| Author | Message | ||
     Jeff Roy New member Username: Jeffr Post Number: 91 Registered: 03-2001 Rating: N/A |
I agree that 5220 at the joint is the best way to prevent water from getting to the steel plate. At the recommendation of the yard that rebedded my keel I agreed to have it done with 5200. They used 5200 between the keel around all the keel stubs and under the backing plates I made to go under the keel nuts and washers. I used a wide razor blade scraper to trim the 5200 flush. A few years later when I faired my keel there was no signs of cracking or weeping. When I faired it I covered the 5200 joint with fairing compound. A year after the fairing there is still no cracking or weepage. My bilge used to be rust stained. After I had the keel rebedded and replaced all the mild steel nuts and washers I painted the bilge white again. I have no rust stains any more. | ||
| Scott Corder New member Username: Pastcommodore Post Number: 44 Registered: 02-2001 Rating: N/A |
Gary Hendrickson's insights regarding the keel - stub attachment and fairing are well founded. I'd simply like to add a separate but related observation to this discussion. As most of us know, S2 struggled with flexibility in both the mast step and the entire bilge throughout the life span of the boat's production. The factory's many attempts to correct this problem with various changes in construction have been rather well documented. Those who have been patient enough to read my lengthy posts regarding mast step/bilge repair issues will recall my personal experience replacing a handful of the stringers with stainless steel (versus the original balsa/mahagony). The results on my boat convinced me of the many merits of a stiff bilge. My point is this: Older boats (lower hull numbers) have inherently more flexible bottoms than later hulls. Furthermore, extremely low numbered hulls even had fewer keel bolts than later models. These early boats (like mine hull #2) did not benefit from keel bolts at the extreme fore and aft areas of the keel thus leaving the keel somewhat "cantilvered" at each end. Thus, the flexibility of the bilge, the number of keel bolts and the tighness of the keel bolts all can contribute to ongoing cracking at the keel seam, especially fore and aft. The conclusion drawn by me and my very reputable yard was clear: unless the entire bilge was stiff and stable, and the keel very securely attached - the keel was going to move a little under load - and we could expect at least a small amount of cracking annually. Unfortunately, the slam-dunk solution is not a cheap or easy fix - as it requires stiffening of the all the ribs that support the keel stub. I can report however that, in my case, the rigidity of my totally rebuilt bilge has totally eliminated all cracking on my keel joint for nearly 6 years now. For more reading, see my posts under 'mast step and bilge repair". | ||
| Gary Hendrickson New member Username: Garyh Post Number: 24 Registered: 02-2001 Rating: N/A |
Regarding the issue of fairing at the hull-keel joint: A year or two after I invested the effort, as described by my articles under the topic to fair Keel, Deep Draft , especially at the keel/hull joint, I saw that cracks were developing again at the joint. After re-checking the tightness of the keel nuts (the torque recommended by my surveyor was changed to 200 - 250 ft-lbs) and discussions with wise people, I concluded that further cracking here is inevitable. Also, I remembered that construction of the keel stub includes a glassed-in flat mild steel strengthening plate that the keel studs pass through. A well-developed joint crack and an aged, hardened keel bedding compound layer could possibly permit sea water to communicate up along the keel stud threading to this steel plate, enabling corrosion. My solution to this issue followed the suggestion of friends working in the yard at Palmer Johnsons: I ground through the joint crack maybe a quarter inch deep all around with a small cutting burr, maybe 3/16 diameter, in a Dremel machine. The resulting trough was filled in with 3M 5200 adhesive. On a warm day this stuff will sag, so two applications might be needed. After the goop set up and cured for 2 - 3 weeks, I went one step further -- the excess hardened goop was planed down to be essentially fair with the adjacent surface. This sealed the gap up nicely with a flexible "gasket." | ||
| Jeff Roy New member Username: Jeffr Post Number: 90 Registered: 03-2001 Rating: N/A |
I wish I had more time to post more on this subject. I took hundreds of photos too. I had my keel dropped and rebedded a few years ago. Nothing you add to the surface of the keel/hull joint is going to make a difference to how well it is bonded to the hull. S2 epoxied the keel onto the hull with what appeared to be microballoon filled epoxy. The keel nuts and washers on my boat were very corroded and I had a weep of water coming from the keel/hull joint. I spent a good month getting the keel nuts off (documented elsewhere on this site), no small task. The first thing the yard did was grind the outside of the keel/hull joint down to lead so they could see exactly where it was and get it apart. I was there when the yard removed the keel from the hull. They had the hull in the travel lift and the keel secured in a special keel cradle. As they lifted the hull the keel and cradle came off the ground! This is with NO nuts or washers on the keel bolts. They had to hammer oak wedges into the joint all the way around the keel to pry it off the hull. They were very carefull and the tear away was minimal. Once it was off they did have to use a grinder to clean up all the ripped epoxy. I have not seen any cracking at my hull/keel joint since I did these repairs. I did not use any chopped strand in my epoxy but did mix in some colloidal silica to stiffen it up more. You have to mix the epoxy very thick to prevent sagging. I also put wax paper on the epoxy after I layed it on. This makes it easier to smooth with a plastic squeegee and prevents any blush from forming, which can be a paint to remove (must be done). When I was done I put on 3 coats of WEST with the WEST brand barrier coat additive for the same reasons Mike used Interprotect. I found that the drawing of grids as described in the article on keel templates was critical to being able to judge fairness. Without them it is guesswork. I drew several extra "vertical" lines on the front 10% because that is the most criticatl and the most difficult to fair. It takes many cycles of putting fairing compound on and sanding off with to get it perfect. If you redraw the grid lines at every step you can avoid having to remeasure it all because some part of every line is visible at every step. | ||
