View Full Version : Boatbuilding Notes Part II

gary porter
11-04-2003, 03:32 PM
Continued Notes from the Forum:

another question:

posted 08-11-2002 07:41 PM

I have some seam leaks in my Kettenburg 40. I am unable to find
(library, Web, Woodenboat archive) useful information to help me
decide how to proceed. (Yes, there are WBs that discuss caulking,
but none that answer my questions--I should write this article,
once learn.)

In dry weather at the dock, the bilge pump kicks in about once a
week--no problem. Under way, the pump kicks in about every 15
minutes--big problem.

I need to know:

1) how far fore and aft of a weepy seem to reef.

2) is cotton or oakum the better choice.

I like the idea of oakum. It sounds like a choice that will
really stop water. But, as far as I know, the boat is all cotton
now. Is that a problem?

According to the former owner, the boat was fully recaulked about
5 years ago, about 2 years before I bought it.

I am not very knowledgeable about caulking. My last boat of many
years was built tight-seam in Copenhagen where they really know
how to do that. It never leaked.

The only other K-40 owner I know here in Oregon advises sheathing
the hull underwater in stapled chopped strand alternated with
woven roving.

The Kettenburg Web site reports on some owners drying their boats
out in Baha and then "caulking" with "glass rope."

I am not averse to new technology, but if I could solve my
problem with a little, say, oakum, I'd be happier than taking a
chance on chemicals that lead I know not where.

I just need better information than I have in order to make a

I will be greatly appreciative for any sound advice or clear

RGM's response:

Supposedly the boat was recaulked five years ago and it leaks
now, especially when driven. Sounds like an improper or
inadequate corking job. Do you know who did it? Can you contact
them to find out how many lineal feet they did? Which seams? What
was used for corking material? Seam compound? Were the freshly
corked seams painted or primed prior to seam compound being
installed?. Were any planks refastened after reefing the seams
and prior to the seams being corked? Sounds like she needs to be
hauled out and the seams (all of them) inspected. Not necessarily
reefed. Your boat maybe the victim of some spot corking repairs.
A number of things could be wrong and there is only one way to
find out. So you may as well haul the boat. Things will not get
any better or cheaper. Regarding cotton and/or oakum. You never
use oakum by itself, it won't stop water. You can use cotton by
itself. If you use oakum it's because you have thick planks and
big seams. Prior to corking with oakum you cork your seams with
cotton. I doubt if the planks on your K-40 are thick enough to
have seams that require oakum. You might be able to squeeze in a
very thin strand of oakum in the garboard, stem, stern post, horn
timber and transom seams, maybe. Sometimes there is plenty of
room in those seams beacause some idiot that didn't know what he
was doing over drove the seams and beat the hell out of them.
This may very well be one of your problems. Don't sheath the boat
in fiberglass or use "glass rope". Your boat will be dead or
dying in no time. It will also adversely affect a survey. You
need some one that knows what they're looking at to check out
your boat. In a proper corking job the vessel owner should be
able to create a "map" of his planking seams and by himself or
hopefully with the help of a corker, a real one, mark up corking
repairs (with dates) on this "seam map" with colored pencils,
marking pens, whatever. Include names and places, we're not
interested in protecting the innocent here. That way you always
know where and when you've done these types of repairs and
hopefully what should be scheduled for the next haul out. Of
course this same map could be used to record plank replacements,
butt block relocations, all that fun stuff. The possibilities are
endless. Boatyards, shipwrights ,surveyors and new boat owners
appreciate this kind of stuff. Anyway, I rambled on a little too
long here, must be the coffee. Good luck.

Seam question from Larry Exum
for his Cris Craft.

On my Chris Craft Constellation 45' the caulked seams show proud
in a few areas and perfectly smooth (parallel with the planks) in

I would like to "Define" the plank seams better by cutting a very
fine "V" between the planks only about a millimeter or two deep.
This must be done very evenly, and very straight with no side to
side wandering, as the view down the side of the boat must show
perfectly parallel lines at each plank junction. I will then
repaint the entire hull.

My question is: Is there a tool devised which will neatly trim
the caulk and maintain a straight line while working on the side
hull ?

