Phill is right about the +-45, and on top it is a dream to work.
The question is, do you really need an overlap? If not there is a nice way to deal with the problem. You just let the two layers overlap, wet them out and then with a very sharp knife you cut trough the two layers. take of the exess on top and carefully lift the toplayer and remove the exess on the underside.
It takes some practise and a very sharp knife

Interesting idea.

Phill,

great tip about how to make invisible overlaps, thanks! (I think you have mentioned it before, but now I'll remember it).

My source for the carbon comment is Bjørn Thomasson in Sweden (http://www.thomassondesign.com), the kayak/canoe designer/builder. According to him the density of the carbon fibres in the weave is larger than glass fibres. To get a good matrix around the fibres you would need more epoxy, especially if laid up by hand. With vacuum you come closer to the same amount of epoxy as you would use for the same weight of glass. With a lighter carbon cloth I suppose there are some gains, but it looks like there is a crossing point for carbon vs. glass for this application. It would be good to know if he (I) am wrong or even completely wrong. <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

I know the hull will be stiffer (as in less deflection) with a +-45 layup outside the core. But I was intrigued to hear that the panel integrity also will be better. Thinking about it, it becomes quite attractive to put the cloth on with overlaps due to the points you made.

Rolf,
Also if you lay the glass gunwale to keel and then keel to gunwale and then gunwale to keel you end up with almost no waste and significantly less waste than running it length ways.

I have found similar data suggesting that in order to achieve a significant weight savings with Carbon you would need to go to cloth weight that is the THINNER than the glass weight you originally specced. With these lightweight laminates you need to control resin weight which is partially done by keeping the fiber thickness to a minimum (thicker fibers need a thicker coat of resin to wet out). This would provide a laminate that is slightly stiffer and about the same weight.

Couple of thoughts I have had: have you considered using slightly thicker strips?? 5mm or even 6mm?? Remember stiffness goes up exponentially with the thickness of the panel. One of the reasons a Marstrom T is so stiff is that they use a 10mm core thickness. I would consider: 6mm thick strips with 200 gsm S-glass on the outside layed with the fibers at +45/-45 and then a lighter 100-130 gsm inside laminate of either Kevlar or tightweave glass (4-Harness or 8-Harness). I think you could get close to the minimum weight, gaining maybe 4 lbs. per hull doing this. You could even try to make up for it by making carbon rudder stocks and carbon beams.

keep us posted!!

Rolf,

Check this site. they have done several panel tests relevant to what you are doing. (it is in english units, as a quick reference, 200gsm cloth is about 6oz) Again, good luck!!

http://www.thag-o-mizer.net/index.html

Hi Rolf

So, have you done the working out for strip planking or has Phill made alternate plans for you. I only ask as I wouldn't mind trying it out myself, I have access to ply, but have wanted to do some strip planking for a long time.

Regards

Matt,
I hope Rolf does not mind me answering this question.
I prepared something specific for Rolf.

Regards,
Phill

Not at all Phill, I hoped you would reply.

Hi Matt,

didn't think you had that much of a death wish.

"I wouldn't mind trying it out myself, I have access to ply, but have wanted to do some strip planking for a long time."

Do you ever want to get out of your shed again <img src="http://www.catsailor.com/forums/images/graemlins/crazy.gif" alt="" />.

Strip planking sounds nice and soft and fuzzy. But it is the method of the DEVIL <img src="http://www.catsailor.com/forums/images/graemlins/shocked.gif" alt="" />. To much trying to deal with soft timber and hard glue lines and the fairing NEVER ENDS <img src="http://www.catsailor.com/forums/images/graemlins/mad.gif" alt="" />.

ARGH! I am having flash backs, got to go sailing to get rid of them <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />.

Sounds like you have been trough a "labour of love" once and still need psychotherapy to get over it <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />

These two guys obviously have an experience waiting for them <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Hi Gary

I like to live on the edge......of insanity <img src="http://www.catsailor.com/forums/images/graemlins/smirk.gif" alt="" />

I won't commit myself to doing it just yet, but certainly like to consider it.

Regards

That picture is just asking for a caption contest! <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Have a go at it, could be fun, but please do it in another thread. It should not be too hard to guess what we discussed, but that would be no fun. <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

Building is fun when you can not sail.
Just have a look at the lastest updates on our building blog. <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Hi Rolf (Darthvader)
It looks as if you're cutting 4mm strips off your approx 25x450mm spruce plank. In my experience I would definitely be using the table saw I've seen in earlier posts. You mentioned previous amateur builders using 'Skilsaws' (your DeWalt) but this may be because they didn't have access to a table saw? I only mention this as you'll have to cut close on 200 strips for 6 hulls I would imagine.
Being a qualified joiner I'm very interested in your project so please keep posting and don't let your family commitments hinder you too much <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Mark,

the skilsaw vs. tablesaw isse have been much debated. The person I know who has the most experience building small strip plank boats reccomends using a skilsaw instead of a table saw. His experience is that the skilsaw produces just as good strips as the tablesaw for less work (setup, running planks trough it, breaking strips while handling etc). The short experience we have with the skilsaw is pretty good. We will at least give it a serious try.
Strips are 5mm btw. We expect to remove a full millimeter while sanding.

You are a professional woodworker? Whow! We will keep on posting updates to the blog and do a reminder her from time to time. Please keep comments, suggestions and everything else coming.

I left school and became a qualified Joiner, worked my way up and off the tools, went to university and completed a Bsc (Hons) degree in Project and Construction Management. Worked in management roles for various National Construction companies but really missed the feeling of producing things with my own hands instead of the pen. For the past two years I have been self employed as a Joiner, Carpenter and Builder and I'm loving it. There are certainly different pressures involved but the benefits far out way being just a payroll number in a National Company!!
By the way, I hope to design and build a Cat this year I have a lot of ideas in my mind I just have to put them onto paper and tell the wife and I'm sure the later will be the hardest task of this project!!

Why have you not spoken up earlier? We amateurs at woodwork need all the advice we can get <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />
What kind of cat is it you want to design and build? F-16 or something completely different?

Ok Mark, last night we ripped a respectable sized pile of strips. After the first 5-8 strips we really got the hang of it and from then on cutting perfect strips was a no-brainer. It was very easy to just walk the skilsaw along the plank. Dont think we will bother with setting up a table saw after this experience. Our kayak building/designing friend was spot on with the skilsaw. Hopefully the rest of his "easy-strip" building methods are as good. I.e. we are not going to glue the strips together individually but do them all in one go once they are in position. <img src="http://www.catsailor.com/forums/images/graemlins/shocked.gif" alt="" />

Next up for ripping are a few 2x4, to make up the sides. Hopefully they are as easy to do as the thin strips.