Bounty 27 – Osmosis & Gel Coat Delamination
The Bounty 27 c1970 was lifted ashore for the purpose of a pre purchase survey. As with most GRP vessels of this vintage the hull and superstructure had been painted white while the bottom was badly fouled with organic growth (having not been pressure washed). In other words nothing out of the ‘ordinary’ for a surveyor to inspect.
Similar Bounty 27 boats………….
However, serious GRP hull ‘problem’ areas started to become apparent
When inspecting the bottom, some osmotic blisters were visible intermittently on port side but the interesting bit was found on the starboard bow. Where the osmotic blisters were much more concentrated and over time have merged to form a much larger blister.
Gel coat delaminating Gel coat removed from sample area
This resulted in lifting and detaching the gel-coat from the substrate.
The gel-coat being under pressure has cracked, allowing water to get into the substrate. This process is known as wicking.
Wicking happens when the substrate is unprotected either by gel-coat or adequate paint. The strands in the fiberglass mat act as a straw and suck moisture into the substrate and consequently weaken the structure. Those single strand becoming saturated with water will turn white and be visible and easy to spot in the substrate.
Moisture (whicking) taken up in substrate Blister burst by applied thump pressure only
In the above left hand photo we see the white strand of the mat indicating wicking is taking place as well as gel-coat crack and delamination.
In the above right hand photo the area of visible gel-coat delamination equals to approximately 1 square foot. However when carrying out a ‘tap test’, the area of trouble was much greater and extensive. Note the wet patch which is a burst osmotic blister with ‘blister juice’ – this was burst using thumb only
Above left hand photo shows numerous osmotic blisters which will most probably merge in the future into a single large blister with probable delamination. The right hand photo shows ‘other’ damaged areas.
The gel coat delamination is from a buyer’s point of view a major concern as it can be expensive to put right and has to be addressed. However the boat can be repaired and probably will be structurally stronger following the repairs.
But the question is always the same, at what financial cost ? In my opinion this should be repaired since the rest of the boat is in much better structural condition, and there is still a lot of life and future enjoyment left in this boat
For more information contact European Marine Services Ltd – Marine Surveyors & Consultants Tel : 01603 327 123 www.europeanmarinesurveys.com