View Full Version : how green?
01-26-2002, 11:05 AM
I've been reading this forum off and on for years. I recently acquired a 1925 Nat. Herreshoff s-boat (28 ft, deep keel). Lulworth, in case you're wondering, was the original name (you can see it as an entry in the list of s-boats in LHF's book on capt Nat.) The thing has been in storage for 10 years but a reputable builder was hired before it was put away to reframe it before storage -- so its still got a resonable shape. The first job is (of course) the most daunting -- I've got to replace a split aft keel(son). The keel timber in question is to be white oak (as original) and is 15 ft long, 2" thick and 12" wide (at the widest point). There is some bending to be done at least in the forward section. The plan is to drop the ballast (a whole different can of worms), replace the after keel up to the original butt joint. My question is, how seasoned do I want this hunk of wood? The butt joint now, after 10 years in storage, is remarkably tight so I am inclinded to believe that the original timber was quite dry when installed. On the other hand, when the timber gets wet (after the 3 to 5 year long rebuild, it will be bone dry) it will swell (check me on this) up to 0.25" per foot. The advice I've gotten from the local experts is to use "kinda seasoned" oak. Any other bets?
01-26-2002, 11:52 AM
In my experience, white oak is a poor choice for much of anything below the water line. It does not hold fasterers well, rots easy and splits easy.
For a keel or keelson, I do not think it critical to keep everything "original". My choice would be cypress. It will never rot or split. It holds fasteners equally well in both cross grain and end grain.
If you want it to swell, season a green piece untill there is at least a 30% weight reduction.
If you do not want it to swell, season a green piece and then saturate with west system epoxy.
Cypress is pleantyful and cheap in Florida. Email me at firstname.lastname@example.org for a source of rough sawn, green timber.
Not much white oak in Florida. White oak is what it was and what it should be, if you believe Captain Nat. S-boat number 1 is outside my shop, 83 years old and her white oak keel is quiet solid. If you are going to steam it for bending, some green will be good. If you keep laying on linseed oil you can minimize checking. I think Herreshoff steamed them and bent them over the molds. You would be doing that on the hull or on a form. Good luck. Great boat.
01-26-2002, 10:02 PM
Cypress that is "plentiful and cheap" in Florida is 99% "pond cypress",useless crap unfit for much of anything unless veneered under 1/8 and COMPLETELY epoxy saturated. Saturating the surface of large timbers of this stuff leads to nothing but trouble. This stuff bears no resemblance to oldgrowth tidewater or black cypress that got the wood a good reputation. For all practical purposes those woods are now extinct. Only found burried in bogs and riverbeds now, and more expensive than Mahoganey or some teak.
01-26-2002, 11:09 PM
I pondered this question for Sonja's forekeel and was directed to Bud McIntosh's book, where on page 29 it reads (sort of) -the keel will spend most of it's time underwater and will....never lose much of it's moisture. It should be at it's maximum size when fitted to the ballast casting....if it's dry it'll swell 5% and hang out over the casting and strain the floor fastenings....and should be kept at that size throughout the building process....using linseed oil and kerosene....If the wood will take a pencil mark, it's dry enough. If too wet for pencil, mark it by scoring it.--
He talked about 'properly seasoned white oak', and I read between the lines and his comment on scoring if it's too wet to mean green is good. At least for the keelson.
I can tell you from experience that when I used dry white oak for Sonja's new sternpost 20 years ago, after a month in the water it swelled out and back far enough to bind up the rudder post. I had to haul her and plane down the excess. It kept on swelling and at season end it was a half an inch farther than when I planed it. Cod knows what kind of a strain the keel was under at that point and needless to say, I had me a learning experience.
If that joint is still tight, the whole thing might have been pickled with whatever secret recipe the builder used to replace the water in the cells. I think this is where all the talk about ethylene glycol might come in.
[This message has been edited by Rich VanValkenburg (edited 01-26-2002).]
01-28-2002, 01:03 AM
White oak is incredibly rot resistant, holds fasteners wonderfully well,and has traditionally been the timber of choice and specification of the majority of American yacht designers and naval architects when it comes to the backbone and framing.The problem is that it is slow to season and shrinks considerably.Years ago yards inventoried large amounts of seasoned timber-these days it's hard to find.My advice is to seek out a suitable piece of locust-black locust is best, but honey locust will do.It's the most rot resistant wood in America and because it's dimensionally stable as it dries(shrinkage is insignificantly small)you can saw it out of a newly felled tree, shape it and install it immediately.I've used locust for stems,floors and frame repairs for decades with great success.Locust trees often grow with wonderful natural sweeps in them which can often be used to great advantage-try to get the tree sawn "through and through"(a bandsaw mill is best)to take advantage of this.Good Luck. P.S. S-boats are great fun to sail.
