Glassing inside and omitting bottom stringers?

[Rune Forsberg]

Hi!

I've started building a CS-17, and what a nice and rewarding job this is!

I'm building in Sk

[Peter HK]

Hi Rune

Great choice of boat- I'm also building a CS17.

Regarding the bottom stringers- I don't think that glassing is a substitute. My brother is an engineer in failure analysis and he tells me that glassing only increases the stiffness of a panel of ply (approximately) by the increase in the thickness of the panel from the layer of glass. Thus there would still be a fair amount of flex in those panels. I've put stringers in mine and it wasn't a lot of work- the panels became much stiffer. Remember that an I beam increases its stiffness dramatically with the width of the section.

Perhaps Graham will comment.

Peter HK

[Rune Forsberg]

Hi Peter!

You are probably right the glassing doesn't add much structural stregth...I just wanted to get rid of all possible water retainers (easier to clean, etc)

I'll just go for them stringers as the design says.

/rune

[Peter HK]

Rune

I also had a concern with water entrapment so finished the stringers an inch or two from the bulkheads (and each other in the forward compartment). Technically the stringers need to mate with the bulkhead and each other to prevent failure of the epoxy due to peel stress. I simply glassed over them- it really only needs to be done at either end.

Peter HK

[Tom Lathrop]

I recently did a boat with extreme twist in the bow that needed 6mm ply to make the curve.  I laminated 18 oz biaxial non woven glass on the inside in the bow.  This stuff is much stiffer than woven glass or wood so that would work also.  It will weigh more than the stringers but is easier than laminating another layer of ply.

[Tom Lathrop]

Ray,

I scarfed the 6mm flush to the outside of the 9mm.  The biax then goes on the inside after the side panels are on.  Easy.  I don't really know how much thickness the biax adds but could dig up some old data from some tests I made if it's important.

If the concern is rupture from hitting flotsam or lurking dragons, having the fabric on the inside of the panel is much more puncture resistant than having it on the outside.

I do add a second layer of ply to the outside forward bottom panel of another boat but it is a much bigger one where 3/4" is scarfed to 1/2".  I think the inside biax would work in this case also but the full 3/4" bottom sounded better to the client.

[Peter HK]

Ray said

If I could lay the 6 mm down and glass and yield an additional 2 mm thicknes oon top of that it would be interesting to consider as opposed to cold molding 2 layers of 4 mm ply.

If it helps Ray, I did some measurements when I made my mast track spacers out of 12 oz biaxial tape. 6 layers resulted in a thickness of about 3.5 mm. Thus 12 oz by itself would be about 0.6mm thick and 18 oz about one mm.

Peter HK

[Tim]

Hej Rune,

How's the weather in Sk

[Greg Luckett]

........I'm building in Sk

[Charlie Jones]

Greg- it still has all that info- you just have to click on the person's name in the avatar.

For example, yours says your age is not available  ;D

[Greg Luckett]

Greg- it still has all that info- you just have to click on the person's name in the avatar.

For example, yours says your age is not available  ;D

Thanks for the heads up, Charlie.  Hmmmm??  Your age isn't showing either.  Must be a problem with the forum database? :  I know we are both young enough to still love adventures. ;D  What does age matter anyway once becomming legal adults?

Charlie, you built a CS17 didn't you?  Memory problems again.....more coffee needed.

[Charlie Jones]

Yep, I did- last year. From B and B so far I've built a Minipaw, two Birders, a Princess 22, a Core Sound 17 and am closing in on a Core Sound 20.

Deck is on, coamings are installed. Working on hatch framing and lids this weekend. Then she should be ready for paint, masts and rig out.

That is, working on the CS 20 this weekend , in between working on a Condor 40 trimaran at the marina trying to find and stop a deck leak in one of the amas..

After coaming curve

The CS 17

[Rune Forsberg]

Hi Tim and Greg!

Thanks for replying, I haven't been on the computer for a couple of days...

Well weather in sk

[Greg Luckett]

Rune,

It all starts with a dream, for most of us anyway.  Welcome to the club!

[P Doug (WA)]

Welcome to the best forum going Rune.  You are correct, you learn a lot here.  I hope they have cameras in Sweden, hint, hint.  We like to see pictures.  You are correct, those CS's have beautiful lines.  I hope to build one someday.