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Post by jaysen on Jun 12, 2020 12:05:23 GMT
Don, A couple questions: * Where are with with the mandated "class supplied" chainplate/pintle/gudgeon hardware? * Is there any reason we can not get the keel built and certified in advance of the hull construction?
We are hoping to start addressing the components that I would need to acquire from specialty suppliers (that don't require explicit fitting to the hull) as it will make the timeline a bit less hectic once we are full swing into the build.
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pete
Junior Member
Posts: 56
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Post by pete on Jun 12, 2020 14:58:26 GMT
+1 for this plan while I wait for the kit to get cut. Have also dben thinking about the keel and am about to generate a CAD file (.dxf) of the profile from the hand drawn plans so i can send it out to get some quotes for waterjet/ plasma cutting here. The 8mm section that bolts to the keel floors has a slight curve though, so was going to wait until i have at least the bulkheads in place on the stongback and a stringer (the same depth as the final planking + glass) clamped up to get the correct profile before it gets final welded. (also would allow pre-drilling the mounting holes through the oak floors and the plate for precise alignment).
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Post by jaysen on Jun 12, 2020 15:34:26 GMT
My plan was to have the keel undrilled and make that part of the installation process. I'll need to be at a boatyard to get the keel mounted and they will have the ability to drill the holes at the time. The curve is something I hadn't considered, but I think, should one follow the plans carefully, any variation should be very minor and fillable with sealing compound/tape.
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Post by Admin on Jun 12, 2020 22:50:45 GMT
Don, A couple questions: * Where are with with the mandated "class supplied" chainplate/pintle/gudgeon hardware? * Is there any reason we can not get the keel built and certified in advance of the hull construction? We are hoping to start addressing the components that I would need to acquire from specialty suppliers (that don't require explicit fitting to the hull) as it will make the timeline a bit less hectic once we are full swing into the build. Hi..sounds like a good idea and yes the build schedule is up to you I am also organising, mast, tailer, and many other things as well as keel etc. seperate to the build..we will have a waterjet keel cutting file and bulb 3d pattern next week for those interested and we are in the process now of getting the Quotes for all chainplates...etc so should have a supplier decision end of this month as well as prices...then we will group the first 25 buyers and make the first batch...it will include two 114mm dia 3mm snubbing winch backing plates and a large backing plate for the two leading keel bolts and four SS strips to back up the bottom bolts of the Daggerboads so you do not rip the transom off if you hit something. will advise when all ready...goood luck!
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Post by Admin on Jun 12, 2020 22:54:37 GMT
My plan was to have the keel undrilled and make that part of the installation process. I'll need to be at a boatyard to get the keel mounted and they will have the ability to drill the holes at the time. The curve is something I hadn't considered, but I think, should one follow the plans carefully, any variation should be very minor and fillable with sealing compound/tape. You can shape a plywood template to the curve of the Hull Rocker and give that to the steel cutter to match. It is very important as you need good fit...good luck!
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pete
Junior Member
Posts: 56
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Post by pete on Jun 13, 2020 15:06:12 GMT
The keel cad file and bulb 3d model would be useful. I'm lucky enough to have access to a 3d printer and was going to print the bulb (in a number of pieces so it fits on the printer) then use it to create a concrete mold - the 3d model would have location divots for subsequent drilling already incorporated to make alignment more accurate.
I've got as far as modelling the bulb from the sections in the plans, and making some assumptions with curves to make it fair, mainly in order to check the mass assumptions are correct.
If I use pure lead as a material (1.135g/mm^3) in the cad program I get a bulb half that weighs ~67.5kgs - which, even allowing for some clearance recesses for bolt heads that i haven't drawn (the through bolt holes are there though) is still too heavy by ~5kgs per half (material sheet in plans pack calls for 125kgs lead total, so 62.5kgs/ half).
It is unlikely that the lead will be 100% pure, so given the extra 5 kgs above equates to a little more volume in the mold this would still allow a sufficient pour of lead to meet or exceed the 62.5kgs required and can be shaped down (on the flat side) to meet the precise weight required before fitting.
Let me know if you want me to share the file I've got so far, or if you want to wait for Janusz (or whoever is cadding this up) to provide one.
