Stringers !! everyones favorite subject

**tunnels** · 08-09-2017, 10:03 PM

What are strIngles mainly used for ?? decoration ? to trip over and mount things on top of ?? or to make the bottom of a hull stiffer!!
What can they be made of ?? ply on edge stuck to the hull and glass to hold them there ?? Wood ! every one loves wood same thing on edge and glassed in place !! How many should there be and how tall and what about the hull glass ?? has a pad of a couple or 3 layers of glass been laid and stepped for the extra pressure that will be applied from the stringer to distribute its loading over a wider bigger area ?? mmmmm I don't think so !
What about foam stringers ?? OOPS possibly hit a raw nerve there !! how can you make stringers out of foam ? stupid person !! he must be joking !!
Stringers and girders are always made from foam in big boats ! foam is just to form a shape that can be glassed over, and doesn't rot !! hehehe !
Its the type of glass fabrics and method used of laying the glass thats very very important and where its flexural strength comes from !! but I don't want it to flex !! so use the right glass the right way then!!

Please NOTE the woven roving is obsolete and has no place in modern boat building !! Oh my God this guy really is crazy , it been used for centuries !! Yes that's the problem old technology and old habits and in this day and age ITS OBSOLETE !!

Modern boats have increased in speed very rapidly with bigger lighter motors but building methods haven't hardly changed or improved at all and have stagnated !! Glass manufactures have been busy testing and coming up with all kinds of new things and changing there ways as old problems have had a face lift that not to many people have noticed !
SO LETS HAVE IT !!

**powerabout** · 08-09-2017, 10:31 PM

how about no stringers just make the laminate stiff enough?

**tunnels** · 08-09-2017, 10:48 PM

Originally Posted by powerabout

how about no stringers just make the laminate stiff enough?

mmm that has more to it than first meets the eye ! making any laminate stiff takes some serious thinking about and careful planning !!
I have suggested this a few times for guys doing re-coring but silence !!

**powerabout** · 08-09-2017, 11:32 PM

I just watched the trend in all carbon racing yachts over the last 20+ years and slowly all the hard points have been removed to just a tube.
So I wondered if that technology would transfer to a powerboat?

**tunnels** · 08-10-2017, 02:23 AM

Originally Posted by powerabout

I just watched the trend in all carbon racing yachts over the last 20+ years and slowly all the hard points have been removed to just a tube.
So I wondered if that technology would transfer to a powerboat?

Tube as in?? the shape ?
Years ago also lots places all over the world tried desperately to use spiral winding for making boats ! so no hull and deck joins any where !! that never worked or they couldn't make it work no way !!
Would you believe there's a company using this exact technique to make parts of the new range of planes a company is building they even mould in the window frames with continuous strands so no joins any where all made with the same width of carbon strip ! very intriguing and clever !!

Have you ever built anything using only unidirectional glass ?? its the next step to spiral winding sort of , I build surf life saving boats and only used 4 layers of uni matt , the orientation of the glass is my secret !!, they were Light and incredibly strong and out lasted all the other boats by years and last time I heard about the boat they were still being use in the surf and they were 15 years old !!

The racing yachts I project managed for the 2007 South Korean first international boat show the 8 boats we made I'd definitely use the same lay up for a power boat for sure !! fancy this , 1 layer of 0/90 out side then trips of uni matt laid in strategic stressed places then a H 80 foam core all over and the uni repeated over the core with another 0/90 inside and that was it total !!
Unbelievable how strong It ended up the internal framing inside has a sequence to be fitted in the hull as it was all egg crated together interlocking together and all glassed tabbed each side . The construction and assembly was bloody clever that's for real !!

The young America boat when it broke in half it was taken to he place I was working Salt house marine in Henderson , The tented off a big part of the factory and was a closed area ,Goetz BOAT BUILDER IN THE STATES BUILT IIT so the flew a team out to nz to do the repairs and make it sailable again before being shipped back home , Mr BRUCE FAAR WAS THE HEAD DESIGNER ! it was UNBELIEVABLE HOW THIN THE CARBON LAYERS WERE and you could actually see through parts of the laminate ! Plus what a complete major cock up with the internal framing !! where it broke there was not framing or stringers or anything supporting that area it simply folded up like wet news paper .

