?Dory Book by John Gardner

[vincent]

Hello
i have a question to the people knowing this book ;-)
one the page 219 there is a plan for a centerboard for a 21' Dory
one the page 237 there is a plan for a centerboard for a 14' Dory

the thing i am not sure - both centerboard have the same size - it is normal or did i miss something?

have a nice day
vincent

[kenjamin]

I know the book well but have not memorized it. I'll check that out when I get home tonight. For dory lovers like myself, Mr. Gardner's Dory Book is the bible for dories with Mr. Gardner being only a few steps down from God himself but he may have had a moment of laziness and included the same specs for each size dory. I think it's pretty safe to assume the board for the 14 footer could be scaled down a bit but maybe not as much as you might think. The bigger board on the smaller dory might help some with the tenderness of such a short dory.

[dm_scott]

I don't see them as the same, the first has a c/b length of 3' 8 1/2" in a 4' 0 1/2" box, the second has a 3' 4" board in a 3' 8 1/2" box.

they are close

[boylesboats]

I just looked in mine.. they do look close. One on page 237 have more detail.
Don't worry you're okay til you get another big book titled "Building Classic Small Craft" Complete Plans and Instructions for 47 Boats.. you'll see some repeat with different names

[dredbob]

The thing to keep in mind is that these are two very different boats; one a narrow bottomed dory and the other a relatively broader (on the waterline) skiff. So the difference in overall length is not the thing to focus on. Look at the area of the sail rig for each boat, and you'll see that they are pretty close, and this is much more relevant to the size of the underwater lateral resistance than the length.

Bob

[vincent]

@dredbob
thanks for this feedback,
i am building the lumberyard Skiff and would like to add a sail so i will need a keel too. reading this book i found out - i just belived if my boat is 14' and i take the plane of another 14' boat it would fit. so it is not like that?
have a nice day vincent

[Daniel Noyes]

HI all
I know the 21'er well as I built one this past summer, the Alpha dory board is 3ft 8.5 inches the semi dory is 3' 2 inches, the inside measurement of the semi dory board box is 3' 4".
The boards are similar because the sail area of the boats is similar, the Alpha dory carries about 120 sqft and the semi dory around 100-110. I think the semi dory board is a good guideline for a 14' skiff centerboard, you could even go a little smaller if you wanted.
Dan
http://dansdories.googlepages.com
http://farm4.static.flickr.com/3170/3098800687_306cd453ef_m.jpg (http://www.flickr.com/photos/dansdories/3098800687/in/set-72157608651860941/)

[wtarzia]

So what is the rule for square feet of sail to square feetof board? (I mean, "board in the water" not total area including board in the trunk). Would leeboards need more area because they have ventilation inefficiency? -- Wade

[Bruce Hooke]

i just belived if my boat is 14' and i take the plane of another 14' boat it would fit. so it is not like that?

No, it is a lot more complicated than that. You need to consider whether the boat you are "borrowing from" is generally shaped similar to your boat (i.e., look at other flat bottom skiffs in your case), how much existing resistance to slipping sideways each boat has, how stable each boat is and thus how much sail it can carry, which in turn determines how large a centerboard you need. Those are just some of the factors that should be considered.

You have a few options:

1. Build the boat to the plans and don't try to outsmart the designer! ;)

2. Get someone who knows small craft design to design you a sail and centerboard.

3. Look for a truly similar boat (similar length, shape, bottom width, etc.) and borrow the sail and centerboard layout from it.

With small boats this is not rocket science, but it does take some knowledge and understanding, and a dose of experience is a very good thing.

Another factor that is very important is the fore and aft location of the centerboard in relation to the sail. Get this wrong and you will either have a boat with lee helm, which means you are pushing the rudder away from you to stay headed up and a gust causes the boat to turn away from the wind ("fall off") (not good at all!) or a boat with too strong a weather helm, which means you are constantly hauling hard on the tiller to keep from turning into the wind.

[vincent]

@Thanks all for the feedback
Normali the would be a Idea for doing the lumberyard Skiff with Sail. But i am a beginner so i need a detail plan for building and found something in the book.
so i hope it still will work the way i exept.
have a nice day
vincent

[bucheron]

So what is the rule for square feet of sail to square feetof board? . . . . . .Would leeboards need more area because they have ventilation inefficiency? -- Wade

There might be more to it than the simple ratio of sail area to board area. Your question about leeboards reminded me, from looking at many illustrations of traditional-looking leeboard vessels, that small boats seem to have leeboards that are much larger, in proportion to the boat's overall size, than do larger boats.

I just happen to love the look of leeboards, to the point of not caring how good/bad they are for sailing. I have not yet sailed a boat that has them!

cheers buchie

[vincent]

Hello
this ma thematic game - i would also love to learn!
Where on the boat axis the mast have to be?
where on the boat axis the keel should be?
How to find out what would be the perfect square size of the Sail?
but maybe there is a book around to learn! ;-)

have a nice day
vincent