Hard Chine.

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Len
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Hard Chine.

Postby Len » Wed May 9th, 2007, 11:59 am

I have long wondered why so many boats intended for amature construction are hard chine. Even conic projection does not make it easy to twist the bottom planks up to the stem. It just makes it possible. I can well rember how hard it was on my small Herron dinghy, and the planks were only 3/16 in. thick. Half inch ply twisted through 70 degrees or so ??? A duoble chine hull is not only a better shape but also makes the twist easier by dividing it between two narrower planks. Possibly a bit more work, but easier work especially short handed.

Why, then are / were (?) so many plywood boats designed as hard chine ?
Or have I missed something ?
Does hard chine have some major advantage over double chine ?
Leonard_Woods

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Why Hard chine?

Postby Eventide Owners Group » Wed May 9th, 2007, 10:20 pm

I think it is because the designer can ensure the framework is simple and strong, though double chine may be better for the shape on the water, nearer to the round bilge optimum.

However there is another side to Hard chine or single chine. The inherent initial stability built in to the designs built this way.

compare a half walnut and an open matchbox. Float them in a bowl of water, drop a small coin in each. The half walnut will turn over!

Having sailed all sorts, from Thames Barges, (There is a Hard Chine boat for you!) to ocean racers, I chose an Eventide every time!

John
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chris s
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Postby chris s » Thu May 10th, 2007, 8:24 am

I must say that apart from the pros and cons with regard to the sailing qualities of single and double chine hulls, the double chine is in my opinion 100 times better looking, but there again I could possibly biased being a Senior owner :wink:

Len
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Joined: Wed September 27th, 2006, 1:06 pm
Location: Kösching, Germany

Hard Chine

Postby Len » Fri May 11th, 2007, 2:46 pm

Yes, I was aware that a hard chine hull has a bit more initial stability than a double chine. But I could not convince myself that that was sufficient to explain the almost total dominance of hard chine. As Chris says, a double chine certainly looks much better and must be more easily driven and more sea-kindly. Hard chine is intrinsically neither stronger nor weaker than other hull forms.
The double chine is, I think, the major point that attracts me to the Senior.
Another small point is a hard chine hull has a bit more space inside it. (?)

Could it be that it is simply less work for the designer ? Important if he/she has to work to a price.

An interesting case is the Wild Duck. Very closely related to the YM 3 tonner (no name ?) but a bit cmaller and hard chine instead of round bilge carvel planked. The latter for amateur construction ?!?! If then the initial stability of the 3T was OK, then surely, a double chine would have been a better interpretation of the 3T for easier building and the Wild Duck would have been even prettier. A pitty Mr. Buchannen cann't tell us why. Perhaps double chine had not been invented at that time ?

By the way, do you have drawings for these two ?
Leonard_Woods

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Drawings available

Postby Eventide Owners Group » Fri May 11th, 2007, 8:19 pm

Hi Len,

Double chine and single chine have both been about for years, and yes a single chine boat is more spacious inside too, see the Thames Barges or the WW or Eventide....

they do not sail badly either, for as the boats heel the hull presents a Vee to the water and therefore cuts it better.

As for the drawings, we have the 3 Tonner, for that is what she was called, and the Wild Duck on CD's. our own drawings scanned. Available at cost. £5.00 per CD uk inc P&P, £6.50 overseas.

Most of the drawings are that price, the exception the Faggetter designs, where we promise a small royalty to the designer.

See the designs page of the site,

Regards,
John Williams
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chris s
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Postby chris s » Sat May 12th, 2007, 1:10 pm

Apart from twisting the bottom planks a single chine hull is considerably more simple to construct than its double chine counterpart.

Len
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Joined: Wed September 27th, 2006, 1:06 pm
Location: Kösching, Germany

Hard Chine

Postby Len » Thu May 17th, 2007, 9:51 am

Yes, as I said above, more work but easier, especially for one like me who is single handed most of the time. However, the bare hull is not even 50% of a completed boat and all the rest is the same.

Many thanks for your responses. I hope I am not making a nuisance of nyself. I did not want to criticise any hard chine designs, especially not your beloved Eventides. I would dearly like to start building a Senior but down here I have noware to sail such a boar within reasinable distance. so I content myself with designing a modified version (Senior Mk 4 ?) and making smaller boats. Last year a pram this year one or 2 canoes. For the latter, there is enough water in beautiful rivers.
Thanks.
Leonard_Woods

AdrianCox
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Postby AdrianCox » Wed September 17th, 2008, 11:55 am

Hi All

Another theory to add to melting pot :)

Is't it better to have one larger sheet of marine play to form in to shape rather than 2 smaller? and to then take extra care and cost to caulking?

In think this may well have been aimed for the home builder as it may have been easier for construction for those with less woodworking skills.

Regards
Adrian


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