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Alan Stewart

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Everything posted by Alan Stewart

  1. We had a very successful albeit HOT capsize camp on Saturday Here is the proof I mean footage!!! An enormous thanks to Will and Rob for bringing there really nice CS-17 and offering themselves up to the camera and spectators! They did an amazing job, no boats or humans were damaged and everyone learned a lot. Thanks also to Nick for the extra video footage, Rob for coming out and taking our Spindrift 12 for a much needed spin, Tana (the main camera woman), Dawn and Taylor for being our "rescue swimmers" slash "I'm going to cool off in the water now" spectators and Dejah and Zoey for moral support aboard Southbound the camera boat. We will have info up soon on the mast head float and how you can get one. We will be offering them as easy to put together kits which will pop right onto any existing Core Sound boat's mast.
  2. Justin, You are correct on assembling the transom, you will need that assembly and the center frame assembly done before you fold the boat up. Glue the transom stiffeners to the transom and the center frame doublers to the center frame. For lamination like that (the technical term for making a wood sandwich) I like to assemble all the parts dry and use drywall screws to hold everything together then I disassemble it all and apply glue and then re-assemble with the screws. Without some type of alignment pins or screws it's practically impossible to get the parts in the right place with slimy epoxy on them. The screws don't have to be all the way in in fact it's better to leave the heads proud a bit. Then I add clamps, as many as I can fit on there but not so many that I don't make it impossible to clean up most of the epoxy squeeze out. Sometimes, I'll clamp it up then remove the clamps one at a time or at least rotate them so that i can get most of the squeeze out. If needed, i'll back out one of the screws so the wood can pull together more (with clamping pressure) then re-insert it. 2 screws per part is minimum but 3 allows any one to be taken out at the time after it's assembled. After about 6 hours the epoxy is like dried up chewing gum, nothing is going anywhere now but the glue up is still not fully strong. At this point it is safe to take off the clamps IF there was not a lot of stress in the wood. For example you wouldn't want to do that it it was a gunwale you were gluing since it was under tension. It's important to take the screws out at this point because if you wait until the next day they are likely to snap right off if you forget to heat them up. If you do wait until the next day you just need to hit the heads with a torch for a second and they will instantly release and come right out. This is easier to do if you left the heads proud! The final step would be cleaning up any remaining squeeze out and puttying in the screw heads. Sometimes it's easier to drill the screw hole out larger say 1/4" hole and fill it in with epoxy than to try and putty in a 1/8" hole where you can't get much epoxy in the hole before it seals itself off and you get the air plunger effect. Some cheap plastic syringes are great for filling small holes like this but a putty knife pulled slowly over the hole does the job.
  3. Yeah that is a good idea and probably what i would do for a remote steering station. Weve also thought of putting a little side station like on a whaler which could go just ahead of the bench.
  4. Justin, Looking good. Glad to see you post some pictures and that you were able to get started on the boat finally. I like your casters on the support frames i'm sure you will enjoy being able to slide the boat around the garage. For cleaning up that epoxy squeeze out, a "mini-grinder" with a heavy grit sandpaper disk like 36 grit is an essential tool at our shop. It will make quick work of the majority of those cured epoxy blobs just be real careful not to gouge the panel and do the final 1/16" with a block of sandpaper or a flat machine sander like a 1/2" sheet sander or random orbit. Looking forward to seeing her folded up!
  5. The second annual Capsize camp is right around the corner. Scheduled for the 20-20 (weekend after next). If you can't make it to the shop don't worry! we'll have another one with more advanced warning. The schedule will be the same as last year which was basically sail around and capsize your boat as you like! We hope to demo version 2 of the mast head float as well. -Alan
  6. This boat was built from plans and was on display at the Beaufort Boat show this year. The boat looked very nice and although Craig made a few changes to the boat it looked like it would be a great running boat. I took some pictures.... https://photos.app.goo.gl/QTTXLc9pNDey8qV49 I just saw it posted on Craigslist and there are more pictures there.... https://eastnc.craigslist.org/boa/d/avon-23ft-cold-molded-custom-carolina/6917609861.html
  7. I never have. Sounds like a lot of work but i havent used brightsides just 2 part poly devoe and awlgrip.
  8. I think that is a typo in the drawing, at one point we were playing with putting a block on the cb itself but decided against. There should just be the one block which is labeled.
