jetboy 0 Posted December 1, 2015 Share Posted December 1, 2015 Lots of new home built and production small trimarans getting to the market. Thought I'd share a few pics of how I built mine in its own thread rather than derail another one. It's a PP honeycomb core with fiberglass and epoxy. The floats are from a Nacra 5.2 donor boat. Because of how small it was I decided to try something different with the assembly using sliding AND tilting amas. I've found that it works very poorly so far. The aluminum tubes I chose only have .026 inches of clearance and at that amount they bind. I have yet to find a good solution for that problem. So far I've polished them. Used UHMW tape. And used various lubricants. The only real workable option so far is lithium grease - and it's a mess. So this winter I'm probably going to cut it apart and replace with farrier style folding arms. My current setup time is around 45 minutes. that's 30 minutes too long. Most of it is fighting with the telescoping mechanisms. The rest goes together very quickly. I think folding arms will get me into the 15-20 minute setup time range that I want. Otherwise I've been pretty pleased with it. I don't have any video as of yet. I've only had it on the water a handful of times. It sails better than any boat I've owned as an all around fun lake boat. It's not a racer, but it's faster than almost every other boat on the water. It's a great day sailer that has lots of room and comfort and is dry and flat. It's based on a Scarab 18 plans from Ray Kendrick. I modified the cabin to make it much smaller and further forward. I also totally changed the beams and floats. I wouldn't have been able to build this on my own without the plans from him. Link to post Share on other sites
jetboy 0 Posted December 1, 2015 Author Share Posted December 1, 2015 Way to many hours of this: Link to post Share on other sites
Doug Lord 1,219 Posted December 1, 2015 Share Posted December 1, 2015 Good job, jb! Can you sit in the cabin? Link to post Share on other sites
jetboy 0 Posted December 1, 2015 Author Share Posted December 1, 2015 Yes - but not comfortably. And due to the beam running through it - you can really only access from the hatch on the top forward deck. It's hard to get in from the companionway. It's also very short for me at 6'3". It is a sail and gear locker, not really a cabin for my use. I would not want to try to spend a night in it, or even more than a brief rain storm. Link to post Share on other sites
mojounwin 0 Posted December 2, 2015 Share Posted December 2, 2015 Looks great. You've done well Cheers Mojo Link to post Share on other sites
jamez 5 Posted December 3, 2015 Share Posted December 3, 2015 Nice job. The smaller cabin is probably better on this design. Could you still add the designed beams and folding system? Link to post Share on other sites
jetboy 0 Posted December 3, 2015 Author Share Posted December 3, 2015 Thanks! I do think I can still add a folding system, but it may not be exactly like the one from the designer. The main reason for that is that the original beams are a really time consuming task to build a mold and lay up a complex layup of fiberglass 4 times. And the internal structure is also pretty time consuming to manufacture. So my intention is to design my own system in aluminum and have all the parts cut on a water jet and then weld them. I have aluminum welding experience and equipment, so it's pretty cheap for me to go this route. I'll probably be into the materials and cutting for around $5-700. Between that and fiberglass it's probably a wash $ wise, heavier, and doesn't look nearly as nice as the original design, but it's fast. And I'm really wanting to do more sailing than building. This would be a 2 or 3 day project from start to finish. The fiberglass beams would be around 200 hours by my best guess. If I had more experience with infusion I have a vacuum pump and maybe that could be a good option to save a lot of time by making an infusion mold and laying in all the glass dry, but I've never done it before. I've been playing with various design options on a computer, but haven't settled on a final decision on how they will look. If I can find some type of coating that will allow the beams to slide without binding, I'd rather go that route. The way it works now is excellent, with that exception. It's very rigid and sails well. But if setup time isn't dramatically quicker, it's just not practical as a day sailer. Link to post Share on other sites
