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Re: David's Cataproa
I have been adding a little to my Cataproa blog each week. Today, I added about collecting materials, sail track attachment and some cabin storage schemes. I found a huge cost benefit choosing a slightly larger Aluminum cross beam section. However, I then needed to adjust the beam support structure to fit. Here is my sketch of the beam pivot.
You can see more drawings on the David's Cataproa 3 section of my blog: mancebodesigns.com Here is a drawing of my scheme to access storage aft of the cabin. Again, the blog has more info and drawings of the feature: David M |
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Re: Building tiny tri for Grandson while waiting for marine ply for 520
Hi Michael See again the photo from the green tri. There you can see the fuller (roller). See drawing 22 (mast extension). There is at the right the furler.? As mast, you can use an Al tube with a length of 5500 mm. As mast, we use in France windsurfing masts. They have the diameter to fit into the extension. Best regards Bernd
Le mardi 21 septembre 2021, 12:35:27 UTC+2, Bernd Kohler <bernd@...> a ¨¦crit :
Hi Michael Nice to hear that your tri is coming along. To your questions Drawing 1/3? The sail is a fat head sail. So the top line is the end of the sail.? The black line is a seam. You need soft sail battens like on the Hobie mirage tandem is using for the same rig.? The battens are also wound around the mast Drawing 2 You need a fang to stabilize the wishbone boom. The drawing shows how to bend and build the free rotating fang rope holder. (see also attached photo. Have fun? Bernd Photo TT-rig on an different tri
Le lundi 20 septembre 2021, 18:15:47 UTC+2, Michael Mitchell <mitchellwm4mm@...> a ¨¦crit :
I have the tri mostly built but do not understand the sail drawings .Attached can you explain the parts. I do not understand the furling system. Can the sail be lowered unfurled? Thanks |
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Re: Building tiny tri for Grandson while waiting for marine ply for 520
Hi Michael Nice to hear that your tri is coming along. To your questions Drawing 1/3? The sail is a fat head sail. So the top line is the end of the sail.? The black line is a seam. You need soft sail battens like on the Hobie mirage tandem is using for the same rig.? The battens are also wound around the mast Drawing 2 You need a fang to stabilize the wishbone boom. The drawing shows how to bend and build the free rotating fang rope holder. (see also attached photo. Have fun? Bernd Photo TT-rig on an different tri
Le lundi 20 septembre 2021, 18:15:47 UTC+2, Michael Mitchell <mitchellwm4mm@...> a ¨¦crit :
I have the tri mostly built but do not understand the sail drawings .Attached can you explain the parts. I do not understand the furling system. Can the sail be lowered unfurled? Thanks |
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Re: Carbon mast failures and successes
I enjoyed reading about Phil's infused carbon mast building. He took a different path than I did with my infusion. My infusion failed because my mandrel was not airtight. But I have used the method successfully with airtight molds. So how is my method different?
I use staged infusion. This means placing resin supply lines every meter. For a small laminate like a mast, I use 4mm ID, hard, polyethylene tubing for resin supply. It supplies plenty of resin for infusing a mast and does not allow the infusion front to race too fast. If you look at my picture, you can see the resin supply tubes and the vacuum tube (same tubing material) nearest the camera. One advantage of this particular tubing material is that I can seal it by simply kinking it and taping the kink until I want resin flow. This is effective and very inexpensive compared to clamps. Resin supply lines every meter or less for staged infusion. Infusion set-up from other end. You can see the kinked tubes instead of clamps to seal the tubes. Note also, the ends of the resin supply tubes are cut at an angle so they cannot seal against the bottom of the resin bucket. As Phil noted, a key element of infusion is to prevent wrinkles in the laminate. In my infusion there are at most 4-layers of reinforcement. Each layer is tightly rolled using Super 77 adhesive to keep them in place. This was not as difficult as a full length mast because, for this job, reinforcements are only added to the bottom 3.6 meters of the spar. Also, with at most 4-layers, tightly wrapped, previous experience has shown impression resulting from the spiral tubing resin distribution lines will be minimal. For this process I never wrap one layer multiple times around the mast because I believe doing so can increase the chance of inducing wrinkles. My infusion setup is: laminate; peel ply; infusion flow media; vacuum bag. My resin distribution lines are 10mm id polyethylene spiral wrap fed by 4mm id resin supply lines. They