9 Reasons You Can’t Sell Your Boat

Have you ever wondered what is going to come back in the survey when you go to sell your boat? Seemingly you’ve spent thousands on the boat, but was it on the clear covers or the mechanical components?

Over the past few years I’ve completed thousands of hull and engine surveys. With experience, you start to see a trend of common problems found. A lot of these issues are the same, as a fair number of inspected vessels are between 10-20 years old. I’ve written this article with bigger boats in mind – over 30 foot and shaft driven with diesel engines, although some points are relevant to all boats.

1. Presentation

Imagine showing up to a boat filled with the old owners belongings, a thick layer of dirt and then being asked to pay top dollar! As simple as it sounds, getting your boat washed before a potential buyer steps on-board can greatly increase the chances of getting an offer. It gives a much more positive feel that you care for the boat, hence improving the value.

2. Sea Cocks

When left untouched, sea cocks will cause you trouble when you go to sell your boat. These valves are used to stop the flow of water, and are fitted on the inside of a vessel skin fitting. Because of the salt water environment and barnacle growth, they can become stuck. Now this doesn’t present a risk immediately, but if you have a hose blow you may want to turn it off real quick. Operating them every few months is usually enough to keep them serviceable. However if left for years at a time, they can seize and snap off when turned off. Sea cocks can often be hidden out of sight and in difficult areas to access hence why they’re forgotten.

sea cock

3. Shaft Seals

Shaft seals that are original with the age of the boat have a tendency to leak only when under load. So this means unless you’re getting down into your engine room while the boat is underway, you may never know they’re leaking – or better yet, spraying salt water around your engine room. They are often water cooled, depending on the make and model. To be sure these cooling fittings haven’t become brittle or corroded, they must be checked. If one of the shaft cooling fittings snaps and goes unnoticed on a trip, you risk overheating your seal and essentially blowing your bellows and seal to bits – leaving no barrier between the ocean and the inside of your boat. Not great for when you go to sell your boat!

PSS Shaft seal

4. Salt-Water Cooling System Service

Saltwater service, meaning anything related to cooling the engine, is often overlooked and can be an issue on many surveys. Things such as the after coolers, heat exchangers, and oil coolers all need removal and inspection at certain intervals (as advised by the manufacturer). This ranges from 2-5 years, and the majority of owners aren’t aware of this. To avoid disappointment, I suggest that every buyer assumes this will NOT be completed in their offer. Giving up a deal for 10k worth of service work, only to find the next boat needs the same work, is a waste of time. Some owners claim the manufacturers recommendations are excessive, but as a bare minimum you want to know when it was done in your ownership and then you can decide if the risk of not doing it is worth it.

blocked cummins after cooler
A clogged aftercooler core on a Marine Cooling System

5. Bilge Pumps and Float Switches

Electric bilge pumps that are nearing 10-20 years old are starting to wear, and often become intermittent. Maybe there is a dirt build up, or maybe they work one day and not the next. Often they are not secured or connected. Sometimes they appear to be working but the impeller is snapped. For the few hundred it’s worth, it can be a boat-saver paying to have them replaced.

rule bilge and float switch

6. Sea Pumps

Sea pumps are classified as part of the cooling system service. It is very common going to a boat finding it riddled with leaks due to the sea water pump. For the 5 minutes it takes to check, it’s well worth getting down into the engine bay before you decide to sell your boat.

leaking sea pump
A leaking sea pump, observed from the stain beneath

7. Hydraulic Steering Cylinders

After 10 years of hydraulic pressure behind the seals, it’s relatively normal to find air in the steering system. Most people will jump to the conclusion that it just needs to be bled. However in order to stop a continued leak, a new seals or a steering cylinder will need to be fitted.

8. Ice-Maker / Fridge

If you’ve got over 10 years out of your ice maker, you’re doing well. Often the component’s arms get stuck, or stop cooling. They take a few hours to drop a cube, so even if it’s getting cold its easy to believe it works, and then find out leaving it on overnight still hasn’t produced any ice. Make sure to check this before you go to sell your boat.

9. Worn Cutlass Bearing

A cutless bearing supports your propellor below the water line. If, at any stage your engine is out of alignment with the propellor, you will wear through this bearing ever so quickly. The cutlass bearing can be checked when the vessel is out of the water by moving the propellor shaft around by hand and inspecting for play. The propellor shaft and bearing should be a snug fit.

Shaft and rudder

About the Author


Aaron O’Donoghue is a qualified Marine Surveyor & Engineer with nearly two decades of experience in the industry. He is an experienced boater from Sydney who grew up on the waters of Sydney Harbour. He left school at 15 to complete an apprenticeship as a Marine Mechanic. In 2015, he founded BoatBuy, where he has inspected thousands of boats and is passionate about helping others enjoy their time on the water. He has a wealth of knowledge and experience in the field. Do you have a boating related question? Feel free to reach out to me via email here.

Explore More

articles | 5 March 2024

How To Get Your Boat Surveyed

How to Get Your Boat Surveyed Whether you're in the market to buy or sell, a boat survey is likely an important step. It offers peace of mind to the buyer and ensures transparency for the seller. Let's dive into the process of arranging a boat survey, highlighting key steps...

articles | 3 March 2024

How Long Does a Boat Survey Take?

How Long Does a Boat Survey Take? Understanding the time commitment for a boat survey is an important question asked by buyers and sellers before a sale. Having inspected over 1,500 power boats across Sydney, Darwin, Gold Coast, and Melbourne since 2015, my experience offers insights into the duration of...

articles | 30 January 2024

A Professional Perspective on Pre-Purchase Oil Samples

A Professional Perspective on the Effectiveness of Pre-Purchase Oil Samples In my years of experience with marine mechanical diagnostics, I've frequently encountered a topic of debate: the effectiveness of pre-purchase oil samples. Having conducted over 600 oil analyses on boat engines, I've observed a pattern and wish to clarify some...