slip knot 0 Posted December 5, 2015 Share Posted December 5, 2015 Have you tried graphite powder? Link to post Share on other sites
Rantifarian 7 Posted December 6, 2015 Share Posted December 6, 2015 Or a proper machined bush out of PTFE or something similar. Call up a seal supplier and tell them what you want, should be $10 each or so for the size you are after for a custom bush in a hard, slippery plastic Link to post Share on other sites
jetboy 0 Posted December 6, 2015 Author Share Posted December 6, 2015 I've tried graphite, silycone dry lube, and a few others. The bushing would be great - but I don't think there's room for bushings. There's only .026 clearance on paper - with .012 of possible variance in manufacturing. So it's really tight. Unfortunately the next size down in tube jumps to .276 gap. And that's with 3.75" OD, which is pretty hard to find cheaply. 3.5OD is easy and cheap buy leaves .526 gap. Maybe that would work with some bushings? the way the tubes slide though, they must be removeable entirely, so the bushing in the middle section gets tricky unless it's a full length tube liner. FWIW - I built it specifically to fit nicely in my garage during the winter and I live in the mountains so it goes inside for 5 months or so per year - so dissasembly is kinda important to me. Link to post Share on other sites
jetboy 0 Posted December 6, 2015 Author Share Posted December 6, 2015 I've thought about trying some fo this stuff to see how it works: Link to post Share on other sites
EdVB 0 Posted December 6, 2015 Share Posted December 6, 2015 Why not call Windrider and ask how Astus does it with their trimarans? Since they are importing them they can at least give you an idea how it is done. They do not seem to have problems with their trimarans. Worth a shot. Link to post Share on other sites
AdventureTri 0 Posted December 6, 2015 Share Posted December 6, 2015 Nice job on the boat Jetboy! Good idea Ed, and I'd like to get the down low on that myself for my most recent project. Link to post Share on other sites
Rantifarian 7 Posted December 7, 2015 Share Posted December 7, 2015 Currently you are relying on metal/metal contact over the full length of the outer tube, correct? This will ways be a higher friction setup, prone to binding. What you ideay want is clearance around the majority of the tube, and a bearing surface in chosen locations. Where do you need to support inner tube? Ideal would be just at either end of the outer tube. Have a look at James Walker anti wear rings, probably the uhmpe one. PDF warning https://www.jameswalker.biz/en/pdf_docs/222-engineered-seals-in-ptfe-high-performance-plastics-issue-2 One of those, 3" or so wide at each end of the outer tube, machined to a free running fit over the 3.5" inner tube size would slide well without binding Link to post Share on other sites
phillysailor 2,580 Posted December 7, 2015 Share Posted December 7, 2015 Awesome finish jet boy, and your work estimates lead me to believe you've got some powerful skills. That one pic up thread had me confused, and then I realized the garage door openers were on the bottom of the photo... The way the amas tuck is sweet. 15 minutes set up with that boat would be killer. Link to post Share on other sites
jetboy 0 Posted December 7, 2015 Author Share Posted December 7, 2015 Why not call Windrider and ask how Astus does it with their trimarans? Since they are importing them they can at least give you an idea how it is done. They do not seem to have problems with their trimarans. Worth a shot. I believe they have some type of custom made tubing that is coated with a uhmw plastic or something like that. If I drop down to a 3.75OD tube I could probably make it work really nicely. Maybe that's the best bet? It's about $475 for a 20' piece of 3.75OD 6061 tube. And I'd need 2 of them. In comparison for example a 4" OD .125 wall 6061 tube at my price is only about $120 per 20' length. So the oddball size is a lot more $. Not prohibitively so, but significant when compared to alternative options. A sheet of 1/4" 6061 waterjet cut to my patterns to make folding arms is about $500 plus the extra stuff i'd need to stick it all together to make a folding system. That's kinda the dilemma I have right now. I really appreciate all the ideas from everyone! It's making me re-think the choice to scrap the sliding mechanism all together. Might save a bunch of work if I can figure out a good solution for the binding. Aluminum on aluminum is one of the highest coefficients of friction in metals. I should have considered that before. Link to post Share on other sites
