Composite Beams - Wharram Builders and Friends2024-03-29T15:32:18Zhttp://wharrambuilders.ning.com/forum/topics/composite-beams-1?id=2195841%3ATopic%3A16872&feed=yes&xn_auth=noI've been having to repair sm…tag:wharrambuilders.ning.com,2017-04-10:2195841:Comment:1507142017-04-10T02:07:12.400ZBrad Ingramhttp://wharrambuilders.ning.com/profile/BradIngram
<p>I've been having to repair small nicks and dings in my wooden beams almost every time I take Beto apart, and it is getting quite annoying! The front beam especially takes a lot of abuse. I know <a class="nolink"> </a><a href="http://wharrambuilders.ning.com/profile/ReinhardKaeferboeck">Reinhard Käferböck</a> has aluminum square tubing with no issues, and I think I will eventually crack and go for the same thing. Woods uses aluminum tubing on his Strider design, so I'm sure the 4"x1/8" wall…</p>
<p>I've been having to repair small nicks and dings in my wooden beams almost every time I take Beto apart, and it is getting quite annoying! The front beam especially takes a lot of abuse. I know <a class="nolink"> </a><a href="http://wharrambuilders.ning.com/profile/ReinhardKaeferboeck">Reinhard Käferböck</a> has aluminum square tubing with no issues, and I think I will eventually crack and go for the same thing. Woods uses aluminum tubing on his Strider design, so I'm sure the 4"x1/8" wall that Reinhard has would be perfectly strong enough for Beto and.......................wait for it...............no maintenance! Having to only worry about maintaining the hulls would make for a much better peace of mind and way less annual yard time, I think. After doing the endless fillets and other bullshit on my wooden beams, I almost wish I had gone with the $500 (for all 3) aluminum tubes instead from the get go. </p> The earlier Wharrams flexed a…tag:wharrambuilders.ning.com,2017-04-09:2195841:Comment:1505512017-04-09T15:33:32.552Zboatsmithhttp://wharrambuilders.ning.com/profile/qe0j3ojqb10
<p>The earlier Wharrams flexed a great deal. This made the boats not very rigid. This lack of structural rigidity made for a rig that was unable to hold any headstay tension. This certainly contributed to the lack of windward performance. The newer lashing design allows for a much tighter structure. We tighten our lashings forever more tight. With your hand on the beam and hull together one can feel some movement but it is not visible.</p>
<p>We built two T8m for day charter use in SW florida…</p>
<p>The earlier Wharrams flexed a great deal. This made the boats not very rigid. This lack of structural rigidity made for a rig that was unable to hold any headstay tension. This certainly contributed to the lack of windward performance. The newer lashing design allows for a much tighter structure. We tighten our lashings forever more tight. With your hand on the beam and hull together one can feel some movement but it is not visible.</p>
<p>We built two T8m for day charter use in SW florida at the Marco Island Marriott Resort. While these boats do not cross oceans and do not often see big wind or waves, they do go out three times a day 7 days a week for 7 years now. In late 2015 one of the boats was on the hard for maintenance and was struck by lightning. The lightning came down a shroud to the chainplate and blew a hole through the side of the hull,then through the bottom paint to one of the keel blocks (12'x12"x 30"), blowing it apart leaving a basketball sized hole in the concrete. We brought the boat back to the shop or repairs. We thoroughly surveyed the entire boat at that time. The beams showed no signs of wear or degradation.</p>
<p> These beams I designed in house with no engineering other than experience and intuition.They were rectangular in section and were constructed of 1708 and unidirectional fibers over a solid Divinycell foam core. They had extra layers of glass in way of the mast step and where the lashings are located.</p>
<p> When it came to the Ariki 48 I went to Eric Sponberg (naval architect/engineer to help me design the beams. We discussed various building methods and materials. We ended up building female molds for the beams and the beam bottoms. The beams were built hollow with a couple of layers of CSM and 5 layers of 24oz triaxial e-glass. There are internal bulkheads in way of the mast step and lashing points. These beams have so far worked out with no problems.</p>
<p> Building the molds fo these beams cost a lot. For us that is ok because we will use them repeatedly. For a one-off building the beams over a solid foam core would be much more cost effective. I would recommend the use of an engineer to establish cross-sectional area and lay-up schedule. </p>
<p>Beams are a big part of these boats. Wood is maybe the easiest and cheapest route to go but the trade off is weight and longevity. Building beams of aluminum is certainly a viable option. We are more comfortable working in composite.</p> someone else in another threa…tag:wharrambuilders.ning.com,2017-04-09:2195841:Comment:1507072017-04-09T07:34:46.219Zdave tomlinsonhttp://wharrambuilders.ning.com/profile/davetomlinson
<p>someone else in another thread was talking about alloy as a building marteirial, and 10 in alloy tube as beams, they would be very strong and stiff at that size but alloy can fail with repeated flexing where wood is naturally flexible.</p>
<p>someone else in another thread was talking about alloy as a building marteirial, and 10 in alloy tube as beams, they would be very strong and stiff at that size but alloy can fail with repeated flexing where wood is naturally flexible.</p> I'm impressed by the thought…tag:wharrambuilders.ning.com,2017-04-08:2195841:Comment:1507042017-04-08T20:26:50.041ZAxelhttp://wharrambuilders.ning.com/profile/Axel
