Vespera’s Hull, Hydrolysis in Outer Laminate

Vespera’s 50 foot hull was ground down to the first layer of roving and the hull was then faired using West epoxy and micro-balloons. The gelcoat and mat had to be removed because the gelcoat was cracked and the mat was hydrolyzed. Next preparation began to add two new layers of epoxy laminate.

This picture shows a section of cracked gelcoat that was scraped off of the hull. You can see the white fiberglass mat on the backside of the gelcoat. Notice, there is little resin on the mat. The resin may have been removed from hydrolysis and/or the mat may have been poorly wetted out when the laminate was originally laid up. Also notice how thick the gelcoat is, about 1/8 inch.

Each section of fiber glass cloth was cut to the correct length and Masonite strips were glued to the edges to attach the bungees.

Both layers of cloth were test hung to make sure that they fit. Notice the layers of overlapping cloth with two sets of bungees. The cloth in his photo was over 15 feet by 4 feet. It would be impossible to work with pieces of cloth this large without a system to hold it in place. It would also be impossible to keep the cloth from bagging and sagging.

Mission accomplished, two layers of cloth and West epoxy were applied to the hull, wet on wet and a fair hull emerged. Without the bungee hanger system for the cloth, it would have been impossible add the laminate and keep the hull fair. Our goal was to avoid the use of fairing compounds on top of the new epoxy laminate and also avoid uneven thickness in the new laminate that results from fairing.

Note, we faired the hull BEFORE the new laminate was added. This was an important departure from the traditional repair where fairing is done after new laminate is added.

Fairing is typically done AFTER because it is very hard to keep the hull fair when new laminate is added. Stretching the cloth with bungees allowed us to overcome this problem.

Next three coats of Interprotect 2000 were rolled on to create the thickest possible build-up. The Interprotect 2000 was given a light cosmetic fairing and three more coats of 2000 were applied.

Finally a coat of Interprotect 3000 was applied and before it was cured, bottom paint was applied so that we could get a chemical bond between the 3000 and the bottom paint.

To be positive that good adhesion was achieved new laminate samples were soaked in salt water for 9 months. The lay-up samples came from through-hull cut outs.

 

Stan Sroga
stansroga@sailtraininginc.com
sailtraininginc.com

 


 


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