what keels are made of

[pilot_ed]

I have seen small sailing craft, have the keel made out of laminated ply glued together to make the thickness need but on all larger sailing craft it is formed out of a large tree. why is this so, is it that the keel is easier to make from several pieces of lumber? A curious mind would like to know if anyone has any input on this!

[Wild Dingo]

My take for what its worth :rolleyes: and yeah that aint much I know... but what the heck he asked!! :D And hopefull someone will pipe up and set the record straight!!

Small boats have less stressors placed on the keel... less weight etc... ergo less need for the full tree trunk!... and well consider the wee boat with a flamin great lump of tree under her... her waterlines, centre of effort... or anything else would mean tiddly squat if shes sitting the bottom of the seabed :eek: ... I would think... here I go thunking again sigh gotta control that habit :( ... anyway due to that the requirement or rather small boats are more adept to handling the smaller loads placed upon it and is therefore able to have a laminated keel... it is quite easily done {read get on the water faster} and within reach of anyone {read cheep}...

Whereas...

Large vessels have large loads stressors etc that need a sound base on which to lay... ergo need for something far more solid on which to "grow" the boat... ergo full tree trunk!!... imagine putting a laminated keel under a 50fters bum tie some of those 3 or 5inch futtocks on that and see what gives first!! :eek:

Then of course youve got that ruddy great lump of lead to attach to the keel... tree trunk good! laminate mmmm worry!

Horses for courses...

Of course then we have the question of what one calls large there is large and then there is FLAMIN HUGE!! :D and there is of course correspondingly small and smaller...

Well I thunk... maybe... then again maybe someone else will wake up shortly... have a quick snort of rum hoist the britches and squinting their one good eye... yell from the poop deck with a wide flurry of cuss words... "NOW JEST YOALL WAIT A GALDDURN SECOND HERE LADDIE BUCK!!... " and well... there goes my 2 bobs worth straight down the gurgler... on the other hand... I may well learn something too!!... :cool:

So... Come on all you Old Codgers & Cudgmony types get outta bed!! tongue.gif

Take it easy
Shane

[Seth Wood]

Biiiiggg keels, arh arh....

There's a fundamental and critical difference between a laminated keel and one hewn from a solid timber. The laminated one, made, for example, of 3/4" material glued with resorcinol, will swell and shrink less than the solid timber, for a variety of reasons: Often the laminates are already air- or kiln-dried to a stable moisture content. The grain directions vary with each layer, so that tends to even out directional swelling. But mostly the laminated piece is more stable because small wood swells less than big wood.

The solid timber keel, often green or nearly green, tends to check as it dries (during construction) and swell when the boat hits the water. There are various ways of minimizing this.

What makes this such an important difference is that carvel-planked boats have the inherent flexibility needed to deal with a big hunk of wood swelling and shrinking (ideally, this happens just once: on launch day).

But laminated keels, since they move much less, are ideally suited for non-flexible construction types such as traditional or stitched plywood, glass-sheathed, etc. Glass-sheathed plywood does not swell when the boat is launched. (If it does, you've got BIG problems.)

Put a solid timber keel on a rigid-hulled boat and you could be in for trouble: fastenings can pull or break, the plywood could be stressed or damaged. You can't have one part of your boat moving but not the rest of it.

AND: apart from all that, one method requires more plastic gloves, clamps and glue spreaders; t'other requires strong back muscles and large-bladed woodshaping tools.

Both have their place, but each has to be thought out to fit the rest of the boat's construction.

Well, I guess that's a start!

[Wild Dingo]

Okay Seth mate...

Originally posted by Seth Wood

The solid timber keel, often green or nearly green, tends to check as it dries (during construction) and swell when the boat hits the water. There are various ways of minimizing this... {emphisis mine}Elaborate please ;)

"Keel timbers 101 now in session" Any other lecturers please feel free to address the student body :cool:

Take it easy
Shane

[ 08-21-2002, 09:50 AM: Message edited by: Wild Dingo ]

[Seth Wood]

Okay, method number one would be to build the boat underwater. No drying out whatsoever!

Failing that, this what I've read and been told and (slowly) learned:

Try to maximize humidity in the boatshed. If you're in a very dry area, a humidifier would not be out of place, nor would periodically hosing down the floor, if it's dirt.

The ends of the timber must be sealed, as soon as possible after cutting the tree down, and as completely as possible. Somewhere here someone described the cellular structure of wood as being like a bundle of drinking straws -- moisture can easily be lost out the ends and, less easily, from the sides. Cover that end-grain! Lumberyards use wax or Anchorseal for this; you can also experiment with latex paint, roofing tar, lots of oil paint, linseed oil/pine tar/turps mixture. Actually I've had the best luck sealing my ends with about two feet of solid timber. That is, buy the log oversized, plan your cut a ways in from the end, and then seal the end you're gonna cut off anyway. That way you have the goop PLUS all that wood protecting what will become the actual end of your finished timber.

As for the non end-grain, again, the linseed oil/pine tar/turps mixture works and has the added benefit of smelling great. Just don't slurp it on and then expect to sneak up on anyone with a sensitive nose. My wife can smell my boatbuilding clothes from one floor away.

On the finished (shaped) timber I've been using CPES and a few coats of thinned red lead. Checking still appears but, I hope, is minimized. Others have had luck with multiple coats of the oil/tar/turps mixture.

The biggest hurdle is figuring out how much checking you're OK with.