Waynemarlow 138 Posted December 7, 2015 Share Posted December 7, 2015 Your boat isnt heavy, would you not be better off to either forget about folding on the water and simply go plug and socket like the Searail and make the sliding mechanism part of the trailer ie the boat is put on the trailer Amas in place, pull out the trailer Ama supports, wiggle out the sockets, turn the Amas on their sides with the beams facing upwards and then move the trailer ama supports inwards on a very simply track system. Or for the price you are paying for the Aluminium, which seems so much cheaper here in the UK at the http://www.aluminiumwarehouse.co.uk/ where its less than $ 100.00, bite the bullet and build the beams out of carbon, it won't cost any more than what your are proposing. Link to post Share on other sites
Rasputin22 2,836 Posted December 7, 2015 Share Posted December 7, 2015 Take a look at how the Stiletto beams telescope. They have more clearance than you would expect but then have little Delrin buttons that fit in drilled holes to take up most of the slop between the two tubes. I think there are two rows of three slider buttons for each connection. A little dry lube such as McLube is all you need and the buttons are easily replaceable when they get worn. There are also two tapered SS drift pins vertically and horizontally that align and pin and fix the sliding mechanism. Here is a good link to a discussion on the merits of this system. http://www.boatdesign.net/forums/boat-design/offset-beams-catamaran-genius-deathtrap-47223-2.html Link to post Share on other sites
m02andy 0 Posted December 7, 2015 Share Posted December 7, 2015 Looks good, Does it float high enough ? I did a similar project a few years back (pic) but it was too heavy / not enough volume - went OK single handed but a bit of a submarine 2 or 3 up.. With hindsight.. I wish i had done a center hull like yours. I did get the telescoping aluminum tubing to work (eventually) with 10thou UHMW tape. I think you could get it as thin as 5thou ? ( I skimmed the inner beams a fraction on a lathe - OK I got a machine shop to do it, but it wasn't expensive.. Might work for you ? Good luck Andy Link to post Share on other sites
Doug Lord 1,219 Posted December 7, 2015 Share Posted December 7, 2015 Andy, that is a flat gorgeous boat-exceptionally good looking! Do you still have it? Ever considered ama foils? Link to post Share on other sites
Doug Lord 1,219 Posted December 7, 2015 Share Posted December 7, 2015 Looks good, Does it float high enough ? I did a similar project a few years back (pic) but it was too heavy / not enough volume - went OK single handed but a bit of a submarine 2 or 3 up.. With hindsight.. I wish i had done a center hull like yours. I did get the telescoping aluminum tubing to work (eventually) with 10thou UHMW tape. I think you could get it as thin as 5thou ? ( I skimmed the inner beams a fraction on a lathe - OK I got a machine shop to do it, but it wasn't expensive.. Might work for you ? Good luck Andy New_sails.jpg Andy, check this out-scroll down: http://www.boatdesign.net/forums/multihulls/small-trimarans-under-20-a-43650-40.html Link to post Share on other sites
m02andy 0 Posted December 7, 2015 Share Posted December 7, 2015 Why not call Windrider and ask how Astus does it with their trimarans? Since they are importing them they can at least give you an idea how it is done. They do not seem to have problems with their trimarans. Worth a shot. I believe they have some type of custom made tubing that is coated with a uhmw plastic or something like that. If I drop down to a 3.75OD tube I could probably make it work really nicely. Maybe that's the best bet? It's about $475 for a 20' piece of 3.75OD 6061 tube. And I'd need 2 of them. In comparison for example a 4" OD .125 wall 6061 tube at my price is only about $120 per 20' length. So the oddball size is a lot more $. Not prohibitively so, but significant when compared to alternative options. A sheet of 1/4" 6061 waterjet cut to my patterns to make folding arms is about $500 plus the extra stuff i'd need to stick it all together to make a folding system. That's kinda the dilemma I have right now. I really appreciate all the ideas from everyone! It's making me