  9. I am jealous. what a sweet boat.
  10. I also like the chair, need to get one of those in my shop. And the boat looks great too!
  11. Whatever the longest piece is is what i was going to make. I think its about 36"
  12. Hi Bob, Well i think you are very wise to consider building one in the first place! Know that you'll have plenty of support from us here on the forum. I would checkout the dutch OB 20 build thread for a step by step guide on best practices. -Alan
  13. The main problem we had with this year in the EC on Southern Skimmer was with the torque line. We were just using a twisted pair of 3/8" double braid line to transmit the torque to the top of the luff the problems come with furling in higher winds it takes a lot of torque to get the sail to start wrapping and then when the sail is half furled the torque required is much less so a lot of twists are built up in the torque line and then they are relieved inside the rolled up sail which causes a bunch of wraps in the wrong direction at the top so then when you go to unfurl it gets all fouled at the top until you can shake the twists out. Part of the problem is that the free standing mast can't generate as much tension in the torque line as a stayed rig can so the torque line is never really super taught even with the backstays full on. So if the torque line doesn't have enough tension it can more easily twist leading to the above scenario or even worse it could pigtail. I don't know what it would cost to have a piece of proper top down furling torque line made up for the boat but I think it might be worth it. They make fancy braided and wrapped torque line exactly for this.
  14. Finally got a quote back on the fiberglass epoxy bonding angle mentioned above https://photos.app.goo.gl/WRCfHXduXu3szT4Q6 It came out about $6 per foot so at this point I think were going to pass on it.
  15. Hahaha, it's something we've been thinking hard about. Steve, I agree it would be nice to have some kind of prevention line on the centerboard but on the flip side it's a rare enough event for a regular Core Sound to capsize let alone a Mark 3 Core Sound so it wasn't a top concern in the design process and Graham I think still isn't convinced it's necessary.
  16. I repeated myself a little bit but it's worth repeating since this is an area that you will not be able to ever work on again without much difficulty!
  17. Correct, not necessary for strength. If you want the lightest boat possible then don't sheath in glass just tape the seams. Every ounce counts on a small tender. It'll make it easier to carry and haul on board. That is what I personally would do. On a small boat it's easy to do little repairs to the bottom if it gets scratched or dinged. You can just flip it over, do the repair and your good to go.
  18. Looking real good Todd! A while back I looked at many cases for the 20mk3. You can see some of the results in the form of stability curves here. https://docs.google.com/spreadsheets/d/1rqaVj7Ncj45HQtIq8PMWILgZhQCXYuGpHj3qkUgu6DU/edit?usp=sharing Sealing the cockpit comings entirely would certainly add some positive buoyancy to the boat in a capsize. The stability curves we calculated assumed the coamings were flooded. Basically you would be increasing the angle of vanishing stability. The water ballast however is by far the largest determinant factor. We think the boat should always be sailed with the water ballast filled unless you are motoring in a dead calm or sailing in drifting conditions. The numbers don't lie and I am confident that the 20-mark 3 WOULD turn turtle without the water ballast in even if the cockpit comings were completely sealed. A small mast had float on the 17 mark 3 and 20 mark 3 can be added to prevent the boat going turtle in all scenarios which would be a good idea if you like to sail the boat without the ballast of if you plan to participate in say the Everglades Challenge for example. I plan to have a mast head float on my CS-20 Mark 3 because I like to sail without the ballast because it's faster! and I don't want to worry about turning turtle when I don't have the ballast in. If you always have the ballast in then no need. With the water ballast filled the boat should not be able to turtle even if the centerboard is up on the 20 mark 3. (maybe not true for the 17 mk3...see below) This is I think attributed to the taller masts which (once partially underwater) provide the missing righting moment lost from the CB which is good because it remains to be seen if the centerboard could be reached from the water if the boat capsizes to starboard (putting the offset board higher up in the air). I intend to test this extensively with my boat. We have only been able so far to test capsizing