And don't put anything rigid in those checks! Soft putty yes, wood wedges no. Once the boat's in the water, the putty will squeeze out but a rigid wedge will tend to force the check to open up towards the center of the piece.

Once in desperation I draped a wet rag over a not-yet-finished area I was shaping. Result the next day? No checking but lots of mildew. Ugh.

All of this is assuming that that timber is fairly green when you start. Finding seasoned timbers is an adventure in itself; the issue with them is not that they will check during the building process, but rather that they will swell at launch more than a green"er" timber would.

Nearly all of this, I repeat, I've learned on this board and from a few books. A year or two ago I was juggling laminating vs. green vs. seasoned keel timbers....you may be able to dig up the threads in a search.

[Wild Dingo]

Keel timbers 101 recieved with thanks and gratitude Seth...

Now onwards on this learning curve.. Keel timbers 102... As before any other lecturers with their slants on what and how to do it... or students with questions please join in all are welcome!... This is a very relaxed campus :cool:

Soooo... say we have a keel timber fresh cut from the forest... say shes 30ft long and what? oh 20 or so inches in diamatre {sp?}... and say we have done as you prescribe above and slathered the beeejimminies out of it... now say that the keel timber for the actual keel is to be cut back to say 24ft long {see we have kept 3 feet at each end as you prescribed ;) } and say 10inches by 5 inches...

1) How long would one have to wait before she would be considered dry enough to use? or would one be able to use it as soon as patience became unbearable?
2) How would one know if she be dry enough?
3) When is dry enough?

Okay different woods etc but is there an average one can work on for hard timbers and soft timbers? {This may be one TonyH could enlighten us with... you there Tony?}

I know that sounds like dumbass question number 100010 - 100014 inclusinve... but some folks just need answers!! :cool:

Yes yes there is the search thingymajig but... ahem... as we are eludicating and edjamakating about this here in this thread... shall we endeavor to resolve as many questions on this matter as we can??

pilot_ed you still with us mate?? ;)

Take it easy
Shane

[ 08-21-2002, 11:02 AM: Message edited by: Wild Dingo ]

[Seth Wood]

Hm, getting a little out of my "depth" (get it?) here, but I'll take a shot.

The general rule for air drying is one year per inch of thickness, so you got 5-10 years. I've also heard anywhere from 6 months to 2 years per inch. Depends on the wood, local humidity levels, and lots of other factors. www.woodweb.com (http://www.woodweb.com) has a sawing and drying forum with some good info on this.

But the main question is "how dry does it have to be?" or "how green can it be?"

I still haven't figured this one out. Green wood will shrink, dried wood will swell, somehow people have been building boats out of trees for along time, and some of them even float! I eventually figured I was spending too much time worrying about it, and went with 1-year dried oak timbers, and lots of checks.

A lot of depends on how fast you build (how long the green wood dries before it hits the water); it also depends on what kind of wood you're using (oak checks early and often; I've heard purpleheart does as well).

A good compromise (is there such a thing?) might be to split the difference between green and dry, as much as your schedule and budget allow, then deal with checks as they occur and stand by with a powerful pump on launch day. That last one seems like a good idea in any case, actually.

[pilot_ed]

Yes I am still with you Wild Dingo. and you both have shed some light on my question, but let me ask you this Seth. You said if the hull was to be covered with fiber glass or some thing to that effect, then the keel could be made out of a laminated material. OK my next question is-- becuase laminating has much more strenght that a solid piece of timber due to the different directions of the grain. Then if a person was to build a 40 footer with a cold molded hull then fiberglassed the whole thing the a laminated kell would do just fine. Would that be a correct statement? thanks again

[Seth Wood]

My thinking is: not only would it do just fine, but it would be a mistake to use a solid-timber keel in a cold-molded hull -- the keel will swell but the hull will not. Glass-covered cold-molded doesn't swell/shrink, neither will a laminated keel (not appreciably, as long as the laminations are thin, that is).

[Dave Fleming]

The originator of this thread and the one in Building...must be going cross eyed jumping from one Forum to the other!

This IMOOP truly belongs in Building and can't see why he posted the same question to (2 ) count'em two different Forums?

Imagine if more folks started doing that just to cover all the bases, so to speak. We would have more chaos than even Miscellaneous can handle. :rolleyes:

[ 08-21-2002, 03:10 PM: Message edited by: Dave Fleming ]

[pilot_ed]

Ok good that was what I was thinking but needed other input before I proceeded. Whast thickness would you consider to be to thick when laminating?

[pilot_ed]

Sorry dave I am new to this forum and was not sure which one to post it in. sorry again for the confusion and I will not do it again!!! LOL

[Dave Fleming]

Geeze Laddy Buck, take it to the Building Forum, PLEASE?

That is why the benifactors of these FORUMS set up several different titled Forums.

Hint, chances of getting a more complete selection of replys/answers depends on which Forum you post to. Ya folla? :mad:

[pilot_ed]

I will apologize again but my question is also a design as well as a building question that is why I had post it in both but I am sorry if I afended anyone.

[Dave Fleming]

Nah, not to worry! smile.gif

We usually go easy on newbies. We were all there at one time, even Shane. ;)

[pilot_ed]

Thanks Dave and if you know who to delete this topic in the design forum can you tell me how so i will just have it in the building forum ?

[Dave Fleming]

Nah don't delete it, for Seth gave some good pointers that should be kept for future reference in the archives.
May I suggest that you just make a comment that all future comments be directed to Building.
'zat suit ya? ;)

[pilot_ed]

Sounds good to me Dave. Well off to the other side lol