re-think the choice to scrap the sliding mechanism all together. Might save a bunch of work if I can figure out a good solution for the binding. Aluminum on aluminum is one of the highest coefficients of friction in metals. I should have considered that before. Jet, I read your post properly this time, Are your center hull beams 4" OD tube .125" thick ? If so same as I used.. For the amas I bought 6061 3.5" ID pipe 1/4" wall (4"OD) (cheaper than the 1/8" wall 4" !) and skimmed it down to 3.73" (Local shop did it for $100) leaving a 10thou gap all round when inserted. After trying most everything and jamming every time, I ran 4 UHMW strips at 3,6,9, and 12.O'clock along the inners. It slid real well and never jammed up, 3 years weekend use. I was a little worried my inner beams were now a bit thin, but they never failed. The UHMW was pricey (50c a foot I remember) and I had to buy a minimum order and I think I have a couple rolls left If you are interested PM me, you can have it for postage cost. It is good stuff but I can't see me needing it again. One thing I really learned is do anything you can to make it quick to get on/off water or you wont go ! ( oh and keep it light..) Andy Link to post Share on other sites
jetboy 0 Posted December 8, 2015 Author Share Posted December 8, 2015 My beams are a combination of 4" nominal size schedule 40 pipe which is 4.5" OD and 4.026" ID (Schedule 40 varies by pipe size, but in 4" nominal pipe size it's .237 wall thickness.) The inside is 4" aluminum tube with a 4" OD. Funny thing was that I went to pick up my tubing at the aluminum wholesaler I intended to buy 4" tube and 3.5" tube and have more clearance and when I was there I played around with samples and the 4" tube/4" pipe looked like a perfect fit. It's just the lack of perfect alignment with such small tolerance that's been a killer for this project. I tried some very thin UMHW tape, but it kept tearing. I think it ended up being so thin it wasn't durable. Worked well a couple times before it failed though. If i had some way to machine in recesses that would be a perfect solution. I think small plugs might work well too. Those I might be able to machine in with some type of right angle drill? Not sure. I agree 100% on the speed of assembly. It's a deal killer for day sailors. I think 15 minutes is achievable as a goal. As for floating - she floats almost perfectly to the lines. And seems to do well with weight. I've had 4 people on at the most, and didn't make a huge difference. Transom was still floating clear. I think that moving the cabin forward about 2 feet made a really big difference in where most people sit in the cockpit and kept the weight balance a bit better with more people. Link to post Share on other sites
gui 0 Posted December 8, 2015 Share Posted December 8, 2015 Looks good, Does it float high enough ? I did a similar project a few years back (pic) but it was too heavy / not enough volume - went OK single handed but a bit of a submarine 2 or 3 up.. With hindsight.. I wish i had done a center hull like yours. I did get the telescoping aluminum tubing to work (eventually) with 10thou UHMW tape. I think you could get it as thin as 5thou ? ( I skimmed the inner beams a fraction on a lathe - OK I got a machine shop to do it, but it wasn't expensive.. Might work for you ? Good luck Andy New_sails.jpg I think that tri of yours deserves its own thread! Com on Andy, don't be shy. Link to post Share on other sites
EdVB 0 Posted December 8, 2015 Share Posted December 8, 2015 Well it looks like a few ideas might work out for you if you stick to the sliding tube theme. You could also still try Windrider or E-mail Astus and ask for some detailed pictures and clearance measurements before going further just to make sure you are on the right track. It took five years to refine my Raptor 17.5 outrigger sailing canoe to where it only takes a few minutes to launch. I just slip the sail bag off and slip the carbon mast with furled sail onto the mast support base and pull the lines tight. All lines stay attached even when storing the mast in the cradles attached to the crossbeams. Then all I do is drive to the water and launch or retrieve. So I totally agree in the faster you can get it ready to launch the more sailing you will do:) The nice thing is it is Winter so you have time to thing about it and get it right on the first shot hopefully. Your boat looks super! You did a great job so might as well finish it in the same style you did the rest of the boat. Ed Link to post Share on other sites