I will not have anything to rest against to insure a straight
line. I considered very fine nails into a long furring strip to
use as a saw guide, but really do not want to let an electric saw
get in to a potential runaway situation. I am afraid that would
be overkill, and may end up with new caulk seams which were not
intended. If feasible, I would like to use a hand cutter, but do
not know if there is one devised for this purpose, and if so,
where to acquire it on the cheap. It would only need to be used
once, as I am not going to do this again.
Cleek's answer:

Sure, there's a tool for everything! Some you do have to make
yourself, but in this case, you are in luck. Store-boughten ones
are available. The standard approach is to use a batten, exactly
as you described, set along each seam as a guide. You then use a
router to make the bevels. You may have to search a little
(Jesada Tool catalog?) for the right router bit, but they're out
there. On the other hand, you are absolutely right that a hand
tool will give you greater control and for this application be a
lot easier to use because of its far lighter weight over a
powered router. (Although you might want to try a Dremel if you
are really patient!)

Hand routers are still made. Check out the specialty tool
catalogs like Highland Hardware and Garrett Wade. I do believe
that O. Lie Neilsen makes a repro of the original Stanley hand
router and has many blades available, including blanks for making
your own. You could also use a combination plane, like the
Stanley 45 or 55 with a veining blade, although it would be
heavier (and a lot more expensive.)

Now, that's the answer to your question. On the other hand, maybe
you might think about the answer to the threshold question...
"Why would you want to do a crazy thing like that to begin with?"
Your Connie is a classic or close to it. It would be a shame to
give her a "seamed" look when she was never intended to have one.
Beveled seams can look nice on some designs, but I am afraid it
would look pretty crappy on a Connie, particularly up around the
bow with its unique curves. Not only that but what you are
contemplating is a huge amount of work. Multiply the number of
seams times their length... that's a hell of a lot of routing
without making a mistake, believe you me. For what? You can sand
the proud seams where the stopping has bulged easily enough and
she'll look just like she did the day she came from the factory.
Be careful what you wish for. Cutting seams isn't all it's
cracked up to be. For one thing, I'll bet you anything that when
you go to fitting battens to do the job you are going to find
that some, if not all, of those plank seams aren't perfectly fair
and parallel. They were scribed and cut to fit the one next to
each, and things tend to wobble a bit, particularly on a job
where they never intended the seams to be accentuated. Take two
asprin and fuggedaboudit. You'll thank me in the morning.

Some notes on painting by Cleek.

"Do go back and check out the past posts... but, I'll do it once again
for old time's sake.
Sand her very fair, preferably to bare wood. Soak her in CPES. This
product, by Smith and Company, is the only thing to use. DO NOT use
thinned hard epoxy. Use CPES. (A little goes a LONG way. Ask Smiths how
much. Check the posts on CPES in here... there's a million of them.) The
same day, spray Interlux or Z Spar white undercoat. (If you paint over
CPES within about 36 hours, you will get a molecular bond between the
penetrating epoxy sealer and the paint and it will stick like nobody's
business... this you want.) This stuff has talcum or whatever in it and
it will fill some and also sand easily. Spray, because otherwise, you
will have nothing but brush strokes with this stuff, or else, you will
have to thin it so much that you will have to put fifty coats on to get
where you need to go. Use a decent Binks spray rig, or the equivalent.
Start working around the hull until you CAN'T SEE ANYTHING BUT SNOW
WHITE. If you spray, it should dry by the time you work around to the
start and you can just keep going without down time waiting for it to
dry. (Wear sunglasses or you will go snow blind... no kidding!) Remember
this... and repeat it like a mantra... "My enamel will NOT cover... My
enamel will NOT cover..." Believe me, it will not. That's the base
coat's job.
Now, when it's all white, go over the hull with Z Spar Dual Purpose
Surfacing Putty or the equivalent, filling EVERY little bit of grain and
divit. Then sand again with 120, working down to 220. Make sure the
surfacing putty isn't standing proud anywhere. Repeat this mantra at
this point..."Every imperfection WILL show... Every imperfection WILL
show..." They will. When it is perfectly smooth and there are no dings
or anything left to fill with the surfacing putty... and you now know
how important that first sanding step was way back when... Spray it with
more undercoat, repeating the "My enamel will NOT cover.." mantra. The
previous sanding will likely have raised spots that show through, you
Now, sand carefully with 220, working down to 320. Use your compresson
to blow off all the dust. Then tack thoroughly.
If you want a really decent job and you aren't an experienced painter,
find one to help you on the next step... it's important. Mix your
enamel. You have to consider the temperature, humidity and phase of the
moon. Add Flood's Penetrol to promote leveling. Add the proprietary
thinner for hot or cold weather (fast or slow drying). How much is where
the experience comes in. If you are someplace like Kansas where they
don't have boat painters, maybe you can ask a professional painter, or
if all else fails, practice a bit on some scrap wood until you feel
competent. (A BAD topside enamel job is a sad, sad, sight!) Your enamel
should be about the consistency of light cream or half and half. Now
tack again. Kill a chicken as an offering to the topsides gods. Use a
good brush that's the right size... six inches at least... (forget that
roller and tipping off BS)... keep a wet edge, work fast and let the
paint level itself. Put as much on as you can without starting curtains.
Work out of a big cardboard bucket. Your arm will love you for this and
you won't get paint all over. (If you haven't learned to paint, get a
book on the subject and "brush up" on it! No offense, but about one guy
in ten who works on his own boat knows how to use a brush properly.) Let
it dry. Brush off all the bugs that landed on it. (DO NOT try to remove
them when the paint is wet! TRUST ME.)
Now, sand lightly with 320. Put on more surfacing putty on the spots you
missed if you have to. (There always seem to be one or two.. it's that
snow blindness thing.) If you do this, lay a light coat of basecoat on
the putty spot. Sand it smooth and put a light coat of enamel on the
patched spot. Sand that along with the enameled hull. (If you just put
another coat of enamel on top of the putty, you will get a dull spot
there.) Blow and tack and so on. Put on another coat of enamel. Pray
that that one looks okay. If not... go for another. At some point, you
will either be satisfied or get tired and consider it done. If all else
fails, tell yourself you will do better next haul out! LOL OH... and
have fun doing it. This is one of the most satisfying parts of the game.
Nothing makes me feel better than having my boat in the yard with a
brand new topside job and watching the plastic boaters come up and ask
me what kind of gelcoat polish I use! LOL"
Bob Cleek

