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BT: Compound for sealing leak
Our boat (wooden '58 Chris Craft) leaks a bit. I believe it's where the final "plank" meets the keel. It's not so bad that I'm scard of any serious problem but it is bad enough that a puddle of 10 gallons or so forms in the back when we're running. (It forms in the back because the bow is up, and the bilge pumps are in the front.) I'm thinking I'll use some tool (?) and forms a small groove (kind'a "V" shape) between that last "plank" and the keel and then fill it with ... 4200? Actualy it isn't "planked" it's lap-strake plywood. Make sense? 4200 the thing? Maybe M101. |
On Wed, 9 Mar 2005 15:10:00 -0500, "Gary"
wrote: Our boat (wooden '58 Chris Craft) leaks a bit. I believe it's where the final "plank" meets the keel. It's not so bad that I'm scard of any serious problem but it is bad enough that a puddle of 10 gallons or so forms in the back when we're running. (It forms in the back because the bow is up, and the bilge pumps are in the front.) I'm thinking I'll use some tool (?) and forms a small groove (kind'a "V" shape) between that last "plank" and the keel and then fill it with ... 4200? Actualy it isn't "planked" it's lap-strake plywood. Make sense? 4200 the thing? Maybe M101. I'd use 5200 - binds better, allows the wood to expand and contract without breaking a seal. I have an old, and I mean old, plywood Sunfish style boat that I've kept floating with 5200. :) One of these days, I need to check and see if there is still any wood left under the 5200. :) Later, Tom |
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Gary wrote: " Our boat (wooden '58 Chris Craft) leaks a bit. I believe it's where the final "plank" meets the keel. It's not so bad that I'm scard of any serious problem but it is bad enough that a puddle of 10 gallons or so forms in the back when we're running. (It forms in the back because the bow is up, and the bilge pumps are in the front.)....." Gary, a couple of things spring to mind...a 10 gallon "puddle" seems a lot to me..how long does it take for this to happen? 24 hours or 24 minutes? Are you sure the leak is from the hull planking? Is this an issue while moored or only underway? Could be a cooling system issue (inboard engine?)or a though hull fitting starting to fail. Anyhow I'd be more then a bit concerned! How come the pumps are forward? Usually they are located in the bilge area which is most often at the stern area under the engine. They are only capable of handling a small amount of water, spray, the drip from the shaft through hull packing,etc. While 3M 5200/4200 are great products, just mushing some into and around a seam area doesn't produce a seal. To be structually efective the "seam" or joint needs to be opened up and a uniform bead of 3MXXXX applied and then the joint refastened, the excess sealant removed etc etc. Be careful, the sea doesn't care if you live or not. Mike |
THE LEAK: While the exhuast does drip just a little and the packing may drip a drop or five there actually is a leak. None of the thru-hulls leak a drop. Whether underway or stopped there is a small amout of water coming in. Knowing exactly where it is from is difficult. But basically when look from inside the boat down into the bilge it comes from one area ... closer to the bow than the stern ... maybe 15 feet from the back of the boat. The water appears inside from where the lowest plywood strake meets the large chuck of wood that is is keel. I'm guessing as to the amount of water. Clearly more than 1 or 2 gallons. My guess of 10 is probably the highest it could be. I'm not really sure. It probably takes 30 to 60 minutes in the water to get that much in there. I'm not sure if it comes in any faster when moving than when still. BILGE PUMPS: This boat originally had NO bilge pumps. It had (and has) a suction feed "pump" in the stern. This is still in place but I'm not very sure that it actually gets suction and moves any water. It seems like is doesn't. I put in two 1500 gmp pumps. For some reasoning - not really clear to me now - I put both in the front of the boat. I guess I should move at least one of them to the stern. ~~ BILGE PUMP QUESTION: Since I already have thru-hulls up in the bow -- if I relocate the pump(s) to the stern can I run hoses that entire distance so as not to have to put more holes in my boat? It would be about 15 feet laterally - maybe a little more actual hose. I suppose I should use a check valve at the pump with that much hose so the water in the hose doesn't run back into the bilge?? SEALING THE LEAK: To be structually efective the "seam" or joint needs to be opened up and a uniform bead of 3MXXXX applied and then the joint refastened, the excess sealant removed etc etc. What we're thinking is getting a little dremmel type tool for the end of a drill and going all along the outside of the hull where the bottom-most plywood strake meeds the keel. The idea would be to create a crevease to put the 3M stuff in. I'm pictureing something "V" shapped. You say "...then the joint refastened". I'm not too clear on what that would mean. I mean, how to do it. THANKS Be careful, the sea doesn't care if you live or not. Well put. |
On Thu, 10 Mar 2005 11:18:02 -0500, "Gary"
wrote: What we're thinking is getting a little dremmel type tool for the end of a drill and going all along the outside of the hull where the bottom-most plywood strake meeds the keel. The idea would be to create a crevease to put the 3M stuff in. I'm pictureing something "V" shapped. You say "...then the joint refastened". I'm not too clear on what that would mean. I mean, how to do it. ============================ Gary, I'd recommend reposting your question on rec.boats.building There are a fair number of wooden boat experts that hang out there and can give you a better perspective on the issues and options than I can. It's my understanding that the last plank before the keel is called a garboard, and this is apparently a traditional problem area, probably because of the stresses involved with a somewhat flexible plank butting up to the (hopefully) more rigid keel structure. You first need to understand what was done to keep that area from leaking when it was new, and what has changed since. Has the wood weakened (impending rot issues)? Has the caulking dried out? Have the fastenings for the plank or keel deteriorated allowing movement of the wood joints? These are all common issues with older wood hulls. Until you understand the root cause and address it, all other solutions will be band aids. Another possibility is that the wood has dried out and shrunk. Wood boats are usually built so that a certain amount of moisture swelling will take place and actually help to compress the caulking and lock the entire structure together. You could try leaving the boat in the water at a dock (with suitable pumps), and see if the leakage rate slows down or disappears. Good luck. |
Wayne, Good info. I'm glad you said what you did about "root cause". I really should know by now that there is no use trying something that will probably turn out to be a band-aid...it usually just makes a mess and the problem harder to solve. Thanks for remiding me to do the research on this before goofing with it. Now that I think about it I have briefly met two different pro boat restorers and I'll bet if I took the boat to them on the trailer they'd sped a half hour telling me what they think. That would probably be well worth the expense of the trip and a case of beer and/or some $$ for their time. Thanks! |
On Wed, 9 Mar 2005 15:10:00 -0500, "Gary"
wrote: Our boat (wooden '58 Chris Craft) leaks a bit. I believe it's where the final "plank" meets the keel. It's not so bad that I'm scard of any serious problem but it is bad enough that a puddle of 10 gallons or so forms in the back when we're running. (It forms in the back because the bow is up, and the bilge pumps are in the front.) JB Weld will do the trick. Our shop uses it to repair cracked blocks and heads, so it will certainly work in your ap. |
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