The perils of edgy design offshore

Compared to what?

Against a Colin Archer 30, yes.


Against similar sized boats of the type, maybe not so much:

Wingnuts PHRF = 51

Winged Moore 30 = 30 (shorter, smaller spinnakers)

Winged Taylor 32 = -6

OD 35 = 33 (1.5x heavier, smaller spinnakers, no wings, offshore capable)

Melges 32 = 24 (Shorter, similar dspl, no wings, AVS 120)

Melges 30 = 42 (shorter, no wings)

Mumm 36 = 42 (twice the weight, smaller spinnakers, offshore capable)

Mumm 30 = 54 (shorter, heavier, smaller spinnakers, offshore capable)

 

The Perils of Edgy Weather in Any Boat

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PHRF Class E and F here , for a start. It's known as a very fast boat and you know or should know that.

http://www.yachtscoring.com/event_scratch_sheet.cfm?eID=314

 

In that regatta it was in a class with two Mumm 30s (shorter, heavier, smaller spinnakers, rated the same) and a NM36 weighing 1.5x as much, rating the same.

Wingnuts finished last in the class for the regatta.

So yes, compared to racer/cruisers that weigh 2.5x to 3x as much for a similar length it is "fast". Compared to similar type boats, not so much.

 

Horse, dead, beat.

Repeat
Repeat
Repeat

 

Have you made any progress?, not that you'd ever actually admit it. Nothing else has changed.

And what compromise?
You accept now maybe that Naval Architecture can quite reasonably predict a vessels response to a sea state and identify dangerous features.

That’s the only compromise possible you can’t agree to ‘compromise’ with a flat earth view if you are in a space station and the contender that the earth is apparently flat has never been beyond his parents village. (And he doesn't like reading science because it goes out of date )!

There’s nothing in any of your posts that contains any contrary information at all it’s all rudeness, prejudice, diatribe and polemics. Go back and read what you’ve posted.

You still won't be drawn on Wingnuts suitability for the conditions it was in. Or are you letting Doug do that for you? You were wrong weren't you !


Just as you are wrong about arch conservatism driving Naval Architecture. It's just bog standard science which is getting more and more refined.

 

MJ, you come out with extremely naive statements, about art, likening it merely to style, style is not art, style is the interior design sort of stuff, clothing and so on, usually fashionable but quickly changed the following year, good art lasts and good art, for Fargo truck''s sake, is not vacuous style or just a yachts sheerline, that is simplistic.. Good art (including engineering) is Concorde, Dick Newick's trimarans, or Lock Crowther's same, or Nigel Irens and LVDP's works of art, all including high performance, or L. Francis Herreschoff's day sailers, Len Couldrey's superb race dinghies, Farr's Ceramco, Young's Rocket, and so on, all combinations of vast experience, empirical knowledge and innate, natural, artistic abilities.
I said from the beginning of this overdone thread, that I didn't like the flat wings of the O.J design, that I preferred the Young, Elliott type. But I defend the owner's right to try what he believed in ... and that is the crux of my argument. You keep dragging up your boring dogma - and I thought (naively) that this thread had lived its life and was petering out. But since it hasn't - still would like to see your engineering (but never stylist) renderings, sketches, concept, even plans of your improved OJ design. And if my comments affect your fine sensibilities, well, as Grant Dalton would say, HTFU.

 

Second time I've used this today...

 

I was just climbing up with you on your soapbox and pointing out that there was no imagined compromise, that's just your easy out .

As for designs the idea was for you to post one and we would comment. You haven't posted one either and that was a sideline with nothing to do with Wingnuts.

And nothing offends my sensibilities I kill myself laughing on this thread you can't even see the irony in your own insults.

 

See the irony yet?

You have more than a slightly narcissistic attitude and the comments you use above are as a replacement for fact. You use insult to support opinion.

And if that doesn't offend my sensibilities disagreeing with me certainly won't.

 

Having read the report and other constructive posts on this thread, including the only one by someone who had actually sailed that model of boat, I have come to the conclusion that WINGNUTS may have been unwittingly mishandled.

Apparently, this type of this type of boat likes to round up into the wind when over pressed. By striking the main and leaving the some of the jib up, a sensible move on multihulls when expecting fierce squalls and having a reasonable amount of sea room, such rounding up was thwarted. The hull was trying to round up and the jib was trying to make it fall off (sail down wind). If the two tendencies came to any sort of balance, the boat would hold its beam to the wind, the absolute worst position for this type of boat.

Most monohulls that I have been on (light, beamy center boareders, with limited ranges of stability) have had a weather helm and thus a proclivity to rounding up into the wind. In the event of a sudden squall, I've just let the boat do its natural thing and knock downs and capsizes were prevented.

