Checks below the waterline while the boat is ashore

5 November 2021 | | Reading time 2 minutes

In this article, we’ll be taking a practical look at the maintenance of your catamaran, specifically inspections beneath the waterline when your boat is ashore.

When a boat is taken out of the water, take the opportunity to perform a series of checks on the propulsion systems and hull equipment located in the normally-submerged part of the boat.

Rudder, P-bracket and propeller:

  • Rudder: check that there is no play in the rudder stock and check overall condition.
  • P-bracket and stern tube: check the fixing, cleanliness and overall condition.




Stern gear: general

Stern tube: closer detail

Propeller anode: check it is tightly secured.



Anodes and ground plates:

Anodes and ground plates: if there is more than 50% wear, the anode must be changed.  A Lagoon dealer will be able to supply you with the right product for your needs.


Ground plate:

Through-hull fittings:

Check the condition of the boat’s skin fittings (through-hull fittings, ventilation fittings, etc.). These must not be blocked by algae, sand, mud or any other object that prevents air/water from getting out or in.

It is important to remove any algae or other external elements that may block the fitting.


Log impeller:

The condition of the log impeller blades should be checked: ensure there is no algae in the mechanism.

Optional: check the calibration of the sounder and the under-keel clearance offset.



Undertake a hull condition assessment to check the state of the antifouling and thus know if it is still good or if it needs to be redone (with or without a new coat of primer).

It is essential to scrape or pressure wash any non-structural element of the boat below the waterline.

Tap the hull one square meter at a time looking for any breakage, holes, cracks or delamination.

If possible, get a hull survey done.

If you have any questions, do not hesitate to contact your Lagoon dealer or complete this contact form.