Just to show you some progress on my new cat design based on the platform I showed a while back. This is it with a light carbon rig, but it will also be able to take a slightly modified IOM rig. Quite alot of work still to do tweaking things but the renderings look kinda cool so I’d thought I would share them. Your comments please!
Luff 'em & leave 'em.
<font color=“red”>EDIT FOR SIZE//WIS</font id=“red”>
NICE ONE!!!
Again the kid from the UK is making, designing and building???
congrats
-Wis
_/ if it isn’t broken, don’t fix it! _
[:-bouncy]<font color=“red”><font size=“3”>Why is this posting so wide?</font id=“size3”></font id=“red”>[:-bonc01]
Do it NOW before it`s too late.
Cos’ I didn’t crop the images, bloody hell Ian! Was up till 5am working on this thing, brain was screaming bed by that time, now its 8:15 and I’ve just got up. Some people honestly! Anyway I’m now going for a cruise to Cowes and back, there’s a building 10 knots from the north east and clear skies, damn student life is so hard!
No worries!
Luff 'em & leave 'em.
<blockquote id=“quote”><font size=“1” face=“Verdana, Arial, Helvetica” id=“quote”>quote:<hr height=“1” noshade id=“quote”>Originally posted by IanHB
<font color=“red”><font size=“3”>Why is this posting so wide?</font id=“size3”></font id=“red”>
<hr height=“1” noshade id=“quote”></blockquote id=“quote”></font id=“quote”>
Ian - perhaps it is because <font size=“4”><u>WIDE</u></font id=“size4”> catamarans are fast ! [;)][;)][;)]
Nice job Matt.
Couple more;
Luff 'em & leave 'em.
OK - enough with the pretty pictures [
:D]
Now lets get some cross sections posted at two (2) inch intervals so they can be shaped from 2" thick foam insulation sheets for a nice fast build. [:-graduate]
Very nice design.
Just courious…[:-dunce] How much displacement have you calculated for your design? Looks like a little bit under 1 kilo?
Marcus
Matthew,
A couple observations:
The guy wires between the bows and the carbon tube that sticks forward to support the jib tack look kinda worthless. You are not getting much downward pull out of them and if your carbon tube is strong enough to react the upward loading of the jib stay, then it should be strong enough for the lateral loads as well.
I would run the sidestays about 70% up the mast and about 50% out on each cross arm rther thant all the way to the top of the mast and all the way out to the hulls.
I’m not sure you need the dolphin strake under the main cross tube. Any carbon tube I have seen for this size application is going to be plenty strong without needing that support. If you move your shrouds inboard (as I describe in Item #2) that will help reduce the bending load on the crossbeam as well.
I assume you have sized your “pod” with some sort of RC gear in mind? It looks a little wide to me (especially if this is to be a 2 channel boat).
I have a spreadsheet for calculating the Ackerman angles for your rudder system. Let me know if you would like a copy.
I like the nice low main boom and jib foot. you may want to consider a compression vang for the main boom.
Looks good! Keep refining.
Will Gorgen
<blockquote id=“quote”><font size=“1” face=“Verdana, Arial, Helvetica” id=“quote”>quote:<hr height=“1” noshade id=“quote”>Originally posted by wgorgen
The guy wires between the bows and the carbon tube that sticks forward to support the jib tack look kinda worthless. You are not getting much downward pull out of them and if your carbon tube is strong enough to react the upward loading of the jib stay, then it should be strong enough for the lateral loads as well.
I would run the sidestays about 70% up the mast and about 50% out on each cross arm rther thant all the way to the top of the mast and all the way out to the hulls.
I’m not sure you need the dolphin strake under the main cross tube. Any carbon tube I have seen for this size application is going to be plenty strong without needing that support. If you move your shrouds inboard (as I describe in Item #2) that will help reduce the bending load on the crossbeam as well.
I assume you have sized your “pod” with some sort of RC gear in mind? It looks a little wide to me (especially if this is to be a 2 channel boat).
I have a spreadsheet for calculating the Ackerman angles for your rudder system. Let me know if you would like a copy.
