Dragonfly 28 capsize ?

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jean louis
Posts: 15
Joined: Tue 30 Sep 08, 16:05
Your Country: dinard britanny france

Dragonfly 28 capsize ?

Post by jean louis »

Another DF 28 capsize ?
Surfing on the web ,this afternoon…..
"Silverruddet regatta" in Denmark ?
Only 30 knds wind (organisator Yacht Club infos )
Are our nice DF boats becoming too "ultimate" for us, ordinary sailors ?
Be carefull
J.Lo
Double Horizon
Posts: 440
Joined: Wed 09 May 07, 0:18
Your Country: USA

Re: Dragonfly 28 capsize ?

Post by Double Horizon »

jean louis wrote:Another DF 28 capsize ?
Surfing on the web ,this afternoon…..
"Silverruddet regatta" in Denmark ?
Only 30 knds wind (organisator Yacht Club infos )
Are our nice DF boats becoming too "ultimate" for us, ordinary sailors ?
Be carefull
J.Lo
30K and full sail is just pilot error.

Can you drive a Ferrari around a 90-degree bend at 100kph in rain?
Larry - Former Owner DF-1200
Stefan Kolmodin
Posts: 62
Joined: Mon 08 Nov 10, 21:50
Your Country: Sweden, Varmdo

Post by Stefan Kolmodin »

Indeed, must have been a strong wind, locked sheets and wrong turn (upwind) to flip it without gennaker. And don't mention the resque completely destroying the boat!
DF800R, SWE-257
Jakob Madsen
Posts: 7
Joined: Fri 31 Jul 15, 23:41
Your Country: Copenhagen

Post by Jakob Madsen »

Do anyone know the statistic of capsized dragonflys.

As I remember it is something like:
- 7 or 8 DF 800
- 3 DF 28
- perhaps 1 DF 920 but I am not sure

A couple of boats has capsized because of back swinging wings due to structural defects or forgotten safety lines but these are not included in above
Jakob Madsen, DF28
jean louis
Posts: 15
Joined: Tue 30 Sep 08, 16:05
Your Country: dinard britanny france

DF capsize

Post by jean louis »

If you look at the video of the recovery of the skipper on You Tube , the weather conditions don't appear so bad.
J.Louis
EarthBM
Posts: 206
Joined: Fri 17 Sep 10, 0:54
Your Country: USA, So Cal -- So Florida

Post by EarthBM »

Virtual copy/paste of my table from another DF 28 capsize thread... the last line shows the "righting moment index": 28S is two times less stable compared to 35T....

the 28 was built to get under 10 meters when folded to get away with registration and tax in some Euro countries.

Here is my back of the envelope stability calculation. Sail force is linearly proportional to sail area, so at any given wind speed there is linear righting moment dependency on mast height, sail area, beam, and weight. 28 sport is clearly pushing the envelope compared to 920 and 35:

_________28t___28s__920t__920x__35t___35x
Beam m__6.5___6.5__6.8____7.8___8.2___8.2
Main sq m_35___42___37____44____54____65
Mast m__13.7__15.2__13.1__14.6___16____17.5
Displ, t___1.9___1.9___1.9___1.9___3.9____3.9
(Main X mast)/(displ X beam):
_________39___52____38____43___27____36

And sail force is a function of apparent wind speed squared, so at 30kt there is 4x as much capsize moment as at 15kt.
Ivan -- DF 35 #29 "Lykke"
gminkovsky
Posts: 210
Joined: Wed 01 Nov 06, 19:58
Your Country: USA, Long Island Sound

Post by gminkovsky »

@jacob madsen: every capsize should be counted.

Operator error; design failure; material failure - it doesn't matter. The only thing that matters is that there is a catastrophic event. Compare these stats to any other boat, multi or mono, and you will see a pattern. Trimarans and catamarans have a higher proportion of of these events. That's why my insurance is at least double of what it would cost to insure a similarly priced mono.

28 is an undersized overcanvassed boat as EarthBM pointed out. And that is before accounting for wave action which is not even considered in standard loads and stability calculations.

I actually maintain a much more precise table of stability loads for my boat that accounts for reefing and true weight loads (not published displacement numbers that have nothing to do with reality). On my 920 (cruising) I do not want to be out sailing in anything much above 25 kn unless there is no other choice.

I was caught in a storm in a water spout - a tornado on water - during a race in a relatively safe Long Island Sound a few years ago on a friend's 40 foot mono. It was the scariest experience in my life. I ran all calculations for my boat and discussed this with a number of experienced mono and multi sailors. My feeling is that this type of event may result in a loss of life on a DF920. There are quite a few design characteristics that make 28 a far more dangerous boat, e.g. lack of traveller.

IMHO, 800, 28 and 920 are for protected waters. 35 and 1200 are blue water. 1000 is probably an overbuilt safe sturdy ocean boat (despite TC's desire to lighten up).
Double Horizon
Posts: 440
Joined: Wed 09 May 07, 0:18
Your Country: USA

Post by Double Horizon »

gminkovsky wrote:snip
IMHO, 800, 28 and 920 are for protected waters. 35 and 1200 are blue water. 1000 is probably an overbuilt safe sturdy ocean boat (despite TC's desire to lighten up).
The 1000 folding mechanism is not as strong as the 35 or 1200. The later designs are more rigid.
Larry - Former Owner DF-1200
John55
Posts: 1
Joined: Mon 05 Mar 18, 10:10
Your Country: London

Post by John55 »

Its sad but it happens. What is important is to always inspect the reason why the given ship went down. Same as a plane crash. It can be only a fault of the inexperienced crew or there can be some severe design flaw.
EYS
Posts: 7
Joined: Thu 28 Oct 21, 1:09
Your Country: USA SanDiego/bay

Re: capsiize

Post by EYS »

Bad things can happen with any boat. That said experience with multihulls points to a common trend, push a multi too far and it may push back. The same rule holds for monohulls but at a higher level of forgiveness. I think of the times I pushed my multi into the high teens as being similar to ridding my motorcycle at high speed on a wet road. Serious racing in windy conditions usually precludes the wisdom of caution, so some boats may capsize.
Ancient marina
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