24 -26 foot catamaran designs (plans)
09-07-2008, 09:48 AM
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24 -26 foot catamaran designs (plans)
I have been searching the web for cat plans and designs.......I would like to find a source for plans to see if i can build one out of aluminum....I am sure it has been done before....I have put a roof on my uncles machine shop (collets) and we have been kicking around the idea of building our own boat out of aluminum...He has the cnc's and water jets to cut all the pieces and i can get the material extremely cheap so what the hell........Any help would be appreciated..
09-08-2008, 06:31 AM
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They used to build aluminum boats but don't anymore, simply because of the weight issue. And hull cost is just a small portion of the project- engines and all the rigging componentry are going to represent a big expense.
Without engineering support and the ability to design it in CAD, then do stress analysis modeling, you're going to have to build it on the conservative side, which makes it even heavier. The last thing I'm guessing you want to do is do real-time testing at 100+ with you inside.
I understand the desire to build something yourself and the satisfaction that brings, but you're setting the bar kinda' high on this one.
If you have to do it, go find an old aluminum Cougar 38 and spend a week or two measuring everything, then scale it down.
Without engineering support and the ability to design it in CAD, then do stress analysis modeling, you're going to have to build it on the conservative side, which makes it even heavier. The last thing I'm guessing you want to do is do real-time testing at 100+ with you inside.
I understand the desire to build something yourself and the satisfaction that brings, but you're setting the bar kinda' high on this one.
If you have to do it, go find an old aluminum Cougar 38 and spend a week or two measuring everything, then scale it down.
09-08-2008, 06:39 PM
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They used to build aluminum boats but don't anymore, simply because of the weight issue. And hull cost is just a small portion of the project- engines and all the rigging componentry are going to represent a big expense.
Without engineering support and the ability to design it in CAD, then do stress analysis modeling, you're going to have to build it on the conservative side, which makes it even heavier. The last thing I'm guessing you want to do is do real-time testing at 100+ with you inside.
I understand the desire to build something yourself and the satisfaction that brings, but you're setting the bar kinda' high on this one.
If you have to do it, go find an old aluminum Cougar 38 and spend a week or two measuring everything, then scale it down.
Without engineering support and the ability to design it in CAD, then do stress analysis modeling, you're going to have to build it on the conservative side, which makes it even heavier. The last thing I'm guessing you want to do is do real-time testing at 100+ with you inside.
I understand the desire to build something yourself and the satisfaction that brings, but you're setting the bar kinda' high on this one.
If you have to do it, go find an old aluminum Cougar 38 and spend a week or two measuring everything, then scale it down.
09-08-2008, 07:05 PM
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The biggest challenge will be in the reinforcing structure. You're going to have to cerate a pair of longitudinal members, then add in a series of lateral reiforcements.
I always thought someone might someday attempt a monocoque design with honeycomb skin, but composite technology just moved forwars do quickly that metal got left behind.
I'm surprised that we haven't seen entire composite airframes yet on larger aircraft
I always thought someone might someday attempt a monocoque design with honeycomb skin, but composite technology just moved forwars do quickly that metal got left behind.
I'm surprised that we haven't seen entire composite airframes yet on larger aircraft
09-11-2008, 02:20 PM
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I've got some lines designed for a 28 catamaran ( not yet finished-I keep revising it). I'll post images tomorrow when I get to my home computer.
I'm an automotive designer, and have thought of the same thing. I like aluminum because you won't have soggy balsa in the floor or transom. But for me aluminum is too expensive ( you need a pulse welder etc). However, I think aluminum will weight more than a balsa cored fiberglass boat. If you can incorporated honeycomb in certain areas maybe you can reduct the weight. I'm not sure how you optimize aluminum structures without finite element software.
If you look around on this site you can find some line drawings.
I'm considering making a hull from plywood and polyester fabric. The biggest problem is I don't have the indoor space for a 28.
If have access to the equipment and materials you possibly could expense the materials on your taxes.
If you need a design flatten for aluminum -we can work something out.
email me at [email protected] (remove the xx's) I'll show you some of my line drawings.
ray
I'm an automotive designer, and have thought of the same thing. I like aluminum because you won't have soggy balsa in the floor or transom. But for me aluminum is too expensive ( you need a pulse welder etc). However, I think aluminum will weight more than a balsa cored fiberglass boat. If you can incorporated honeycomb in certain areas maybe you can reduct the weight. I'm not sure how you optimize aluminum structures without finite element software.
If you look around on this site you can find some line drawings.
I'm considering making a hull from plywood and polyester fabric. The biggest problem is I don't have the indoor space for a 28.
If have access to the equipment and materials you possibly could expense the materials on your taxes.
If you need a design flatten for aluminum -we can work something out.
email me at [email protected] (remove the xx's) I'll show you some of my line drawings.
ray
Last edited by vtec; 09-11-2008 at 02:24 PM.