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Post by captdan on Jun 13, 2020 18:03:58 GMT
The keel cad file and bulb 3d model would be useful. I'm lucky enough to have access to a 3d printer and was going to print the bulb (in a number of pieces so it fits on the printer) then use it to create a concrete mold - the 3d model would have location divots for subsequent drilling already incorporated to make alignment more accurate.
I've got as far as modelling the bulb from the sections in the plans, and making some assumptions with curves to make it fair, mainly in order to check the mass assumptions are correct.
If I use pure lead as a material (1.135g/mm^3) in the cad program I get a bulb half that weighs ~67.5kgs - which, even allowing for some clearance recesses for bolt heads that i haven't drawn (the through bolt holes are there though) is still too heavy by ~5kgs per half (material sheet in plans pack calls for 125kgs lead total, so 62.5kgs/ half).
It is unlikely that the lead will be 100% pure, so given the extra 5 kgs above equates to a little more volume in the mold this would still allow a sufficient pour of lead to meet or exceed the 62.5kgs required and can be shaped down (on the flat side) to meet the precise weight required before fitting.
Let me know if you want me to share the file I've got so far, or if you want to wait for Janusz (or whoever is cadding this up) to provide one.
Hi pete, I also did a model of the bulb. Its kind of fun to that kind of stuff. In fact, the model that I did is on the 580 website. When I did the weight on mine, it worked out to 69.72kg without removing the material for the bolt holes and counterbore for bolt heads and nuts. one hull #1 bulb is complete and fitted, there might be an adjustment on the weight of the halves. A couple of kilos probably wont make a world of difference on these boats. As long as they are all the same .... I like all of the data your program gives you. What are you using for modelling?
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Post by captdan on Jun 13, 2020 19:06:17 GMT
+1 for this plan while I wait for the kit to get cut. Have also dben thinking about the keel and am about to generate a CAD file (.dxf) of the profile from the hand drawn plans so i can send it out to get some quotes for waterjet/ plasma cutting here. The 8mm section that bolts to the keel floors has a slight curve though, so was going to wait until i have at least the bulkheads in place on the stongback and a stringer (the same depth as the final planking + glass) clamped up to get the correct profile before it gets final welded. (also would allow pre-drilling the mounting holes through the oak floors and the plate for precise alignment). Hey pete and jaysen, I agree about waiting until your hull is well on its way on the strongback / jig for finding the actual arc of the hull in that area. I am building my boat all by hand so I want to see what the real arc is on my hull because it might be slightly different than a computer generated profile. My plan is to have both plates profile cut, layout and drill the holes in the mounting plate, bolt the plate to the hull and thru the oak beams, stand the keel up on the mounting plate ( check the fit - you dont want gaps ... ), fit the keel plate to mounting plate ( ensuring alignment fore and aft as well as vertical ), tack the keel plate to the mounting plate with appropriate fitting supports. Keep in mind that the 8mm plate will bend very easily when welded to the thicker keel plate ( that is a lot of weld along the length of the keel on both sides) The person welding should ensure that the 8mm plate is flat in the port/stbd direction when welding is complete. If you have the right person doing the job, this shouldnt be a problem. I plan to do all of this after glassing the hull and before I flip the hull to work on the deck. There are a few ways to do this but I can be galvanizing or epoxy painting the keel while I am finishing the deck and interiors etc. Thoughts???
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martellmarine
Junior Member
Husband & wife team building boat #71.
Posts: 61
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Post by martellmarine on Jun 13, 2020 20:58:15 GMT
I modelled one too. Except I used a NACA 0012-64 foil shape as the basis. Same principle dimensions. Same weight. Slightly different distribution of volume +/- 4mm difference in shape. Just for fun! Attachments:
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martellmarine
Junior Member
Husband & wife team building boat #71.
