bond stregenth question

[the1much]

Originally Posted by tinhorn

Gotcha. Instead of typing "to avoid obvious overlaps" I should have typed "to make your overlaps less obvious".

ooo,,,,o.k.

[pescaloco]

Much and others thanks, for the replies that is discourging, but i think i read in Ken Hankinson, fiber Glass Boat Building for Amatures that a butt joint had "almost" equal stregenth to a over lap.

any way to give you a little better picture the glass schedule is 1.5 oz mat over core cell 3/4 in foam the matt has the edges torn / feathered the 18oz biax cloth "has been butted" then the final will be of course 1.5 oz matt, this will be inside and out.

now any dry layup / resin drain out (my error - one small section in the whole scheme ) or non continious lay up (my error) these things aside, would this not be considered a sound layup ??

I can fix what isn't right, but wanna do it right

mark

[pescaloco]

here are some pictures

[ondarvr]

Nice project.

With only one layer of Biax a butt joint will be very weak, it will only have the strength of the two layers of mat covering the joint and hopefully the mat joints aren't in the same place. For less fairing you could have recessed the surface of the foam where the over lap will be, this way you would get full strength.

[tinhorn]

I'll leave it to the boat guys to pass judgement on the strength of the part - my background is in car bodies and industrial products. Am I reading correctly that your layup is mat, biax, mat, foam, mat, biax, mat?

There isn't any danger of water getting onto your rolls of glass, is there? Water removes the sizing from the glass fibers that the resin needs in order to adhere to them, creating dry, white spots when you try to wet it out.

[the1much]

well if,,Ken Hankinson, fiber Glass Boat Building for Amatures ,,said it,,it must be right,,,i cant imagine anyone writing a book full of idiot ideas,,,,,,my opinion is the dude is an amateur,and doesnt know much about fiberglass,,,i dont claim to be a fiberglass king,,,but theres a few things i KNOW,,,,and 1 of those things are that ANY butt joint , made out of anything,,glass,metal,,wood,,ANYTHING,,,is weaker then EVERTHING around it.
i would take that book,,and burn it,,,,then find that idiots address and ask him if he'll sign a contract, that you'll follow his instructions,, and he'll stand behind his words and pay all bill,medical bills, and replacement of ya boat,,,,and insure the boat from,,,freakin falling apart.

[TollyWally]

LOL 1,

Tell us what you really think!

[pescaloco]

Wooooow, now I would probably not call this a crtitical lay up where life and limb were at stake REMEMBER this is not a hull, I bought that from a professional builder. Any way that aside this way too much work and money to piss away.
just for the sake of saying it I will give you a little excert (foam panels / using 3 or more layers of laminate

"While it would seem that lapped joints would be much stronger than butted joints, this is really true only if joints are considered in a SINGLE layer of laminate. But when considered in the TOTAL laminte, there is very little loss of strength in the laminate as long as all butt joints do NOT occur at the same point. Tests show that the difference in strength characteristics between butted and lapped joints in laminates can be discounted for all practical purposes in the majority of most boats that an amateur would be involved in when using conventional materials in the laminate. For example, flexural strength remains virtually the same, as does innerlaminar strength, while tensile strength decreases only about 10% and compressive strength by only about 7%." (KEN HANKINSON, NAVAL ARCHITECT)

[pescaloco]

Any way, for what its worth Much there is a little read for ya, and still appreciate the feedback.

tin horn - yes the glass has been stored inside my enclosure under a tarp and it has rained a lot, it is possible the glass has absorbed moisture from the air but deffinetly no direct exposure. whats the scoop on moisture test or dry out period? I think I am about ready to go buy a roll of nytex instead of this straight cloth any way, the mat backer will make life easier for me

thanks, mark

[the1much]

still horse pucky,,,ive seen it happen too many times to let some book learned dude tell me any different,,,,most times i say,,"my opinion" few things i say i KNOW,,,,,,well,,i dont believe everything i read,,,in fact i dont believe half of what i read,,( and i read VERY little hehe),,,and i dont point people to books,,,but i do point to what i have seen myself many many times,,,i KNOW this dude aint crap of a F.G. dude,,,no matter what his little pieces of paper on the wall says....if done correctly,,and in 1 lay-up,,,an overlap joint will ALWAYS be stronger,,,,,do the simple common sense math,,,,more surface area to bond together = more of a bonding strength,,,,< was more saying that to diploma dude ,,heh,,not you pescaloco
and this..(be discounted for all practical purposes in the majority of most boats that an amateur would be involved in when using conventional materials in the laminate),,,WTF is that suppose to mean?,,,to me it means a damn canoe,,or row boat,,,,if you plan on taking ya boat out farther then you can swim,,,,ya better not be thinking like an amateur,,unless ya life aint worth crap,,,just because you are an amateur,, doesnt mean ya shouldnt be smart enough to ask people that know,,and do a better job,,or care about it more,,,then just what 1 would call "amateur",,,,and ANY part of your boat that you walk on,,lean on,,hang on,,or depend on should be considered "life and limb" at stake,,,,,magine a wave hitting,,you grab a fiddle head,,it breaks,,you fall,,,hit head,,drop cig,,knock yaself out,,burn to the water line,,,magine walking cross ya deck,,,ya leg goes through that butt joint,,ya brake 1 leg..ya other went ta ya side so bad ya hip got displaced,,your stuck there,,,,,,all sound stupid or way overboard??,,,i can give HUNDREDS more examples,,,,,,,,how many can navy dude give ya.
heh,,,,o.k.,,,,,before ya even say it kapt.,,,,im taking my meds and going to bed
and loco,,,,,stop reading books,,,hahahaa

[pescaloco]

na, it's cool, the real world, engineers and books I get it

I don't do anything half ass and have a pretty fair amount of mechanical appitude and common sense.

But I know to consider and apply the advise of those that are professionals in their field, (like guys that build / repair boats) you do that don't ya

thanks, look forward to alot more itche / scratchy grinding & nicely overlaped joints

[ondarvr]

If you look back at my responce to butt joints, you will see I said "with one layer of biax", If you had multiple layers of Biax it wouldn't be as important. Currently you will be relying on that one layer for most of your strength, that strength stops at the butt joint, the two layers of mat are carrying the load at this point and they're not cabable of even coming close to being as strong as Biax. Will it fail, maybe, maybe not, but if it's stressed severely it will fail at the weakest link and that weak link will be the butt joint.

[tinhorn]

Originally Posted by pescaloco

whats the scoop on moisture test or dry out period?

I've never had a wetout problem that I could blame on humidity, but I live in high desert country where periods of high humidity last maybe two or three days. My concern, seeing your rolls of glass at the very end of your "shop", was that perhaps rain could drip onto them.

[the1much]

i forgot the humidity thing hehe,,,,i built boats in maine,,,,90% humidity on the dry days,,,,,,and same as tin.,,,,,we never had a problem with it,,,,even glass thats been rained on a time or 2,,as long as its been dried,,,and isnt wet when ta use it should be o.k.

[pescaloco]

Thanks guys.

overlaps it is, why take a change, it's not so far along that it can't be corrected.