basildog 5 Posted December 14, 2015 Share Posted December 14, 2015 This may sound really dumb but I'll ask anyway. What about using round tube for the sliding beams and square sections for the fixed to hull sections? This would stop binding but would held in 4 places on the round beams. Just thinkin! Link to post Share on other sites
EdVB 0 Posted December 14, 2015 Share Posted December 14, 2015 Jetboy probably would like to do it the easiest and less costly way. Redoing the beam inside the boat would take a lot of time and effort. Getting smaller diameter beams or skimming the ones he has on a lathe to fit the UHMW tape might be a better solution at a lower cost. Just my thoughts. Ed Link to post Share on other sites
guerdon 154 Posted December 14, 2015 Share Posted December 14, 2015 Have you tried teflon shim stock? We used on 1/4 ton molded rudder supports and it worked great. When it wore out we just replaced it with a new sheet. Link to post Share on other sites
mojounwin 0 Posted December 23, 2015 Share Posted December 23, 2015 Looks good,Does it float high enough ?I did a similar project a few years back (pic) but it was too heavy / not enough volume - went OK single handed but a bit of a submarine 2 or 3 up..With hindsight.. I wish i had done a center hull like yours.I did get the telescoping aluminum tubing to work (eventually) with 10thou UHMW tape.I think you could get it as thin as 5thou ?( I skimmed the inner beams a fraction on a lathe - OK I got a machine shop to do it, but it wasn't expensive..Might work for you ?Good luckAndyNew_sails.jpg Would love more details about this boat. looks great Link to post Share on other sites
m02andy 0 Posted December 23, 2015 Share Posted December 23, 2015 Looks good,Does it float high enough ?I did a similar project a few years back (pic) but it was too heavy / not enough volume - went OK single handed but a bit of a submarine 2 or 3 up..With hindsight.. I wish i had done a center hull like yours.I did get the telescoping aluminum tubing to work (eventually) with 10thou UHMW tape.I think you could get it as thin as 5thou ?( I skimmed the inner beams a fraction on a lathe - OK I got a machine shop to do it, but it wasn't expensive..Might work for you ?Good luckAndyNew_sails.jpg Would love more details about this boat. looks great Thanks Mojo, I learned a lot, mostly that I wish I knew at start what I knew at the end.. My design (with zero boat design experience) ,I built all the alum and carbon bits, a super skilled carpenter friend build the hulls in 1/4" strip cedar, with foam bulkheads and floor. We coated it in 1 layer 6oz glass. 19x14ft, telescoped to 10ft for storage (had to be as narrow as a Tornado.) 4" alum beams, F18 mast, custom sails It weighed in at about 480lb sailing.. (target was 400) It went well in light airs, especially single handed. I based dimensions on larger boats, had visions of a scaled down 60fter flying it's center hull ! -learned a lot about scaling, buoyancy.... Maybe made it too strong (heavy) nothing ever broke. Hindsight, should have gone either with much larger amas so center hull would lift, (but even heavier) or with a much bigger center hull like Jets' boat. With 2 up it would top out at about 15Knots with the center hull still kissing the water and the ama looking like a torpedo In any sort of waves it resembled 3 high speed submarines lashed together - Not a dry boat.. Also it too long to rig / derig and was a bitch to pull up the slip single handed... You live and learn luckily it was a really cheap project. (joke) Andy Link to post Share on other sites
mojounwin 0 Posted December 26, 2015 Share Posted December 26, 2015 Looks great. Any other pictures? How did the f18 mast go? stiff enough? Cheers Mojo Link to post Share on other sites
jetboy 0 Posted December 29, 2015 Author Share Posted December 29, 2015 For now she's put up in the garage for the winter. I have very few sailing pics that would show much, but lots of pictures along the build process. If you have anything in particular you'd like to see let me know and I'll find some pictures. Here's a few along the way. more Link to post Share on other sites
jetboy 0 Posted December 29, 2015 Author Share Posted December 29, 2015 more Link to post Share on other sites