Posts: 61
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Post by martellmarine on Jun 13, 2020 21:51:52 GMT
My plan is to have both plates profile cut, layout and drill the holes in the mounting plate, bolt the plate to the hull and thru the oak beams, stand the keel up on the mounting plate ( check the fit - you dont want gaps ... ), fit the keel plate to mounting plate ( ensuring alignment fore and aft as well as vertical ), tack the keel plate to the mounting plate with appropriate fitting supports. Keep in mind that the 8mm plate will bend very easily when welded to the thicker keel plate ( that is a lot of weld along the length of the keel on both sides) The person welding should ensure that the 8mm plate is flat in the port/stbd direction when welding is complete. If you have the right person doing the job, this shouldnt be a problem. I plan to do all of this after glassing the hull and before I flip the hull to work on the deck. There are a few ways to do this but I can be galvanizing or epoxy painting the keel while I am finishing the deck and interiors etc. Thoughts??? My approach would be to take measurements of the centreline rocker before glassing, make a template of the rocker and take it and the flange plate to a fabricator who could roll the shape into the plate. Meanwhile I would have drilled oversized holes through the hull and floors and glued in fibreglass tubes with an internal diameter 1mm bigger than the keel bolts. I would then temporarily screw the shaped plate in position and mark from the inside of the hull the hole positions. Remove the plate and drill keel bolt holes. I would double check the rocker shape in the top of the fin using the template and the flange, make any adjustment for fit and then send it to the fabricators for welding with clear instructions on flange position and squareness on top of the other requirements needed for registration. Meanwhile I would fibreglass the bottom of the hull ensuring there is a proper overlap of the hull glass and the ends of the keel bolt tubes for waterproofing purposes. During the fairing process I would be using the template as a guide to see what was happening in the keel flange area... When it came time to fit the keel, assuming I have the boat suspended and the keel set up underneath, I would lower the hull onto the flange and check for fit. There will be a lot of heat generated from the welding process and therefore the possibility of a slight distortion built into the flange. If I was worried that there was an unacceptable difference between hull and flange shape, I would tape the top of the flange with packaging tape, apply a little mould release wax, mix and apply a structural bog to the flange and lower the pre prepared hull onto the plate creating a well fitted mating pad. Once cured, lift the hull, detail the new mating surface if required and clean off the top of the keel. Should be ready to go then!
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pete
Junior Member
Posts: 56
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Post by pete on Jun 13, 2020 21:54:35 GMT
captdan - yeah i think waiting until the hull shape is known is the best option in terms of the 8mm plate. I'm going to try to limit the damage i will do to my wallet if i screw up any work by trying to get the plate drilled without any other work being done to the steel. i.e. before it is welded to the 15mm keel plate itself - so i only have to replace the 8mm plate when i get it wrong...
In the same vein as you, I've been thinking about the welds too - 8mm to 15mm is waaaay beyond my skill level, and the distortion will be a thing for a pro to deal with for sure. I've been toying with the idea of tabbing the keel plate to add extra weld. You can get about 30-50% more depending on the size of the tabs. The tabs would need to be chamfered in the usual way, then root pass, fill and cap etc then ground down to flush. Then the fillet welds as per the original design can be done. This way you gain a mechanical advantage from the cantilever (albeit 8mm deep...) and a lot more weldment.
I've sketched it in exaggerated form - hopefully the image attaches correctly...
Caveat - I'm just a hobbyist, so this may have a bunch of issues i'm not aware of - happy to be corrected by an expert!
and btw - this is onshape i'm using. I use SW in the day job, so onshape is basically identical, but free if you don't mind not owning the drawings... Which for my lash-ups is fine if it saves me the £3k license fee!
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pete
Junior Member
Posts: 56
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Post by pete on Jun 13, 2020 21:59:50 GMT
My approach would be to take measurements of the centreline rocker before glassing, make a template of the rocker and take it and the flange plate to a fabricator who could roll the shape into the plate. Meanwhile I would have drilled oversized holes through the hull and floors and glued in fibreglass tubes with an internal diameter 1mm bigger than the keel bolts. I would then temporarily screw the shaped plate in position and mark from the inside of the hull the hole positions. Remove the plate and drill keel bolt holes. I would double check the rocker shape in the top of the fin using the template and the flange, make any adjustment for fit and then send it to the fabricators for welding with clear instructions on flange position and squareness on top of the other requirements needed for registration. Meanwhile I would fibreglass the bottom of the hull ensuring there is a proper overlap of the hull glass and the ends of the keel bolt tubes for waterproofing purposes. During the fairing process I would be using the template as a guide to see what was happening in the keel flange area... When it came time to fit the keel, assuming I have the boat suspended and the keel set up underneath, I would lower the hull onto the flange and check for fit. There will be a lot of heat generated from the welding process and therefore the possibility of a slight distortion built into the flange. If I was worried that there was an unacceptable difference between hull and flange shape, I would tape the top of the flange with packaging tape, apply a little mould release wax, mix and apply a structural bog to the flange and lower the pre prepared hull onto the plate creating a well fitted mating pad. Once cured, lift the hull, detail the new mating surface if required and clean off the top of the keel. Should be ready to go then! all of this. literally all of this is what i am now going to do. good to have someone around who clearly knows their shit.
