and Bruce.

 

[DDW]

Yeah -- when the boat is lifted bodily up and falls vertically onto its side, the finer points of yaw characteristics rather fall by the way. (Tho you could say a boat with optimal broach resistance is less likely to find itself beam to a breaking wave, so the hydrodynamics are still worth considering.)

Classic wave theory has the water molecules moving in a circle. The implication of this is that on the face of a wave, "down" as measured by say a pendulum, is normal to the water surface. This continues until the wave is steep enough that the rotation can no longer be circular as the accelerations required are too great, the water slips and spills down the face - it breaks. A ballasted monohull with no mass (curious concept...) would roll so that it was always unheeled with respect to the water surface. Of course its real mass and moment of inertia in roll resists this cyclical motion - one reason why a mastless boat may roll over more easily. Once the wave breaks there are many dynamics involving the boat's characteristics in play. At least that is my understanding of it. 

Keeping the pointy end down the wave of course helps, but with large enough waves, pitchpoles have the same physics, and the greater longitudinal stability only hurts in that case. 

 

[Blue Crab]

It only hurts when I luff?

 

[Jud - s/v Sputnik]

I like that Idea.  

A recreation of the '82 Cabo disaster.

If I remember correctly, most of boats that did not drag ashore were using CQR and Bruce.

Ugh!  It’s becoming, like everything, an anchor thread!!!    Everyone needs a good one. 

 

[estarzinger]

.....

that makes me curious - how much empirical testing of procedures like that are done in climbing?  And are the 'bottom quartile' of climbers more knowledgeable with better judgement than the similar sailors?

to my uninformed eye, that particular anchor seems dependent entirely on the ice quality. Which he does not really mention/discuss (other than it should be dry so you can recover the rope).  And I personally would be reluctant to give that sort of equivalent direction to sailors because someone would try to follow it in the equivalent of obviously bad ice.

 

[Diarmuid]

that makes me curious - how much empirical testing of procedures like that are done in climbing?  And are the 'bottom quartile' of climbers more knowledgeable with better judgement than the similar sailors?

to my uninformed eye, that particular anchor seems dependent entirely on the ice quality. Which he does not really mention/discuss (other than it should be dry so you can recover the rope).  And I personally would be reluctant to give that sort of equivalent direction to sailors because someone would try to follow it in the equivalent of obviously bad ice.

Pretty much all ice gear falls under the category "psychological protection." Maybe it'll catch a fall, probably it won't, can give the leader a sense of comfort having something to clip a rope to. Ice climbers are a special bunch.

Once you enter that world, you are buying into such a large carton of misery, self-abuse, risk, uncertainty, and disappointment that mere shitty gear placements are the least of your problems. Reading horror stories of climbers burrowing thru summit mushrooms in Patagonia, you're like: Well yeah, you bought the ticket my friend.

 

[Panoramix]

btw . . . I am not intending particularly to 'pick on, or disagree' with you . . . . but whenever someone uses absolutes ('always keep...', 'absolutely want to...', etc) it raises flags in my mind.  My experience is that there are quite few absolute rules for yachts.  Soundbites rarely adequately cover correct seamanship. It may just be your writing style, but it may also reflect a lack of breath of experience.

OK, so let me phrase it in a non absolute way. Designers of "proper lifting keel" boats warn you that it is unsafe to lift completely the keel except in sheltered waters so I wouldn't do it.

