Shoal draft Atkins centerboarder Jaqueline

[JimD]

A 20-Foot Skipjack

Here we have the designs of a skipjack that will measure 21 feet 6 1/2 inches in overall length; 20 feet on the water line; 7 feet 6 inches in breadth; with a draft of 1 foot 4 inches. The freeboard at the bow is 3 feet 2 inches; at the lowest place, 2 feet; and at the stem, 2 feet 3 1/2 inches. Jaquelin is knockabout rigged, staysail and main, and has a sail spread of 243 square feet; 57 square feet in the staysail which, by the way has small overlap; and 186 square feet in the mainsail. I would stow about 500 pounds of lead ballast each side the keel between stations 3 and 9; 1,000 pounds in all.

The deck plan shows a forward deck 7 feet 2 1/2 inches long; deck house 6 feet 5 inches long; bridge deck 1 foot 6 inches long; cockpit 3 foot 6 inches long and after deck 2 feet 11 inches. The cockpit is approximately 5 feet 6 inches in width. The well floor is 9 inches above the load water line and will be self-draining. The deckhouse is low with an average width of 5 feet 3 inches; this leaves a waist deck somewhat over a foot wide each side and 17 inches wide at the forward end of the house.

The cabin plan shows work tables each side aft, these to be used for a single-burner alcohol stove, lockers, sink, dishes, and other house-keeping equipment. There is a seat each side abreast the centerboard trunk. With swing tables each side the trunk in good old cat-boat style, two persons can have the nicest little snug cabin one might ask for. And then forward there is a big bunk wide enough for two. The headroom under the companion way slide is 4 feet 3 inches and under the top carlins slightly less than 4 feet. There will be the temptation to raise the line of the sheer and the height of the deckhouse. I would not advise either change. In the first place the appearance of the boat will be ruined and the sailing ability destroyed. If more room is needed build a different kind of boat.

The lines show a hull having throughout its length straight sections; the topsides have generous flare from bow to stern. Plenty of flare in the topsides of any skiff or skipjack is a sure indication of stability under sail or at rest. The chines and the rabbet have a common beginning at the heel of the stem and gradually diverge in easy sweeps to the stern at which point they are about 5 inches apart. Thus the deadrise increases from bow to stern. The advantages of this are: there is a nice tuck-up in the after buttock lines permitting easy water flow along the bottom when the boat is heeled down; the bottom is very easy to frame and plank because there are no violent twists to overcome; there are no acute angles forward at the chine corners; and the side planking can overlap the edge of the bottom strakes of planking thus covering all the "jib-ends" of the latter where they run out into the chines.

And so we have the little skipjack Jaquelin in MoToR BoatinG's family of boats. And an excellent kind of boat it is, too, wholesome, simple, easy to build, inexpensive and full of character.






This one would be easy to modify for plywood and gets added to my list of 20ish foot trailerable plywood centerboarders. I like the barn door rudder for shoal sailing. Good and sturdy and no kick up required. I'd redraw the centerboard to a more triangular shape and cut it out of steel plate. It might come in around 400#s or so and would place a good chunk of the ballast well below the water line. Of course that would mean beefing up the CB trunk and keelson a bit but that's not rocket science. Any comments? Wayne, you out there?

[Venchka]

I was away in the far north...grandkid visit.

The plans are cheap. Buy them. Make a mock up of the bow and see if plywood bends around it. Figure out the scantlings for plywood planking. Doug-fir framing with MDO planking, decking and house. Give us a report.

My theory on centerboards: 1.) Move them out of the middle of the boat. 2.) Don't make them a significant part of the total ballast. The extra weight down low is nice. What about the extra weight up high when the board is up? Hey? Not cool at all. 1,000 pounds of lead in her tummy should be more than adequate and always right where you want it. Add framing to keep the lead off the plywood. If you want more weight down low add a steel shoe to the keel.

I am really attracted to all of the Atkin's flat or almost flat bottomed cruisers. I prefer the sloops the the knockabouts. My problem is how big to build.

Wayne
In the Swamp.

[JimD]

Wayne, I know what you mean about heavy centerboards but about the only time its going to be up is when sailing in three feet of water. And even in the up position its not that far up. Let's say only about half of it is nominally above the water line and then there's still all that extra inside ballast in the very bottom of the bilge. I already have this arrangement in my Glen-L Minuet and it works out just fine.