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martellmarine
Junior Member
Husband & wife team building boat #71.
Posts: 61
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Post by martellmarine on Jun 13, 2020 22:07:08 GMT
I was thinking about tabs like you have illustrated as well. As I have talked with inspectors and surveyors, there is a consistent mention of the possibility of fatigue due to the long term cyclical pendulum nature of the structure. We have been reassured that the structure as designed is over spec'd. So maybe tabs not necessary.
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Post by Admin on Jun 13, 2020 23:46:42 GMT
The keel cad file and bulb 3d model would be useful. I'm lucky enough to have access to a 3d printer and was going to print the bulb (in a number of pieces so it fits on the printer) then use it to create a concrete mold - the 3d model would have location divots for subsequent drilling already incorporated to make alignment more accurate.
I've got as far as modelling the bulb from the sections in the plans, and making some assumptions with curves to make it fair, mainly in order to check the mass assumptions are correct.
If I use pure lead as a material (1.135g/mm^3) in the cad program I get a bulb half that weighs ~67.5kgs - which, even allowing for some clearance recesses for bolt heads that i haven't drawn (the through bolt holes are there though) is still too heavy by ~5kgs per half (material sheet in plans pack calls for 125kgs lead total, so 62.5kgs/ half).
It is unlikely that the lead will be 100% pure, so given the extra 5 kgs above equates to a little more volume in the mold this would still allow a sufficient pour of lead to meet or exceed the 62.5kgs required and can be shaped down (on the flat side) to meet the precise weight required before fitting.
Let me know if you want me to share the file I've got so far, or if you want to wait for Janusz (or whoever is cadding this up) to provide one. The shape is designed with a typical topedo shape and then a Flat section at the bottom..make that Flat extention section bigger!!!!! as the final weight is the criticle one and if you need to add weight later..low desity lead etc...total nightmare, but it is easy to plane the flat back down with a electic wood plane to make it lighter....ofcourse the design o the 5.80 will be great and ballast right but I am waiting to sail HULL 01 TREKKA and sea trials to check many things...icluding power etc..so we are not expecting any changes...but if you do not need to mould keel before end of September then hold off...Looks like Trekka will be first one sailing...so first real tweeking..checking all aspects of the boat etc.. all the best...thanks..
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Post by Admin on Jun 13, 2020 23:59:33 GMT
WOW!...THANKS!! Martell Marine above...this is the best description ad process I have seen on the best way to do KEEL things and I really like the idea of the GLASS tubes for keel bolt holes....I think this should be the absolute best option for all and will recommend it as a standard proceedure....first read of this it could all sound complicated..read it three or four times and it is just perfect and really quite simple and failsafe...well done and THANKS!!!! Here it is.... My approach would be to take measurements of the centreline rocker before glassing, make a template of the rocker and take it and the flange plate to a fabricator who could roll the shape into the plate. Meanwhile I would have drilled oversized holes through the hull and floors and glued in fibreglass tubes with an internal diameter 1mm bigger than the keel bolts. I would then temporarily screw the shaped plate in position and mark from the inside of the hull the hole positions. Remove the plate and drill keel bolt holes. I would double check the rocker shape in the top of the fin using the template and the flange, make any adjustment for fit and then send it to the fabricators for welding with clear instructions on flange position and squareness on top of the other requirements needed for registration. Meanwhile I would fibreglass the bottom of the hull ensuring there is a proper overlap of the hull glass and the ends of the keel bolt tubes for waterproofing purposes.
During the fairing process I would be using the template as a guide to see what was happening in the keel flange area...
When it came time to fit the keel, assuming I have the boat suspended and the keel set up underneath, I would lower the hull onto the flange and check for fit. There will be a lot of heat generated from the welding process and therefore the possibility of a slight distortion built into the flange. If I was worried that there was an unacceptable difference between hull and flange shape, I would tape the top of the flange with packaging tape, apply a little mould release wax, mix and apply a structural bog to the flange and lower the pre prepared hull onto the plate creating a well fitted mating pad. Once cured, lift the hull, detail the new mating surface if required and clean off the top of the keel.
Should be ready to go then!
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