Like most Frenchmen, I have never ever reached the Southern seas. I also try to avoid storms, the scariest breaking waves I've seen were in 30 knots established in the Bay of Biscay where the seafloor rises suddenly from deep ocean to continental shelf and that was scary enough for me, I've run once ahead of bad weather in 35 knots of wind but that was along the Southern coast of Brittany where the sea is well mannered so although the swell was big it wasn't dangerous at all (thanks god as that was on a boat designed for inshore racing, we were young and foolish and took the kite down when got worried of burying the bow at the bottom of a wave!) so you can call me inexperienced of "proper 10m breaking waves" if you want. Nevertheless like many Frenchmen of my generation, I've learnt to race on a boat with a lifting keel (First class 8) and I know from experience that when you lift the keel the boat completely looses its stiffness and morphs in a boat which is somewhere in between a 505 and a keelboat! I will let you experiment alone offshore what it feels like but don't count on me to crew as I don't have the skills to keep the thing upright in breaking waves! Having raced said "Class 8" in heavy air, I know about the dynamics of these keels and this is why I said that raising the keel sometimes increases directional stability but lifting it completely in heavy seas would terrorise me. 

As for fin keels downwind in bad weather, most people here just get the storm jib up, as long as you keep the speed up, steer the boat, it is very unlikely that you broach. Most of these lightish offshore fin keel boats have a big NKE hydraulic autopilot with a "true wind angle" mode for a reason...

 

[Bryanjb]

There is a risk of 'knock over' (eg 70-90 degrees) with almost all designs (in breaking waves). And you build your boat for the south just assuming you are going to get knocked over every couple years (at the very least least).  Empirically it seems (with a high degree of variability and noise) that the boats with board up may get knocked over more frequently but get knocked down (>90 degrees) less often than deep keel boats. 

I would think with a centerboard boat the risk of capsize would be minimized in breaking waves with the board up for the simple fact the boat would skid when hit broad side.  I don't have experience with a cruising centerboard boat in those conditions so it's just conjecture on my part.  Of the one design boats I've raced we always pulled up the centerboard when deep.  If some bite was needed when broad reaching we added maybe 1/4 board.

 

[CapDave]

Back in the mid-1970s, when my wife and I and several of our friends first lived on boats, we used to say "when the revolution comes, we are ready to get away."

I was living in NYC on 9/11. I heard about the attack within a few minutes of the first plane, friend phoned me. The first thing I did was mentally review the location of the sailboat fleets on Manhattan - no way I was getting stuck on that island! Then we went to the bank and got $10,000 cash and my wife and I carried 10 gallons of drinking water into our cave in the sky and filled both bathtubs as the authorities closed the bridges and tunnels. We waited to see if there were more attacks - anything else, we'd have grabbed a boat and left.

 

[CapDave]

one of our approaches to Bermuda, the night before landfall we saw a sail on the horizon (sailing 90 degrees to our course).  He called us up on the VHF and said 'do you know where you are? I'm trying to get to Bermuda but my GPS went out 2 days from Montauk'. 

One of my favorite historical factoids is that back in the days of sailing navies before Harrison made a reliable chronometer, the British Navy had standing orders not to spend more than two weeks looking for Bermuda. If they couldn't find it, carry on to the next destination in their orders! Sure you could get on the right latitude and sail back and forth, but not as easy it sounds in a square rigger.....

I also had a similar experience - enroute from Antigua to Columbia in the vicinity of the ABC islands a sail in the distance raised us on VHF and asked if we had a chart of Curacao. I didn't, but I had a Pilot with a written description of the approaches and harbor navigation and I dictated it to him over the radio.....

 

[estarzinger]

 Designers of "proper lifting keel" boats warn you that it is unsafe to lift completely the keel except in sheltered waters so I wouldn't do it.

Can you provide links to direct quotes of knowledgeable designers saying that?  I would love to read them, see what detail and context they provide.  I am sincerely interested in educated insight about this. 

One of my good friends sails a boat with what I think even you might consider a 'proper lifting keel'  - 2.7m draft when it is down, 39% ballast ratio.  They run with it up. And they have huge offshore experience (even more than I do).  But their hull shape is NOT the vendee/open shape - and perhaps that makes a difference idk - I would be interested in learning.  I actually would have thought the Vendee/open shape would give more initial stability so would be better rather than worse with the keel up.