Thaddeus J. Van Gilder
01-28-2002, 08:04 AM
cypress for keel timbers??????
that'sa new one on me!
If you wanna season a 8/4 white oak keel, steam it for two hours, bend it to the cuveture you need, and she's seasoned! works great. I have even done it on oak that isn't being bent.
01-28-2002, 12:57 PM
Hi Dave! Just remember, when it comes to advice, "People oft pay too dear for what's given freely."
01-28-2002, 04:35 PM
Thanks for the ideas -- all appreciated. For the record, I am going with white oak. The discussion of how wet it should be is probably moot since I will need to buy it green (from the sawmill) and by the time I bend it and cut the rabbet, and fit it for the umpteenth time it will be quite a bit drier than when I started. The keel actually curves under the ballast, past a well raked-back rudder then up past the waterline along a long straight overhang and into the hackmatack transom knee so part of it acts as a horn timber and, in this boat, doesn't have direct contact with water. So, the bottom line is that its going to have a gradient of moisture levels even when in service.
One more question. According to legend, two versions of s-boats exist. In one (mine) Herreshoff drilled blind holes through the deadwood (predrilled, I presume with a larger diameter hole) and into the lead ballast. Then threaded bronze keel bolts were screwed into the lead essentially tapping their own holes. Has anyone ever backed such bolts out of the lead? By the way, the bolts from the top of the ballast to the top of the floor timbers look (at 77 years old) pretty darn good so cutting them would not be a good choice for me. Obviously I am going to try to screw them out and see what happens but my fall back plan is to lift the boat off the ballast pulling the bolts through the floors (chiselling them out of the floors if necessary). The plans (actually still available) show the bolts are parallel to each other so this isn't as nuts as it sounds. Any ideas?
01-28-2002, 05:24 PM
Are you sure they weren't drilled through to a cavity and fastened in side the lead? I'd be surprised if they were just threaded rod.
here's a better pic-
David, with oak (which is a fine choice in material despite Yachtdoc) one concern in addition to normal dimensiona shrinkage is cupping...this can be substantial on a 12" flat sawn piece Try to ge a piece that is mostly if not all quartersawn. Regarding seasoning: A board loses a lot of moisture after being freshly sawn before it begins to shrink..ALOT, this is called "free water" once all of that is gone then the "bound water" stars to go and the board begins moving. With oak this can take quite awhile due to it's extremely dense fibres and sealed pores. Steaming definetly helps this procces along, but a green board steamed for a few hours is by no means "seasoned" Best of luck with the project
01-28-2002, 08:22 PM
Ouch, just when you think you've got it figured out someone says something that sounds right too.
First the question of the bolts -- it's strange but true: Herreshoff was known for some off-the-wall things, this may be one of them. The fix, if all else fails and I cut the bolts (last resort) is to dig pockets into the sides as Rich shows so nicely in his pic and drill parallel holes. I hope it doesn't go this way. Inspiring pictures, by the way, Rich.
The question of the timber is more ambiguous (in my mind). I'm replacing the keel in part because part of the rabbet is rotted away (below the lazarette) but mostly because the keel has a longitudinal split that clearly leaked for the previous owner. The split was probably made worse by the placement of an oak dutchman epoxied into the widest (presumably leakiest) part of the split which no doubt wedged the split open more with every cycle. To avoid though-thickness splitting I was planning on finding a flat sawn timber but now I see Rob's post and I see that cupping isn't a nice prospect either. I will have to investigate this further...
Despite what many people think, a flat sawn timber is More prone to splitting. This results from several rerasons: Incresed movement and resulting stress as well as inherent weakness in that dimension. Growth rings are not planes of weakness, although they seem like they would be (this is especially true of oaks which have strong ray structure tying annular rings together). Think about splittin firewood. It is easiest to split radially ...which is to say across the flat. When you try to split along the growth rings (tangentialy) it is difficult and the split usually vears off the log.
The problem is uasually finding a tree big enough to give you a wide clean quarter sawn board withou any pith (which would be the worst thing to have). Thats why I suggested looking for a board that is mostly quartersawn, at least that way the cupping is reduced and the high stress center will be strongest in resistance to splittting.LOL
01-31-2002, 12:30 AM
OK Yachtdoc, fess up. You were only joking about White Oak weren't you? How about putting your occupation in your profile.
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