Guest Posted January 9, 2012 Share Posted January 9, 2012 So why do people do it - put resin in the holes with the bolts when bolting bulbs to fins, invariably the poor b@stard having to remove the bulb (me today ripping off the dog of a jandal) end up destroying damn near everything surrounding the bolts. Luckily we got away with a neat tidy job but 4 hours to remove 3 bolts is painful and lots of potential to go really wrong with rounded off bolt heads etc. Last time I just cut them through with a sabre saw - was the only way (not Energy) I dont see the upside - 400 kg bulb - 3 x M16 316 Stainless bolts each with a tensile strength of around 17Ton each so roughly 50 T in tensile strength holding 400kg. They wont undo cos they have a mechanical lock with the epoxy bog surrounding the octagonal head so why do it? Seems like massive overkill. The bolts were like brand new after 20 years BTW. Happy to be proved otherwise - thoughts, other than they don't want them to fall off which is the obvious. It just seems like overkill. EE Link to post Share on other sites
SanFran 12 Posted January 10, 2012 Share Posted January 10, 2012 Knot something to do with keeping air from the metal? I went through the process of replacing keel bolts a year or 2 back, which had had epoxy poured down around them. After 30 odd years a couple of the bolts had wasted through about 50 per cent. Even the high quality stainless steel replacements were epoxied in. Link to post Share on other sites
col j 0 Posted January 10, 2012 Share Posted January 10, 2012 i'll have a guess the bolts are epoxied in to stop the buggers moving, only needs an ants cock of play in the holes to get a crack going, then moisture. id also have a guess that they are a bigger gauge than needed strength wise to get the surface area up so the lead doesn't gradually get pushed out of the way creating some movement? Link to post Share on other sites
wheels 543 Posted January 10, 2012 Share Posted January 10, 2012 col j wins the cupi doll. Yeah it's a pain in the A, but it is to keep everything tight and secure. You do not want them coming loose. In timber, it is good practice to ensure the timber does not rot around the thread and the timber remains hard etc. In GRP, it is about keeping it tight. Timber moves a fair amount and can reamin tight against a thread when subject to some movement, but Resin does not move at all and the slightest movement will cause it to become lose. Link to post Share on other sites
khayyam 68 Posted January 10, 2012 Share Posted January 10, 2012 i think ee means the bulb, not the keel bolts proper? Link to post Share on other sites
wheels 543 Posted January 10, 2012 Share Posted January 10, 2012 The bulb must be lead. I would not trust a thread in lead alone. Link to post Share on other sites
Guest Crafty 1 Posted January 10, 2012 Share Posted January 10, 2012 My 2 cents worth. Years ago when you Bedded keels onto the Keelsons (or bulbs onto fins) we used to buy dedicated Epoxy bedding compunds from Epiglass. These were designed to stick like the proverbial, have some Compressional and tensional movement (not to rigid to crack, especiaslly on wooden Keelsons), be very water proof, and make Removal a bit easier. I suspect most people now use standard Epoxy fillers which are generally made for Gap filling, Filling and fairing and easy to sand. While these may work ok they are a right royal pain in the ass to disassemble. We used to use heat to soften them but only to 100 C and in certain circumstances. In fact i think you cannot buy deidicated Epoxy bedding compounds anymore?... can you? Link to post Share on other sites
TimW 1 Posted January 10, 2012 Share Posted January 10, 2012 The main reason for the practice comes from how you fit a Bulb to a Fin or a Fin to the Boat. Once you have your bolt pattern from the Fin (you make a template out of Ply). You use that to dril quite big holes with a holesaw. This is because you have no way of getting the holes all perfect, and the Studs in the Fin are unlikely to be dead straight. The holes are quite big but they allow the Fin to be correctly aligned to the Hull (or the Bulb to be correctly aligned to the Fin). To set up a Keel. First you would Level up the Keel on its Cradle. Then you Would Lower the Boat onto the Keel, also Levelling the Boat and Making Sure the Fin is in the Middle. If for any reason any of the Studs are hitting the sides of holes preventing this we would generally lift the boat and bash and bend the studs (but sometimes open out the hole). When it all perfect you set the boat back down on the Fin. Its bedded on Epoxy (generally). Then you carefully climb in the boat and Pour Epoxy round all the Studs. (We used to put release agent on the Studs). The exact same applys to fitting a Bulb to a Fin. Link to post Share on other sites
Guest Posted January 10, 2012 Share Posted January 10, 2012 ok thats all cool however....I can set it all up perfectly in the workshop (just building the jig now to drill the bulb) so the clearances will be an ants cock and there will be no play in the M16s up the 3 x 22mm 316 SS inserts epoxied into the bulb They are bolted through the lead and into a galv steel plate in the bottom of the fin thats welded to vertical rectangular section with the foil glassed around it. The original drawings had two studs extending down but the builder (rightly) added another a bolt in the center pointing up and into a threaded hole in the plate so 3 x M16. Its a trailer boat so not permanently immersed and the bulb is then glassed to the fin so water ingress is much less of a problem - it probably spends 3 weeks of the year in total in the water. I'm putting 22mm SS tube inserts into the lead to bush it out and spread the loads (epoxied in) with the M16s up the guts of those and will be locktiteing the threads as well as the mechanical detent the bog surrounding the 8 x flats on the head of the bolt provides which is pretty significant, but I wont be epoxying the shaft of the bolts if I can help it. If it were permanently immersed I probably would for the reasons you guys give above but the only way to remove the foil is to drop the bulb off and lift it out the top so I'm just not keen on gluing them in. The fit will be bang on as i can set it up in the workshop. The bulb has been milled dead level (router did it nicely) so its more of a precision engineering exercise than bore it oversize and fill the gaps. On that basis do I still need to epoxy the shafts of the bolts? Link to post Share on other sites