| Mike Bergmann Unregistered guest Rating: N/A |
My keel was very well faired when I got the boat in 1996. I did hit a rock in 2000 which knocked a lot of the faring off, and I ended up re-fairing the lower third of the keel about 1 ft. aft from the leading edge. I mostly followed the same procedure Jeff did, and I also highly recommend the West System products. I did not use the round rod for the leading edge (mainly because I didn't think of it). I did not have too much trouble fairing with the same MIcrolight filler. (PS - I use a fair amount of the chopped cotton fibers in this mix with the Microlight filler - it helps keep it from sagging on a vertical surface.) I did all the shaping with a straightedge - the idea is to keep the straightedge sloped fore & aft in proportion to the overall keel dimensions. In other words, if the top of the straightedge is 30% aft from the leading edge, keep the rest of it 30% aft also. I did reinforce the bottom at the leading edge with fiberglass fabric, as that is the place that will get hit first. When you finish fairing, I recommend applying one or two coats of Interlux 2000. Since the West System is completely impervious to water, you don't need it as a barrier coat, so you don't need the recommeded five coats. However, I find that my bottom paint (Micron Ultra) sticks to the 2000 primer much better than to a sanded epoxy surface. I think all the boats had a few layers of fiberglass covering the joint between the keel stub and the lead. Mine was OK until I hit the rock, and then it cracked all around. I haven't completely solved that yet. I think I may have to re-tighten the keel bolts first and then repair the fiberglass. One problem is that the weight of the boat is resting on the keel when it is out of the water during repairs, but the keel weight is supported by the bolts and the fiberglass when the boat is launched. The stress on the joint increases a lot just when the boat is picked up, and you may notice that cracks will open up at this time. I would not worry too much about filling the space with epoxy. The filler here is just to provide a smooth base for the fiberglass overlay. You could use a hard caulking compound or a Bondo type filler just as well. | ||
| Brad Stone New member Username: Bstone Post Number: 2 Registered: 06-2004 Rating: N/A |
A follow-up question, and thanks for the quick response Jeff... If this gap between the lay-up and the keel/stub joint is filled with anything epoxy based, will that make it tough for the keel to be dropped at some point if need be? I think I've read here and heard elsewhere that with too good a bonding around the joint, parts of the boat or stub can crack off with the keel when it's dropped. I was wondering if S2 left the slight gap in for that purpose. Thanks again. | ||
| Jeff Roy New member Username: Jeffr Post Number: 89 Registered: 03-2001 Rating: N/A |
Brad, I tackled fairing my keel last spring. I completely redid the front and leading edges, they were both a mess. The Article titled Keel, Deep Draft by Gary elsewhere on this board is an excelent source of information. I made my own templates for the front 10% of the keel out of foam core, getting the numbers from a text on airfoil design. I faired the middle of the keel be fair and smooth, but did not make any major changes to the shape there. I did fill quite a few hollows and ground down a few high spots. On the trailing edge I ground back the last few inches to lead and then built it up with some fiberglass tape before fairing it all in. My keel was 3/4" short and adding that 3/4" brought the tail to a nice narrow sharp edge. I am a loyal user of WEST System Epoxy. I follow their guides and have had excellent results. You will go through a lot of epoxy as much of it gets sanded off. You can use the Microlight fairing compound for most of it, but I used a mix of Colloidal Silica and High Denistiy Filler for the leading and trailing edges and the bottom edge so they would be more resilient. I had a big hollow between the rounding of the hull and the hull/keel joint on the starboard side of my boat. You should fill in all hollows and grind down obvious bumps. One thing I did that I highly recommend is I got a 3/8" hollow G10 rod from McMaster-Carr for the leading edge. I ripped it in half and then epoxied it onto the front of the keel. I then faired in behind it with epoxy. This is much easier than trying to get the shape of the front 1% of the keel right with just fairing compound. It also makes the leading edge ruler straight and is very strong to resist damage if you hit something. Because the keel is taperd the amount of fairing that creeps around the G10 rod increases as you go up the keel. When I was done, most of the half round of the rod was visible at the bottom of the keel and only the middle 1/4" or so was visible at the top. It is a lot of labor, took me several months, working on it quite a bit. I noticed a HUGE difference in upwind performance. I can now climb up on boats that use to walk over me. The boat does not stall as easily. It was the best performance enhancing project I have done. | ||
| Brad Stone New member Username: Bstone Post Number: 1 Registered: 06-2004 Rating: N/A |
Hi all... I'm the new owner of hull #60, and in the buying process over the last few months I've read much here with great interest. I must say this is a most helpful and comprehensive source of information, and my hat off to all who've worked so hard to make it so. My membership app is in the mail and am proud to be aboard. Right now she's on the hard, and in stripping the bottom I've found the cracked fairing compound front and rear of the keel written about here, plus a nice sized crack on the port side above joint level. I've ground out the fairing compound in these areas, making the stub/keel joint visible in front and rear, and I've got a few questions: I notice a glass layup from the keel insert on the hull, rounding down the stub, and to the keel. There is a small, consistant void running fore and aft on both sides, about joint level, between the stub/keel and this layup. Is this normal? Should I fill this area somehow, and with what... or should I just re-fair the cracked areas, and what sort of fairing material should I use? Brand names will definitely help. Thanks all, Brad |