Perhaps, with WINGNUTS, the jib should have been struck and the fully reefed main should have been left standing (with maybe another set of reef points added to the main in anticipation of of this). Failing that, perhaps all sail could have been struck and maybe a storm sail (which should be required equipment on all boats participating in any race where fierce gales can be expected) set.

My guess is that the skipper wished to continue in the race, after taking what he thought were reasonable precautions. I don't think he knew his boat as well as he thought he did.

I also see the possibility that changes he made in it may have changed its handling characteristics. In a previous post, I speculated that some ballast had later been removed. Apparently that is not so. Apparently, the ballast had been increased to improve ultimate stability (another move that seems quite sensible), then left at that.

Apparently the fore triangle had been increased. Not a good move, IMHO. By doing such, the Center of Area of the sail plan gets moved forward. This can be bad for a boat designed to save itself by rounding up.

As for the design. I would not chose it for myself. I would chose a wave smasher, more like what Mike Johns favors, and hope to win by handicap. But I wouldn't feel quite right in legislating against it either, in an overnight race with so many potential rescue boats around.

Had this accident happened in 'protected waters', I don't see how the ending would have been any different. Some of the fiercest squalls I have encountered have happened in 'protected waters' (Lake St. Clair). And one of them was in the class and duration of the one that capsized WINGNUTS.

It was the capsize itself that caused the unfortunate deaths, not the length of time it took rescuers to get there. Even with quick release harnesses, the drownings would have still occurred. When you're knocked unconscious, it is very hard for you to undo even the simplest of fastenings.

If I were to inherit WINGNUTS, I would remove the wings and sail it as an odd looking narrow monohull. IMHO, the performance gains from having the wings don't justify the hazard they represent.

If I had a co-owner who wished to keep the wings, I would devise a way for the wings to quickly fill and drain, when upside down, automatically. I am thinking of a device to make this possible. It is so simple and potentially reliable, it aught to be patented. If the wing on one side could fill and the one on the the other drain quickly enough, the boat could right itself in a short enough time to prevent anyone trapped under it from drowning.

I would also change the rig back to a more fractional one, with a larger main and smaller jib, even at the loss of some sail area, to insure the boat could and would round up in a squall. I would order and drill the helms persons to round up in extremely squally conditions. No point in having a capsize if it can be prevented.

Perhaps I'm not cut out for sailboat racing.

 

This fact is also noted in the report:

"..The assumption that the owner and crew understand what they are getting into does NOT hold up..."

Not sure you can patent holes!

Holes are self draining...on the bulwark, we call them freeingports, and perform ostensibly the same action.

 

I've rougly modelled something like a k35, based on the images and data here published.
Offcourse, this should not be taken as accurate data nor as representative of a Kiwi35 sailboat. Anyway, someone can find this useful.
Here are my results:
AVS 120 deg
VCG 0.29 m over keel
Initial GM about 1.9 m
maximum GZ: 1.25 m at 55 deg of heeling
maximum RM: 1.67 tm
minimum (negative) RM: -1.296 tm at 160 deg
At 35 deg of heeling, the wing goes into the water increasing GZ and RM (and drag)
Sail area (main plus jib) is in doubt: 42m2 published as data, 54m2 from the profile drawing.
The boat is hardly oversailed at 15-17 knots, so it needs people at windward almost all the time.
The RM curve looks really tender.
Block and Prismatic are really low.
I can send the .fbm file if someone still has interest.

 

Nice contribution queuqen.
It seems to me the volume in the wings of the Kiwi is smaller than the one in you modelled hull, so their righting effect would be less for the real thing.

Are you considering the wings when calculating the block and prismatic coefficients?

 

Interesting, "something like" real data with something to back it up.

A far cry from loud opinions supposedly backed up by engineering.

MJ, perhaps if you had concrete suggestions then possibly quequen would model them and show the "something like" real effects.

I was going to ask if anyone knew how to opt out of a subscription to a thread, but this might be interesting. If there are any actual changes proposed so the effects could be understood by all.

Thanks quequen.

Marc

 

Very nice contribution quequen!

Just three objections:
1) the wings look a bit too voluminous, as Guillermo has pointed out (perhaps it's just a matter of coloring scheme);
2) how did you estimate the vertical CoG? It's value will have a significant influence on AVS, possibly up to +/- 10° for 0.2 meters of change in VCoG.
3) the report states that the boats' displacement was 1800 kg, while yours is 1300 kg.

I think you should check the first two items and correct the third, in order to have numbers which are closer to (official) reality. It will surely give more food and energy to our fighters.

Cheers!