Case Study
Sealine 34 – Pre-Purchase Survey That Prevented a Costly Mistake
Client Challenge:
A prospective buyer engaged Midlands Boat Surveys to carry out a Pre-Purchase Survey on a 23-year-old Sealine 34 motor cruiser. At first glance, the vessel appeared well maintained—both topside and below decks. The Volvo engines performed well during an extensive river trial.
However, during the lift-out inspection, serious concerns were identified. Approximately 25–30% of the hull's underwater surface showed gelcoat blisters caused by osmosis. The blisters were up to 3mm deep, with the starboard side being significantly more affected than the port side. Testing revealed a Strength 3 acidic pH and a distinct vinegar odor, both indicative of severe osmosis degradation.
Recommended Action:
We advised the client to seek a specialist GRP (Glass Reinforced Plastic) repair assessment. The resulting quote for remedial work came to a significant five-figure sum.
Outcome:
After reviewing the risks and costs, the client chose not to proceed with the purchase, avoiding what would have been a major financial and operational liability.
Survey Value:
This is a textbook case of how a professional marine surveyor can protect clients from hidden costs and unforeseen issues.
Stern Drive Gearbox – Emulsification Case
A routine survey on a sports cruiser with petrol engines uncovered emulsification in the stern drive gearbox oil—a critical indicator of water ingress and potential mechanical failure. This finding led the client to withdraw interest immediately, once again saving considerable time, expense, and potential future repairs.
Two-Pack Epoxy vs. Traditional Blacking – Narrowboat Paint Process Insight
Traditional Blacking:
Most narrowboat owners opt for bitumen-based blacking due to affordability and ease of application. However, it is prone to peeling and degradation within 12–18 months, especially when exposed to locks, drydocking, or mooring abrasions.
Two-Pack Epoxy Paint:
Our preference is to use two-pack epoxy paint systems (brands like Epifanes, International, Hempel, Jotun). They offer:
-
Greater resistance to fuel, UV rays, and environmental pollutants
-
Harder, more durable finish than single-pack paints
-
Protection against micro-blistering due to chemical curing, not air drying
Two-pack paints involve a chemical reaction between acrylic/melamine resin and a hardener (poly-isocyanate resin), forming a robust barrier.
Important Note: Avoid shortcuts like applying two-pack over existing blacking (e.g. as marketed by some brands). Several narrowboat owners have reported disappointing results with this method.
Why These Case Studies Matter
Each case highlights how independent marine surveying ensures informed decision-making, whether buying, maintaining, or restoring a vessel. Our findings don’t just help avoid expensive pitfalls—they give peace of mind and help clients move forward with confidence.
Got questions or considering a vessel? Let’s discuss how a tailored survey can support your plans.