Boats Sinking at the Dock is 4x More Than Underway
Date Posted: February 15, 2023
Source: Vincent Pica Commodore, 1st District, Southern Region (D1SR) USC

If I told you that statistics on boats sinking showed that the dock is four times more dangerous than the open waters, you might tell me to check my calculator, amongst other things. But study after study show that four times as many boats sink at the dock than underway! Why is that?

Real-Time Reactions Well, candidly, there are lies, damn lies and statistics.  If you are underway and you see water coming up from below, you are going to do something about it right away. Thus, the underway problems are going to be dealt with in real time and the odds are way in your favor that you can save the vessel, even if you have to drive her on to the beach to do so. But why do so many boats sink at their docks? Why didn't the bilge pump save her, to start with? Many people believe "big boat, big bilge pump. Little boat, little bilge pump." Wrong! Big boat, LOTS of bilge pumps. Little boat, BIG bilge pump. You need to get the water OUT of your 17' Seahunt as fast as possible.  500 gallons per minute isn't half as good as 1,000 GPM. It is less than half as good because, once she goes down, no bilge pump can re-float her.  And experts estimate that it costs 40% of the original value of the boat to re-wire her and restore the engine. Oh, and throw out the radio, GPS and fish finder. So, your $20,000 17' Seahunt will cost you as much as $8,000 to repair/restore versus the $200 1,000 GPM bilge pump. Is she worth that much today?

Buying Time And remember, bilge pumps don't save boats. They buy you time. Time from what? Well, again, the statistics say that boats sink at the dock for 2 major reasons. Half the time, a thru-hull fitting gives up the ghost and water eventually overwhelms the battery/bilge pump arrangement. So, check the thru-hulls with every lay-up. And check the screws around them. If the screws "rot*" away, it is another source of water to enter that isn't so obvious. But it will add up.

The second most common source of sinking at the dock is snow and rain (30%). I had one happen to one of my boats because the self-bailing scuppers clogged from leaves. Rain followed – and followed – and followed – until I had a submarine. Also, many skippers believe that biminis and canvas covers prevent water from entering the boat. Wrong again. They slow it but don't stop it. In the winter, stow them someplace dry and shrink-wrap the boat. So, over 80% of the boats sink for two reasons – all of which adds up to checking the boat from time to time. Or paying the dock hand to – or your teenager that wants some extra spending money to go with his or her new driver's license – but check it. Would you leave a box with $20,000 unattended on your lawn for months at a time?

So, if 4 out of 5 boats sink at the dock, what about that other boat? Well, that is a story for another time – and soon.

As a side note, marine screws don't rot. They get eaten away by electrical charges in the water. This is due to poor "galvanic isolation". More on that in the weeks ahead!

If you have questions on this column or you are interested in being part of USCG Forces, email me at [email protected] or go directly to the US Coast Guard Auxiliary "Flotilla Finder" at and we will help you "get in this thing."

Comment Submitted by Vincent Pica - March 15, 2023

Gaz, stainless steel is only stainless in the presence of oxygen. No O2, rust, and stains, ensue.

Comment Submitted by Gaz - February 27, 2023

There is no substitute for proper and preventative maintenance. The big issue I have is with so called stainless steel clamps rusting away. Even the West Marine very expensive 316 stainless steel ones don't last long so I check them every year. Basically when the boat is on the hard I step on the hose at the fitting. If anything breaks I'm happy it happened then and not underway. Not everyone has this option but when I had my boat built I had most thru hull fittings placed above the waterline. The only ones below the water lines are for the engine pickups (2 -1.5" valves) and for the Groco grinder ( 1-2.0" valve) which provides raw water for everything else on the boat. All other holes in the boat are above the water line except, and this is what keeps me up at night as there are no valves for these holes, the dripless stuffing boxes (2 -1.5" holes). Otherwise I saw no need to have holes through the bottom of my boat. I also made sure all the valves on the through hull fittings were easy to access. If I had a chance to do it again I would also include valves for all the other thru hull holes above the water line and also consolidate them. Why can't there be only a few? Of course this does not guarantee anything. I have sheared off the heads on these above water line fittings on several occasions and found out by having water enter the boat while underway. At lease I had them installed in semi easy to reach areas. Next time I will insist all fittings are countersunk to be flush with the hull.

Comment Submitted by Vincent Pica - February 22, 2023

Julie & Alicia, your both 100% right. Thxs for weighing in! Vin

Comment Submitted by Julie Goodnight - February 22, 2023

This is a great reminder to regularly check and clean bilge pumps! Christmas day, a 36' cruiser sunk on the lines, at the dock across from me, in our marina in Colorado. Subzero temps and improperly winterized by the owner, frozen/cracked strainer caused leak. Ice storm then caused power outage, so who knows if the pump was bad or the battery went dead or if it would have been overwhelmed anyway. They also had not properly secured a low portal, so once the water reached that level, the boat was completely swamped, hanging from the lines. Almost dark when it was discovered (no one was around all day), they refloated the boat and hauled it out the next day. Sadly, I think it's a total loss after 24 hours in the drink (also was inadequately insured).

Comment Submitted by Alicia K - February 22, 2023

I'm a Marina Manager in Marina del Rey. The thru-hulls or drive shaft seals are the main 2 culprits for sinking at the slip. Even worse, usually the boat has let their insurance lapse, so they are paying for everything out of pocket! This is a good reminder to double check your vessel policy, and ensure you are prepared for the worst case scenario.

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