jetboy 0 Posted December 29, 2015 Author Share Posted December 29, 2015 Looks great. Any other pictures? How did the f18 mast go? stiff enough? Cheers Mojo So far the mast is fine, but I haven't really pushed it yet. I have another mast I acquired from IIRC a Solcat 18 - it is normally used without any diamond wires and is a stronger extrusion. If the Nacra 5.2 mast fails, I'll swap out to the heavier mast and add some wires to it. I have a set of spreaders for it already. Just a matter of swapping over all the hardware to the mostly bare pole. Link to post Share on other sites
dayneger 0 Posted January 6, 2016 Share Posted January 6, 2016 As others have suggested, I don't see any reason at all why you shouldn't be able to modify your existing system to work properly without a major rebuild, time commitment, expense, or weight addition to the lovely boat you built. It looks great! You currently have 2 pairs of parallel tubes with zippo tolerance gap and no guarantee that anything's dead true either, plus metal on metal, so not a lot of surprise that they're not sliding well. But, that can be corrected. The 2 options in the thread both seem like good approaches: A) Have a machine shop turn a bit off of the OD of the current inners and use glide tape on the outers Pick up some 3.5" OD and make/have made 2 nice glide bushings per tube, one mounted on the end of the inner and the second on the outside of the outer As a general rule with linear sliding and rotating mechanisms you leave air gap along most of the system and only constrain via bushings/bearings/etc in very short zones. This is more obvious in above, but can be done with minimal gap in A) as well. Hope that helps! Link to post Share on other sites
dayneger 0 Posted January 6, 2016 Share Posted January 6, 2016 So, now I know that "B" followed by a ")" is the text shortcut for ... Link to post Share on other sites
AdventureTri 0 Posted January 6, 2017 Share Posted January 6, 2017 Jetboy, I was searching for my own build but thought I'd share some resources I found for UHMW tape for those sliders, t least once you get them milled or order smaller OD sections. Tape thickness ranges from .03" to .12", or 3 mils to 125 mils. http://catalog.cshyde.com/viewitems/ategories-tapes-with-adhesive-uhmw-tapes-1/uhmw-tape-acrylic-adhesive https://www.findtape.com/film-tape/uhmw-skived-teflon-tape/c124/ http://www.eplastics.com/slick_strips Link to post Share on other sites
jetboy 0 Posted January 12, 2017 Author Share Posted January 12, 2017 Thanks for the suggestions! I found a workable solution for now. I ended up making the outer parts clamp. They clamp down really well and I made the straps out of 1" x 1/8" stainless, so they're really strong. Once the outer tubes are released the system slides pretty well with just a little car wax to lubricate it. I do still want to move to a folding mechanism just for ease of assembly and coolness factor, but for now it works. I've timed it from parking to water in around 30 minutes. I'd like to have it at 15. Over 20 minutes of the time is for folding out and assembling the trampolines. Here's a picture of one of the clamps. I think the whole system is way overbuilt as a result of the aluminum tubes I have available off the shelf. Link to post Share on other sites
AdventureTri 0 Posted January 13, 2017 Share Posted January 13, 2017 Nice! That's a good idea too! I was close to an hour from trailer to water previously, I want to get down in the 15-30 range myself. Down here in TX you melt if it takes too long! I have carbon inside carbon tubes, but with a lot more gap. I think thick UHMW tape at 9, 12, 3, and 6 will do the trick for me. Link to post Share on other sites
MultiMacGreg 13 Posted January 13, 2017 Share Posted January 13, 2017 Nice! That's a good idea too! I was close to an hour from trailer to water previously, I want to get down in the 15-30 range myself. Down here in TX you melt if it takes too long! I have carbon inside carbon tubes, but with a lot more gap. I think thick UHMW tape at 9, 12, 3, and 6 will do the trick for me. Hi AdventureTri! I'd like to see your carbon crossbeams. Do you have water stays too? A guy near me wants to build a tri from 3 Supercat 20 hulls and I might grab the 4th hull and use Supercat 17 hulls (no boards) for amas. We need to build strong cross beams but don't need to telescope since we will keep them on the waterfront and disassemble for infrequent transport. Link to post Share on other sites
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