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View Poll Results: What Sinks Sailboats (wood excluded)– Survey
Hitting something or being hit - damaging the hull 12 24.00%
Failure in the hull/deck construction 1 2.00%
Leaking thruhulls 25 50.00%
Shaft log or packing failure, Loss of propeller shaft 12 24.00%
Loss of keel 4 8.00%
Bilge pump failure – batteries, wiring, plumbing or pump 20 40.00%
Rigging failure – chainplates, couplers, shrouds, stays, boom or mast 0 0%
Rudder failure 5 10.00%
Fire or Engine explosion 6 12.00%
Multiple Choice Poll. Voters: 50. You may not vote on this poll

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Old 25-02-2005, 11:56   #1
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What Sinks Sailboats (wood excluded)– Survey

I’m doing a little survey just out of curiosity.

I’m excluding wooden boats due to the fact that over time they’ll rot or brake apart in time without continuous maintenance and/or refitting. Plus there is a combination of failures that could lead to the sinking of wooden boats.

Where as, fiberglass and metal boats are basically a single construction with maybe a single hull/deck joint.

Also I’m excluding sailboats in a storm where the vessel was washed up on the shore or hit by another boat/object. I’m looking for failures of the boat construction or it’s properties.

The sinking could be at sea, at the dock or on the hook.

This can be your boat, let’s hope not, or someone else’s that you heard or read about. And, if you would, please post the manufacture of the vessel and some explanation to the sinking.

By learning what the most common causes of a sinking, is the first step to avoidance for all! As well, this maybe a wake up call to something that has been put off too long.

………………………………………………………………………._/)
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Old 25-02-2005, 14:16   #2
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When I bought my present boat the former owner LET the boat sink in the slip because he did not feel like replacing the antisiphon valve on the bilge pump. The pump would cycle and the water would come back in until the pump failed. It was not equipment failure it was stupidity. It was however good for me as a buyer. So I guess I will vote bilge pump failure.
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Old 25-02-2005, 14:51   #3
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Around here it is ice forming in the cockpit drains and blowing the hose apart either in the water or before launch.

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Old 25-02-2005, 19:17   #4
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Sinking

On my neighbours 23 foot boat the cockpit drains were at the forward end and the boat would sink almost every winter in the manner Jeff described.
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Old 26-02-2005, 18:45   #5
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Can't back it up...

I read some report (but can't back it up with a link) stating that most sinkings were right at the dock/mooring. Also, the cause was said to be related to thru hulls.

I'm not sure I would classify bilge pump failure as a reason, since to me anyway, a bilge pump is something that is used to help clean up an existing problem (the boat leaking).

The root cause might be whatever is filling the boat with water in the first place.
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Old 26-02-2005, 22:01   #6
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Bilge pump

Like gunner was saying, if it isn't set up properly the there's going to be a failure.

My boat gets water in thru the keel stepped mast. It's basically a dry boat except when it rains and that's what it does here in the PNW. In a wet month I'll take on 30 gallons of fresh water and if my cockpit drains were to freeze up and break, like Jeff was saying, I'd get a whole lot more.

If a persons boat just sits in the water 365 and they don't go down to check it out once in a while it's bound to sink. Pumps go bad, batteries die, lines break, fuses blow or corrode, and on and on. I just read somewhere that a guy found out his boat had a foot of ice inside while his boat is the hard.

When I use to live aboard in San Diego (Mission Bay) I can't remember how many sinking boats I rescued before the Harbor Patrol could get there. One was right across the finger from me in the middle of the night. I heard all the ruckus and I looked out and my neighbor was out there with a bucket bailing like hell. A wooden power boat! He woke up because his bed got wet.
I grabbed my 1/4 hp submersible pump and dropped in his bilge and pumped away. Between that and the buckets, we kept it from going down any farther, but the water was still comming in.

It took about a half an hour before the Harbor Patrol got there with their big pumps.
The guys bilge pump failed and the boat got up to a level where there was no caulking in the planks and it started coming in, and the deeper it got the faster it was coming in. A catch 22. Fortunately he was able to wash everything down with fresh water right away to keep the metal stuff from rusting up.

This guy should have had at least two pumps and then checked them both on a regular schedule.
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Old 04-03-2005, 13:41   #7
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so i gather from the poll that the number one cause of boats sinking is to much water on the wrong side of the hull right?
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Old 04-03-2005, 19:19   #8
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Not unless you fill the boat with rocks.

So far, failing bilge pump systems are the largest factor. Just as I expected, the lack maintenance.
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Old 05-03-2005, 20:35   #9
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Open hatch

I have a rather unique way of sinking a boat! For some reason, the manufatures of Privilege catamarans used a Lewmar Ocean type hatch for there emergency escape/entry hatch. All French catamarans have been required to have a means of entering and leaving an overturned catamaran. Great idea, BAD execution. As many may know, Lewmar on there Ocean and other hatches have two positions. One is fully closed and battened, the other position is partially closed and allows for ventilation. Well on my boat, the prior owner left this Ocean type emergency hatch in the ventilation positon. Easy to do, hard to see it is not fully battened. Now, mind you, this hatch sits all of 4 inches, okay, maybe 5 inches off the water line. If you combine that with a hurricane (Jeane) that was generating 4 foot surges and wave in the Intercoastal Water ways of Hollywood florida and the fact that all the bilge pumps were manually activated, you get, you guessed it! Sunk hull.