<p>I'm impressed by the thought and courage in designing and making your own beams. As someone who has made T38 beams I was astounded at how heavy they are once finished. I have not weighed them but I can tell you that 2 strong men can just about manage one of the longer ones and it really isn't safe at that level. It struck me that with the rest of the boat being relatively light, with a better engineered beam one might be able to reduce the overall weight of the boat by perhaps 15%. Continues…</p>
<p>I'm impressed by the thought and courage in designing and making your own beams. As someone who has made T38 beams I was astounded at how heavy they are once finished. I have not weighed them but I can tell you that 2 strong men can just about manage one of the longer ones and it really isn't safe at that level. It struck me that with the rest of the boat being relatively light, with a better engineered beam one might be able to reduce the overall weight of the boat by perhaps 15%. Continues to bother me but once I had built mine, I wasn't going to redo them in a different format. </p>
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<p>I will be very interested to see how yours do. And did you see the earlier posts about someone who had CF tubes fabricated for a T30 (? if I remember right) </p> That's good to hear! Thanks f…tag:wharrambuilders.ning.com,2017-04-04:2195841:Comment:1505092017-04-04T06:43:30.819ZRobert Hugheshttp://wharrambuilders.ning.com/profile/RobertHughes
<p>That's good to hear! Thanks for the update Thom<br></br> <br></br> <cite>Thom delForge said:</cite></p>
<blockquote cite="https://wharrambuilders.ning.com/forum/topics/composite-beams-1?xg_source=msg_com_forum&id=2195841%3ATopic%3A16872&page=4#2195841Comment150364"><div><div class="xg_user_generated"><p>It’s been a while since all of this, but need to say my beams are still pretty much as I built them. A few scraches later, but no signs of stress. No ocean crossings either, but has seen…</p>
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<p>That's good to hear! Thanks for the update Thom<br/> <br/> <cite>Thom delForge said:</cite></p>
<blockquote cite="https://wharrambuilders.ning.com/forum/topics/composite-beams-1?xg_source=msg_com_forum&id=2195841%3ATopic%3A16872&page=4#2195841Comment150364"><div><div class="xg_user_generated"><p>It’s been a while since all of this, but need to say my beams are still pretty much as I built them. A few scraches later, but no signs of stress. No ocean crossings either, but has seen some high seas ...</p>
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</blockquote> It’s been a while since all o…tag:wharrambuilders.ning.com,2017-04-03:2195841:Comment:1503642017-04-03T21:52:31.151ZThom delForgehttp://wharrambuilders.ning.com/profile/ThomdelForge
<p>It’s been a while since all of this, but need to say my beams are still pretty much as I built them. A few scraches later, but no signs of stress. No ocean crossings either, but has seen some high seas ...</p>
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<p>It’s been a while since all of this, but need to say my beams are still pretty much as I built them. A few scraches later, but no signs of stress. No ocean crossings either, but has seen some high seas ...</p>
<p></p> Andy - The quantity you need…tag:wharrambuilders.ning.com,2014-02-12:2195841:Comment:1138472014-02-12T10:38:19.325ZGalway Bayhttp://wharrambuilders.ning.com/profile/GalwayBay
<p>Andy - The quantity you need is called Young's Modulus Of Inertia. It is available for all materials. I have not checked for ply but if you think about it wood is uni-directional fibre, ply is bi. So 50% of ply is only core material in any one direction. I would be slow to use it as structural material in the sort of compact beams we use although with much larger sizes it would become useful. It is of course excellent for core material as with the web in an I beam, where it has great…</p>
<p>Andy - The quantity you need is called Young's Modulus Of Inertia. It is available for all materials. I have not checked for ply but if you think about it wood is uni-directional fibre, ply is bi. So 50% of ply is only core material in any one direction. I would be slow to use it as structural material in the sort of compact beams we use although with much larger sizes it would become useful. It is of course excellent for core material as with the web in an I beam, where it has great resistance to the shear loads as the top and bottom faces try to "slide" past one another under load. The ply embedded in the laminated faces also gives huge stability to these. I packed the beams out solid for 6" long at each lashing. I would consider the same at the bolt position but I used blocks on the bottom of the beam instead of the bolt.</p>
<p>The failure of my beams was due to water saturation. Seemed wetting could happen but not drying. The failures were of the glue joints at the bottom of the hollow sections and rotting timber. This has turned me against hollow beams.</p>
<p>Wharram's beams were basically 8" X 4" with hollow sections so small as to do almost nothing except add to the complexity of building. I decided to use a solid 8" X 4" as my base value and my beams are similar to the example given, but scaled up. My beam 1 & 3 have faces 2 1/2" deep and beam 2 is a little heavier in all dimensions. It carries the mast. Partly these decisions were based on what timber I had on the shelf.</p>