Guest Posted January 10, 2012 Share Posted January 10, 2012 Milling the bulb dead level.... Link to post Share on other sites
Guest Crafty 1 Posted January 10, 2012 Share Posted January 10, 2012 ok thats all cool however....I can set it all up perfectly in the workshop (just building the jig now to drill the bulb) so the clearances will be an ants cock and there will be no play in the M16s up the 3 x 22mm 316 SS inserts epoxied into the bulb They are bolted through the lead and into a galv steel plate in the bottom of the fin thats welded to vertical rectangular section with the foil glassed around it. The original drawings had two studs extending down but the builder (rightly) added another a bolt in the center pointing up and into a threaded hole in the plate so 3 x M16. Its a trailer boat so not permanently immersed and the bulb is then glassed to the fin so water ingress is much less of a problem - it probably spends 3 weeks of the year in total in the water. I'm putting 22mm SS tube inserts into the lead to bush it out and spread the loads (epoxied in) with the M16s up the guts of those and will be locktiteing the threads as well as the mechanical detent the bog surrounding the 8 x flats on the head of the bolt provides which is pretty significant, but I wont be epoxying the shaft of the bolts if I can help it. If it were permanently immersed I probably would for the reasons you guys give above but the only way to remove the foil is to drop the bulb off and lift it out the top so I'm just not keen on gluing them in. The fit will be bang on as i can set it up in the workshop. The bulb has been milled dead level (router did it nicely) so its more of a precision engineering exercise than bore it oversize and fill the gaps. On that basis do I still need to epoxy the shafts of the bolts? How much is an "ants cock"? Link to post Share on other sites
Guest Crafty 1 Posted January 10, 2012 Share Posted January 10, 2012 On that basis do I still need to epoxy the shafts of the bolts? What else would you use? Mastic?, .. On some bulbs we did, we used a combo. Mastic around bolts and most of all faces, then 10-15mm Epoxy around the edge of all mated faces for waterprooffness. These bulbs were very well fitted and had all the strength and movement regulated by the bolts. External bolt/nut recess's were filled with either glued HD foam llug the epoxy filled or glassed over. Removal was never a big problem. Link to post Share on other sites
Guest Posted January 10, 2012 Share Posted January 10, 2012 An ants cock is pretty small in dia. Even by your standards Crafty The faces will be a machined fit so yes I'll probably use a polyurethane sealant on the faces and around the bolt/nut heads, marine bog the holes, glass over to keep her water tight. The if it needs to come off its only a cutting wheel through the glass and a stanley knife through the poly, grind the glass over the bolt heads, chisel the bog and undo. Given its easy to inspect when its on the trailer any movement will be easy to spot. Given the fit and the size if the fixings plus the glass I'm not expecting any movement. The center-case and the rest of the boat will tear apart well before that. EE Link to post Share on other sites
Guest Crafty 1 Posted January 10, 2012 Share Posted January 10, 2012 An ants cock is pretty small in dia. Even by your standards Crafty The faces will be a machined fit so yes I'll probably use a polyurethane sealant on the faces and around the bolt/nut heads, marine bog the holes, glass over to keep her water tight. The if it needs to come off its only a cutting wheel through the glass and a stanley knife through the poly, grind the glass over the bolt heads, chisel the bog and undo. Given its easy to inspect when its on the trailer any movement will be easy to spot. Given the fit and the size if the fixings plus the glass I'm not expecting any movement. The center-case and the rest of the boat will tear apart well before that. EE Well that sound bloody excellent to me! and all with in an Ants penis looking good EE Link to post Share on other sites
203 0 Posted January 11, 2012 Share Posted January 11, 2012 How much lead is there? Link to post Share on other sites
TimW 1 Posted January 11, 2012 Share Posted January 11, 2012 The method I described is mostly used in a commercial environment, i.e. very good results in very short time. It is much easier than spending ages making all the holes a perfect fit. The seating of the Epoxy poured in is also pretty good but for sure it has disadvantages. For mine, if it came to fitting the Studs into a Lead Keel Floor (like we used to have to do), or a Lead Bulb, or Wooden Keel Floors, I'd use the Big Hole/Filled with Epoxy every time. It is fast and works really well. The Epoxy is also more Crush resistant than Lead or Wood. Link to post Share on other sites
Murky 1 Posted January 11, 2012 Share Posted January 11, 2012 Don't know about the rest of you but I am loving the finesse that EE has shown as he keeps luring Mr Wolf into talking about lead. He must be on the verge of having his multihull owner's card withdrawn or at least temporarily suspended by now Lead Link to post Share on other sites
Guest Posted January 11, 2012 Share Posted January 11, 2012 I was going to post this into the TimberWolf thread just to incite him, its soooo sexy! Link to post Share on other sites
Guest Posted January 15, 2012 Share Posted January 15, 2012 Tim - I see what you mean - Drilling lead is an in-precise art, you need the slight clearance to make it fit no matter how much time you spend on it and therefore the resin as a slight gap filler. So does putting a release wax on the bolts help with the removal? Should do in theory? And no, the trailing edge of the fin is knot that fat!, that's just the dia of the smallest router bit I had to router the top of the bulb down for a perfect fit against the plate on the bottom of the foil. EE Link to post Share on other sites
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