**powerabout** · 08-10-2017, 02:29 AM

Yes tube like no joins, the parts should be fully laminated together, hull to deck join is a serious design flaw and you see that in powerboats when they crash as most are a hard point full of holes ( with bolts in them) so its a hidden instruction to tear along this line, which is exactly what they do when under strain.
F1 cars used to be made from a top and a bottom laminated together, not sure now?

**powerabout** · 08-10-2017, 03:25 AM

any criteria on a balsa or foam core that is too thick?

**tunnels** · 08-10-2017, 03:49 AM

Originally Posted by powerabout

any criteria on a balsa or foam core that is too thick?

ok two for one deal !! balsa or foam to thick ?? why to thick ?what's the problem ?? to ridged ??

Hull and deck joins ! In the Korean sale boats the had a rollover gunwale and the deck actual join was 150 mm further inboard from the rolled over corner !! was really neat and yes they were into crashing together and had a few dings but was easy to repair !! the deck tread started with the deck edge so its never suffered any damage the roll over was a 60 mm radius so we used a 120 mm plastic pipe inset into the plug to form the removable gunwale off the mould to get the boats out It was so easy to release the boats the find the balance point and a special hook each side and one person holing the hull and up and out into the special cradles that were the perfect shape of the hull so there was no changing shape during the fitting and glue joining of the decks and all the deck gear !

**powerabout** · 08-10-2017, 03:54 AM

so a core can be as thick as you like?

**tunnels** · 08-10-2017, 04:06 AM

Originally Posted by powerabout

so a core can be as thick as you like?

tell me more of why and what you are using the core to make something !!

**powerabout** · 08-10-2017, 04:16 AM

I was wondering if there are any guidelines of when to stop making the core thicker and adding stringer/grid?
I would think you can just go thick core and skip any internals
which would be lighter?

**tunnels** · 08-10-2017, 04:25 AM

Originally Posted by powerabout

I was wondering if there are any guidelines of when to stop making the core thicker and adding stringer/grid?
I would think you can just go thick core and skip any internals
which would be lighter?

You could just simply go with a well designed grid and no core at all just the glass hull !! but the laminate for the hull would have to change to do such a thing possibly !

**powerabout** · 08-10-2017, 04:57 AM

I would guess a layup with core is lighter and stronger than a single laminate and any type of grid, especially if you use carbon

**powerabout** · 08-10-2017, 05:04 AM

Originally Posted by tunnels

You could just simply go with a well designed grid and no core at all just the glass hull !! but the laminate for the hull would have to change to do such a thing possibly !

would that be a molded grid, so expense to make but ok for production runs

**tunnels** · 08-10-2017, 05:27 AM

[QUOTE=powerabout;2978800]I would guess a layup with core is lighter and stronger then a single laminate and any type of grid, especially if you use carbon[/QUOTE

Not necessarily so just use different fabrics IN DIFFENT PLACES within the laminate stake could be all that's needed !! so a trip to a composite engineer and you telling him exactly what you wanting and how it can be achieved the lightest way possible !
if you dealing with glass I could help you quite easily !! ,but carbon you on your own! Personally I cant stand the over rated crap stuff !! have had to do to many replacements of special things made with from carbon and rebuilding the same item with glass they've lasted for ever !!

Making grids and fixing them in place also has to be sorted !!
gluing them in !! no way they have to be glassed !! There construction has to be sorted where the strength needs to be and how to make it work to get the full advantage from it !
The last boat company had a lot of problems !! So still using the old mould but cut the flanges off so no more bogging saved lots of bog and hours of work time !! Just sat the grid in place held in with weights and glassed it !! less than half the time and no more pull marks any where from the extra glass and the heaps of bog they used to get forced under the flanges every where !