I like the nice low main boom and jib foot. you may want to consider a compression vang for the main boom.
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1, Spotted that already, wondered who would notice it first! The prodder will have to go up a bit.
2, There is no backstay so the sweep in the shouds is there to stop the lot going over the front, if anything they need to go further aft, you wont be needing to sheet out far enough to hit them. As the carbon tube mast aint gonna bend much and its a masthead rig it shouldent be much of a problem. If it is some intermediates could be put in.
3, No the dolphin striker would most likely used with ali beams, if you were building a low cost version with an iom rig (Although the more I think of it I will probally design a higher volume pair of hulls for an iom rig, as with that its going to be alot heavier) with carbon tube beams the compression shouldn’t be a problem.
4,Yes it is wide, I designed it to look pretty more than anything else! Most pods look like tupperwear boxes, so i was trying to avoid that!
5, Yes Please, will save some sketching and messing about!
6, The main boom might have a gnav (compression vang) or I might go with a track on the pod, if I figure out the best way to do it. I think with the jib it might be possible to make a cool little cuved track out of a curved carbon rod instead of the usual boom which raises the jib foot too high for my liking.
The displacement should be under 1.5kg, 1.2 being about perfect. The transoms will be a little low in the water when the boat is not moveing but it wont take much breeze to make the bows go down a little to compensate. Having the boat trimmed this way should also help tacking. The rudders will have T foils, just I havent drawn them in yet, the daggerboards and rudders on there are just for show, I havent done much work on them yet.
Dick, If you think you can get foam hulls light enough then I’ll post some…I cant see myself building one of these so if anyone wants to have a go they are more than welcome.
Luff 'em & leave 'em.
Email to me - PDF or DWG or DXF or ??? and I will print to size. Give me a scale drawn on the file, or maximum beam dimension of the hull at one of the stations so I can make sure they are to your drawn volume. I will make a comparison to the beam sizes for my IMPULSE MultiONE - but keep in mind, my main hull on it was designed for BOTH tri and cat config.
In reality, I think my main hull is too big for a cat, but the floats are too small to use for a cat.
The file (cross sections) drawings for mine are posted several places on different forums, although I can email back to you if you wish, and would be fun to do a comparison.
Just using the foam as a plug - I wouldn’t leave it inside with such small hull volumes.
I agree with Will that shrouds only need to come up about 60% of mast height - and let tip do what it wants. I agree with you that I would move the shrouds back behind the daggerboards by a few “clicks”.
Don’t be in a haste to dump the carbon fore-tube, as it “could” function as your jib club/boom, and have a small traveler track mounted to the front of your cross beam to control the leech - sort of a mini horizontal traveler. Could even radius the track to match the swing of the jib.
Hmmm - maybe I will fool with a foam plug and send it off to Cougar. He can add his own rig and sails from his IOM and certainly he has ability to fair and finish the hulls.
What do you think Cougar ? Up to finishing building one of these for a test sail?
Dick, the prodder/bowsprit/fore tube whatever is staying, just going a bit higher. My Mini 40 had a setup like this and it worked fine, but with a convetional jib-boom as well. This time I want to put a curved track just infront of the mast, Tornado/F18 style. I’ll work out the sections and send them to you sometime tomorrow.
Luff 'em & leave 'em.
can I intrest you in a nice little compression main boom gooseneck made out of Carbon and ball bearings? This are currently being designed to work with bantock 8mm and 10mm mast sections and sit right at, or just above deck level.
<font color=“red”>EDIT: For size reference, the penny in the picture is .75" in diameter, or just over 19mm.</font id=“red”>
This piece is shown in its deck mounted offset configuration, but in this not so good picture below is the SAME carbon piece with a set of bearings that will fit nicely with the 10mm mast section and an 8mm mast butt. This picture also shows the compression screw and part of the boom.
-Todd
<font color=“red”>EDIT FOR SIZE//WIS</font id=“red”>
I think this cat should stay CHEAP and it also has the noob in multi in mind…also wanting to use an existent Rig (IOM or whatever)
-Wis
_/ if it isn’t broken, don’t fix it! _
Todd - nice stuff.
