35ft Catamaran Hull: Filament Winding Possible?

Hi all

this is my first post in this forum. I think there are alot of very knowledgable people in this forum.

I was asking myself why it is not possible/cost effective to build a catamaran hull (or triamaran ama) by building a frame and using this as a mandrel in a filament winding machine? Of course not for racing boats but for cruising boats.

I could elaborate why I think this is a good idea but I am very sure that there is a good reason that no one else did this before (as far as I know).

I would greatly appreciate any hints, thoughts, links, stories, formulas, numbers, drawings, ...

Best
babu

 

Its been tried long long time ago in the UK i think !so its not new !!!

Hi
Long time ago many people had the same thoughts , even myself its not the glass thats the problem its the way its done . A boat hull is a pretty inticate object and its only since americas cup boats that stress guages have been fitted in all differant parts of the hulls to find out what really goes on and how much load gets place in the various places . twist ,racking and flex are all everyday things that happen thousands of times a hour as a whole and in differant places and at differant places , pushing ,pulling and twist and flexing that we never see untill something breaks and we are left scratching our head wondering why did that happen !!!
Unidirectionall glass is the best glass to use and is the basis of all the fabrics made today that are on the market .
Spiral winding is just that, unidirectionall glass used in strips wet out and laid to a computer progamed pattern . because of the size of a boat hull and deck all intergral mounted and revolving slowly its one hell of a project . and the program used to lay the glass and get it all in the right angle and right place would be mind boggling .
Simpler to just buy cloths and make a boat the good old fashioned way still using unidirectionall glass and getting it engineered properly !!
http://www.vectorply.com/newsite/search2.aspx just about all these products are simply unidirectionall glass !!

 

It is not cost effective. Try to search for the cost of a filament winding machine.

Filament winding is great for pressure vessels or cored laminate as the filaments are continous, unbroken, and packed tight. Examples are pressure tanks, rocket nozzles, airplane fuselages, and windmill blades.

For boats, hulls, amas, the exterior has to be finished and faired and the interior has to have a series of stiffeners.

So for interior lay up, automatic continous fiber placement machine is the choice. But, it is also very expensive, probably more than the filament winder.

 

Filament winding works well for pressure vessels for two reasons, the "loading" is outward on the vessel, and the shapes are simple smooth, mostly round, with no hollows or sharp edges. The loading on boat hulls is very different (bending, flexing, point loaded, torsion, etc), complex, often indeterminate and transient, and not always understood (most design methods are based on tables built up over many centuries of observing how and where hulls fail, but no really detailed structural analysis), and most hull designs have too many sharp edged, many hollows, and have large holes or cut-outs that severely weaken continuous filament wound vessels. And as pointed out, large machines are very costly, typically number of any one model of boat sold is not that large. So given limits, cost, tooling, and other problems with it, boat hulls are just not suitable for this construction method.

Might be worth considering on a submarine or torpedo casing, a non-magnetic hull is a highly desirable feature, and loading is very different, all hull surfaces in compression.

 

Thank you

Thank you very much for your answers!

some thoughts on the points of the posts:
a) AFAIK the purpose of the hull is twofold: 1) seal off the inner of the ship from the water on the outside, 2) provide the structural/shape. In kayaks ("skin on frame" type) the frame is necessary for 2) and the skin provides 1). I ask myself: why does this idea not scale to bigger dimensions: e.g. have a aluminum alloy frame skinned by a FRP skin. You named:
o the difficulties to properly handle all the different forms of stress which is applied to a boat hull during its life. I hoped that by using a cheap method (like the pre hand lay-up FRP techniques) the hull could be much overdimensioned.
o finishing/fairing troubles. I have no idea how much is just an optical problem and where it starts to severely impact the performance or strength. Filling shouldn't be a problem, right?
o sharp edges and holes.
o one must have control over the directionality of the fibres

b) machine cost: for a one-off build it would hopefully be possible to give an order to a company owning one (an perhaps seeking to enhance their portfolio)

Sorry when I use technically incorrect formulations, English is not my mother tongue and I didn't spend an awful lot of time on boat design questions before that, nevertheless I am very interested in all answers.

Babu

 

This guy Fanie was on a search for long rolls of 12" wide cloth and eventually the use for it was mentioned...

http://www.boatdesign.net/forums/boat-design/biased-glass-weave-44330.html

That's all that was mentioned about "winding a hull" but you might send him a private message or something. If you find out anything, be sure to post it here.


.

 

If you are thinking along this size, the image (Composites Design Guide by Terry Richardson) should give you an idea of the cost involved.

SamSam. I posted on Fanies thread.

 

I saw that on the other thread. When the glass is put on dry, how is it wet out? There must be a limit of thickness that can be wet out at one time..?
A side inquiry, do you know of any descriptions or plans of how to make a do it yourself resin impregnater?

 

You mean with the fabricated rolling gantry? We wet it out the usual way. The laminators along with the resin batch ride on the gantry. It is very efficient. The laminators pulls the basket from side to side, the ground crew pushes it forward or back, and a full time mixer hands them a fresh batch whenever their resin is low.

I will try to look for it as I could not remember the article. Just like a wet filament winding, there is a guide roller to dip the glass into the resin batch, a couple of roller to squeeze out the excess resin, and a wet fabric guide or tensioner. The roll of cloth rides in the basket.

Here is something similar from Marine Composites by Eric Greene Associates

 

Literature Studies

I was able to fetch a copy of the book "Composite Filament Winding" by S.T. Peters, printed 2011 from the library. Perhaps I'll have some time to study it in the next few weeks. The only thing about boats I found on a first quick pass through the book is on page 75 pp:

"Filament-Wound Boat"
A car-top boat was made of completely filament-wound material, except for the balsa and brass fittings (Fig. 6.22). It is called a car top because it weights 60 to 65 lb (27 to 29.5 kg). The mandrel was a series of boxes bolted together and removed from the overwound cockpit area, then discarded after cure. The quantity of edge-grained balsa within the hull allows it to float when full of water. Three seats are filament winding over balsa planks. The glass fibres and epoxy resin combination with edge balsa make a very resilient and damage-resistent vesel. Edge-grained balsa density is 7 to 9 lb/ft^3 (0.11 to 0.14 g/cm^3). Filament-wound sheet windings were used for the transom and to form the bow. The aft and forward holes for the mandrel shaft were patched with filament-wound sheet. Travel over rocks in a swift stream has left the surface without abrasion. The boat is easy to row and uses up to a 6 hp outboard."

There is a grayscale, low-res picture of the boat. It's a small motor boat (approx 4 m in length). The transition from the deck to the hull seems to have a bending radius of approx 10 cm.

Babu

 

I have the same book but printed by SNAME, Second Edition. Seems it has a different page numbering system. Could not find the boat on page 75. Can you post the picture?

 

The publisher of my version is "ASM International" ISBN-13: 978-1-61503-722-3. Author of chapter 6 "Control of Filament Winding Parameters" is J. Lowrie McLarty.

link



Sorry for the bad image quality. Can make a better scan later if needed.

Best,
Babu

 

SamSam

Not the commercial variety but exactly what you want. The DIY version.

You can ask for a reprint from ProBoat, Issue 119 June/July 2009, "Wet out box for tabbing" for the full article if not, I will scan all of the pages and send it to you. I think Fanie will also benefit for his for his current project.

 

Look for the page on making windblades (if we have the same contents, but unfortunately not). A windblade profile is similar to a wave piercing cat hull or ama.

 

Thanks for posting that. I got locked out of the forum for 10 days and just noticed the reply. I must have that issue, I'll look for it.