View Full Version : recaulking hull
08-11-2002, 06:41 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 choice.
I will be greatly appreciative for any sound advice or clear direction.
08-11-2002, 06:53 PM
Mate, you need a copy of Allen Taube's book "The Boatwight's Companion, subtitled (repairs below the waterline) Published by International Marine, Camden Maine 04843, 207-236-4837. Or try your inter-library lending service if you cannot find one locally.
This book ought to be in every wood boat's library because any question you may have, he has the answer, and it's not using some new-fangled miracle goo! Good Luck!
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.
08-12-2002, 07:38 AM
I'd be really suspicious that she leaks when underway. Is a plank or frame that's loose, and getting worked? Or mast step etc.? Or perhaps it's seams above the waterline that haven't closed up properly?
08-12-2002, 11:13 AM
I know your boat well. The Kettenburg was constructed in San Diego by the yard of the same name. My boat, the Fellows & Stewart Island Clipper, is a near sister to the Kettenburg PCC (46').
You should recaulk these boats just as they were built. Most likely underway she has some loose connection where the forefoot (gripe) meets the keel. This is a problem area on my boat since it is just under the mast step, and hard sailing makes her leak a bit. You need to haul this boat and assess. I think you will find it is more than a caulking problem, but definately not a huge job.
The glass rope method you've seen is practiced by a guy down in San Diego who restores mainly Kettenburg PCs (36') that live on trailers. This isn't for you. Do it the old way.
Don't use oakum. Cotton is just fine, and is more forgiving IMHO.
e-mail me directly if you need any more info or help (email@example.com)
08-12-2002, 11:32 AM
Any wooden boat that pumps once a week while at rest is properly caulked. Motion may be the problem. A poorly bedded small diesel will shake seams pretty good. Have you look down in the bilges when underway to see where the source of water is. Do you have any old through hull fittings that are not in use but may under extra pressure when cruising..causing leaks. Without knowing more about the boat, hull fastenings (how old) its hard to say this is the problem.
However, something significant is happening down in the bilges that you should be able to see. One week to 15 minutes is a specific viewable problem. Wait until she is bone dry and you and a friend go for a cruise, give her the tiller/wheel and you pull all the floor boards and have a real good look.
The other suggestions are for when all else fails solutions.
Find the source, its there!
08-12-2002, 12:01 PM
RGM and Adam C have said it all. Stay clear of fixes other than what was done originally.
I have sailed both a K40 and a PCC on San Francisco Bay, and both had problems when sailing into the typical ebbtide chop with 25-30 knots of wind. These boats were built fairly light and were most popular in southern California where most of the sailing is light. On the Bay, on both of them the mast pressure pumped the garboards and 1st broads a bit, but they closed up after the pressure was off. It sounds like your boat does that same thing. If leaks persist after appropriate re-caulking, and the fasteners check out OK, not to worry. Just make sure your automatic bilge pump works while you are slamming into the chop, and in all probability she will close up when the pressure is off.
If this problem persists as the boat gets older, one solution is to install two or three 1/8x3" stainless straps, outside the hull in the way of the mast step. The lower end fastens to the wood keel, and the straps extend up about four planks. They are let into the keel and planking so they are flush. Use short but wide screws (e.g., 3/4x14) countersunk in the steel.
Or you can put some backing blocks inside and use longer screws. For bedding, use 3-M 5200 or similar. The straps must be installed while the planking is still moist and after caulking and paying this area.
The "Boatwright's Companion" is well worth obtaining.
08-12-2002, 12:18 PM
My hull once had strapping, but it has since long corroded away. Could you please clarify your idea on inside hull strapping? Mine was originally installed between the frames and planking, a place totally inaccessible now unless youpull of planks.
I'm not sure I'd do outside strapping.
08-12-2002, 12:56 PM
My remarks were about outside strapping, with which you can tie it into the keel and a few lower planks, thus preventing the seams from opening inordinately from pressure by the mast.
The original design for my Hinckley Sou'wester was for a deck-stepped mast. Someone since 1947 decided to install a keel-stepped mast. It was obvious that the step needed some backing up, since several stealers end in that area. So he installed three stainless straps on each side as I have described, I don't know when but at least thirty years ago. It's all still in good shape, no corrosion and very little leaking.
08-13-2002, 12:17 PM
I don't think that this problem is all that unusual. This can happen from not being structurally sound to a bad caulking job. A word of caution! I had an area under the mast step which let go of its cotton a few years ago. It let go on both sides of a plank, on both sides of the boat,about eight feet back, in particularly nasty seas (of course).
The pounding and the mast pressure were enough to spread the planks apart allowing the water to completely wash the cotton out. I could see day light through the seams. Made for a rather attractive waterfall from the bow. However I was knee deep in water and neck deep in Coast Guard in short order. I rebuilt the entire bow structure and added three new and overbuilt floor timbers to keep things tight. Point is, make sure that your planks are tight enough to hold the caulking. I think your best shot is to survey the hull and fasters and if they seems ok, a tighter caulking job may be in order. How long has the boat been in the water?
[ 08-13-2002, 01:19 PM: Message edited by: mariner2k ]
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