are placed at most 1-meter apart. The infusion flow media stops about 50mm from the vacuum line. There is a "brake" between the flow fabric and the vacuum line to slow the resin. The brake I use for masts is a single layer of 200 g/m^2 balanced glass cloth with peel ply on top.? To infuse this part, I would have first pulled a vacuum for at least 4-hours. Next I would do a pressure drop test by closing the valve on the second resin trap. If after an hour, I had not lost more than 2 psi (on the gauge of the first resin trap), I would be ready to infuse. I would have started the infusion at the butt of the mast (away from the vacuum line) and allowed the resin front to pass the second resin supply tube. I would then close (kink and tape) the first resin supply line and open the second resin supply line. This process would continue until the resin front reaches the "brake" before the vacuum line. I would then close the valve on the second resin trap (i.e. disconnect the vacuum pump from the laminate). I usually don't need to engage the vacuum pump again but would briefly if the vacuum fell more than 4 psi. David M |
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Re: Carbon mast failures and successes
Suunto,? Yes prepreg can work in some cases. If the item is round oval or so and then it is wrapped with a shrinking plastic and then cured, I have seen them also using vacuum.? The main issue is that the carbon have to be compressed into a single compound layer if the layers are not compressed properly they tend to be separate layers and the strength is not there. It needs to be a homogene layer. I will attach the file here. Cheers? Philip Malan
On Friday, 17 September 2021, 17:40:28 SAST, David Mancebo via groups.io <mancebodesigns@...> wrote:
Hi Phil. I think placing a tube inside would work well. I would enjoy your link to your mast fabrication even though my mast has already been laminated. Be sure to send the link to Bernd's forum too. David M
On Thursday, September 16, 2021, 06:24:27 AM PDT, Philip Malan via groups.io <malan.philip@...> wrote:
David, To infuse the mast I used a plastic tube inside the mast and then again a tube outside then you seal the ends together. In other words the air pressure/vacuum pushes the two plastic sheets together for 100% seal and no stress on the structure.? I built a 11.6 m mast for a 26 ft sailboat? that weighed 29 kg. If you want I can send you a file of my built. regards Philip Malan
On Wednesday, 15 September 2021, 21:49:03 SAST, David Mancebo via groups.io <mancebodesigns@...> wrote:
I have struggled converting a carbon fiber mast for use on a modified Cataproa. I think the failures and successes are informative for those interested in carbon spars. I used to do this kind of work in my carreer, first as a fabricator and later as a Materials and Process Engineer. So I am embarressed by the failures. I have had successes in the past. For example, here is a cutt-off from a custom carbon mast that was a success: You can read more about this on my blog: http://gator2002.temp.domains/~mancegns/2021/09/13/davids-cataproa-2/ David M |
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Re: 7 photos uploaded
#photo-notice
Hello Zee
Thank you for the update. Nice progress. The hulls look great. The transom area is a busy region. Unusual for the North hemisphere persons are the aft cockpits. You in the South are used to it and have experienced the practicality of this arrangement.?? Cheers Bernd |
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Re: Carbon mast failures and successes
Hi Phil. I think placing a tube inside would work well. I would enjoy your link to your mast fabrication even though my mast has already been laminated. Be sure to send the link to Bernd's forum too. David M
On Thursday, September 16, 2021, 06:24:27 AM PDT, Philip Malan via groups.io <malan.philip@...> wrote:
David, To infuse the mast I used a plastic tube inside the mast and then again a tube outside then you seal the ends together. In other words the air pressure/vacuum pushes the two plastic sheets together for 100% seal and no stress on the structure.? I built a 11.6 m mast for a 26 ft sailboat? that weighed 29 kg. If you want I can send you a file of my built. regards Philip Malan
On Wednesday, 15 September 2021, 21:49:03 SAST, David Mancebo via groups.io <mancebodesigns@...> wrote:
I have struggled converting a carbon fiber mast for use on a modified Cataproa. I think the failures and successes are informative for those interested in carbon spars. I used to do this kind of work in my carreer, first as a fabricator and later as a Materials and Process Engineer. So I am embarressed by the failures. I have had successes in the past. For example, here is a cutt-off from a custom carbon mast that was a success: You can read more about this on my blog: http://gator2002.temp.domains/~mancegns/2021/09/13/davids-cataproa-2/ David M |
Bernd Kohler
Bernd Kohler
Philip Malan