09-11-2008, 03:57 PM
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i have built probably 250 monocoque chassis from al. its not that difficult a skill set but is, in fact as noted, more of a complex design exercise. you don't need cad but you do need a pretty comprehensive understanding of airframe practice and the stresses involved.
the benefits would be weight. it would, in fact be much much lighter than wood/glass and heavier than carbon /kevlar. it would also be an order of magnitude less money than carbon kevlar.
and, if done properly, there would be very very little welding involved. if done properly it would be bonded and buck riveted
from heat treated materials like 2024 t-3 or 6061-t6 . the weldable alloys would all be too soft and would have to be thicker and as such, heavier again and the areas of the welds would be prone to cracking. the bulkheads could be fabricated plate or NC billet .... and on and on...
but the bottom line and what would make it likely impractical is corrosion. its why you see airliners fall out of the sky periodically. even in a non salt and relatively benign environment and using zinc chromate and very rigid inspection schedule, the high stress areas will corrode very quickly and the resultant stress cracks will lead to catastrophic failure pretty quick. on the race cars we would find cracks in 50 hours and while they would see some very significant stress , those stresses i can imagine would be many orders of magnitude less than an offshore racer or high performance hull would see.
so... the answer, like so many others is " yes" ... you can do this. but the next question would have to be that given the time and expense required vs the fairly short life span and associated maintainance nightmare of an alloy boat in salt water, why would you want to when there are probably 5 dozen very interesting historic offshore racers with great provenance languishing around that you could buy for a song and restore.
there was a 42 apache ( or was it a 50 ?...big triple...) up on stands here. had a cover on it and they never took the plugs out. one day i see water trickling out of a small screw hole near the deck...
i climb up and have a look and it is full of rain water to the absolute brim. and had been like that for probably a year.
that boat sold for 15,000.
find one of those for a project. you'll be way better off.
the benefits would be weight. it would, in fact be much much lighter than wood/glass and heavier than carbon /kevlar. it would also be an order of magnitude less money than carbon kevlar.
and, if done properly, there would be very very little welding involved. if done properly it would be bonded and buck riveted
from heat treated materials like 2024 t-3 or 6061-t6 . the weldable alloys would all be too soft and would have to be thicker and as such, heavier again and the areas of the welds would be prone to cracking. the bulkheads could be fabricated plate or NC billet .... and on and on...
but the bottom line and what would make it likely impractical is corrosion. its why you see airliners fall out of the sky periodically. even in a non salt and relatively benign environment and using zinc chromate and very rigid inspection schedule, the high stress areas will corrode very quickly and the resultant stress cracks will lead to catastrophic failure pretty quick. on the race cars we would find cracks in 50 hours and while they would see some very significant stress , those stresses i can imagine would be many orders of magnitude less than an offshore racer or high performance hull would see.
so... the answer, like so many others is " yes" ... you can do this. but the next question would have to be that given the time and expense required vs the fairly short life span and associated maintainance nightmare of an alloy boat in salt water, why would you want to when there are probably 5 dozen very interesting historic offshore racers with great provenance languishing around that you could buy for a song and restore.
there was a 42 apache ( or was it a 50 ?...big triple...) up on stands here. had a cover on it and they never took the plugs out. one day i see water trickling out of a small screw hole near the deck...
i climb up and have a look and it is full of rain water to the absolute brim. and had been like that for probably a year.
that boat sold for 15,000.
find one of those for a project. you'll be way better off.
09-11-2008, 10:12 PM
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Well I can't post pics anymore.....so email me if ya interested
As for aluminum hulls ...I like the safe boats international hulls.
these guys make an offshore v bottom...not sure of the weight.
http://www.liquidtechnologiesllc.com/
I think they make those jet river racers (which are usually aluminum) and applied the construction technique to a large offshore style boat.
As for aluminum hulls ...I like the safe boats international hulls.
these guys make an offshore v bottom...not sure of the weight.
http://www.liquidtechnologiesllc.com/
I think they make those jet river racers (which are usually aluminum) and applied the construction technique to a large offshore style boat.
Last edited by vtec; 09-11-2008 at 10:16 PM.
09-11-2008, 10:17 PM
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Talk to Wayne at Liquid technologies in Oregon, although he is buliding large aluminum Vees I'm sure that he could give you some input.
http://www.liquidtechnologiesllc.com/
http://www.liquidtechnologiesllc.com/
09-11-2008, 10:21 PM
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The difference between now and 1982 (when the cougar's ruled) is pulse welding and cnc waterjet etc. I did read that time and motion studies calculated that it still takes longer to make a fiberglass boat than a wood one (a la chris craft). So a modern production line creating aluminum hull could be feasible. But everyone likes the compound curvature fancy Sea Rays now (every damn piece has a mold).
If I had a pulse welder and a cnc water jet, I'd be making all kinds of stuff.
If I had a pulse welder and a cnc water jet, I'd be making all kinds of stuff.