a CS-17 Mk3. Based on these few tests, the 17mk3 was easily righted by one person with the tank full and the board down and even while at the same time scooping the crew into the cockpit. The one test we did with the board UP it looked like she wanted to turtle even with the ballast tank filled. The boat tested did not have sealed cockpit coamings. There were a few extra variables in this test though such as the mizzen being flipped over and could have been scooping water as they tried to right the boat with no CB. Also this test pointed out the possible usefulness of a line tied to the trailing edge of the CB that could be pulled on from the water to re-lower the centerboard. The 17mk3 is still quite stable without the ballast with an angle of vanishing stability of around 70-80 deg or so. We tested the angle of vanishing stabilty of Grahams 17mk3 here but with no sails at the time and got 85 deg w/o ballast. And we did a similar test of the first CS-20 Mark 3 with the ballast in only here. Only because it is pertinent to the above we are also working on a new design...(spilling the beans here) we are currently calling the Core Sound 17/20 SR. (SR stands for self righting). We're pushing the limits of the water ballast in a remake of the original CS-17 and 20. The boat below has almost the same hull shape as the CS-20 mk3 but with added sheer height to gain the maximum righting moment from the cockpit coamings which are now completely sealed. The water ballast tank is a full 550lbs in the CS-20 SR and there is 4 inches of blue closed cell foam blocking between the underside of the cockpit sole and the top of the water in the ballast tank. The purpose of this is to push the center of volume of the water ballast lower in the boat thus reducing the vertical center of gravity. It has the added benefit of being able to fill the tank without topping off with buckets or pumps since the entire tank is below the waterline. It is very hard to get a shallow draft boat to self right and it's impossible to do it without sealing the cockpit coamings. That also makes the boat very stable in the inverted position. To solve that problem. One of the coamings is flooded automatically if the boat turns turtle allowing the boat to be rotated back on her side and then righted. If I had this boat, I would also have a mast head float on it for the same reasons as above. I like to sail w/o the ballast (because it's fast) and don't want to worry about turtling. The 17 and 20 SR will also have an integral outboard well in the stern of the cockpit, a longer forward cockpit seating area for camping under a dodger and we're shrinking the weighted CB down so just the top of the trunk sticks up above the sole.
  19. Ben, The angle between the sheer and the top of the bow transom is approximately 115 deg. That would be the angle of the forward quarter knee (or very close to it). The bevel angle of the stiffener on the bow transom will not be this angle because the bow transom has a lot of rake compared to the stern transom. Measuring the angle at 90 degrees to where the side and bow transom come together (shown with a disk below) is much closer to the given angle of 127 deg. I can see how that would be confusing but that is the angle you would set your bevel gauge to in order to cut a bevel on the end of the bow transom stiffener. Let me know if that make sense. -Alan
  20. Update #4: bunk top egdes glassed and ballast tank bh4 mostly glassed in. Started fitting bh3 and the port sheer strake in place. Also i talked about how the side stringer causes the side panel to deform slightly outward and how the side panel shrunk a bit on my boat due to the neutral axis of the plywood.
  21. Just in case, I would double check the overall width of the hanging knees and make sure they aren't bowing under the squeezing pressure of the temporary batten. I see you have a spring clamp on there but I can easily see it slowly creeping and then your width being out. Double check width, re-clamp wit a stronger c-clamp then see how the fit is. I suspect it will be tight and want to push the temporary gunwale outward and the gap will be resolved. The fact that one of the hanging knees cracked also supports this hunch. Let us know if that helps! -Alan
  22. Very true. I think at this point we are going to press on with the well as is and see how it works. Probably splash the boat before paint so we can try it out. I want to have an insert to fill the hole smooth regardless. Also, note to past self... you shouldn't have glued the sheer strake panels together until you were ready to put them up on the boat because they are very long and very in the way in the garage.
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