 

[CapDave]

I’ve nothing but huge respect for those who can cross oceans using a sextant (or none at all, i.e., using natural navigation).  And I think it’s a way to connect with the cycles of your environment too, which ain’t a bad thing

I just use my sextant to keep my GPS honest these days....it's also fun to see how close I can get. Steadily inside 3 miles (and often inside 2) with waves under 6', with the error growing with sea state after that. 

By complete coincidence I was in Cape May NJ coastal hopping North from FL on May 17th, 1984 when Marvin Creamer sailed in, completing his circumnavigation with no instruments whatsoever - not even a compass. Amazing sailor, fun talking with him! He told us he had expected to arrive quite a few days earlier, but when he took a left to close land he found he was much further offshore than he estimated! Nailed the latitude though!! 

In that same boat as the above story in August 1983 I sailed out of Baiona, Spain heading South to Lisbon, and a few hours out of port became really ill with what turned into a full blown case of food poisoning. I was the only one on the boat who could navigate. I gave the crew a course that diverged slightly to seaward from the rhumb line to Cape Roca above Lisbon and told them on no account to sail to port of that course. Then I went below to die. When I could once again drag my carcass on deck I shot a noon sight to get latitude, and we were at Lisbon near enough, so we took a left. I studied the log and figured we were 30 miles offshore. Well, the crew had been a little overenthusiastic following instructions - we were 90 miles offshore, took us a long time to get into Lisbon!

 

[Panoramix]

It tends to be written in the boat user manual, I couldn't find the Pogo 12.50 user manual online but I found the extract about the keel for the RM 10.50 : https://rm-asso.org/utav/fichiers/QR.pdf

It is a vertically lifting keel but the Physics are the same, it is in French but clearly says "When sailing the keel must be down" (the bit below "Avertissement"). When I was racing "Class 8" we were careful about this, "I forgot the keel" was even a classic joke to scare the skipper but we were young and facetious!

 

[shaggybaxter]

btw . . . I am not intending particularly to 'pick on, or disagree' with you . . . . but whenever someone uses absolutes ('always keep...', 'absolutely want to...', etc) it raises flags in my mind.  My experience is that there are quite few absolute rules for yachts.  Soundbites rarely adequately cover correct seamanship. It may just be your writing style, but it may also reflect a lack of breath of experience.

The big difference between the Pogo and a lift keel is where the ballast position ends up.

"Lifting" a board on doesn't move the ballast fore or aft. The 12.50 'swings' the ballast aft 3mtrs.

Pogo's standard advice is keel must be down when sailing, which makes a lot of sense selling to a generic level skill set. Quietly they will tell you running with the keel up is fine if you want to, just don't go broad reaching due to the loads this puts on the keel head.   

After hitting a whale several times bigger than the boat I'm a huge fan of the 'crumple zone' the swing keel design gives you. Now a lift keel with the same anti crash characteristics as a swing keel (and no intrusion into the cabin space) would be awesome, but the physics does my head in.

 

[estarzinger]

 RM 10.50

Can you find a stability curve for the RM10.50?  I would be curious how it compares to a Pogo curve, which honestly does not look so terrible with the keel up - more tender certainly, but I also note shaggy's comment that it moved weight distribution aft, which I think, (again I'm not at all any expert on this aspect) would help running in strong stuff - when I was racing light boats we certainly tried to trim weight aft in those conditions..

I would be quite interested if you can find any discussion which included a 'designers comments', say in an interview with an experienced sailor. That would likely be more insightful than a warning in a user manual, which often have a huge legal CYA component to them. I can well imagine the lawyers wanting this to say 'put the damn keel down when you are sailing', and that that might or might not represent best practice in the edge case (downwind in big waves) which most used dont get themselves into. 

 

[estarzinger]

. Quietly they will tell you running with the keel up is fine if you want to, just don't go broad reaching due to the loads this puts on the keel head.   

we really need you to get your boat back and do a series of test runs in the gulf stream with 50 NEly  :blink:

We can get DDW to instrument up the boat so we get good big data comparisons of yaw and roll.