For an F-48 mast (mine) I would be looking for something that would work on a mast with at least a 1/2 " diameter section. I am also using that size on my MultiONE since they are so stiff and only need shrouds, no diamonds.
Carbon x-c ski pole stock, tapered and very strong in compression.
Do you do custom builds - or are you sticking to a specific size?
Its very pretty Todd, thanks for hijacking this with an advert for somthing so complex and expensive. Yes it looks good, and would be on a suited nicely to a marbelhead or some other super expensive excuse for a development class but it isn’t in the spirit of the subject of this thread. I’m not interested in selling anything here, I’m doing this as a cad and design exersize with the aim of making somthing somone might want to build and have fun with, it appears you are just flogging somthing.
Luff 'em & leave 'em.
My apologizes . . .
I did not mean to hijack the thread at all. I will delete the post(s) if you would like. I only posted it because someone mentioned that this specific design could benefit from having a nice low mount compression boom vang, and I thought I could help.
As an aside, I am always trying to push cost down, and for me, it is always cheaper to make parts out of carbon rather than machine them out of AL (dont have a machine shop) or but them. I build my own boats, and dont sell anything. This piece can be home built by just about anyone for under $5.00 + bearings, and being a slip on piece, subscribes to the KISS philosiphy very nicely which I do believe is in the spirit of this “class” and forum.
Once again, Im not trying to sell anything, im not in that business. I am into the business of home building and helping others home build on the cheap. I posted this in the spirit of that philosiphy. I would be more than willing to tell anyone how to build one of these on the cheap, or send them a piece of the carbon that is needed the next time I make one for myself (preferably I would get the cost of materials back, but heck, if im going to thow the scrap away anyway . . . its better off on someone elses boat!). Maybe this next time when I build one, I will take a photo log and throw up a how to page.
So once again matt, I do apologize, it was not an attempt to hijack a thread, or sell anything. As an attempt to make it up to you, I will be flying though the UK (matt, you are in the UK right?) in January. Would you like me to drop some of this carbon section in the mail to you from the airport? Drop me an e-mail and I could probably make it up to what ever size you wanted it. depending on your mast.
Dick. I currently have 2 ski pole rigs, so I know exactly what you are talking about. My problem was getting a big enough bearing at .5 inch ID that was light enough to put on any of these boats! Your only choice at that size is to go with a metal or glass ball bearing in a plastic race. TOO MUCH SLOP. What ski poles are you using?
Ill start a new thread about this stuff in General called “neat rigs on the cheap.”
<font color=“red”>EDIT: new thread started http://www.rcsailing.net/forum1/topic.asp?TOPIC_ID=1085</font id=“red”>
-Todd
nice post Todd!! GREAT…formidable!!! No need to be sorry for anything…[:)]
-Wis
_/ if it isn’t broken, don’t fix it! _
Sorry Todd for flipping out at you slightly, I just mis-read your post I suppose and saw red. That part looks so professional I really thought you were trying to sell it! If its not too much bother to you to drop an offcut in the post I would be very greatful, The second year of the course I’m on involves building an R/C monohull (which will probally be the next model I’ll build) so no doubt I’ll fit it in there somhow, hopefully I will be able to get the rest of the boat to match that standard.
Luff 'em & leave 'em.
Matt,
drop me you address in an e-mail to brownt@alum.rpi.edu and then send me a reminder mid january and I will throw a piece or two in my bag. Its a fun little section to know how to make.
I made a slightly lager version of the same section that works as a battery holder. the slot on it is the same width as my keel trunk, and the ID is the OD of my battery back. Glue it to the back of the keel trunk, drop the battery pack in. Doesnt move at all, very light. . . and no velcro or stickey tape. Same piece, just a little bigger, and built with 1 layer of carbon instead of 3. Carbon battery holder for under 3 bucks (and the minimal diameter for a 4 up AA pack works great with 5 up AAA packs).
Todd