Category Archives: New Designs

New Designs

Surveyor

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I was introduced to the surveyor. The surveyor, Matt asked if I knew his father, Robert Harris? Robert Harris wrote Racing Cruising and Trimarans, the book that got me started in this. Robert also helped me with a deadbeat customer and the courts once. Yes! What a great surprise. Great surveyor too. Matt Harris. www.harrismarinesurveys.com

mattharris

And the book.  I need to take a better pic than I found online.

harrisbook

New Designs

Discontinued and Odd Lots Glass, Carbon, and the Fabric Whose Name Shall Not Be Spoken

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Here is the first armload of fabric ends for my builders. Let me know if any looks like what you want.

  FABRICS INVENTORY OCTOBER 2014        
           
PRODUCT DESCRIPTION AREAL WEIGHT ROLL WIDTH TOTAL WEIGHT  
           
FIBERGLASS Rolls are typically between 150 and 250 lbs each with 9 rolls per pallet        
           
Roll price $0.75/lb       Pallet price $0.50/lb                  
           
X1300 BIAX STITCHED+- 45° 13 oz 50      > 5,000 lbs  
  for Polyester/ Vinylester        
           
WF1800 UNI 90° for EPOXY 41 OZ 50 1414  
  500+ lbs rolls!        
           
C3000 Uni stitched 30 oz 50 1403  
           
C5500 Uni stitched 55 oz 50 2745  
        450  
NEMPC 1708 BONDING TAPE 17 oz + 8 oz 8 626  
  BIAX STITCHED+- 45°     519  
           
F1802 PLAIN WOVEN TAPE 6 oz 6 651  
  for finishing off joints        
  and taped areas        
           
U614 CFM 2oz 18 oz 51 900  
           
U614 CFM .75 oz 6.75 oz 72 200  
ECM 3610 Stitched 0-90 with mat 36 oz + 10 oz 30 150  
           
Q4700 QUAD 47 oz 50 120  
           
CFM 2415 Stitched 0-90° with CFM backing 24 oz+ 15 oz 50 208  
           
WR 2400 WOVEN ROVING 24 oz 50 450  
           
WR 2400 B BALLISTIC woven roving 24 oz 50 400  
           
F1802 WOVEN TAPE 24 oz 50 600  
           
DBX 2400 Stitched +- 45 24 oz 50 200  
           
QM4008 QUAD 40 oz + 8 oz 50 341  
           
EXM1208 BIAX STITCHED+- 45° 12 oz + 8 oz 50 1347  
           
CM3208 Stitched 0-90° with mat 32 oz + 8 oz 50 400  
           
PPG 2002-1650 INPUT ROVING type 30 N/A Pallet #1 2009  
  for winding or weaving   Pallet #2 1964  
           
KEVLAR HYBRID          
           
Roll Price $ 5.00 lb.       Pallet price $4.00/lb                
           
N526 32.86 OZ WOVEN 8H 32 oz + 8 oz 50    > 10,000 lbs  
  WITH CSM STITCHED      
  50% glass/50% kevlar      
CARBON          
           
Roll Price $ 6.00/lb              
           
CBX300 BIAX STITCHED +- 45 9 oz 50 860  
           
CBX800 BIAX STITCHED +- 45 24oz 50 2,130  
           
KT420 12K PLAIN WOVEN 12 oz 50 802
RE670 12K TWILL 20 oz 50 360
New Designs

Kevlar Comments

7 Comments

I got this note from someone reading a posting on Steamradio.

“Interestingly Shuttleworth recently posted on Steam radio re. Kevlar as follows:”
“We put Kevlar inside. It is partly because it is significantly better in tension than compression, but also when water penetrates the resin fibre matrix it acts like a wick and the water will migrate into the laminate – not something you want in a material that is very close to the water all the time. Small areas of damage that are not attended to can make this a problem. The third reason is that in an impact the outer skin will rupture – the foam will distort It is is either Airex R63.80 or Corecell A500 and the inside skin will stay intact even if the resin starts to fracture. The idea is that the foam and outer skin absorb a lot of the energy before it gets to the inner skin – which is ultra strong in tension. this combination has proved very successful in a number of cases of grounding or high impact on the hull.

Kevlar does need to be laid in a combination with glass, because the resin does not stick to the fibres very well. For the bigger boats we use a unidirectional fabric with alternate tows of kevlar and glass 50:50 by volume. This means that each layer is 660 gms/m2 Aramid/Glass – 237 gms/m2 Aramid, 422 Glass Unidirectional.”

Regards

John Shuttleworth
for Shuttleworth Design Ltd.

At first I thought, doesn’t he know?  So many things wrong as I see it. Those all seemed like reasons to never use Kevlar. A grounding or impact is usually bow or keel line. I cannot see tension strength helping against basically shear load.
The multihull will not sink so holing is not the worst of worlds. The disadvantage of tensile strength across in interior panel is that a small impact can make a huge delamination inside. Especially since the Kevlar is not bonding to anything else.
The Kevlar in combination with glass seemed to be a bad solution for a couple of reasons. Even if the glass is a good laminate, the poorly bonded Kevlar between glass lams means very poor shear transfer between layers. So why bother with the Kevlar at all?
Finally if the Kevlar is for impact, a woven fabric is much better than a uni or a knitted fabric.
Then I recalled my earlier comment that the only use for Kevlar is as a yuppie magnet, for boat sales.  I realized that the way he uses Kevlar is brilliant.  He puts it in the place on a hull where it can do the least harm.  Then the boat sellers can attract yuppies with it.  Like the carbon fiber cleat pads on Gunboats.  Utterly wrong material, but it confirms to yuppies that they are indeed high tech.  And that tiny bit of fabric visible is the evidence.  Brilliant.