<p>My new are 2 X 35kg plus 1 X 40kg = 110 kg. I suspect the old should have been about 50kg ea. but were a lot more due to water saturation. So the old beams best case 4 1/2 X 50kg. = 225kg. A weight saving of 115kg. and in practice more. Yes I do feel it in the boat's sailing performance.</p>
<p>I also felt it in the building time and in my wallet. I built the full set in a week part-time evenings plus all Saturday, not including painting.</p>
<p>I have been waiting for some eagle-eyes to point out that in the example given in the earlier post the horizontal value is only 50% of original. This can be easily overcome with a small increase [ + 25% ] in width. However I was limited by using the old troughs and was not able to compensate fully. But after some severe use I am happy.</p>
<p></p> Thanks Galway bay. I think if…tag:wharrambuilders.ning.com,2014-02-11:2195841:Comment:1137432014-02-11T19:52:11.515Zstellahttp://wharrambuilders.ning.com/profile/x
<p>Thanks Galway bay. I think if one is to change the plans, there are two ways:</p>
<p>-trial and error (usually more expensive) but this is why Tom delForge's discussion is going, because he made plastic beams still holding after 3 years. i really like the idea of severe testing as in aviation and have friends in self-build ultra lights and planes - but they test after sticking to the plan!!</p>
<p>- calculations like engineers do, but in the world of amateur builders, I've gotten…</p>
<p>Thanks Galway bay. I think if one is to change the plans, there are two ways:</p>
<p>-trial and error (usually more expensive) but this is why Tom delForge's discussion is going, because he made plastic beams still holding after 3 years. i really like the idea of severe testing as in aviation and have friends in self-build ultra lights and planes - but they test after sticking to the plan!!</p>
<p>- calculations like engineers do, but in the world of amateur builders, I've gotten "professional" and engineers advice (which I sunk the money and time into) which wasn't so good - so it should be someone with catamaran experience.</p>
<p>I didn't think of the hollow beams being stronger than whole ones, and would have made them whole to limit rot, if out of wood..</p>
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<p>To Andy BestDunkley: I had some without the hardwood triangle under the bolt. As I posted before, I believe (due to trial and error) this is the key point which avoids splitting the lamitation.</p>
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<p>Can anyone PM me a scanned plan the Tiki i-beam in exchange for a Pahi beam plan, for consultation only. As the Pahi came later, I would expect an evolution with a reason. Jim seems to have done his calculations, and then a lot of trial and error...</p> Thanks for the formula Galway…tag:wharrambuilders.ning.com,2014-02-11:2195841:Comment:1139392014-02-11T18:56:06.295ZAndy Best-Dunkleyhttp://wharrambuilders.ning.com/profile/AndyBestDunkley
<p>Thanks for the formula Galway Bay - but I have a question: in your case the material (solid wood) is the same. Do you have any comparative values for the material coefficient q? For example on my pahi, the original beams are laminated from solid timber, but if I made a similar sized beam from plywood, maybe I-beam construction, how would this compare? (The original beams to plan actually contain oval cutouts to lighten them but these are definitely weak points for letting water in, that's…</p>
<p>Thanks for the formula Galway Bay - but I have a question: in your case the material (solid wood) is the same. Do you have any comparative values for the material coefficient q? For example on my pahi, the original beams are laminated from solid timber, but if I made a similar sized beam from plywood, maybe I-beam construction, how would this compare? (The original beams to plan actually contain oval cutouts to lighten them but these are definitely weak points for letting water in, that's why I've replaced with a solid laminated beam.) Also how can I design for enough strength where the beam locating bolts are fitted (horizontally through the beam trough)? I haven't seen the tiki-style beam upgrade plans, but I understand they don't use the bolt at all, whereas I'd prefer to keep it.</p> Without knowing enough of the…tag:wharrambuilders.ning.com,2014-02-11:2195841:Comment:1138422014-02-11T18:48:24.907ZJeremy Walkerhttp://wharrambuilders.ning.com/profile/JeremyWalker
<p>Without knowing enough of the details regardingThom's beams -- perhaps the foam web and putruded sections were wrapped in ample E glass reinforcing, well keyed for bonding purpose and then the whole beam was resin infused in one shot-- I don't know. But on the whole I am with you Galway.</p>
<p>Sure it is possible to gain a lowered weight advantage by increasing the depth of an I beam, and I think it is possible to achieve sufficient diagonal bracing of the entire structure to make up for…</p>
<p>Without knowing enough of the details regardingThom's beams -- perhaps the foam web and putruded sections were wrapped in ample E glass reinforcing, well keyed for bonding purpose and then the whole beam was resin infused in one shot-- I don't know. But on the whole I am with you Galway.</p>
<p>Sure it is possible to gain a lowered weight advantage by increasing the depth of an I beam, and I think it is possible to achieve sufficient diagonal bracing of the entire structure to make up for the loss of horizontal stiffness in the individual beams.......adding weight to total structure. This woulcd be a significant departure from classic Wharram design though, so is not worth persuing in this thread.</p>
<p>What is of relevance is the effort in achieving an aesthetic effect fitting the Wharram ethic, and here I would go with wood.</p>