Cloth Lap

[alyeska]

Hi Guys,
Just want to know what the minimum overlap on cloth joins I can get away with. Layup is 1 x 450grm 0/90 double bias ( outside skin ) over 10mm corecell. Whats the best method of laping cloth so as to keep the joint "bump" small for ease of fairing?

Well,
the minimum is zero, and that would solve the prob with fairing.

But that was not what you wanted to hear.

A bit more info about the structure you are building may help to get a answer you expect.

Regards
Richard

[tinhorn]

Zero overlap would be a butt joint. Bad idea. Since it's going over Corecell, I'd just sand a shallow groove in the foam wide enough for the overlap. Since I'm not an engineer, I'll leave it to others to recommend the amount of overlap.

[tunnels]

Originally Posted by alyeska

Hi Guys,
Just want to know what the minimum overlap on cloth joins I can get away with. Layup is 1 x 450grm 0/90 double bias ( outside skin ) over 10mm corecell. Whats the best method of laping cloth so as to keep the joint "bump" small for ease of fairing?

Put a slight recess in the foam where the join will be so the join can be filled over rather than sanding it off .

[alyeska]

Thanks for the replies, will go with the rebate in the foam, I'm guessing 30mm overlap should be enough.

[tunnels]

Originally Posted by alyeska

Thanks for the replies, will go with the rebate in the foam, I'm guessing 30mm overlap should be enough.

Make the recess 35 mm wide and the depth of one layer of glass!! Wipe a layer of filler over the whole join before you sand the hardened resin and glass and press it into the join , let it set and then sand filler and glass level just a fraction below so when you wipe the top layer its sanded and gives a perfect finish .

Originally Posted by alyeska

Thanks for the replies, will go with the rebate in the foam, I'm guessing 30mm overlap should be enough.

Where is that guess based on?

You have a uncommon single layer setup here, and only 0,5 -0,6 mm laminate thickness. I would not (and did not) give any recommendation without knowing the whole story.

All nice thoughts tinhorn and tunnels, but to advise in a serious manner we have to know more about the application.

Regards
Richard

[alyeska]

Laminate is a single layer outer skin over 10mm corecell on a 6m hull, using ampreg 22 resin

Well one can hardly call that much more info.

So be it........

[alyeska]

If you tell me what extra info you need........

That sounds very thin and flimsy. Is it for a canoe or the ama of a multihull?

I just wanted to grasp how much safety factor is required in your layup.

As far as I understand it, that will be the entire structure of the boats hull?

1mm glass 10mm foam?

We use already 10cm overlap on our wood epoxy hulls which are just sheathed for abrasion resistance! They are 2x 300gsm making roughly 1mm.

Regards
Richard

[alyeska]

Layup is inside 1x 300gsm - 12mm corecell (not 10mm my mistake ) - 450 gsm 0/90 biaxial outside. Boat is a 7.5m sportsboat with lots of internal structure including carbon reinforcement around keel/ shroud structure

[AndrewK]

If this is a sports boat and your are using carbon and glass then I am guessing that your are vacuum bagging as well. If this is the case your laminate thickness will be <0.5mm so not worth the effort to rebate.

[SamSam]

For all those who don't have any idea what a "sportsboat" is, I'm thinking this must be it.....

http://en.wikipedia.org/wiki/Sportsboat

The hull is 6m long. Or 7.5m long.

Your mission, should you decide to accept it etc, etc, etc.....As always, should you or any of your IM Force be caught or killed etc, etc, etc..... this tape will self-destruct in five seconds.

[tunnels]

Ok another word for a trailer sailer !!
Had one long time ago but got sick of living my life on a 45 degree angle just about every where i wanted to go, And getting from point A to B via every other letter in the alphabet used to piss me off !!
I like to look at where i want to go , turn the key and get there asap !!
I like yachts , i love building yachts and have made 100s of all differant sizes over my life time but i like powers boats better ,But that just me !!