How's that for working unique way of sinking your boat. Of course, it didn't sink. Just filled up one hull and sat there for 3 days. Now try that in a monohull!


Keith
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Old 22-03-2005, 03:34   #10
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Two boat sunk at the dock at our marinia in the past 4 years. A Catilina owner left his thru hull valve open that supplies his head. Something let loose in the toilet and sunk his boat. The bildge pump ran long enough to complete drain his batteries.

The Ericson, two boat down from the Catalina, partially sunk causing some significant engine problems and a mess inside at the cabin also. If I recall correctly, a leaky shaft log was the root cause of this sinking.
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Old 22-03-2005, 09:57   #11
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A failed bilge pump is a symptom, not a cause of sinkings.

Most sinkings happen at the dock and are caused by failed thru-hulls or rain/snow.

A surveyor once told me that with few exceptions, bilge pumps are only designed for nuisance leaks.
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Old 25-03-2005, 10:00   #12
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Bryan beat me to the punch about toilet seacocks. Actually, nothing needs to go wrong in the system. Depending on where the waterline is and how the toilet is plumbed, leaving the seacock in the open position after use can very...very...slowly siphon seawater to fill the bowl over a day or so, just sitting at the dock. My old Cape Dory 30 had that problem; I came down to the boat one weekend to find the bilge full to just beneath the sole, and the batteries drained from running the bilge pump continuously for five days. Thank goodness I didn't let it go any longer than that! Thereafter, my mantra to anyone who used the head was, "Did you turn the lever?" She'd fill alarmingly fast if left open while sailing on a starboard tack.

A shipwright friend of mine also reported that he's had three boats which sank from a lightning strike; all three had bronze thruhulls blow out like champagne corks. I know this is in the Act of God category and thus not really on topic, but perhaps a different grounding system might have prevented that from happening.
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Old 25-03-2005, 21:27   #13
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Geoff S.

It blew out bronze the seacocks????

Was the boat steel or aluminum?

The cocks being grounded, I believe, wouldn't have caused this. Most ground wires are usually not more than a 8 gage that I've seen. I would imagine that the wire would fry before the seacock got hot enough to blow out.

Just courious........................_/)
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Old 26-03-2005, 05:24   #14
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Lightning & Thru-Hulls

Lightning protection for boats is a very complex problem - and I’m pretty much “burned out” on the subject
Some years ago I was writing a series of articles for “Good Old Boat” magazine - and “lost” about 15,000 words (and all my research) on the subject. I’ve never had the resolve to revisit the endeavour.

FWIW: There are two principal mechanisms describing how a lightning strike can “blow out” a through-hull fitting.

Resistance Heating:
The through-hull (and/or it’s bonding conductor) may present too small an electrical contact area to the water, resulting in a relatively high resistance connection, with the resultant current rise, and heat. A hi-resistance, or low-mass ground provides inadequate conductivity (or too little mass to dissipate the generated heat), and a powerful strike is almost certain to generate enough heat to melt the fitting right out of the hull.

Explosive Boiling:
Alternatively, the water trapped within a through-hull (or the ‘pores’ in a scintered ground plate) may be explosively boiled (due to the high discharge current). This super-rapid expansion (of water to steam) can actually disintegrate the fitting.

See the ‘IEEE Paper’ & ‘Sea Grant Pamphlet SGEB17’ at:
http://www.thomson.ece.ufl.edu/lightning/IEEE.pdf
http://www.thomson.ece.ufl.edu/lightning/SGEB17.html

“The Applicability of Lightning Elimination Devices to Substations and Power Lines”
by Abdul M. Mousa, BC Hydro, IEEE Transactions on Power Delivery, Oct 1998.
Read this one if you believe lightning eliminators (static dissipaters) really work.
http://www.strikeshield.com/Lightnin...issipators.pdf

See ABYC Section “E-4" Lightning Protection:
4.9.2: Seacocks and Through-Hull fittings, if connected to the lightning ground system, shall not be connected to the main down conductor.
They shall be connected to (*#6 AWG or 21.2 mm2 Cu.):
~ The underwater grounding strip, or
~ The lightning ground plate, or
~ The internal equalization bus

* ABYC recommends a minimum of a #4 AWG copper wire for the primary lightning protection system conductor (down conductor), and a minimum of a #6 AWG copper wire for the secondary conductors (bonding conductors).

"Bigger is Better"

Regards,
Gord May
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Old 26-03-2005, 19:23   #15
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Thanks Gord!

I didn't think about the water boiling factor. Good reading!
Apparently, most or all the boats I've been on wasn't set up lighting protected. I should have put lighting strikes in the survey
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