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| What’s Unique About J/125’s
Construction?
The J/125 is built to ABS offshore specifications by TPI Composites using the SCRIMP resin-infusion process. Tests conducted by the US Naval Surface Warfare Center at Carderock, MD established that the properties of laminates produced by TPI's patented SCRIMP resin-infusion process are superior to low-energy pre-pregs used by many custom boat shops and twice the strength of hand lay-up. J Boats was hesitant to enter the lightweight race boat market until something like SCRIMP/Carbon technology became available. In our judgment, SCRIMP construction greatly reduces the chances of warranty claims due to laminate failures resulting over time from pounding into waves and/or rig tension or ballast loads.
SCRIMP Process The entire laminate is placed in the mold dry. A high vacuum eliminates any air voids, then resin feed tubes draw in only enough epoxy to "wet" the laminate. This is the TPI patented SCRIMP resin-infusion process. The last step in the process is to post-cure the hull and deck at 140 degrees in a closed oven. As can be seen from the chart, SCRIMP laminate properties in terms of compression strength, flexure, and tension are twice the strength of hand lay-up and significantly stronger than low energy (vacuum bagged) post-cure pre-pregs. There is no entrained air in a SCRIMP laminate. 1% void content reduces flexural strength by 10%. Note that 50% fiber content in a carbon laminate equates to 67% carbon/33% resin by weight. See the comparison of composite properties of low cost fabrication methods in the chart above. Weight of Construction, after subtracting weight of keel plus 1000 pounds of rig, engine and hardware, J/125 at 2700 pounds is as much as 1500-2500 pounds lighter than competitive designs. Not all of this has to do with the J/125’s narrower beam. Hull & Deck Laminate Design of the J/125 is stronger for its weight than E-Glass/epoxy laminates using slit CoreCell foam. J/125 uses epoxy with a combination Kevlar & E-Glass for the outer skin with two layers of carbon fiber (bi-axial & unidirectional) for the inner skin. The higher strength of these exotic materials allows a thinner, lighter skin than the equivalent E-Glass structure. The CoreCell A500 and A600 foam cores of the J/125 laminate is further processed for strength and to save weight by (a) thermoforming to the shape of the boat in a second set of tooling to avoid having to slit the foam to bend it to the shape of the boat, and (b) perforating on 2" centers to form epoxy rivets between hull skins. If the core is slit to bend to the boat, then either resin fills the slits and adds weight, or there are air pockets in the laminate which reduce strength. Hull & Deck Laminate Design of the J/125 is stronger for its weight than E-Glass/epoxy laminates using slit CoreCell foam. J/125 uses epoxy with a combination Kevlar & E-Glass for the outer skin with two layers of carbon fiber (bi-axial & unidirectional) for the inner skin. The higher strength of these exotic materials allows a thinner, lighter skin than the equivalent E-Glass structure. The CoreCell A500 and A600 foam cores of the J/125 laminate is further processed for strength and to save weight by (a) thermoforming to the shape of the boat in a second set of tooling to avoid having to slit the foam to bend it to the shape of the boat, and (b) perforating on 2" centers to form epoxy rivets between hull skins. If the core is slit to bend to the boat, then either resin fills the slits and adds weight, or there are air pockets in the laminate which reduce strength. Keel The keel design of the J/125 is unique to this size boat in three ways important to the owner. (1) The strut is cast of an NAB (nickel/aluminum/bronze) alloy rather than from steel/iron which can rust causing maintenance headaches, (2) The integral flange of the strut has a six square foot interface with the hull in two parallel rows of ten 7/8" stainless bolts. And, (3) Built into the leading edge of the keel as an option is a San Diego style kelp cutter. Keel The keel design of the J/125 is unique to this size boat in three ways important to the owner. (1) The strut is cast of an NAB (nickel/aluminum/bronze) alloy rather than from steel/iron which can rust causing maintenance headaches, (2) The integral flange of the strut has a six square foot interface with the hull in two parallel rows of ten 7/8" stainless bolts. And, (3) Built into the leading edge of the keel as an option is a San Diego style kelp cutter. Weight Tolerances. Controlling weight variations in a one-design class is important. There are two reasons why this goal is easier on the J/125. Less total weight of resin involved, the usual culprit, and the SCRIMP process which insures minimal variation from boat to boat. TPI Composites is currently building the J/125 within +/- 1% total boat weight tolerance. No part has a variation greater than a +/-2% tolerance. In addition to hull and deck, the following component controls are important to assure competitors of a level playing field without having to use compensator weights. Target tolerances are as follows:
Other Components Minimum/Maximum weights listed in Class Rules for certain required components which can be removed or changed such as the Rudder, Boom, Sprit, Batteries, Head (WC), Stove, Pipe Berths, Steering System and Cooler. Other Components Minimum/Maximum weights listed in Class Rules for certain required components which can be removed or changed such as the Rudder, Boom, Sprit, Batteries, Head (WC), Stove, Pipe Berths, Steering System and Cooler.
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