Saludos, cofrades.
Unas rondas antes de nada
Les adjunto un par de documentos en inglés sobre el tema de la hidrólisis :
http://www.yachtsnet.co.uk/osmosis.htm
http://www.yachtsurvey.com/BuyingBlisterBoat.htm
Muy interesantes ambos en mi opinión. A partir del segundo pueden consultar decenas de páginas sobre tipos de blisters (ampollas), reparaciones, higrómetros (moisture meters) etc.
http://www.yachtsurvey.com/blisters.htm
Un extracto:
Is the Repair of Blistered Bottoms Mandatory? Based on the foregoing discussion, the obvious conclusion in most cases is negative. If the blisters cannot be shown to be causing significant damage, then repair is certainly not mandatory, despite the many horror stories you may hear from people trying to sell you a costly repair job
A pesar de que estos autores no vean necesaria, en muchos casos, la reparación de los cascos que presentan ampollas, todos coinciden en que un casco con ampollas se devalúa bastante (problemas en la reventa, posibles costosas reparaciones si se agrava el problema...)
Este otro señor, entre otras muchas cosas, identifica tipos de ampollas que merecen una rápida reparación:
http://www.mckaymarine.com.au/Surveying%20GRP.php
When unbroken, the Type 3c blister presents the same outward appearance as the previous Types 3a and 3b. On breaking open, however, this type is characterised by the presence of resin free, often fluffy, glass fibre strands. The cavity beneath is usually deeper than that found beneath the blisters of Types 3a and 3b and may contain foul liquids even for a considerable amount of time after the vessel has been slipped. This type of blister requires early rectification and remedial treatment should not be delayed for any significant time. With this type of blister progressive increase in the defect size may be anticipated and the possibility of an area of delamination developing cannot be discounted if the repair is unduly delayed. This type is also frequently associated with wicking. Whilst not of immediate significance to the hull’s integrity when first detected, leaving a blister of this type to develop over a number of months may lead to a localised weak area in the hull.
Respecto al rastrero tema de ocultar las ampollas para evitar un importante regateo del comprador... Se hace sí o sí, con "reparaciones" chapuceras que multiplican los costes a la larga, con dobles capas de antifouling de matriz dura para que dificulte la localización de ampollas etc. etc.
Les va a salir una hidrólisis en el hígado, señores. 
http://www.yachtsurvey.com/BlisterBlues.htm