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Glass Globe 580 Ballast ratio.

Created by MAGNESIUM MAGNESIUM  > 9 months ago, 21 Jan 2025
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MAGNESIUM
MAGNESIUM

222 posts

21 Jan 2025 6:24pm
Anybody else think 220kg ballast is a bit light for boats going offshore ?
not much better than most trailer sailers
sailboatdata.com/sailboat/classglobe-580/
Planter
Planter

NSW

165 posts

22 Jan 2025 5:35am
Lake Boat !
Quixotic
Quixotic

ACT

219 posts

22 Jan 2025 1:56pm
Not a marine engineer, and those who are may correct me,

I'd have thought issue is stiffness and righting moment rather than just ballast.

Rule of thumb is the capsize screening formula should be less than 2 for an offshore boat. CSF is not definitive, it's a guide based on relationship between the beam and displacement. Sailboat data gives this design a CSF of 2.58, so well outside the rule of thumb. By way of comparison, a S&S39 has a CSF of 1.77.

I think the more important value is the righting moment at various angles of heel, and ultimately the angle of vanishing stability (when the boat capsizes rather than just laying over). classglobe580.com/specification/ gives the AVS as 142 degrees. That's higher than I'd have expected, but may reflect the hull cross-section/profile (presumably the centre of buoyancy moves leeward as the hull heels, improving the righting moment, until the centre of gravity passes over the centre of buoyancy and there you have the AVS).
Yara
Yara

NSW

1314 posts

22 Jan 2025 2:33pm
IMHO the problem that I can see, is that for long passages they are going to need a lot of stores and water. The weight of this stuff is significant on a small boat, the size of a trailer-sailer. One interview I saw, the skipper was storing lots of water containers at a high level in the cabin. That can destroy the stability.
Larger, powerful boats can get energy from solar or hydro generators, and use that energy to drive a water-maker. Not really possible on a small boat. You can also get water makers hand powered, but that would rapidly sap a solo skipper's energy.
I hope these sailors stay safe.
p3p4p5
p3p4p5

WA

65 posts

22 Jan 2025 12:47pm
140 degrees range of positive stability is good number that would ensure immediate self righting.

What is important is the negative stability curve which is a relatively short shallow righting arm meaning that it will quickly self right. If you wanted to be sure, just fill the mast with foam or seal it to offset the impact of the fully loaded condition. The capsize screen number is well above 2 however its a simplistic ratio whose design has been validated. The Mini 6.5's get pulled to check its self righting abilities. I am not sure if this has been done for the class 5.80 in a loaded state. It would be interesting to see the result if they pulled it over.

The cost estimates that I have seen for a new build is well over 100K, it just makes no economic sense considering what you can buy for 100 grand. Even fully equipped Golden Globe yachts sell for a lot less fully equipped.

Every sailor has their own dream and path they wish to forge, good luck to those wanting to spend so much in achieving the dream.

The offshore sharpie designs seem to becoming more popular, designs like those in the youtube channel wave rover seems like another good design.

There is a designer who specialises in small craft design and he himself is a vid sailor. His designs appear professional and he has full stability data as well issuing CE rating data. Jerome uses all the latest design tools, however his skills cant make up for inadequacies of a small size.

duckworks.com/jerome-delaunay/

Bigger is better and might is right, especially when you consider that all it takes is wave size that is half the beam width to roll anything. 5.8 metres is small.. If I was going small it would be something like a Vertue, Folkboat or TopHat. Something small and sensible.
Ramona
Ramona

NSW

7737 posts

23 Jan 2025 8:55am
Select to expand quote
MAGNESIUM said..
Anybody else think 220kg ballast is a bit light for boats going offshore ?
not much better than most trailer sailers
sailboatdata.com/sailboat/classglobe-580/


They don't have a problem crossing the Atlantic.

classglobe580.com/
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