A note on cribbing
and hauling out.

posted 09-28-2003 12:46 PM

I always hate to see nice boats leave the PNW for other parts of the
country. Oh well, that's the way it goes. First off, the vessel has
a "Docking Plan" available somewhere. The Docking Plan is an
engineered drawing that details block placement, etc. It may be on
the boat someplace. Did you get a set of drawings with the boat. If
so, great,it should be with the drawings. Get a set of drawings if
you don't have them. Hopefully, the Docking Plan came with the boat.
If not, the folks at Keyport or Inian Island, WA.(where did it work
out of?) probably have it or know how to get it. If you can find out
who hauled it out last they may very well have a copy of the Docking
Plan. The "Docking Plan" will direct you on block placement, shoring
and other haul out details. Is the boat presently in the water? If
so great. The next step is VERY important. With the boat in the
water and hopefully off of the trailer for about two to three weeks,
hire a diver to accomplish a "hull profile". A hull profile goes
like this; The diver stretches a tight wire from the forefoot to the
fartest point aft on the keel. This wire has previously been
measured off and marked in one or two foot increments. The diver
measures and records the distances, if any, between the vessel's
keel and the tight wire at the predetermined points. This is how you
accurately measure a vessel's keel profile (hog). Once the data is
taken and recorded (underwater clip board and pen) the keel blocking
onshore is built and shimmed to duplicate the hog or any other
discontinuities along the length of the keel. The vessel is then
placed on the blocking by predetermining some index points (X marks
the spot on the forefoot that lands in the middle of the first keel
block and the rest of the blocking should hopefully line up with the
keel profile). If a boat is hogged, build to the hog unless you are
going to essentially build a new hull beneath the piplot house. This
sounds like alot of trouble, but it's worth it. More people should
do this for their boats. Don't block it flat unless you know it's
flat. Please take my advice, I know what I'm talking about, I've
been responsible for drydocking alot of wooden boats, including a
number for the US Navy. We might even have a Docking Plan for your
boat at our yard. I'll take a look on Monday. Feel free the send me
a Private Message thru the Forum if you wish. Good luck, don't get
in a hurry, I'll be in touch.

Fleming on Battens:
Dave Fleming
Caveat: this my own personal, emperical knowledge and experience!

Wood for Battens: Eastern White Pine, True Mahogony, Alaska Yellow
Cedar, Port Orford Cedar, Douglas Fir ( old growth if possible) ,
are to be preferred. Rarely hardwoods for battens of length. Ash is
fine for short ones say 6 to 8 feet. Shorter lengths of most any
wood can be used for say diagonals or places where there is no

Sheer= 1/2 x 2 inch and longer by several feet over both

Waterlines= 1/2 x 1 1/4 inches with a TAPER on both ends. Taper
allows the batten to tuck up a bit at the forward and aft sweeps.

Body Plan= 1/2 x 1/2 inch with if possible a thinner center to flex
around the lines.