Also, I just purchased what I hope to be a design book comprehensive enough that I can start tinkering on my own design. I'll try to get my scanner working and post my ideas. You and the rest of the motley crew can cut them to pieces for me . If I come up with a good design maybe you'd like to build one too.

[ 05-08-2005, 10:41 PM: Message edited by: JimD ]

[shoal_draft_fantasies]

go for leeboards, and a drop down rudder (like lfh's meadowlark or a lot of dinghies).. I think that boat will have ferocious weather helm when heeled in a blow otherwise.

[Venchka]

Originally posted by JimD:
Wayne, I know what you mean about heavy centerboards but about the only time its going to be up is when sailing in three feet of water.

That's not how I learned how to sail a centerboard boat. Anyway you want to look at it, you will be raising the C.G. of the boat when the board is up and that's not cool in boats this size.

Stay tuned for Wayne's Dumb Centerboard Questions thread.

Wayne
In the Swamp.

[JimD]

A raised heavy centerboard only raises the center of gravity when compared to the board down center of gravity. Since the board down C of G is going to be lower than if the boat had a wood CB and only inside ballast on the whole you won't be worse off with a raised steel board than with a wood board in any position.

[WWheeler]

My comments:

An ok design but it isn't really one of the better Atkin designs, since it neglects some of the qualities that makes them so appealing:

1) Why not a gaff-rig? Atkin has some great ones.

2) Don't know about the flat bottom. It's ok for skinny water, but if you're headed to the coast, you'll probably regret it.

Atkin has several V-bottom gaff rigs in the same size.

[ 05-09-2005, 08:49 AM: Message edited by: WWheeler ]

[Venchka]

Originally posted by JimD:
A raised heavy centerboard only raises the center of gravity when compared to the board down center of gravity. Since the board down C of G is going to be lower than if the boat had a wood CB and only inside ballast on the whole you won't be worse off with a raised steel board than with a wood board in any position.

Anybody who knows care to reply?

Wayne
In the Swamp.

[htom]

It's going to depend on the locations of the CG of the board in its up and down locations. I can imagine heavy boards with high CG when up giving a higher CG for the boat than a light board with very low ballast. (I can imagine the other case, too.)

Best would seem to be having the weight of the board (heavy or light) concentrated in the leading edge / lower edge corner, so that it's the last part brought into the case.

[JimD]

As I mentioned in one of Roger Long's threads, arguably the two most successful trailer sailer designers in the business, Glen-L and Hartley, both have veritable fleets of ballast steel centerboarders. These companies have not flourished for decades by designing boats that capsize and drown their owners.

If I may offer a personal anecdote as I have built and now sail one of said Glen-L designs, one time I forgot to lower the board and we were surprised by a very strong gust that jibbed us, heeling the 15 footer almost to the point of dumping us in the drink. But she quickly rolled back on her feet and we were again on our way, after lowering the board, of course. So I'm a believer in heavy centerboards provided the design thoughfully distributes the weight. They are not nearly the liability some think they are.

[ 05-09-2005, 09:49 PM: Message edited by: JimD ]

[Venchka]

Didn't mean it was a liability. As designed, the C.G. is one place. With a 400+# CB in in the tunk the C.G. will be higher than the C.G. Mr. Atkin designed for. Different. Maybe not bad. Why do you feel like you need another 400+ pounds of ballast anywho? By the way, what % of the total ballast is the steel board in your Glen-L boat? If it's 75%-100% of the total, then you're talking apples and oranges, in my opinion.

No worries. With 1,400+ pounds of ballast, she'll be plenty stiff.

Wayne
In the Swamp.

[JimD]

Guess I wasn't clear enough in my first post. Sorry about that. I would not add approximately 400#s of ballast. I would make the board, redesigned to keep the weight as low as possible when in the up position (hence the triangular shape)and then subtract the 400# from the total, so roughly 600 would be inside. All of which could prove to be completely unecessary and even detrimental to how she sails

Now, for my Lyle Hess inspired trailer boat of my own design...this sweetheart would probably have a steel board slotted through a scrap filled ballast box. Such a set up would not only keep the weight as low as possible and reduce the intrusion into the cabin, but would require no casting. I would figure out a way to lock the board in the down position for added safety in heavy weather.