Long lengths are spliced with about a 12 inch splice. The glued up
splice is made proud and planed or scraped down to final dimension.
No rivets or nails through the splice. You want it to be as flexible
and fair as the rest of the batten. Weldwood Plastic Resin glue was
favoured but later on we did use the yellow stuff even though there
were rumours that it creeps under load. Cannot recall ever seeing
that myself.
Nails are driven along side the batten NEVER through the batten.
Initially blocks of steel, edges smoothed off with felt or neoprene
glued to the bottom would be used to nudge the batten into fair.
After lots of squinting and bending over and looking at the line, it
would be nailed( alongside!)to the loft floor. Sometimes a pail of
awls would be used to set the batten in place but usually it was the
nails alongside the batten. Blue Plaster nails were mostly used for
this work. Thinner shank and being dark blue or black did not cast
another distraction to the eye. Lines were drawn with drafting
pencils and artists colour pencils NEVER pens or marking pens.
Reason? Those inks would bleed through the paint when the floor was
prepped for the next job. Oil based paint in palest grey or white
tinted with black was used. Natural light or flourescent light was
preferred over incandescent. Incandescent casts shadows don'cha

As mentioned before, I have used battens 1 x 3 inch x 40 FEET long
out in the field. Took most all the layout crew to 'conga line' that
batten out to the hull. Approximate measurements were taken,
soapstone marks were made on the steel plate, clips were tacked on,
batten set in clips, wood wedges used between batten and clip to
raise batten to line marked. Leadman would stand back, waaay back,
look at the line and with hand signals indicate which wedges needed
to be snugged up or slacked off to bring batten into a fair line.
After much squinting and after everyone had a chance to look at the
line and add their approval, a soapstone line was drawn on the
The batten removed and 'conga lined' back to the loft and the layout
people assigned to that section would then punch dimples in the
plate along the line at about 3 or 4 foot intervals. Then the
section became the domain of the ship fitters and burners under the
watchful eye of the layout person.

Right handed people it is best to look at long lines on the loft
floor through your legs backwards...Picture the cartoon with the
fellow kissing his arse goodbye, folla?
Left handed people don't need to look at the line this way.
Something about Right brain vs Left brain. Believe me it does make a
When in 'white hat' mode, I would use my left handed people for
layout and special fitting jobs. Rightys, unless old pharts like me,
didn't have the training or experience to over come that brain

[ 10-31-2003, 06:55 PM: Message edited by: Dave Fleming ]

About joint desing
posted by the Chemist:

Member # 1468

posted 07-06-2000 11:33 AM

I ran across this article in a recent issue of the magazine Machine
Design. It seems extremely relevant to the design, construction and
restoration of wooden boats. With their permission, I am posting it
here. It is the best and most succinct summary of important
principles in this subject I have ever seen, stated in plain


Stress plays a significant role in the success or failure of a joint
bonded with adhesives. Engineers must have a solid understanding of
stress distribution across two mating substrates to design the
strongest possible joint.

Five types of stress commonly affect assemblies bonded with
adhesives. Tensile stress tends to elongate and pull an assembly
apart. Compressive stress squeezes an assembly together. Shear
stress pulls parallel objects apart lengthwise, causing a sliding
motion in opposite directions. Peel stress results when a flexible
substrate lifts or peels away from the substrate to which it is
bonded. Cleavage stress is similar to peel stress, but it arises in
inflexible substrates when a joint is forced open at one end.

In use, most joints experience a combination of these forces.

Most adhesives offer excellent resistance to tensile, shear, and
compressive stresses, but are weak in cleavage and peel strength. To
design the strongest possible adhesive joints, distribute loads as
evenly as possible over the entire joint area. The goal should be to
maximize tensile and compressive stresses, minimize shear stress,
and avoid cleavage and peel forces.

The best joint designs maximize the bond area and rely on both
mechanical locking methods and adhesive bond strength. Because the
ends of a bond resist more stress than the middle, joint width is
more important than substrate overlap to successful joint design. By
increasing the width, the bond area at each end increases, along
with overall joint strength.

Regardless of the adhesive, surface preparation is critical to the
bonding process. The degree of adhesion between substrate and
adhesive to a great extent determines bond strength. Recommended
practice includes removing unwanted surface films, using primers to
create active surfaces on substrates, and preparing the plastic
substrates for bonding using plasma treatment, corona discharge, or
chemical etching techniques.

The most frequent reasons for joint failure do not involve adhesive
strength. Typically, an adhesive joint fails due to poor design,
inadequate surface preparation, or selecting an adhesive
incompatible with the substrates and operating environment. Always
thoroughly test assemblies during the design phase to ensure
successful bonding over the life of the device.